Diurnal Temperature Range

Continuous measurements of near-surface weather variables using an automatic weather station and intermittent measurements of surface energy, momentum and carbon dioxide fluxes using Bowen ratio, eddy covariance, and sigma-T systems were collected for 13 months at a semi-arid Sonoran Desert site near Tucson, Arizona. Comparisons between measured fluxes made simultaneously with different instrumental systems show acceptable agreement. To investigate the influence of Crassulacean Acid Metabolism plants on carbon dioxide flux, measurements were sustained through the night. Observations were analyzed to characterize the typical magnitude of diurnal and seasonal variations in surface energy and carbon dioxide exchanges fbr this vegetation type and were then used to validate and calibrate the surthce energy balance simulated by the Biosphere-Atmosphere Transfer Scheme. Using the standard "semi-desert" soil and vegetation parameters specified in the National Center for Atmospheric Research Community Climate Model version 2 gave a poor description of surface energy exchange. However, a combination of site-specific soil and vegetation parameters, and a simple optimization to modiI the value of minimum surfüce resistance and plant wilting parameters, substantially impmved the model performance. The site-specific parameters reflect the lhct that the vegetation fraction is greater than assumed in the standard parameter set, leaf area index and minimum stomatal resistance are less, soils at the study site contain more clay, but the plants' wilting point is lower than this clay fraction would imply. These modified parameters more accurately describe the conservative character of the semidesert vegetation and the moderate nature of its response to the seasonal water cycle. Semi-arid environments cover 40% of the Earth's land surface, and therefore are a significant component of the Earth's climate system . Semi-arid regions are climatologically sensitive -slight shifts in global climate may have a significant impact on local surface conditions, leading to major changes in the local climate. It is therefore essential to develop an understanding of the complex interactions between unique plant physiology, extreme seasonality in precipitation and solar forcing, and large diurnal temperature ranges which characterize these semi-arid environments and determine their role in the Earth's climate system. Surprisingly little is known about the spacial and temporal variation in energy and water fluxes and how they are affected by vegetation and soil properties in semi-arid regions. Though several field studies have been conducted to address these issues, these have mainly been focused on investigating spatial, rather than temporal variability, and were generally of short duration (see Section 1.2.1 below). The primary objective of this research was to investigate the temporal variability of energy, water and carbon dioxide exchanges in a pristine semi-arid environment, by measuring and modeling surface fluxes over a period of one year in order to better characterize the climate-related signals in the surface fluxes. To compare direct and indirect measurement methods, fluxes were measured simultaneously using eddy covariance, Bowen ratio and sigma-T instrumentation. A secondary objective was to investigate whether there

The effect of towns on plant phenology, i.e. advancement of spring development compared with a rural environment, via the urban heat island (UHI) phenomenon, has been shown for many towns in many countries. This work combines experimental and observational methodology to provide a better and deeper view of climatic habitat in an urban context with a view to understanding the relationship between plant development and urban climate on the intra-urban scale (by taking into account town structure). A dense network of 17 meteorological stations was set up in Rennes, France, enabling us to identify and quantify climatic changes associated with the UHI. Meanwhile, phenological observations were made during early spring (March and April) in 2005 on Platanus acerifolia and Prunus cerasus to study the relationship between climatic and phenological data. The results show that there is both a climatic gradient and a developmental gradient corresponding to the type of urbanisation in the town of Rennes. The town influences plant phenology by reducing the diurnal temperature range and by increasing the minimum temperature as one approaches the town centre. The influence of ground cover type (plants or buildings) on development is also shown. The developmental phases of preflowering and flowering are influenced to differing extents by climatic variables. The period during which climatic variables are effective before a given developmental phase varies considerably. The preflowering phases are best correlated with the mean of the minimum air temperature for the 15-day period before the observation, whereas flowering appears to be more dependent on the mean of the daily diurnal temperature range for the 8 days preceding the observation.

Although the seasonal variation and the effect of cold temperature on heart failure (HF) morbidity have been well documented, it is unknown whether the temperature variation within a day, that is, diurnal temperature range (DTR), is an independent risk factor for HF. We hypothesized that large DTR might be a source of additional environmental stress and, therefore, a risk factor for HF exacerbation. We aimed to test the association between DTR and HF hospitalization and to examine the effect modifiers, such as age, sex, and season. We collected daily meteorologic data and emergency HF hospital admissions from 2000 to 2007 in Hong Kong. We used Poisson regression models to fit the relationship between daily DTR and emergency HF hospitalizations, after adjusting for the time trend, seasonality, mean temperature, humidity, and levels of outdoor air pollution. We confirmed the seasonal variation of HF with peak hospital admissions in winter in Hong Kong. The adverse effects of DTR on em...

Existem muitas evidências de que as cidades influenciam o climalocal, particularmente no que diz respeito à temperatura, ocasionando uma “ilha decalor urbano”, com impactes negativos no conforto bioclimático e na saúde humana.Durante o século transacto, sobretudo a partir de 1980, ocorreu um aumento da temperatura dos meses de Verão (Junho, Julho, Agosto e Setembro, JJAS), particularmente no que diz respeito à temperatura mínima média. Verificou-se igualmente umaumento de noites “quentes” (de temperatura mínima superior a 20ºC), em especialem Junho e Setembro e uma diminuição significativa da amplitude térmica diurna,nomeadamente nos últimos anos do século XX. Estes factos poderão ser devidos nãosó ao efeito urbano, mas também ao aquecimento global.

Geographic location data for 383 accessions of five Passiflora species from five Andean countries (P. cumbalensis, P. mixta, P. tripartita var. mollissima, P. natistipula, and P. manicata) were linked to interpolated continental surfaces of monthly mean rainfall, monthly mean temperature, and monthly mean diurnal temperature range. This permitted us to identify the potential distribution of each species and document its

Since the middle of the last century, global surface air temperature exhibits an increasing trend, with nocturnal temperatures increasing at a much higher rate. Proposed causative mechanisms include the radiative impact of atmospheric aerosols on the nocturnal boundary layer (NBL) where the temperature response is amplified due to shallow depth and its sensitivity to potential destabilization. A 1-D version of the Regional Atmospheric Modeling System is used to examine the sensitivity of the nocturnal boundary layer temperature to the surface longwave radiative forcing (SLWRF) from urban aerosol loading and doubled atmospheric carbon dioxide concentrations. The analysis is conducted for typical midlatitude nocturnal boundary layer case days from the CASES-99 field experiment and is further extended to urban sites in Pune and New Delhi, India. For the cases studied, locally, the nocturnal SLWRF from urban atmospheric aerosols (2.7-47 W m -2 ) is comparable or exceeds that caused by doubled atmospheric carbon dioxide (3 W m -2 ), with the surface temperature response ranging from a compensation for daytime cooling to an increase in the nocturnal minimum temperature. The sensitivity of the NBL to radiative forcing is approximately 4 times higher compared to the daytime boundary layer. Nighttime warming or cooling may occur depending on the nature of diurnal variations in aerosol optical depth. Soil moisture also modulates the magnitude of SLWRF, decreasing from 3 to 1 W m -2 when soil saturation increases from 37% to 70%. These results show the importance of aerosols on the radiative balance of the climate system.

Observations at the Mauna Loa Observatory, Hawaii, established the systematic increase of anthropogenic CO 2 in the atmosphere. For the same reasons that this site provides excellent globally averaged CO 2 data, it may provide temperature data with global significance. Here, we examine hourly temperature records, averaged annually for 1977-2006, to determine linear trends as a function of time of day. For night-time data (22:00 to 06:00 LST (local standard time)) there is a near-uniform warming of 0.040 • C yr -1 . During the day, the linear trend shows a slight cooling of -0.014 • C yr -1 at 12:00 LST (noon). Overall, at Mauna Loa Observatory, there is a mean warming trend of 0.021 • C yr -1 . The dominance of night-time warming results in a relatively large annual decrease in the diurnal temperature range (DTR) of -0.050 • C yr -1 over the period 1977-2006. These trends are consistent with the observed increases in the concentrations of CO 2 and its role as a greenhouse gas (demonstrated here by first-order radiative forcing calculations), and indicate the possible relevance of the Mauna Loa temperature measurements to global warming.

Human activities have been suggested to result in weekly changes of meteorological variables, called the “weekend effect.” Recent debates on its statistical significance, however, reveal that there still remain huge uncertainties as to the anthropogenic origin of the weekend effect. We show that atmospheric Rossby waves induce the “natural” weekend effect, which is much stronger than the “anthropogenic” weekend effect. The “natural” weekend effect does not completely disappear even with averaging over 61 years of data; as a result, true “anthropogenic” weekend effect is obscured by the natural component. We attempted to remove the “natural” component in the diurnal temperature range and the resulting pattern is an overall positive weekend effect over North America.

Spatial and temporal characteristics of extreme temperature events in northeastern Spain have been investigated. The analysis is based on long-term, high-quality, and homogenous daily maximum and minimum temperature of 128 observatories spanning the period from 1960 to 2006. A total of 21 indices were used to assess changes in both the cold and hot tails of the daily temperature distributions. The presence of trends in temperature extremes was assessed by means of the Mann-Kendall test. However, the autocorrelation function (ACF) and a bootstrap methodology were used to account for the influence of serial correlation and cross-correlation on the trend assessment. In general, the observed changes are more prevalent in hot extremes than in cold extremes. This finding can largely be linked to the increase found in the mean maximum temperature during the last few decades. The results indicate a significant increase in the frequency and intensity of most of the hot temperature extremes. An increase in warm nights (TN90p: 3.3 days decade -1 ), warm days (TX90p: 2.7 days decade -1 ), tropical nights (TR20: 0.6 days decade -1 ) and the annual high maximum temperature (TXx: 0.27 • C decade -1 ) was detected in the 47-yr period. In contrast, most of the indices related to cold temperature extremes (e.g. cold days (TX10p), cold nights (TN10p), very cold days (TN1p), and frost days (FD0)) demonstrated a decreasing but statistically insignificant trend. Although there is no evidence of a longterm trend in cold extremes, significant interdecadal variations were noted. Almost no significant trends in temperature variability indices (e.g. diurnal temperature range (DTR) and growing season length (GSL)) are detected. Spatially, the coastal areas along the Mediterranean Sea and the Cantabrian

Sunshine Duration (SD) has an important role in climate change or the weather on the earth. Climate change can be indicated by changing SD values (dimming/brightening) in recent decades. SD and diurnal temperature range (DTR) analysis needs to be done to find out how significant the impact of climate change. The daily dataset from 1981-2019 of SD, DTR, Tmean, Tmax, Tmin, and rainfall in Pontianak, West Kalimantan, is analyzed with Continuous Wavelet Transform (CWT) and wavelet coherence (WTC). Results of CWT using the Morlet wavelet SD have a dominant period of 8-16 months. DTR has a dominant period of 8-16 months and 32-64 months. The increase in SD indicates that Pontianak is in a brightening period caused by changes in the characteristics of clouds and aerosols. It causes an increase in the amount of solar energy reaching the earth's surface. Climate change has been detected by the decrease in DTR. A negative correlation was found between DTR and SD (r = -0.80). DTR is a very good indicator of climate change because of its sensitivity to radiative energy balance. Changes in SD have a significant impact on Tmean, Tmax, and Tmin. The increase of Tmin, faster than Tmax, causes a decrease in DTR. Tmin is predicted to be higher. Tmean and Tmax have dominant periods of 8-16 months, while Tmin has dominant periods of 12-20 months and 32-64 months. The increase in temperature detected during this period is associated with peatland forest fires in Kalimantan. This condition occurs due to the effect of the brightening period and increasing concentrations of greenhouse gases in the atmosphere. Rainfall is detected in the period of 4-8 months and 8-16 months. The drought associated with the El Nino event resulted in a large amount of rainfall deviation from normal.

The study reveals significant rise in air temperature in the northwest Himalayan (NWH) region by about 1.6°C in the last century, with winters warming at a faster rate. The diurnal temperature range (DTR) has also shown a significantly increasing trend. This appears to be due to rise in both the maximum as well as minimum temperatures, with the maximum increasing much more rapidly. The results are in contrast to the findings in the Alps and Rockies where the minimum temperatures have increased at an elevated rate. Conforming to the global trends, the study confirms episodes of strong warming and cooling in the NWH in the last century. Real warming appears to have started from late-1960s and highest rate of increase was experienced in the last two decades. The study also shows teleconnections between temperatures and an epochal behaviour of the precipitation till late-1960s. These teleconnections seem to have weakened gradually since then and rapidly in the post-1991 period, indicating the waning effect of the natural forcings in this period. 1 Introduction Prevalence of varied climatic conditions that are similar to those of widely separated latitudinal belt, within a limited area, make the high mountain areas such as the Himalaya, the Alps, the Andes, the Rockies etc. the ideal sites for the study of climate change. The wide range of altitudes obtainable in these regions amplifies the variations in precipitation and temperature (Liu and Chen 2000; Thompson et al. 2000). Such regions have played a vital

The Climate System Model, a coupled global climate model without ''flux adjustments'' recently developed at the National Center for Atmospheric Research, was used to simulate the twentieth-century climate using historical greenhouse gas and sulfate aerosol forcing. This simulation was extended through the twenty-first century under two newly developed scenarios, a business-as-usual case (ACACIA-BAU, CO 2 ഠ 710 ppmv in 2100) and a CO 2 stabilization case (STA550, CO 2 ഠ 540 ppmv in 2100). Here we compare the simulated and observed twentieth-century climate, and then describe the simulated climates for the twenty-first century. The model simulates the spatial and temporal variations of the twentieth-century climate reasonably well. These include the rapid rise in global and zonal mean surface temperatures since the late 1970s, the precipitation increases over northern mid-and high-latitude land areas, ENSO-induced precipitation anomalies, and Polemidlatitude oscillations (such as the North Atlantic oscillation) in sea level pressure fields. The model has a cold bias (2Њ-6ЊC) in surface air temperature over land, overestimates of cloudiness (by 10%-30%) over land, and underestimates of marine stratus clouds to the west of North and South America and Africa. The projected global surface warming from the 1990s to the 2090s is ϳ1.9ЊC under the BAU scenario and ϳ1.5ЊC under the STA550 scenario. In both cases, the midstratosphere cools due to the increase in CO 2 , whereas the lower stratosphere warms in response to recovery of the ozone layer. As in other coupled models, the surface warming is largest at winter high latitudes (Ն5.0ЊC from the 1990s to the 2090s) and smallest (ϳ1.0ЊC) over the southern oceans, and is larger over land areas than ocean areas. Globally averaged precipitation increases by ϳ3.5% (3.0%) from the 1990s to the 2090s in the BAU (STA550) case. In the BAU case, large precipitation increases (up to 50%) occur over northern mid-and high latitudes and over India and the Arabian Peninsula. Marked differences occur between the BAU and STA550 regional precipitation changes resulting from interdecadal variability. Surface evaporation increases at all latitudes except for 60Њ-90ЊS. Water vapor from increased tropical evaporation is transported into mid-and high latitudes and returned to the surface through increased precipitation there. Changes in soil moisture content are small (within Ϯ3%). Total cloud cover changes little, although there is an upward shift of midlevel clouds. Surface diurnal temperature range decreases by about 0.2Њ-0.5ЊC over most land areas. The 2-8-day synoptic storm activity decreases (by up to 10%) at low latitudes and over midlatitude oceans, but increases over Eurasia and Canada. The cores of subtropical jets move slightly upand equatorward. Associated with reduced latitudinal temperature gradients over mid-and high latitudes, the wintertime Ferrel cell weakens (by 10%-15%). The Hadley circulation also weakens (by ϳ10%), partly due to the upward shift of cloudiness that produces enhanced warming in the upper troposphere.

Low, mid and high daily climate scenarios (2000-2070), as per the International Panel on Climate Change (IPCC) were generated using the Australian Commonwealth Scientific and Industrial Research Organisation's (CSIRO's) global atmosphere models. These scenarios based on IPCC's 21st century emission scenarios that combine a variety of assumptions about demographic, economic and technological driving forces likely to influence such emissions in the future, were used as input to a crop model to predict the impact of climate change on wheat yield at a location in southeastern Australia. At this locality there are important likely changes in the primary climatic variables of temperature, rainfall and solar radiation. Generally, we found a strong and consistent positive trend in mean diurnal temperature range, followed by a significant negative trend in wheat yield under three climate scenarios with and without elevated CO 2 concentration. It is possible that negative trends identified over the future decades may be artefacts of the method of substituting historical variance for future variance. We observed that from present climate to projected low, mid and high global warming scenarios, median wheat yield may decrease by about 29%. Under these scenarios, but with an elevated atmospheric CO 2 climate, median wheat yield may decrease by about 25%. The effect of elevated CO 2 reduces the severity of the warmer air temperatures and lower rainfall but the effect is small (4%). Advances in agronomy and breeding must boost crop yields by around 25% over the coming decades, to keep in step with predicted climate change.

International markets are increasingly signaling demand for quality-differentiated coffee, which the Colombian Coffee Growers Federation (FNC) proposed to exploit to identify those regional coffees that would fulfill the requirements to be classified as denomination of origin. The objective of this study was to develop and implement a sound, robust and repeatable approach with and for the FNC to identify regional causal relationships between coffee quality and environmental characteristics as bases for labels of denomination of origin. Environmental differences between coffee-growing areas in the departments of Cauca and Nariño were statistically significant for several characteristics, including the number of dry months, annual precipitation and diurnal temperature range. The dominant varieties (Caturra and Colombia) did not show major differences in quality attributes, and were pooled for the analyses with the environmental data. There are significant differences in biochemical and sensorial product characteristics between the two departments. The spatial patterns in product characteristics exhibit a non-random, regionally-changing structure that is related to those in the environmental data. The generated results provided ample evidence to support the application for regionally-based denominations of origin. Recommendations were derived to help mainstreaming the developed approach and thereby facilitate policy decisions for its use in other geographies and with other crops. Furthermore, the importance of systematic interdisciplinary institutional collaboration for large-scale denomination of origin projects was corroborated for food policy dialogue and decision making. It seems plausible that producers of high-quality products within other commodities are likely to follow the FNC in seeking denomination of origin for their goods. The presented approach is crucial to facilitate policy.

Existem muitas evidências de que as cidades influenciam o climalocal, particularmente no que diz respeito à temperatura, ocasionando uma “ilha decalor urbano”, com impactes negativos no conforto bioclimático e na saúde humana.Durante o século transacto, sobretudo a partir de 1980, ocorreu um aumento da temperatura dos meses de Verão (Junho, Julho, Agosto e Setembro, JJAS), particularmente no que diz respeito à temperatura mínima média. Verificou-se igualmente umaumento de noites “quentes” (de temperatura mínima superior a 20ºC), em especialem Junho e Setembro e uma diminuição significativa da amplitude térmica diurna,nomeadamente nos últimos anos do século XX. Estes factos poderão ser devidos nãosó ao efeito urbano, mas também ao aquecimento global.

Pakistan is located in one of the fast temperature rising zones and hence, highly vulnerable to climate change. The dynamic variations of the maximum (Tmax) and minimum (Tmin) temperatures pose potential risks to the local people. Thus, the present study assessed spatiotemporal changes in Tmax and Tmin over China-Pakistan Economic Corridor (CPEC) during 1980-2016 based on the 48 meteorological stations across the CPEC. The non-parametric Mann-Kendall (MK), Sen's Slope (SS) estimator, Sequential Mann-Kendall (SQMK), and least square method tests were used to assess the long-term trends in Tmax and Tmin time series during 1980-2016. The results indicate that the trend of Tmax has significantly increased at the rates of 0.22, 0.37, 0.20, 0.23, and 0.31 o C per decade in winter, spring, summer, autumn, and annual time scales, respectively. Similarly, the Tmin exhibited a significant positive trend in winter, spring, summer, autumn, and annual time series with the rates of 0.33, 0.39, 0.25, 0.27, and 0.36 o C per decade, respectively. The spatial distributions of Tmax and Tmin represent a warming trend over the whole country; however, the seasonal and annual Tmax (Tmin) exhibited sharp increasing trends in the northern and southwestern mountainous (southern, southwestern and southeastern) regions of the country. According to the mutation test, most of the abrupt changes in seasonal and annual Tmax and Tmin trends have been detected during 1995-2010. The present study recommends that forthcoming studies should focus on the factors responsible for the spatial and temporal variability of Tmax and Tmin in the target region.

Observations at the Mauna Loa Observatory, Hawaii, established the systematic increase of anthropogenic CO 2 in the atmosphere. For the same reasons that this site provides excellent globally averaged CO 2 data, it may provide temperature data with global significance. Here, we examine hourly temperature records, averaged annually for 1977-2006, to determine linear trends as a function of time of day. For night-time data (22:00 to 06:00, LST (local standard time)) there is a near-uniform warming of 0.040 • C y −1. During the day, the linear trend shows a slight cooling of −0.013 • C y −1 at 12:00 (noon, LST). Overall, at Mauna Loa Observatory, there is a mean warming trend of 0.021 • C y −1. The dominance of night-time warming results in a relatively large annual decrease in the diurnal temperature range (DTR) of −0.050 • C y −1. These trends are consistent with the observed increases in the concentrations of CO 2 and its role as a greenhouse gas, and indicate the possible relevance of the Mauna Loa temperature measurements to global warming.

Long term temperature data from two stations on the island of Cyprus have been analysed. Increasing trends of approximately 18Cr100 years in the annual mean temperatures are found at both stations. However, the minimum daily temperatures have generally increased at a larger rate than the maximum daily temperatures, resulting in a decrease in the long-term diurnal temperature range. This decrease ranges from y0.58Cr100 years to y3.58Cr100 years, depending on the location. The reduction in the diurnal temperature range is consistent with observations from other parts of the globe, and may indicate that the climate in this region of the globe is part of a larger global climate change that has been occurring over the last century. It is possible that long term changes in greenhouse gas concentrations in the atmosphere are responsible for the long-term annual mean temperature increase. Furthermore, the changes in the diurnal temperature range can possibly be explained by increases in cloud cover andror tropospheric aerosols. It is possible that part of these changes is caused by local land-use changes, primarily by the increasing urbanization of Cyprus.

Solar radiation is the single most important environmental factor driving canopy photosynthesis and transpiration. This weather characteristic is measured only in a limited number of weather stations. Hence, in many situations it has to be estimated from other weather characteristics such as sunshine duration and temperature using empirical relations. In this study, the Ångstrom and Hargreaves formulas have been used for solar radiation estimation, based on monthly and annual weather data for three weather stations in Esfahan province, Iran. Deviations of estimated solar radiation from measured values (both absolute and relative) varied with month of the year and with estimation method. Estimated and measured radiation values were used in a crop growth simulation model to explore sensitivity of simulated production with respect to radiation estimation method. Maximum deviation for winter barley and silage maize was around 9%.

Climate change is impacting crop performance and agricultural systems around the world with implications for farmers and consumers. We carried out a systematic review to synthesize evidence regarding the effects of environmental factors associated with climate change and management conditions associated with climate adaptation on the crop quality of a culturally-relevant perennial crop, coffee (Coffea arabica and Coffea canephora). Seventy-three articles were identified that addressed the study's research question including 42 articles on environmental factors, 20 articles on management conditions, and 11 articles on both. While variation was found between studies, findings highlight that coffee quality is vulnerable to changes in light exposure, altitude, water stress, temperature, carbon dioxide, and nutrient management. Both increases as well as decreases were found in secondary metabolites and sensory attributes that determine coffee quality in response to shifts in environm...

Pakistan is located in one of the fast temperature rising zones and hence, highly vulnerable to climate change. The dynamic variations of the maximum (Tmax) and minimum (Tmin) temperatures pose potential risks to the local people. Thus, the present study assessed spatiotemporal changes in Tmax and Tmin over China-Pakistan Economic Corridor (CPEC) during 1980-2016 based on the 48 meteorological stations across the CPEC. The non-parametric Mann-Kendall (MK), Sen's Slope (SS) estimator, Sequential Mann-Kendall (SQMK), and least square method tests were used to assess the long-term trends in Tmax and Tmin time series during 1980-2016. The results indicate that the trend of Tmax has significantly increased at the rates of 0.22, 0.37, 0.20, 0.23, and 0.31 o C per decade in winter, spring, summer, autumn, and annual time scales, respectively. Similarly, the Tmin exhibited a significant positive trend in winter, spring, summer, autumn, and annual time series with the rates of 0.33, 0.39, 0.25, 0.27, and 0.36 o C per decade, respectively. The spatial distributions of Tmax and Tmin represent a warming trend over the whole country; however, the seasonal and annual Tmax (Tmin) exhibited sharp increasing trends in the northern and southwestern mountainous (southern, southwestern and southeastern) regions of the country. According to the mutation test, most of the abrupt changes in seasonal and annual Tmax and Tmin trends have been detected during 1995-2010. The present study recommends that forthcoming studies should focus on the factors responsible for the spatial and temporal variability of Tmax and Tmin in the target region.

The 1221 weather observation stations that compose the U.S. Historical Climatology Network were designated as either urban, suburban, or rural based on data from the Defense Meteorological Satellite Program Operational Linescan System (OLS). The designations were based on local and regional samples of the OLS data around the stations (OLS method). Trends in monthly maximum and minimum temperature and the diurnal temperature range (DTR) were determined for the 1950-96 interval for each of three land use/land cover (LULC) designations. The temperature trends for the OLS-derived designations of LULC were compared to similarly designated LULC based on (i) map-(Operational Navigation Charts) and population-based estimates of LULC (ONCP method), and (ii) LULC designations that resulted from of a survey of the network station operators. Although differences were not statistically significant, the DTR trends (degrees Celsius per 100 years) did differ between the LULC classes defined by the OLS method, from Ϫ0.41 for the rural stations to Ϫ0.86 for the urban stations. Trends also differed, although not significantly, between the methods used to define an LULC class, such that the trends in rural DTR varied from Ϫ0.41 for the OLS defined stations to Ϫ0.67 for the ONCP defined stations. Although the trends between classes were not significantly different, they do present some contrasts that might confound the interpretation of temperature trends when the local and regional environments associated with the analyzed stations are not considered. The general (urban, suburban, or rural) LULC associated with surface observation stations appears to be one of the factors that can influence the trends observed in temperatures and thus should be considered in the analysis and interpretation of temperature trends.

A reduced form metamodel has been produced to simulate the effects of physical, chemical, and meteorological processing of highly reactive trace species in urban areas, which is capable of efficiently simulating the urban concentration, surface deposition, and net export flux of these species. A polynomial chaos expansion and the probabilistic collocation method have been used to develop the metamodel, and its coefficients, so that it is applicable under a broad range of present-day and future conditions. The inputs upon which this metamodel have been formed are based on a combination of physical properties (average temperature, diurnal temperature range, date, and latitude), anthropogenic properties (patterns and amounts of emissions), and the nature of the surrounding environment (background concentrations of species). The metamodel development involved using probability distribution functions (PDFs) of the inputs to run a detailed parent chemical and physical model, the Comprehensive Air Quality Model with Extensions (CAMx), thousands of times. Outputs from these runs were used in turn to both determine the coefficients of and test the precision of the metamodel, as compared with the detailed parent model. It was determined that the deviations between the metamodel and the parent mode for many important species (O 3 , CO, NO x , and black carbon (BC)) were found to have a weighted RMS error less than 10 % in all cases, with many of the specific cases having a weighted RMS error less than 1 %. Some of the other important species (VOCs, PAN, OC, and sulfate aerosol) usually have their weighted RMS error less than 10 % as well, except for a small number of cases. In these cases, the complexity and non-linearity of the physical, chemical, and meteorological processing is too large for the

A study of the long-term changes of various climatic extremes was made jointly by a number of European countries. It was found that the changes in maximum and minimum temperatures follow, in broad terms, the corresponding well-documented mean temperature changes. Minimum temperatures, however, have increased slightly more than maximum temperatures, although both have increased. As a result, the study confirms that the diurnal temperature range has mostly decreased during the present century in Northern and Central Europe. Frost has become less frequent. Two extreme-related precipitation characteristics, the annual maximum daily precipitation and the number of days with precipitation. ; : : , , _ 10 mm, show no major trends or changes in their interannual variability. An analysis of return periods indicated that in the Nordic countries there were high frequencies of 'extraordinary' 1-day rainfalls both in the 1930s and since the 1980s. There have been no long-term changes in the number of high wind speeds in the German Bight. Occurrences of thunderstorms and hails show a decreasing tendency in the Czech Republic during the last 50 years. Finally, using proxy data sources, a 500-year temperature and precipitation event graph for the Swiss Mittelland is presented. It shows large interdecadal variations as well as the exceptionality of the latest decade 1986-1995.

A study of the long-term changes of various climatic extremes was made jointly by a number of European countries. It was found that the changes in maximum and minimum temperatures follow, in broad terms, the corresponding well-documented mean temperature changes. Minimum temperatures, however, have increased slightly more than maximum temperatures, although both have increased. As a result, the study confirms that the diurnal temperature range has mostly decreased during the present century in Northern and Central Europe. Frost has become less frequent. Two extreme-related precipitation characteristics, the annual maximum daily precipitation and the number of days with precipitation. ; : : , , _ 10 mm, show no major trends or changes in their interannual variability. An analysis of return periods indicated that in the Nordic countries there were high frequencies of 'extraordinary' 1-day rainfalls both in the 1930s and since the 1980s. There have been no long-term changes in the number of high wind speeds in the German Bight. Occurrences of thunderstorms and hails show a decreasing tendency in the Czech Republic during the last 50 years. Finally, using proxy data sources, a 500-year temperature and precipitation event graph for the Swiss Mittelland is presented. It shows large interdecadal variations as well as the exceptionality of the latest decade 1986-1995.

The diurnal temperature range (DTR) of surface air over land varies geographically and seasonally. The authors have investigated these variations using generalized additive models (GAMs), a nonlinear regression methodology. With DTR as the response variable, meteorological and land surface parameters were treated as explanatory variables. Regression curves related the deviation of DTR from its mean value to values of the meteorological and land surface variables. Cloud cover, soil moisture, distance inland, solar radiation, and elevation were combined as explanatory variables in an ensemble of 84 GAM models that used data grouped into seven vegetation types and 12 months. The ensemble explained 80% of the geographical and seasonal variation in DTR. Vegetation type and cloud cover exhibited the strongest relationships with DTR. Shortwave radiation, distance inland, and elevation were positively correlated with DTR, whereas cloud cover and soil moisture were negatively correlated. A s...

The two-temperature method (TTM) allows the separation of land-surface temperature and land-surface emissivity information from radiance measurements, and therefore, the solution can be uniquely determined by the data. However, the inverse problem is still an ill-posed problem, since the solution does not depend continuously on the data. Accordingly, we have used some mathematical tools, which are suited for analyses of ill-posed problems in order to show TTM properties, evaluate it, and optimize its estimations. Related to this last point, we have shown that it is necessary to constrain the problem, either by defining a region of physically admissible solutions and/or by using regularization methods, in order to obtain stable results. Besides, the results may be improved by using TTM with systems that possess a high temporal resolution, as well as by acquiring observations near the maximum and minimum of the diurnal temperature range.

Data from the climate station at Skukuza, which has been open from 1912 to the present, are analysed. This exercise was done to provide the South African Regional Science Initiative (SAFARI-2000) experimental program with long-term climate statistics and trends. Climate parameters analysed are rainfall, temperature, humidity and sunshine. In the case of rainfall and temperature, the data was first tested for homogeneity and in only three out of 36 monthly cases, the data proved not to be homogeneous. No monthly rainfall trends proved to be significant (at the 5 % level), with five months indicating slightly negative trends and seven slightly positive. Only the monthly maximum temperature series for June proved to be non-homogeneous. The June maximum temperature trend and the February, March, May, July and December minimum temperature trends were significantly positive. The annual time series for minimum temperature were also significantly positive. The monthly results were reiterated by the seasonal results, with the winter maximum temperature trend and the autumn and summer minimum temperature trends significantly positive. Ten months showed negative temperature diurnal range trends with only March being significant. All long-term statistics of rainfall, temperature, humidity and sunshine were found to be typical of a savanna type climate in the southern hemisphere, although average monthly sunshine hours were somewhat less than the norm, due to frequent influx of moist air from the Mozambique Channel.

Monthly mean maximum and minimum temperatures for over 50% (10%) of the Northern (Southern) Hemisphere landmass, accounting for 37% of the global landmass, indicate that the rise of the minimum temperature has occurred at a rate three times that of the maximum temperature during the period 1951-90 (0.84"C versus 0.28"C). The decrease of the diumal temperature range is approximately equal to the increase of mean temperature. The asymmetly is detectable in all seasons and in most of the regions studied. The decrease in the daily temperature range is partially related to increases in cloud cover. Furthermore, a large number of atmospheric and surface boundary conditions are shown to differentially affect the maximum and minimum temperature. Linkages of the observed changes in the diurnal temperature range to large-scale climate forcings, such as anthropogenic increases in sulfate aerosols, greenhouse gases, or biomass burning (smoke), remain tentative. Nonetheless, the observed decrease of the diurnal temperature range is clearly important, both scientifically and practically.

Low, mid and high daily climate scenarios (2000-2070), as per the International Panel on Climate Change (IPCC) were generated using the Australian Commonwealth Scientific and Industrial Research Organisation's (CSIRO's) global atmosphere models. These scenarios based on IPCC's 21st century emission scenarios that combine a variety of assumptions about demographic, economic and technological driving forces likely to influence such emissions in the future, were used as input to a crop model to predict the impact of climate change on wheat yield at a location in southeastern Australia. At this locality there are important likely changes in the primary climatic variables of temperature, rainfall and solar radiation. Generally, we found a strong and consistent positive trend in mean diurnal temperature range, followed by a significant negative trend in wheat yield under three climate scenarios with and without elevated CO 2 concentration. It is possible that negative trends identified over the future decades may be artefacts of the method of substituting historical variance for future variance. We observed that from present climate to projected low, mid and high global warming scenarios, median wheat yield may decrease by about 29%. Under these scenarios, but with an elevated atmospheric CO 2 climate, median wheat yield may decrease by about 25%. The effect of elevated CO 2 reduces the severity of the warmer air temperatures and lower rainfall but the effect is small (4%). Advances in agronomy and breeding must boost crop yields by around 25% over the coming decades, to keep in step with predicted climate change.

A database of monthly climate observations from meteorological stations is constructed. The database includes six climate elements and extends over the global land surface. The database is checked for inhomogeneities in the station records using an automated method that refines previous methods by using incomplete and partially overlapping records and by detecting inhomogeneities with opposite signs in different seasons. The method includes the development of reference series using neighbouring stations. Information from different sources about a single station may be combined, even without an overlapping period, using a reference series. Thus, a longer station record may be obtained and fragmentation of records reduced. The reference series also enables 1961-90 normals to be calculated for a larger proportion of stations. The station anomalies are interpolated onto a 0.5°grid covering the global land surface (excluding Antarctica) and combined with a published normal from 1961-90. Thus, climate grids are constructed for nine climate variables (temperature, diurnal temperature range, daily minimum and maximum temperatures, precipitation, wet-day frequency, frost-day frequency, vapour pressure, and cloud cover) for the period 1901-2002. This dataset is known as CRU TS 2.1

International markets are increasingly signaling demand for quality-differentiated coffee, which the Colombian Coffee Growers Federation (FNC) proposed to exploit to identify those regional coffees that would fulfill the requirements to be classified as denomination of origin. The objective of this study was to develop and implement a sound, robust and repeatable approach with and for the FNC to identify regional causal relationships between coffee quality and environmental characteristics as bases for labels of denomination of origin. Environmental differences between coffee-growing areas in the departments of Cauca and Nariño were statistically significant for several characteristics, including the number of dry months, annual precipitation and diurnal temperature range. The dominant varieties (Caturra and Colombia) did not show major differences in quality attributes, and were pooled for the analyses with the environmental data. There are significant differences in biochemical and sensorial product characteristics between the two departments. The spatial patterns in product characteristics exhibit a non-random, regionally-changing structure that is related to those in the environmental data. The generated results provided ample evidence to support the application for regionally-based denominations of origin. Recommendations were derived to help mainstreaming the developed approach and thereby facilitate policy decisions for its use in other geographies and with other crops. Furthermore, the importance of systematic interdisciplinary institutional collaboration for large-scale denomination of origin projects was corroborated for food policy dialogue and decision making. It seems plausible that producers of high-quality products within other commodities are likely to follow the FNC in seeking denomination of origin for their goods. The presented approach is crucial to facilitate policy.

International markets are increasingly signaling demand for quality-differentiated coffee, which the Colombian Coffee Growers Federation (FNC) proposed to exploit to identify those regional coffees that would fulfill the requirements to be classified as denomination of origin. The objective of this study was to develop and implement a sound, robust and repeatable approach with and for the FNC to identify regional causal relationships between coffee quality and environmental characteristics as bases for labels of denomination of origin. Environmental differences between coffee-growing areas in the departments of Cauca and Nariño were statistically significant for several characteristics, including the number of dry months, annual precipitation and diurnal temperature range. The dominant varieties (Caturra and Colombia) did not show major differences in quality attributes, and were pooled for the analyses with the environmental data. There are significant differences in biochemical and sensorial product characteristics between the two departments. The spatial patterns in product characteristics exhibit a non-random, regionally-changing structure that is related to those in the environmental data. The generated results provided ample evidence to support the application for regionally-based denominations of origin. Recommendations were derived to help mainstreaming the developed approach and thereby facilitate policy decisions for its use in other geographies and with other crops. Furthermore, the importance of systematic interdisciplinary institutional collaboration for large-scale denomination of origin projects was corroborated for food policy dialogue and decision making. It seems plausible that producers of high-quality products within other commodities are likely to follow the FNC in seeking denomination of origin for their goods. The presented approach is crucial to facilitate policy.

International markets are increasingly signaling demand for quality-differentiated coffee, which the Colombian Coffee Growers Federation (FNC) proposed to exploit to identify those regional coffees that would fulfill the requirements to be classified as denomination of origin. The objective of this study was to develop and implement a sound, robust and repeatable approach with and for the FNC to identify regional causal relationships between coffee quality and environmental characteristics as bases for labels of denomination of origin. Environmental differences between coffee-growing areas in the departments of Cauca and Nariño were statistically significant for several characteristics, including the number of dry months, annual precipitation and diurnal temperature range. The dominant varieties (Caturra and Colombia) did not show major differences in quality attributes, and were pooled for the analyses with the environmental data. There are significant differences in biochemical and sensorial product characteristics between the two departments. The spatial patterns in product characteristics exhibit a non-random, regionally-changing structure that is related to those in the environmental data. The generated results provided ample evidence to support the application for regionally-based denominations of origin. Recommendations were derived to help mainstreaming the developed approach and thereby facilitate policy decisions for its use in other geographies and with other crops. Furthermore, the importance of systematic interdisciplinary institutional collaboration for large-scale denomination of origin projects was corroborated for food policy dialogue and decision making. It seems plausible that producers of high-quality products within other commodities are likely to follow the FNC in seeking denomination of origin for their goods. The presented approach is crucial to facilitate policy.

Long term temperature data from two stations on the island of Cyprus have been analysed. Increasing trends of approximately 18Cr100 years in the annual mean temperatures are found at both stations. However, the minimum daily temperatures have generally increased at a larger rate than the maximum daily temperatures, resulting in a decrease in the long-term diurnal temperature range. This decrease ranges from y0.58Cr100 years to y3.58Cr100 years, depending on the location. The reduction in the diurnal temperature range is consistent with observations from other parts of the globe, and may indicate that the climate in this region of the globe is part of a larger global climate change that has been occurring over the last century. It is possible that long term changes in greenhouse gas concentrations in the atmosphere are responsible for the long-term annual mean temperature increase. Furthermore, the changes in the diurnal temperature range can possibly be explained by increases in cloud cover andror tropospheric aerosols. It is possible that part of these changes is caused by local land-use changes, primarily by the increasing urbanization of Cyprus.

Previous assessments of historical trends of measured surface temperature in South Africa have all shown a general upward trend, in both mean and extreme values, over recent decades. In addition, some regional differences in trends have been identified. Most of these studies focused on the period from about 1961 up to the last year that could be included before publication, as only climate stations situated in the same position for the entire analysis period were analysed. A data homogenisation procedure enabled the combination of time series of stations from which trend analysis could be applied, extending the common analysis period for this study back to around 1931. The trend results, based on the WMO ETCCDI indices, continue to show the general warming trend shown in previous analyses, with a general increase in extreme warm events, and a general decrease in extreme cold events across South Africa. The analysis of seasonal trends show that, while there are noteworthy differences on a regional basis, austral summer shows on average the strongest warming, followed by autumn, winter and spring. The central interior, which exhibited significant cooling in previous analyses, now shows non-significant or similar trends when compared to the other parts of South Africa. There is no countrywide acceleration in the warming trends, but some regional consistencies in the temporal changes in trends could be determined, i.e. increases in trends in the central interior and decreases in trends along most of the coastal region.

One of the most significant signals in the thermometer-observed temperature record since 1900 is the decrease in the diurnal temperature range over land, largely due to rising of the minimum temperatures. Generally, climate models have not well replicated this change in diurnal temperature range. Thus, the cause for night-time warming in the observed temperatures has been attributed to a variety of external causes. We take an alternative approach to examine the role that the internal dynamics of the stable nocturnal boundary layer (SNBL) may play in affecting the response and sensitivity of minimum temperatures to added downward longwave forcing. As indicated by previous nonlinear analyses of a truncated two-layer equation system, the SNBL can be very sensitive to changes in greenhouse gas forcing, surface roughness, heat capacity, and wind speed. A new singlecolumn model growing out of these nonlinear studies is used to examine the SNBL. Specifically, budget analyses of the model are provided that evaluate the response of the boundary layer to forcing and sensitivity to mixing formulations. Based on these model analyses, it is likely that part of the observed long-term increase in minimum temperature is reflecting a redistribution of heat by changes in turbulence and not by an accumulation of heat in the boundary layer. Because of the sensitivity of the shelter level temperature to parameters and forcing, especially to uncertain turbulence parameterization in the SNBL, there should be caution about the use of minimum temperatures as a diagnostic global warming metric in either observations or models.

Background and Aims Seeds buried in the soil detect burial depth through light and diurnally fluctuating temperatures (DFT) and in this way limit losses due to germination too deep in the soil. DFTs and germination also increase in vegetation gaps. However, dry open environments with high DFTs can also increase seedling mortality, creating conflicting selection pressures for reaction to DFTs. Since this questions the general function of DFT detection, we therefore tested if interspecific differences in DFT detection are related to mortality in different soil depths. Methods We buried seeds of ten annual plants including species pairs of increasing and decreasing germination in response to DFTs. Seeds were buried in 5, 10 and 25cm soil depth and exhumed after two different burial times. Seed viability was tested using germination in growth chambers and tetrazolium. We also measured DFTs at these depths using temperature data loggers. Results DFT detection was not related to differences in mortality at three burial depths. Three species showed a clear pattern of depth dependent mortality, however inconsistently related to DFT detection. Conclusions Depth detection mechanisms are more species-specific than expected. Hence, interspecific differences in seed mortalities are difficult to predict by DFT detection alone and alternative soil depth sensing mechanisms should be explored in future.

Background and Aims Seeds buried in the soil detect burial depth through light and diurnally fluctuating temperatures (DFT) and in this way limit losses due to germination too deep in the soil. DFTs and germination also increase in vegetation gaps. However, dry open environments with high DFTs can also increase seedling mortality, creating conflicting selection pressures for reaction to DFTs. Since this questions the general function of DFT detection, we therefore tested if interspecific differences in DFT detection are related to mortality in different soil depths. Methods We buried seeds of ten annual plants including species pairs of increasing and decreasing germination in response to DFTs. Seeds were buried in 5, 10 and 25cm soil depth and exhumed after two different burial times. Seed viability was tested using germination in growth chambers and tetrazolium. We also measured DFTs at these depths using temperature data loggers. Results DFT detection was not related to differences in mortality at three burial depths. Three species showed a clear pattern of depth dependent mortality, however inconsistently related to DFT detection. Conclusions Depth detection mechanisms are more species-specific than expected. Hence, interspecific differences in seed mortalities are difficult to predict by DFT detection alone and alternative soil depth sensing mechanisms should be explored in future.

Existem muitas evidências de que as cidades influenciam o climalocal, particularmente no que diz respeito à temperatura, ocasionando uma “ilha decalor urbano”, com impactes negativos no conforto bioclimático e na saúde humana.Durante o século transacto, sobretudo a partir de 1980, ocorreu um aumento da temperatura dos meses de Verão (Junho, Julho, Agosto e Setembro, JJAS), particularmente no que diz respeito à temperatura mínima média. Verificou-se igualmente umaumento de noites “quentes” (de temperatura mínima superior a 20ºC), em especialem Junho e Setembro e uma diminuição significativa da amplitude térmica diurna,nomeadamente nos últimos anos do século XX. Estes factos poderão ser devidos nãosó ao efeito urbano, mas também ao aquecimento global.

In recent years, demand for databases of high quality weather observations has intensified. While there are many causes for this, increases in the number of climate studies and in the number of businesses employing weather risk management methods are two principal causes driving this increased demand. In response to this need, domestic and foreign governments, academic institutions and a few businesses have made efforts to improve the quality and access to such databases. This paper describes a comprehensive global weather observation database developed by Weather Source, LLC. The Weather Source database (WSDB) consists of daily, hourly and special weather observations from tens of thousands of weather stations from across the globe. The period of record for these observations in most cases covers the period from station inception to real-time if available. A series of quality control and data improvement methods are employed on the data to increase quality; these include both meteo...

The diurnal range of surface air temperature (DTR) has decreased worldwide during the last 4-5 decades and changes in cloud cover are often cited as one of the likely causes. To determine how clouds and moisture affect DTR physically on daily bases, the authors analyze the 30-min averaged data of surface meteorological variables and energy fluxes from the the First International Satellite Land Surface Climatology Project Field Experiment and the synoptic weather reports of 1980-1991 from about 6500 stations worldwide. The statistical relationships are also examined more thoroughly in the historical monthly records of DTR, cloud cover, precipitation, and streamflow of this century. It is found that clouds, combined with secondary damping effects from soil moisture and precipitation, can reduce DTR by 25%-50% compared with clear-sky days over most land areas; while atmospheric water vapor increases both nighttime and daytime temperatures and has small effects on DTR. Clouds, which largely determine the geographic patterns of DTR, greatly reduce DTR by sharply decreasing surface solar radiation while soil moisture decreases DTR by increasing daytime surface evaporative cooling. Clouds with low bases are most efficient in reducing the daytime maximum temperature and DTR mainly because they are very effective in reflecting the sunlight, while middle and high clouds have only moderate damping effects on DTR. The DTR reduction by clouds is largest in warm and dry seasons such as autumn over northern midlatitudes when latent heat release is limited by the soil moisture content. The net effects of clouds on the nighttime minimum temperature is small except in the winter high latitudes where the greenhouse warming effect of clouds exceeds their solar cooling effect. The historical records of DTR of the twentieth century covary inversely with cloud cover and precipitation on interannual to multidecadal timescales over the United States, Australia, midlatitude Canada, and former U.S.S.R., and up to 80% of the DTR variance can be explained by the cloud and precipitation records. Given the strong damping effect of clouds on the daytime maximum temperature and DTR, the well-established worldwide asymmetric trends of the daytime and nighttime temperatures and the DTR decreases during the last 4-5 decades are consistent with the reported increasing trends in cloud cover and precipitation over many land areas and support the notion that the hydrologic cycle has intensified.

Monthly mean maximum and minimum temperatures for over 50% (10%) of the Northern (Southern) Hemisphere landmass, accounting for 37% of the global landmass, indicate that the rise of the minimum temperature has occurred at a rate three times that of the maximum temperature during the period 1951-90 (0.84"C versus 0.28"C). The decrease of the diumal temperature range is approximately equal to the increase of mean temperature. The asymmetly is detectable in all seasons and in most of the regions studied. The decrease in the daily temperature range is partially related to increases in cloud cover. Furthermore, a large number of atmospheric and surface boundary conditions are shown to differentially affect the maximum and minimum temperature. Linkages of the observed changes in the diurnal temperature range to large-scale climate forcings, such as anthropogenic increases in sulfate aerosols, greenhouse gases, or biomass burning (smoke), remain tentative. Nonetheless, the observed decrease of the diurnal temperature range is clearly important, both scientifically and practically.

There has been a paucity of information on trends in daily climate and climate extremes, especially from developing countries. We report the results of the analysis of daily temperature (maximum and minimum) and precipitation data from 14 south and west African countries over the period 1961-2000. Data were subject to quality control and processing into indices of climate extremes for release to the global community. Temperature extremes show patterns consistent with warming over most of the regions analyzed, with a large proportion of stations showing statistically significant trends for all temperature indices. Over 1961 to 2000, the regionally averaged occurrence of extreme cold (fifth percentile) days and nights has decreased by À3.7 and À6.0 days/decade, respectively. Over the same period, the occurrence of extreme hot (95th percentile) days and nights has increased by 8.2 and 8.6 days/decade, respectively. The average duration of warm (cold) has increased (decreased) by 2.4 (0.5) days/decade and warm spells. Overall, it appears that the hot tails of the distributions of daily maximum temperature have changed more than the cold tails; for minimum temperatures, hot tails show greater changes in the NW of the region, while cold tails have changed more in the SE and east. The diurnal temperature range (DTR) does not exhibit a consistent trend across the region, with many neighboring stations showing opposite trends. However, the DTR shows consistent increases in a zone across Namibia, Botswana, Zambia, and Mozambique, coinciding with more rapid increases in maximum temperature than minimum temperature extremes. Most precipitation indices do not exhibit consistent or statistically significant trends across the region. Regionally averaged total precipitation has decreased but is not statistically significant. At the same time, there has been a statistically significant increase in regionally averaged daily rainfall intensity and dry spell duration. While the majority of stations also show increasing trends for these two indices, only a few of these are statistically significant. There are increasing trends in regionally averaged rainfall on extreme precipitation days and in maximum annual 5-day and 1-day rainfall, but only trends for the latter are statistically significant.

Observations at the Mauna Loa Observatory, Hawaii, established the systematic increase of anthropogenic CO 2 in the atmosphere. For the same reasons that this site provides excellent globally averaged CO 2 data, it may provide temperature data with global significance. Here, we examine hourly temperature records, averaged annually for 1977-2006, to determine linear trends as a function of time of day. For night-time data (22:00 to 06:00 LST (local standard time)) there is a near-uniform warming of 0.040 • C yr −1. During the day, the linear trend shows a slight cooling of −0.014 • C yr −1 at 12:00 LST (noon). Overall, at Mauna Loa Observatory, there is a mean warming trend of 0.021 • C yr −1. The dominance of night-time warming results in a relatively large annual decrease in the diurnal temperature range (DTR) of −0.050 • C yr −1 over the period 1977-2006. These trends are consistent with the observed increases in the concentrations of CO 2 and its role as a greenhouse gas (demonstrated here by first-order radiative forcing calculations), and indicate the possible relevance of the Mauna Loa temperature measurements to global warming.

The diurnal temperature range (DTR) is an important climate-change variable and, until recently, it was derived from station observations of surface air temperature (T a). Station-based observations are sparse and unevenly distributed, making the use of satellites an attractive option for evaluating DTR. In this study, satellite-based estimates of DTR are evaluated against ground measurements of surface skin temperature (T s) and compared with weather-station observations based on T a. Geographical and seasonal differences were identified in both ground-and satellite-derived DTRs. Estimates of DTR from station-observed air temperature represent all-sky conditions while satellite estimates of DTR from surface skin temperature represent clear conditions only. For both station observations and satellite estimates, DTRs at rural locations tend to be larger than at urban sites. The DTRs based on T s are larger than those derived from T a under both all and clear-sky conditions. Clouds tend to reduce the magnitude of the DTR. The station-observed DTRs are found to be larger in summer than in winter over the entire U.S. The satellite-derived DTRs are larger in spring and fall than in winter and summer over the eastern U.S., while they are larger in spring and summer than in fall and winter over the western part. Evapotranspiration from land vegetation and the effects of water-vapor radiative forcing have a major effect on the detected spatial and seasonal variations in the DTR patterns. Index Terms-Diurnal temperature range (DTR), effects of evapotranspiration, satellite-derived DTR, station observations of DTR, water-vapor radiative forcing (WRF) on DTR.

Changes in maximum and minimum temperature (T max and T min) are analysed to assess the regional extent of global warming in Xinjiang autonomous region, China, for the period of 1961-2015. Two nonlinear, non-stationary signal-processing methods-the Bernaola-Galván algorithm and the ensemble empirical mode decomposition method-are applied on daily time series of observations from 53 meteorological stations. Statistically significant abrupt change points are identified in 1996 in both annual T max and T min time series averaged for the whole province, while another one is identified in 1976 in the annual T min time series only. At local scale, most stations experience one abrupt change point in annual T max in the 1990s, but two or three change points in annual T min , mainly in the 1980s and 1990s. After the abrupt change points, the frequency and probability density of T max in summer and T min in winter are skewed towards the hotter part of the probability distribution. It is found that the hot temperature extremes in summer occur concurrently with El Niño events. Further results suggest that anomalies in geopotential height at 500 hPa can be associated with the hottest and coldest months. The key regions of the anomalies are over the east of the Ural Mountains and the North Atlantic, while the geopotential height anomalies over Greenland and the east of the Ural Mountains are closely related to the hot and cold spells. KEY WORDS extreme temperature; nonlinear trend; change point; atmospheric circulation; Xinjiang autonomous region

Satellite-borne passive microwave radiometers provide brightness temperature (TB) measurements in a large spectral range which includes a number of frequency channels and generally two polarizations: horizontal and vertical. These TBs are widely used to retrieve several atmospheric and surface variables and parameters such as precipitation, soil moisture, water vapor, air temperature profile, and land surface emissivity. Since TBs are measured at different microwave frequencies with various instruments and at various incidence angles, spatial resolutions, and radiometric characteristics, a mere direct integration of them from different microwave sensors would not necessarily provide consistency. However, when appropriately harmonized, they can provide a complete dataset to estimate the diurnal cycle. This study first constructs the diurnal cycle of land TBs using the non-sun-synchronous Global Precipitation Measurement (GPM) Microwave Imager (GMI) observations by utilizing a cubic s...