Atmospheric movements

A detailed description of the fourth-generation ECHAM model is presented. Compared to the previous version, ECHAM-3, a number of substantial changes have been introduced in both the numerics and physics of the model. These include a semi-Lagrangian transport scheme for water vapour, cloud water and trace substances, a new radiation scheme (ECMWF) with modifications concerning the water vapour continuum, cloud optical properties and greenhouse gases, a new formulation of the vertical diffusion coefficients as functions of turbulent kinetic energy, and a new closure for deep convection based on convective instability instead of moisture convergence. Minor changes concern the parameterizations of horizontal diffusion, stratiform clouds and land surface processes. Also, a new dataset of land surface parameters have been compiled for the new model. The climatology of the model, derived from two extended AMIP simulations at T42L19 resolution, is documented and compared with ECMWF operational analyses. Some of the biases noted for the previous model version remain virtually unchanged. For example, the polar upper troposphere and lower stratosphere is much too cold, and the zonal wind errors become very large above the 200 hPa level. Furthermore, the low-frequency variability is still too small but the errors are reduced by about 50% compared to ECHAM-3. The tropospheric temperature and zonal wind errors are generally smaller than in the previous model, except for the tropics, where the overestimation of Walker-type circulations in the equatorial plane is even more pronounced in the new model and the simulation of the Indian summer monsoon is less realistic. The most substantial improvements, compared to ECHAM-3, are found for the land surface climate. The temperature and precipitation errors are generally smaller than before, and the biome distributions derived from these parameters are more realistic in ECHAM-4. These improvements can be attributed to an improved represention of surface radiation fluxes via larger absorption of solar radiation in the atmosphere due to both water vapour and clouds.

A detailed description of the fourth-generation ECHAM model is presented. Compared to the previous version, ECHAM-3, a number of substantial changes have been introduced in both the numerics and physics of the model. These include a semi-Lagrangian transport scheme for water vapour, cloud water and trace substances, a new radiation scheme (ECMWF) with modifications concerning the water vapour continuum, cloud optical properties and greenhouse gases, a new formulation of the vertical diffusion coefficients as functions of turbulent kinetic energy, and a new closure for deep convection based on convective instability instead of moisture convergence. Minor changes concern the parameterizations of horizontal diffusion, stratiform clouds and land surface processes. Also, a new dataset of land surface parameters have been compiled for the new model. The climatology of the model, derived from two extended AMIP simulations at T42L19 resolution, is documented and compared with ECMWF operational analyses. Some of the biases noted for the previous model version remain virtually unchanged. For example, the polar upper troposphere and lower stratosphere is much too cold, and the zonal wind errors become very large above the 200 hPa level. Furthermore, the low-frequency variability is still too small but the errors are reduced by about 50% compared to ECHAM-3. The tropospheric temperature and zonal wind errors are generally smaller than in the previous model, except for the tropics, where the overestimation of Walker-type circulations in the equatorial plane is even more pronounced in the new model and the simulation of the Indian summer monsoon is less realistic. The most substantial improvements, compared to ECHAM-3, are found for the land surface climate. The temperature and precipitation errors are generally smaller than before, and the biome distributions derived from these parameters are more realistic in ECHAM-4. These improvements can be attributed to an improved represention of surface radiation fluxes via larger absorption of solar radiation in the atmosphere due to both water vapour and clouds.

One of the most reliable methods for the prediction of odour impact from environmental facilities, strongly influenced by topography and local atmospheric dynamics, involves the use of atmospheric dispersion models.The present study focuses on the implementation of a dispersion model for the prediction of odour impact from a large and complex landfill system, localized in Borgo Montello (Latina), in the Lazio Region (Central Italy). The Calpuff dispersion model was selected for the simulations of odour impact, since it is well recognized as the preferred model for assessing the long range transport of pollutants. The odour emission rates, which are the inputs to the dispersion model, were defined on the basis of dynamic olfactometric analyses on air samples taken in the landfills areas. Different scenarios were simulated, with the aim of evaluating the odour impact caused by a project of landfill expansion through height raise. The environmental odour impacts were assessed through t...

The hydrological aspects of the Amazon and the La Plata Basins are interconnected through southward moisture transport performed by the Low-Level Jet east of the Andes and the South Atlantic Convergence Zone. Remote effects of Sea Surface Temperature variability in the Pacific and the Atlantic are of varied periodicities, from multi-decadal to inter-annual This article is protected by copyright. All rights reserved. La Plata Basin, "as in the case of precipitation anomaly reversal between spring and summer in the SACZ region, the hydrological soil memory in the Northwest Argentine Low region affects the inter-annual variability of the LLJ in summer" is formulated. Some the hypotheses formulated above are being investigated by the authors of this article.

Atmospheric levels of 43 PCBs, 22 OCPs, and 14 PBDEs were determined in 16 cities at urban and rural sites by passive sampling to generate the first large-scale nationwide dataset of POP residues in Turkey's atmosphere. Sampling campaign was performed from May to April 2015 with three-month sampling periods at locations on east-west and north-south transects through the country to investigate seasonal and spatial variations, including long range atmospheric transport (LRAT). Factor analysis was conducted to infer on the potential sources. Overall average Σ 43 PCBs concentration was 108±132 pg/m 3. PCB-118 (26.3±44.6 pg/m 3) was the top congener, and penta-CBs had the highest contribution with 54.3%. ΣDDTs had the highest annual mean concentration with 134±296 pg/m 3 among the OCP groups among which the highest concentration compound was p'p-DDE (97.6±236 pg/m 3). Overall average concentration of Σ 14 PBDEs was 191±329 pg/m 3 with the highest contribution from BDE-190 (42%). Comparison of OCPs and PCBs concentrations detected at temperatures which were above and below annual average temperature indicated higher concentrations in the warmer periods, hence significance of secondary emissions for several OCPs and Σ 43 PCBs, as well as inference as LRAT from secondary emissions. The first nationwide POPs database constructed in this study, point to current use, local secondary emissions, and LRAT for different individual compounds, and indicate the need for regular monitoring.

Atmospheric levels of 43 PCBs, 22 OCPs, and 14 PBDEs were determined in 16 cities at urban and rural sites by passive sampling to generate the first large-scale nationwide dataset of POP residues in Turkey's atmosphere. Sampling campaign was performed from May to April 2015 with three-month sampling periods at locations on east-west and north-south transects through the country to investigate seasonal and spatial variations, including long range atmospheric transport (LRAT). Factor analysis was conducted to infer on the potential sources. Overall average Σ 43 PCBs concentration was 108±132 pg/m 3. PCB-118 (26.3±44.6 pg/m 3) was the top congener, and penta-CBs had the highest contribution with 54.3%. ΣDDTs had the highest annual mean concentration with 134±296 pg/m 3 among the OCP groups among which the highest concentration compound was p'p-DDE (97.6±236 pg/m 3). Overall average concentration of Σ 14 PBDEs was 191±329 pg/m 3 with the highest contribution from BDE-190 (42%). Comparison of OCPs and PCBs concentrations detected at temperatures which were above and below annual average temperature indicated higher concentrations in the warmer periods, hence significance of secondary emissions for several OCPs and Σ 43 PCBs, as well as inference as LRAT from secondary emissions. The first nationwide POPs database constructed in this study, point to current use, local secondary emissions, and LRAT for different individual compounds, and indicate the need for regular monitoring.

Five independent multicentury reconstructions of the July Canadian Drought Code and one reconstruction of the mean July–August temperature were developed using a network of 120 well-replicated tree-ring chronologies covering the area of the eastern Boreal Plains to the eastern Boreal Shield of Canada. The reconstructions were performed using 54 time-varying reconstruction submodels that explained up to 50% of the regional drought variance during the period of 1919–84. Spatial correlation fields on the six reconstructions revealed that the meridional component of the climate system from central to eastern Canada increased since the mid–nineteenth century. The most obvious change was observed in the decadal scale of variability. Using 500-hPa geopotential height and wind composites, this zonal to meridional transition was interpreted as a response to an amplification of long waves flowing over the eastern North Pacific into boreal Canada, from approximately 1851 to 1940. Composites wi...

One of the most reliable methods for the prediction of odour impact from environmental facilities, strongly influenced by topography and local atmospheric dynamics, involves the use of atmospheric dispersion models.The present study focuses on the implementation of a dispersion model for the prediction of odour impact from a large and complex landfill system, localized in Borgo Montello (Latina), in the Lazio Region (Central Italy). The Calpuff dispersion model was selected for the simulations of odour impact, since it is well recognized as the preferred model for assessing the long range transport of pollutants. The odour emission rates, which are the inputs to the dispersion model, were defined on the basis of dynamic olfactometric analyses on air samples taken in the landfills areas. Different scenarios were simulated, with the aim of evaluating the odour impact caused by a project of landfill expansion through height raise. The environmental odour impacts were assessed through t...

The Phébus fission product (FP) programme studies the phenomenology of severe accidents in watercooled nuclear reactors. Five tests were performed in the frame of the programme covering fuel-rod degradation and FP behaviour released via the coolant system into the containment. To model FP transport and behaviour in the coolant system, numerous physical and chemical phenomena have to be taken into account. In the vapour phase, for example, FP speciation, vapour condensation and vapour/surface or vapour/aerosol reactions have to be considered. The aerosol phase has to be modelled with nucleation, growth and deposition processes. Finally, remobilisation phenomena like resuspension and revaporisation have to be taken into account for delayed release into the containment. Four Phébus FP tests (FTP0, FPT1, FPT2, FPT3) have been modelled with the ASTEC/SOPHAEROS code. Modelling shows an overall good estimation of retention for the main FPs (e.g., I, Cs, Mo). Furthermore, a strong connection is revealed in the gaseous phase chemistry between I, Cs, Cd and Mo which has a great impact on gaseous iodine release into the containment. The Phébus FP test modelling also exposes disagreement on FP retention when laminar gaseous flow is not well developed. Finally, probably the most significant shortcoming in modelling that Phébus-FP tests highlighted concerns vapour-phase iodine-chemistry modelling at low temperature. The study of this latter point is on going with the experimental programme ISTP/CHIP.

Atmospheric levels of 43 PCBs, 22 OCPs, and 14 PBDEs were determined in 16 cities at urban and rural sites by passive sampling to generate the first large-scale nationwide dataset of POP residues in Turkey's atmosphere. Sampling campaign was performed from May to April 2015 with three-month sampling periods at locations on east-west and north-south transects through the country to investigate seasonal and spatial variations, including long range atmospheric transport (LRAT). Factor analysis was conducted to infer on the potential sources. Overall average Σ 43 PCBs concentration was 108±132 pg/m 3. PCB-118 (26.3±44.6 pg/m 3) was the top congener, and penta-CBs had the highest contribution with 54.3%. ΣDDTs had the highest annual mean concentration with 134±296 pg/m 3 among the OCP groups among which the highest concentration compound was p'p-DDE (97.6±236 pg/m 3). Overall average concentration of Σ 14 PBDEs was 191±329 pg/m 3 with the highest contribution from BDE-190 (42%). Comparison of OCPs and PCBs concentrations detected at temperatures which were above and below annual average temperature indicated higher concentrations in the warmer periods, hence significance of secondary emissions for several OCPs and Σ 43 PCBs, as well as inference as LRAT from secondary emissions. The first nationwide POPs database constructed in this study, point to current use, local secondary emissions, and LRAT for different individual compounds, and indicate the need for regular monitoring.

Oceanic-atmospheric phenomena of different time scales concurrently might affect the streamflow in several basins around the world. The Atrato River Basin (ARB) and Patía River Basin (PRB) of the Colombian Pacific region are examples of such basins. Nevertheless, the relations between the streamflows in the ARB and PRB and the oceanic-atmospheric factors have not been examined considering different temporal scales. Hence, this article studies the relations of the climate indices and the variability of the streamflows in the ARB and PRB at interannual and decadal timescales. To this, the streamflow variability modes were obtained from the principal component analysis (PCA); furthermore, their linear dependence with indices of the El Niño/Southern Oscillation (ENSO), precipitation (PRP), the Choco low-level jet (CJ), and other indices were quantified through (a) Pearson and Kendall’s tau correlations, and (b) wavelet transform. The PCA presented a single significant mode for each basi...

One of the most reliable methods for the prediction of odour impact from environmental facilities, strongly influenced by topography and local atmospheric dynamics, involves the use of atmospheric dispersion models.The present study focuses on the implementation of a dispersion model for the prediction of odour impact from a large and complex landfill system, localized in Borgo Montello (Latina), in the Lazio Region (Central Italy). The Calpuff dispersion model was selected for the simulations of odour impact, since it is well recognized as the preferred model for assessing the long range transport of pollutants. The odour emission rates, which are the inputs to the dispersion model, were defined on the basis of dynamic olfactometric analyses on air samples taken in the landfills areas. Different scenarios were simulated, with the aim of evaluating the odour impact caused by a project of landfill expansion through height raise. The environmental odour impacts were assessed through t...

Thermocatalytic decomposition (TCD) of methane is a promising method to produce hydrogen. A series of experiments was conducted to study the apparent kinetic, catalyst deactivation and effect of mass diffusion for methane TCD to produce hydrogen using palm-shell carbon based activated carbon (ACPS) as a catalyst in a fixed bed reactor. The experiment was carried out under atmospheric pressure at 775e850 C, and different methane residence times calculated based on changing the ACPS weight at a constant methane flow rate or changing the methane flow rate at a constant ACPS weight. A reaction order as found substantially differs from that found in literature. A deactivation order of 0.5 and deactivation energy of 177 KJ mol À1 is obtained and the results fitted well with a simple developed model. Mass diffusion transfers are accounted for by calculating change of Weisz modulus with time on-stream using different weights of ACPS or different flow rates of methane. The result showed that Weisz modulus decrease with time and it is attributed to the deposition of carbon produced from methane decomposition. Surface properties measurements of the virgin and deactivated ACPSs indicated that methane decomposition occurs mainly within AC micropores.