Connection between Caspian sea level variability and ENSO

Izvestiya, Atmospheric and Oceanic Physics, 2011

CIRCULATION, TEMPERATURE, AND HYDROLOGIC CHARACTERISTICS OF THE 2010 SUMMER An anomalously high temperature in summer 2010, together with low humidity in conditions of the blocking regime in the atmosphere, produced a vast drought and, as a consequence, fires, which caused the heaviest pollution of the atmosphere [19]. Droughts are complex phenomena with the strongest regional

Remote Sensing, 2020

Based on 26 years of satellite altimetry, this study reveals the presence of a persistent east–west pattern in the sea level of the Red Sea, which is visible throughout the years when considering the east–west difference in sea level. This eastern–western (EW) difference is positive during winter when a higher sea level is observed at the eastern coast of the Red Sea and the opposite occurs during summer. May and October are transition months that show a mixed pattern in the sea level difference. The EW difference in the southern Red Sea has a slightly higher range compared to that of the northern region during summer, by an average of 0.2 cm. Wavelet analysis shows a significant annual cycle along with other signals of lower magnitude for both the northern and southern Red Sea. Removing the annual cycle reveals two energy peaks with periodicities of <12 months and 3–7 years, representing the intraseasonal and El Nino—Southern Oscillation (ENSO) signals, respectively. Empirical O...

Water, 2017

Endorheic basins (i.e., landlocked drainage networks) and their lakes can be highly sensitive to variations in climate and adverse anthropogenic activities, such as overexploitation of water resources. In this review paper, we provide a brief overview of one major endorheic basin on each continent, plus a number of endorheic basins in Central Asia (CA), a region where a large proportion of the land area is within this type of basin. We summarize the effects of (changing) climate drivers and land surface-atmosphere feedbacks on the water balance. For the CA region, we also discuss key anthropogenic activities, related water management approaches and their complex relationship with political and policy issues. In CA a substantial increase in irrigated agriculture coupled with negative climate change impacts have disrupted the fragile water balance for many endorheic basins and their lakes. Transboundary integrated land and water management approaches must be developed to facilitate adequate climate change adaptation and possible mitigation of the adverse anthropogenic influence on endorheic basins in CA. Suitable climate adaptation, mitigation and efficient natural resource management technologies and methods are available, and are developing fast. A number of these are discussed in the paper, but these technologies alone are not sufficient to address pressing water resource issues in CA. Food-water-energy nexus analyses demonstrate that transboundary endorheic basin management requires transformational changes with involvement of all key stakeholders. Regional programs, supported by local governments and international donors, which incorporate advanced adaptation technologies, water resource research and management capacity development, are essential for successful climate change adaptation efforts in CA. However, there is a need for an accelerated uptake of such programs, with an emphasis on unification of approaches, as the pressures resulting from climate change and aggravated by human mismanagement of natural water resources leave very little time for hesitation.

Geophysical Research Letters, 2021

The Caspian Sea is the largest landlocked water body on the Earth. Five countries border the coastline of the Caspian Sea, which receives most of its freshwater input from the Volga river, which drains an extensive watershed. The Caspian Sea has an average salinity of 12.8 psu and a strong seasonal cycle in temperature and circulation (Gunduz, 2014). Given the large evaporative area of the Caspian Sea and its position in the subtropics, the overall freshwater water balance and the associated sea level can be subject to long-term climate-induced trends (

Theoretical and Applied Climatology, 2020

This study analyzes linear trends and change points in meteorological variables including (a) sea surface temperature (SST) anomalies using three data sets: (1) level 4 of the optimum interpolated SST (OISST) of the Advanced Very High Resolution Radiometer (AVHRR), (2) the Objectively Analyzed Air-Sea Fluxes (OAFluxSST) project, and (3) the observed Improved Extended Reconstructed SST version 4 (ERSST); (b) evaporation (Evap); (c) air temperature at 2 m (AT2m); (d) wind speed at 10 m (wind10m); (e) specific humidity at 2 m (hum2m); and (f) precipitation used from Multi-Source Weighted-Ensemble Precipitation (MSWEP) over the south of the Caspian Sea (SCS) for the period 1982-2016. A significant upward trend is observed in annual SST anomalies over the SCS at the 5% level such that OISST, OAFluxSST, and ERSST data sets, respectively, indicating warming rates of about 1.2, 1.3, and 1.9°C during the study period. Also, a significant upward trend is observed in annual Evap, AT2m, wind10, and hum2m at the 5% level. Both the Student t parametric and Mann-Whitney nonparametric Change Point Models (CPMs) suggested occurrence of common change point for annual OISST in 1994 over the SCS. For the same year, the applied Mann-Whitney test detected change point in annual OAFluxSST. The detected change point for OISST coincides with the change points of the annual hum2m and AT2m anomalies of synoptic stations (Bandar Anzali, Babolsar, and Ramsar), located at the southern coast of the Caspian Sea. The applied CPMs suggested significant change point in Evap in 1997, as evidenced by the increase of 60 mm in the mean annual value. The annual wind10m time series have a change point in 1995. The likelihood ratio test (LRT) confirms the CPM results. For example, the LRT indicates that the annual OISST and OAFluxSST anomalies over the periods 1983-1994 and 1995-2016 are drawn from normal distributions with different means such that difference in annual OISST and OAFluxSST anomalies means before and after 1994 are 0.89 and 0.83°C, respectively.

Climate Dynamics, 2023

The analysis of seasonal and long-term changes of the Caspian Sea level examined from historical long time tide gauge data in order to consider the influence of climate factors on sea-level changes in this lake system. The major peak at spectra corresponds to the annual cycle and semiannual oscillations peak is located at next vigorous. Effects of diverse global and regional factors on lake level changes are investigated by signal processing methods. Results show that annual cycle of Siberian High and Volga River discharge have the considerable effects on the Caspian Sea level changes in global and regional scales, respectively. Analyzing of seasonal cycle is revealed that Volga river discharge was significant on sea level fluctuations by one-month lag in northern and central basins and two months delay for southern basin. The long-term cycle results show ascending trend of evaporation in central basin that it is the main factor to decreasing in the Caspian Sea level since 1990s.

Journal of Hydrometeorology, 2022

A comprehensive ecohydrological analysis is designed to understand the formation and evolution of lake Lop Nur and the environmental change over the Tarim River basin. Three temporal scales from century-based climatological mean to decade-based quasi-steady state change and to annual-scale-based abrupt change test are included. Combining the Budyko and Tomer-Schilling framework, this research first analyzes hydroclimatic and ecohydrological resistance/resilience conditions, then attributes observed changes to external/climate impact or to internal/anthropogenic activities, and finally diagnoses the possible tipping point on ecohydrological dynamics. (i) The arid regions reveal less sensitivity in terms of low variabilities of excess water W and energy U and show high resilience, which will more likely stay the same pattern in the future. (ii) Present towns situated in the semiarid regions with a natural hydraulic linkage with the mainstream of the Tarim River show a higher sensitivity and likelihood to be affected if drier scenarios occurred in the future. (iii) The attribution from two subsequent quasi-steady states indicates increasing effects of the anthropogenic activities increase (1961-80 versus 1981-2000) and provides climatical evidence that the central Tarim River basin was getting wetter before 1960 and then kept drying afterward. (iv) In the Kongqi subcatchment, the excess water reveals a significant decrease-then-increase evolution, from which the years with abrupt changes are observed in the 1960s. Generally, both points iii and iv are in agreement with that the closed-basin lake Lop Nur desiccation until the 1970s and its connection with the eastern part of the Taklamakan Sand Sea.

PLOS ONE, 2017

The worldwide occurrence of complex climate-induced ecological shifts in marine systems is one of the major challenges in sustainable bio-resources management. The occurrence of ecological environment-driven shifts was studied in the Southern Caspian Sea using the "shiftogram" method on available fisheries-related (i.e. commercially important benthopelagic fish stocks) ecological and climatic variables. As indicators of potential environmentally driven shift patterns we used indices for the North Atlantic Oscillation, the Southern Oscillation, the Siberian High, the East Atlantic-West Russia pattern, as well as Sea Surface Temperature and surface chlorophyll-a concentration. Given the explorative findings from the serial shift analyses, the cascading and serial order of multiple shift events in climaticecologic conditions of the southern Caspian Sea suggested a linkage between external forces and dynamics of ecosystem components and structures in the following order: global-scale climate forces lead to local environmental processes, which in turn lead to biological components dynamics. For the first time, this study indicates that ecological shifts are an integral component of bentho-pelagic subsystem regulatory processes and dynamics. Qualitative correspondence of biological responses of bentho-pelagic stocks to climatic events is one of the supporting evidences that overall Caspian ecosystem structures and functioning might have-at least partially-been impacted by global-scale climatic or local environmental shifts. These findings may help to foster a regional Ecosystem-based Approach to Management (EAM) as an integral part of bentho-pelagic fisheries management plans.