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Due to its extension, geography and the presence of several underdeveloped or developing economies, the Central Asia domain of the Coordinated Regional Climate Downscaling Experiment (CORDEX) is one of the most vulnerable regions on Earth to the effects of climate changes. Reliable information on potential future changes with high spatial resolution acquire significant importance for the development of effective adaptation and mitigation strategies for the region. In this context, regional climate models (RCMs) play a fundamental role. In this paper, the results of a set of sensitivity experiments with the regional climate model COSMO-CLM version 5.0, for the Central Asia CORDEX domain, are presented. Starting from a reference model setup, general model performance is evaluated for the present day, testing the effects of singular changes in the model physical configuration and their mutual interaction with the simulation of monthly and seasonal values of three variables that are important for impact studies: near-surface temperature, precipitation and diurnal temperature range. The final goal of this study is two-fold: having a general overview of model performance and its uncertainties for the considered region and determining at the same time an optimal model configuration. Results show that the model presents remarkable deficiencies over different areas of the domain. The combined change of the albedo, taking into consideration the ratio of forest fractions, and the soil conductivity, taking into account the ratio of liquid water and ice in the soil, allows one to achieve the best improvements in model performance in terms of climatological means. Importantly, the model seems to be particularly sensitive to those parameterizations that deal with soil and surface features, and that could positively affect the repartition of incoming radiation. The analyses also show that improvements in model performance are not achievable for all domain subregions and variables, and they are the result of a compensation effect in the different cases. The proposed better performing configuration in terms of mean climate leads to similar positive improvements when considering different observational data sets and boundary data employed to force the simulations. On the other hand, due to the large uncertainties in the variability estimates from observations, the use of different boundaries and the model internal variability, it has not been possible to rank the different simulations according to their representation of the monthly variability. This work is the first ever sensitivity study of an RCM for the CORDEX Central Asia domain and its results are of fundamental importance for further model development and for future climate projections over the area. [ABSTRACT FROM AUTHOR]

Due to its extension, geography and the presence of several under-developed or developing economies, the Central Asia domain of the Coordinated Regional climate Downscaling Experiment (CORDEX) is one of the most vulnerable regions on Earth to the effects of climate changes. Reliable information on potential future changes with high spatial resolution acquire significant importance for the development of effective adaptation and mitigation strategies for the region. In this context, Regional Climate Models (RCMs) play a fundamental role. In this paper, the results of a set of sensitivity experiments with the regional climate model COSMO-CLM version 5.0, for the Central Asia CORDEX domain, are presented. Starting from a reference model setup, general model performance is evaluated for present-days, testing the effects of a set of singular physical parameterizations and their mutual interaction on the simulation of monthly and seasonal values of three variables that are important for impact studies: 2-meter temperature, precipitation and diurnal temperature range. The final goal of this study is two-fold: having a general overview of model performance and its uncertainties for the considered region and determining at the same time an optimal model configuration. Results show that the model presents remarkable deficiencies over different areas of the domain. The combined change of the albedo taking into consideration the ratio of forest fractions and the soil conductivity taking into account the ratio of liquid water and ice in the soil, allows to achieve the best improvements in model performance in terms of climatological means. Importantly, the model seems to be particularly sensitive to those parameterizations that deal with soil and surface features, and that could positively affect the repartition of incoming radiation. The results for the mean climate appear to be independent of the observational dataset used for evaluation and of the boundary data employed to force the simulations. On the other hand, due to the large uncertainties in the variability estimates from observations, the use of different boundaries and the model internal variability, it has not been possible to rank the different simulations according to their representation of the monthly variability. This work is the first ever sensitivity study of an RCM for the CORDEX Central Asia domain and its results are of fundamental importance for further model development and for future climate projections over the area. [ABSTRACT FROM AUTHOR]

The climate instability (millennial-scale rapid climatic oscillations) during the last glacial period has been a hot issue in Quaternary paleoclimate cycle, however, the driving mechanism and involved areas are still unclear. Previous reports mainly came from Green ice cores, North Atlantic deep-sea sediments and loess, stalagmites, lake records in the East Asian monsoon area, however, evidences from the Asian interior arid regions are scarce. Central Asia is distant from oceanic moisture sources and the climate is dominated by the Westerlies and the Subtropical High. Late Pleistocene loess sediments sporadically distributed at the pediments, terraces and basins provide us an opportunity to verify the existence of millennial-scale climatic fluctuations in Central Asia and understand the relations between high-low latitude climate. During the last decades, we have carried lots of loess investigations in Central Asian mainly around the Tienshan Mountains including Xinjiang in China, Kazakhstan, Kyrgyzstan and Tajikistan. In this paper, we report the preliminary results of loess investigations, and divide the loess distribution in Central Asia into three zones, which correspond to different hydrothermal combination conditions; and coupled with previous literatures, we review the progress of paleoclimate study of loess especially chronology in Central Asia, analyze problems of the last glacial climate events in Central Asia, and discusses its process and mechanism. Up to now, paleoclimatic proxies like grain size, mineralogy and geochemistry confirmed that that there are indeed millennial-scale rapid oscillations during the last glacial period in Central Asia, but they are inconsistent in age and variability. These rapid changes may be related to the following aspects: (a) contraction and expansion of the ice sheet in the high latitudes region of North Atlantic, (b) changes in the intensity and extent of the Siberian high pressure which further lead to the variance in wind dynamics, (c) and the north-south migration of the mid-latitude westerlies. The solar radiation is not the main driving factor for the rapid changes in Central Asia. [ABSTRACT FROM AUTHOR]