This study analyzed the temporal precipitation variations in the arid Central Asia （ACA） and their regional differences during 1930-2009 using monthly gridded precipitation from the Climatic Research Unit （CRU）. O...This study analyzed the temporal precipitation variations in the arid Central Asia （ACA） and their regional differences during 1930-2009 using monthly gridded precipitation from the Climatic Research Unit （CRU）. Our results showed that the annual precipitation in this westerly circulation dominated arid region is generally increasing during the past 80 years, with an apparent increasing trend （0.7 mm/10 a） in winter. The precipitation variations in ACA also differ regionally, which can be divided into five distinct subregions （Ⅰ West Kazakhstan region, Ⅱ East Kazakhstan region, ⅢCentral Asia Plains region, Ⅳ Kyrgyzstan region, and V Iran Plateau region）. The annual precipitation falls fairly even on all seasons in the two northern subregions （regions Ⅰ and Ⅱ, approximately north of 45°N）, whereas the annual precipitation is falling mainly on winter and spring （accounting for up to 80% of the annual total precipitation） in the three southern subregions. The annual precipitation is increasing on all subregions except the southwestern ACA （subregion Ⅴ） during the past 80 years. A significant increase in precipitation appeared in subregions Ⅰ and Ⅲ. The long-term trends in annual precipitation in all subregions are determined mainly by trends in winter precipitation. Additionally, the precipitation in ACA has significant interannual variations. The 2-3-year cycle is identified in all subregions, while the 5-6-year cycle is also found in the three southern subregions. Besides the inter-annual variations, there were 3-4 episodic precipitation variations in all subregions, with the latest episodic change that started in the mid- to late 1970s. The precipitations in most of the study regions are fast increasing since the late 1970s. Overall, the responses of ACA precipitation to global warming are complicated. The variations of westerly circulation are likely the major factors that influence the precipitation variations in the study region.展开更多
Four intensive uplift periods, i.e., 60–35, 25–17 and 12–8 Ma (but 18–13 Ma in the Himalayas of the southern Tibet), and since about 5 Ma, can be determined on the Tibetan Plateau by synthetical analysis of low-te...Four intensive uplift periods, i.e., 60–35, 25–17 and 12–8 Ma (but 18–13 Ma in the Himalayas of the southern Tibet), and since about 5 Ma, can be determined on the Tibetan Plateau by synthetical analysis of low-temperature thermo-chronology data, sedimentary deposit records, and structural deformation records of different areas. The strong tectonic uplift periods in different areas on the Tibetan Plateau are penecontemporaneous, except for the Himalayan area of the southern Tibet, where a rapid uplift and exhumation period, controlled by the activity of the South Tibetan Detachment System faults, occurred during 18–13 Ma. These strong uplift and exhumation periods correspond well to intensive deformation activity periods, suggesting tectonically-controlled uplift and exhumation. The deposit records, such as the distribution of coarse clastic sediments, the distribution of tectonically-controlled basins, stratigraphic discontinuousness or unconformity, and fault-controlled geomorphologic evolution, also match well with the strong uplift and exhumation periods. Expanding processes of the plateau are also discussed.展开更多
基金supported by National Basic Research Program of China (Grant No. 2010CB950202)National Natural Science Foundation of China (Grant Nos. 40971056 and 41021091)Fundamental Research Funds for the Central Universities (Grant No. LZUJBKY-2009-82)
文摘This study analyzed the temporal precipitation variations in the arid Central Asia （ACA） and their regional differences during 1930-2009 using monthly gridded precipitation from the Climatic Research Unit （CRU）. Our results showed that the annual precipitation in this westerly circulation dominated arid region is generally increasing during the past 80 years, with an apparent increasing trend （0.7 mm/10 a） in winter. The precipitation variations in ACA also differ regionally, which can be divided into five distinct subregions （Ⅰ West Kazakhstan region, Ⅱ East Kazakhstan region, ⅢCentral Asia Plains region, Ⅳ Kyrgyzstan region, and V Iran Plateau region）. The annual precipitation falls fairly even on all seasons in the two northern subregions （regions Ⅰ and Ⅱ, approximately north of 45°N）, whereas the annual precipitation is falling mainly on winter and spring （accounting for up to 80% of the annual total precipitation） in the three southern subregions. The annual precipitation is increasing on all subregions except the southwestern ACA （subregion Ⅴ） during the past 80 years. A significant increase in precipitation appeared in subregions Ⅰ and Ⅲ. The long-term trends in annual precipitation in all subregions are determined mainly by trends in winter precipitation. Additionally, the precipitation in ACA has significant interannual variations. The 2-3-year cycle is identified in all subregions, while the 5-6-year cycle is also found in the three southern subregions. Besides the inter-annual variations, there were 3-4 episodic precipitation variations in all subregions, with the latest episodic change that started in the mid- to late 1970s. The precipitations in most of the study regions are fast increasing since the late 1970s. Overall, the responses of ACA precipitation to global warming are complicated. The variations of westerly circulation are likely the major factors that influence the precipitation variations in the study region.
基金supported by China Geological Survey (Grant No. 1212010610103)National Natural Science Foundation of China (Grant Nos. 40902060, 40672137)
文摘Four intensive uplift periods, i.e., 60–35, 25–17 and 12–8 Ma (but 18–13 Ma in the Himalayas of the southern Tibet), and since about 5 Ma, can be determined on the Tibetan Plateau by synthetical analysis of low-temperature thermo-chronology data, sedimentary deposit records, and structural deformation records of different areas. The strong tectonic uplift periods in different areas on the Tibetan Plateau are penecontemporaneous, except for the Himalayan area of the southern Tibet, where a rapid uplift and exhumation period, controlled by the activity of the South Tibetan Detachment System faults, occurred during 18–13 Ma. These strong uplift and exhumation periods correspond well to intensive deformation activity periods, suggesting tectonically-controlled uplift and exhumation. The deposit records, such as the distribution of coarse clastic sediments, the distribution of tectonically-controlled basins, stratigraphic discontinuousness or unconformity, and fault-controlled geomorphologic evolution, also match well with the strong uplift and exhumation periods. Expanding processes of the plateau are also discussed.
