Inland lakes and alpine glaciers are important constituents of water resources in arid and semiarid regions. Understanding their variations is critical for both an accurate evaluation of the dynamic changes of water r...Inland lakes and alpine glaciers are important constituents of water resources in arid and semiarid regions. Understanding their variations is critical for both an accurate evaluation of the dynamic changes of water resources and the retrieval of climatic information. On the basis of earlier researches, this study investigated the growth of the Sayram Lake and the retreat of its water-supplying glaciers in the Tianshan Mountains using long-term sequenced remote sensing images. Our results show that over the past 40 years, the surface area and the water level of the lake has increased by 12.0±0.3 km<sup>2</sup> and 2.8 m, respectively, and the area of its water-supplying glaciers has decreased continuously since the early 1970s with a total reduction of about–2.13±0.03 km<sup>2</sup>. Our study has indicative significance to the research of regional climate change.展开更多
Changes in the vegetation and climate of the westerly-dominated areas in Central Asia during the Holocene were interpreted using pollen-assemblages and charcoal data from a 300-cm-long sediment core of the Sayram Lake...Changes in the vegetation and climate of the westerly-dominated areas in Central Asia during the Holocene were interpreted using pollen-assemblages and charcoal data from a 300-cm-long sediment core of the Sayram Lake,northern Xinjiang.Accele-rator Mass Spectrometry(AMS) radiocarbon dating methods were applied to bulk organic matter of the samples.Artemisia spp./Chenopodiaceae ratios and results from principal component analysis were used to infer that the lake basin was dominated by desert vegetation before ca.9.6 cal.ka BP,which suggests a warm and dry climate in the early Holocene.Desert steppe/steppe expanded during 9.6-5.5 cal.ka BP,indicating a remarkable increase both in the precipitation and temperature during the mid-Holocene.Desert vegetation dominated between 6.5 and 5.5 cal.ka BP,marking an extreme warmer and drier interval.The steppe/meadow steppe recovered,and temperatures decreased from 5.5 cal.ka BP in the late Holocene,as indicated by the increased abundance of Artemisia and the development of meadows.Holocene temperatures and moisture variations in the Sayram Lake areas were similar to those of adjacent areas.This consistency implies that solar radiation was the main driving factor for regional temperature changes,and that the effect of temperature variations was significant on regional changes in humidity.The evolution of climate and environment in the Sayram Lake areas,which were characterized as dry in the early Holocene and relatively humid in the middle-late Holocene,are clearly different from those in monsoonal areas.Dry conditions in the early Holocene in the Sayram Lake areas were closely related to decreased water vapor advection.These conditions were a result of reduced westerly wind speeds and less evaporation upstream,which in turn were caused by seasonal changes in solar radiation superimposed by strong evaporation following warming and drying local climate.展开更多
Inland lakes are important water resources in arid and semiarid regions. Understanding climate effects on these lakes is critical to accurately evaluate the dynamic changes of water resources. This study focused on th...Inland lakes are important water resources in arid and semiarid regions. Understanding climate effects on these lakes is critical to accurately evaluate the dynamic changes of water resources. This study focused on the changes in Sayram Lake of Xinjiang, China, and addressed the effects of climate fluctuations on the inland lake based on long-term sequenced remote sensing images and meteorological data from the past 40 years. A geo- graphic information system （GIS） method was used to obtain the hypsometry of the basin area of Sayram Lake, and estimation methods for evaporation from rising temperature and water levels from increasing precipitation were proposed. Results showed that： （1）Areal values of Sayram Lake have increased over the past 40 years. （2） Both temperature and precipitation have increased with average increases of more than 1.8~C and 82 mm, respectively. Variation of the water levels in the lake was consistent with local climate changes, and the areal values show linear relationships with local temperature and precipitation data. （3） According to the hypsometry data of the basin area, the estimated lake water levels increased by 2.8 m, and the water volume increased by 12.9×108 m3 over the past 40 years. The increasing area of Sayram Lake correlated with local and regional climatic changes because it is hardly affected by human activities.展开更多
基金financially supported by the National Basic Research Program of China(2015CB954101)the National Science and Technology Basic Special Project(2011FY11040-2)+1 种基金the National Natural Science Foundation of China(41171332,41571388)the Surveying and Mapping Geoinformation Nonprofit Specific Project(201512033)
文摘Inland lakes and alpine glaciers are important constituents of water resources in arid and semiarid regions. Understanding their variations is critical for both an accurate evaluation of the dynamic changes of water resources and the retrieval of climatic information. On the basis of earlier researches, this study investigated the growth of the Sayram Lake and the retreat of its water-supplying glaciers in the Tianshan Mountains using long-term sequenced remote sensing images. Our results show that over the past 40 years, the surface area and the water level of the lake has increased by 12.0±0.3 km<sup>2</sup> and 2.8 m, respectively, and the area of its water-supplying glaciers has decreased continuously since the early 1970s with a total reduction of about–2.13±0.03 km<sup>2</sup>. Our study has indicative significance to the research of regional climate change.
基金supported by National Natural Science Foundation of China(Grant No.40802084)International Science&Technology Cooperation Program of China(Grant No.2011DFA21240)the CAS/SAFEA International Partnership Program for Creative Research Teams(Grant No.KZZDEW-TZ-08)
文摘Changes in the vegetation and climate of the westerly-dominated areas in Central Asia during the Holocene were interpreted using pollen-assemblages and charcoal data from a 300-cm-long sediment core of the Sayram Lake,northern Xinjiang.Accele-rator Mass Spectrometry(AMS) radiocarbon dating methods were applied to bulk organic matter of the samples.Artemisia spp./Chenopodiaceae ratios and results from principal component analysis were used to infer that the lake basin was dominated by desert vegetation before ca.9.6 cal.ka BP,which suggests a warm and dry climate in the early Holocene.Desert steppe/steppe expanded during 9.6-5.5 cal.ka BP,indicating a remarkable increase both in the precipitation and temperature during the mid-Holocene.Desert vegetation dominated between 6.5 and 5.5 cal.ka BP,marking an extreme warmer and drier interval.The steppe/meadow steppe recovered,and temperatures decreased from 5.5 cal.ka BP in the late Holocene,as indicated by the increased abundance of Artemisia and the development of meadows.Holocene temperatures and moisture variations in the Sayram Lake areas were similar to those of adjacent areas.This consistency implies that solar radiation was the main driving factor for regional temperature changes,and that the effect of temperature variations was significant on regional changes in humidity.The evolution of climate and environment in the Sayram Lake areas,which were characterized as dry in the early Holocene and relatively humid in the middle-late Holocene,are clearly different from those in monsoonal areas.Dry conditions in the early Holocene in the Sayram Lake areas were closely related to decreased water vapor advection.These conditions were a result of reduced westerly wind speeds and less evaporation upstream,which in turn were caused by seasonal changes in solar radiation superimposed by strong evaporation following warming and drying local climate.
基金financially supported by the National Science Technology Support Plan Project (2012BAH28B01-03)the National Natural Science Foundation of China(41171332)+1 种基金the National Science Technology Basic Special Project (2011FY110400-2)the China Postdoctoral Science Foundation (2012M510526)
文摘Inland lakes are important water resources in arid and semiarid regions. Understanding climate effects on these lakes is critical to accurately evaluate the dynamic changes of water resources. This study focused on the changes in Sayram Lake of Xinjiang, China, and addressed the effects of climate fluctuations on the inland lake based on long-term sequenced remote sensing images and meteorological data from the past 40 years. A geo- graphic information system （GIS） method was used to obtain the hypsometry of the basin area of Sayram Lake, and estimation methods for evaporation from rising temperature and water levels from increasing precipitation were proposed. Results showed that： （1）Areal values of Sayram Lake have increased over the past 40 years. （2） Both temperature and precipitation have increased with average increases of more than 1.8~C and 82 mm, respectively. Variation of the water levels in the lake was consistent with local climate changes, and the areal values show linear relationships with local temperature and precipitation data. （3） According to the hypsometry data of the basin area, the estimated lake water levels increased by 2.8 m, and the water volume increased by 12.9×108 m3 over the past 40 years. The increasing area of Sayram Lake correlated with local and regional climatic changes because it is hardly affected by human activities.
