By using daily air temperature and precipitation data, and the weather phenomena data of daily snowfall from 98 meteorological stations over the Qinghai-Tibetan Plateau （QTP）, this paper performs an ＂at-risk＂ eval...By using daily air temperature and precipitation data, and the weather phenomena data of daily snowfall from 98 meteorological stations over the Qinghai-Tibetan Plateau （QTP）, this paper performs an ＂at-risk＂ evaluation on snowfall and accumulated snow over the QTP under current climate situation and future climate warming condition. When rainfall, snowfall, or accumulated snow weather phenomena occur, critical values are determined based on dally air temperature and precipitation for current climate conditions. Air temperature of 0 ℃ is defined as the critical value of temperature for rainfall or snowfall, while 0 ℃ air temperature and 4.0 mm （autumn） or 3.0 mm （spring） snowfall amounts are defined as the critical values for accumulated snowfall. Analyses based on the above critical values disclose that under current climate condition, stations with ＂at-risk＂ accumulated snow account for 33% and 36% of all stations, and the ＂at-risk＂ snowfall stations reach 78% and 81% in autumn and spring, respectively. Spatially, most stations with ＂at-risk＂ accumulated snow are located on the southern and eastern edge of the QTP, and stations with ＂at-risk＂ snowfall are also apparent at the northern edge. If the air temperature increases by 2.5 ℃ in 2050, only the snowfall at a few ＂at-risk＂ snowfall stations will transform into rainfall, while most ＂at-risk＂ accumulated snow stations will face the problem that snowfall is hardly accumulated. Additionally, most stations will become ＂at-risk＂ accumulated snow stations, indicating that both the snow depth and the snow cover duration will decline in most areas of the QTP, including a delay of the start date and an advancing of the end date of snow cover.展开更多
Maritime-type glaciers in the eastern Nyainqêntanglha Range, located in the southeastern part of the Tibetan Plateau, are an important water source for downstream residents and ecological systems. To better under...Maritime-type glaciers in the eastern Nyainqêntanglha Range, located in the southeastern part of the Tibetan Plateau, are an important water source for downstream residents and ecological systems. To better understand the variability of glaciers in this region, we used the band ratio threshold（TM3/TM5 for the Landsat TM /ETM＋ and TM4/TM6 for Landsat OLI） to extract glacier outlines in ~1999 and ~2013. After that, we also generated a series of glacier boundaries and monitored glacier variations in the past 40 years with the help of the Chinese Glacier Inventory data（1975） and Landsat TM, ETM＋ and OLI data. The total glacier area decreased by 37.69 ± 2.84% from 1975 to 2013. The annual percentage area change（APAC） was ~1.32% a-1 and ~1.29% a-1 in the periods 1975-1999 and 1999-2013, respectively. According to the lag theory, the reaction time is probably about 10 years and we discuss the variations of temperature and precipitation between 1965 and 2011. Temperature and precipitation increased between 1965 and 2011 at a rate of 0.34°C /10 a and 15.4 mm/10 a, respectively. Extensive meteorological data show that the glacier shrinkage rate over the period may be mainly due to increasing air temperature, while the increasing precipitation partly made up for the mass loss of glacier ice resulting from increasing temperature may also lead to the low APAC between 1999 and 2013. The lag theory suggests that glacier shrinkage may accelerate in the next 10 years. Small glaciers were more sensitive to climate change, and there was a normal distribution between glacier area and elevation. Glaciers shrank in all aspects, and south aspects diminished faster than others.展开更多
基金supported by the opening fund from the State Key Laboratory of Cryospheric Sciences, Cold and Arid Regions Environmental and Engineering Research Institute,Chinese Academy of Sciences(SKLCS 08-07)the National Postdoctoral Scientific Foundation (20080440342)
文摘By using daily air temperature and precipitation data, and the weather phenomena data of daily snowfall from 98 meteorological stations over the Qinghai-Tibetan Plateau （QTP）, this paper performs an ＂at-risk＂ evaluation on snowfall and accumulated snow over the QTP under current climate situation and future climate warming condition. When rainfall, snowfall, or accumulated snow weather phenomena occur, critical values are determined based on dally air temperature and precipitation for current climate conditions. Air temperature of 0 ℃ is defined as the critical value of temperature for rainfall or snowfall, while 0 ℃ air temperature and 4.0 mm （autumn） or 3.0 mm （spring） snowfall amounts are defined as the critical values for accumulated snowfall. Analyses based on the above critical values disclose that under current climate condition, stations with ＂at-risk＂ accumulated snow account for 33% and 36% of all stations, and the ＂at-risk＂ snowfall stations reach 78% and 81% in autumn and spring, respectively. Spatially, most stations with ＂at-risk＂ accumulated snow are located on the southern and eastern edge of the QTP, and stations with ＂at-risk＂ snowfall are also apparent at the northern edge. If the air temperature increases by 2.5 ℃ in 2050, only the snowfall at a few ＂at-risk＂ snowfall stations will transform into rainfall, while most ＂at-risk＂ accumulated snow stations will face the problem that snowfall is hardly accumulated. Additionally, most stations will become ＂at-risk＂ accumulated snow stations, indicating that both the snow depth and the snow cover duration will decline in most areas of the QTP, including a delay of the start date and an advancing of the end date of snow cover.
基金supported by the National Science Foundation of China (Grant Nos. 41271024, 41411130204)
文摘Maritime-type glaciers in the eastern Nyainqêntanglha Range, located in the southeastern part of the Tibetan Plateau, are an important water source for downstream residents and ecological systems. To better understand the variability of glaciers in this region, we used the band ratio threshold（TM3/TM5 for the Landsat TM /ETM＋ and TM4/TM6 for Landsat OLI） to extract glacier outlines in ~1999 and ~2013. After that, we also generated a series of glacier boundaries and monitored glacier variations in the past 40 years with the help of the Chinese Glacier Inventory data（1975） and Landsat TM, ETM＋ and OLI data. The total glacier area decreased by 37.69 ± 2.84% from 1975 to 2013. The annual percentage area change（APAC） was ~1.32% a-1 and ~1.29% a-1 in the periods 1975-1999 and 1999-2013, respectively. According to the lag theory, the reaction time is probably about 10 years and we discuss the variations of temperature and precipitation between 1965 and 2011. Temperature and precipitation increased between 1965 and 2011 at a rate of 0.34°C /10 a and 15.4 mm/10 a, respectively. Extensive meteorological data show that the glacier shrinkage rate over the period may be mainly due to increasing air temperature, while the increasing precipitation partly made up for the mass loss of glacier ice resulting from increasing temperature may also lead to the low APAC between 1999 and 2013. The lag theory suggests that glacier shrinkage may accelerate in the next 10 years. Small glaciers were more sensitive to climate change, and there was a normal distribution between glacier area and elevation. Glaciers shrank in all aspects, and south aspects diminished faster than others.
