摘要
Vapor pressure deficit（VPD） is an important parameter in modelling hydrologic cycles and vegetation productivity. Meteorological stations are scarce in remote areas,which often results in imprecise estimations of VPD on the Tibetan Plateau. Moderate Resolution Imaging Spectroradiometer（MODIS） provides evapotranspiration data,which may offer the possibility of scaling up VPD estimations on the Tibetan Plateau. However,no studies thus far have estimated VPD using MODIS evapotranspiration data on the Tibetan Plateau. Therefore,this study used MODIS potential evapotranspiration（PET） to estimate VPD in alpine meadows,alpine steppes,croplands,forests and shrublands for the year,spring,summer,autumn and winter in 2000-2012. A series of root-meansquared-error（RMSE） and mean-absolute-error（MAE） values were obtained for correlating measured VPD and estimated VPD using MODIS PET data for each listed time period and vegetation type： whole year（0.98-2.15 hPa and 0.68-1.44 hPa）,spring（0.95-2.34 hPa and 0.72-1.54 hPa）,summer（1.39-2.60 hPa and 0.89-1.96 hPa）,autumn（0.78-1.93 hPa and 0.56-1.36 hPa）,winter（0.48-1.40 hPa and 0.36-0.98 hPa）,alpine steppes（0.48- 1.39 hPa and 0.36-1.00 hPa）,alpine meadows（0.58-1.39 hPa and 0.44-0.90 hPa）,croplands（1.10-2.55 hPa and 0.82-1.74 hPa）,shrublands（0.98-1.90 hPa and 0.78-1.37 hPa）,and forests（1.40-2.60 hPa and 0.98-1.96 hPa）,respectively. Therefore,MODIS PET may be used to estimate VPD,and better results may be obtained if future studies incorporate vegetation types and seasons when the VPD data are estimated using MODIS PET on the Tibetan Plateau.
饱和水汽压亏缺是一个非常重要的模拟水循环和植被生产力的参数。青藏高原上的气象站比较稀少,这限制了饱和水汽压亏缺的精确估计。中分辨率成像光谱仪提供了蒸散数据,这为模拟饱和水汽压亏缺提供了可能。尽管如此,在青藏高原上,还没有研究利用中分辨率成像光谱仪的蒸散数据模拟饱和水汽压亏缺。因此,本研究利用中分辨率成像光谱仪的潜在蒸散数据模拟了高寒草甸、高寒草原、农田、森林和灌木2000-2012年四季的饱和水汽压亏缺。春季的均方根误差和平均绝对误差分别是0.95–2.34 hPa和0.72–1.54 hPa,夏季的的均方根误差和平均绝对误差分别是1.39–2.60 hPa和0.89–1.96 hPa,秋季的均方根误差和平均绝对误差分别是0.78–1.93 hPa和0.56–1.36 hPa,冬季的均方根误差和平均绝对误差分别是0.48–1.40 hPa和0.36–0.98 hPa。高寒草原的均方根误差和平均绝对误差分别是0.48–1.39 hPa和0.36–1.00 hPa,高寒草甸的均方根误差和平均绝对误差分别是0.58–1.39 hPa和0.44–0.90 hPa,农田的均方根误差和平均绝对误差分别是1.10–2.55 hPa和0.82–1.74 hPa,灌木的均方根误差和平均绝对误差分别是0.98–1.90 hPa和0.78–1.37 hPa,森林的分别是1.40–2.60 hPa和0.98–1.96 hPa。因此,中分辨率成像光谱仪的潜在蒸散数据可以用来模拟青藏高原的饱和水汽压亏缺,且需要考虑整合植被类型和季节。
基金
National Key Research and Development Program of China(2017YFA0604801
2016YFC0502006)
National Natural Science Foundation of China(41571042
31600432)
Chinese Academy of Science Western Light Talents Program(Response of livestock carrying capability to climatic change and grazing in the alpine meadow of Northern Tibetan Plateau)
the Youth Innovation Research Team Project of Key Laboratory of Ecosystem Network Observation and Modeling(LENOM2016Q0002)
Natural Science Foundation of Tibet Autonomous Region(Response of species richness and above-ground biomass to warming in the alpine meadow of Tibet)
Science and Technology Plan Projects of Tibet Autonomous Region(Forage Grass Industry)
