Uncertainties in historical changes and future projections of drought. Part I: estimates of historical drought changes
Uncertainties in historical changes and future projections of drought. Part I: estimates of historical drought changes
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DOI：
10.1007/s10584-016-1705-2
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发表时间：
2017-10-01
期刊：
影响因子：
4.8
通讯作者：
Zhao, Tianbao
中科院分区：
文献类型：
--
作者：
Dai, Aiguo;Zhao, Tianbao
随着全球变暖的继续，未来干旱可能会如何变化引起了人们的极大关注。在这项研究的第一部分，我们研究了估计最近干旱变化的不确定性。由于强迫资料(特别是降水、太阳辐射和风速)和定标周期的不同，用Penman-Monteith潜在蒸散量(PDSI_PM)计算的Palmer干旱严重程度指数(PDSI)存在很大的不确定性。经过详细分析后，我们建议使用全球降水气候学中心(GPCC)或全球降水气候学(GPCP)数据集，而不是其他现有的陆地降水产品，因为自1990年代以来，其他数据集的数据覆盖率很低。我们还建议不要将1980年之后的年份纳入PDSI校准期，以避免将人为气候变化作为用于校准的自然变率的一部分。与报告的蒸发皿蒸发量下降一致，我们计算的潜在蒸散量自1950年以来在美国、中国和其他地区显示出负或小的趋势，而从1950年到1990年没有全球蒸散量的趋势。更新的降水和径流数据以及自行校准的PDSI_PM都显示，在1950-2012年期间，大部分非洲、东亚和南亚、南欧、东澳大利亚和美洲许多地区都出现了一致的干旱。虽然这些区域干燥趋势主要是由于与太平洋海面温度几十年振荡有关的降水变化造成的，但自1980年代以来，表面迅速变暖以及由此导致的地表水汽压赤字增加，已成为陆地上普遍干燥的一个日益重要的原因。
How drought may change in the future are of great concern as global warming continues. In Part I of this study, we examine the uncertainties in estimating recent drought changes. Substantial uncertainties arise in the calculated Palmer Drought Severity Index (PDSI) with Penman-Monteith potential evapotranspiraiton (PDSI_pm) due to different choices of forcing data (especially for precipitation, solar radiation and wind speed) and the calibration period. After detailed analyses, we recommend using the Global Precipitation Climatology Centre (GPCC) or the Global Precipitation Climatology (GPCP) datasets over other existing land precipitation products due to poor data coverage in the other datasets since the 1990s. We also recommend not to include the years after 1980 in the PDSI calibration period to avoid including the anthropogenic climate change as part of the natural variability used for calibration. Consistent with reported declines in pan evaporation, our calculated potential evapotranspiration (PET) shows negative or small trends since 1950 over the United States, China, and other regions, and no global PET trends from 1950 to 1990. Updated precipitation and streamflow data and the self-calibrated PDSI_pm all show consistent drying during 1950-2012 over most Africa, East and South Asia, southern Europe, eastern Australia, and many parts of the Americas. While these regional drying trends resulted primarily from precipitation changes related to multi-decadal oscillations in Pacific sea surface temperatures, rapid surface warming and associated increases in surface vapor pressure deficit since the 1980s have become an increasingly important cause of widespread drying over land.