A global dataset of Palmer Drought Severity Index for 1870-2002: Relationship with soil moisture and effects of surface warming
A global dataset of Palmer Drought Severity Index for 1870-2002: Relationship with soil moisture and effects of surface warming
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DOI：
10.1175/jhm-386.1
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发表时间：
2004-12-01
影响因子：
3.8
通讯作者：
Qian, TT
中科院分区：
文献类型：
--
作者：
Dai, A;Trenberth, KE;Qian, TT
1870 年至 2002 年帕尔默干旱严重度指数 (PDSI) 的月度数据集是使用 2.58 网格上全球陆地区域的历史降水量和温度数据得出的。在可获得土壤湿度数据的伊利诺伊州、蒙古以及中国和前苏联的部分地区，PDSI 与暖季月份表层 1 米深度内观测到的土壤湿度显着相关（r = 0.5 至 0.7）。相关性最强的是夏末和秋季，相关性最弱的是春季，此时融雪起着重要作用。流域平均年度 PDSI 与所研究的世界上七条最大河流和几条较小河流的水流密切相关（r = 0.6 至 0.8）。结果表明，PDSI 可以很好地代表地表湿度条件和水流。 PDSI 的经验正交函数 (EOF) 分析揭示了降水和地表温度趋势导致的相当线性的趋势，以及厄尔尼诺南方涛动 (ENSO) 引起的主要年际变化模式作为两种主要模式。全球非常干旱地区（定义为 PDSI < -3.0）自 1970 年代以来增加了一倍多，其中由于 ENSO 引起的降水减少而在 1980 年代初大幅跃升，随后主要由于地表变暖而扩大，而全球非常湿润地区（PDSI > +3.0）在 1980 年代略有下降。全球处于非常干燥或非常潮湿条件下的陆地面积总计增加了：自 1972 年以来下降了 20% 至 38%，其中地表变暖是 20 世纪 80 年代中期之后的主要原因。这些结果为随着人为全球变暖的进展并导致气温升高和干燥加剧而增加的干旱风险提供了观测证据。
A monthly dataset of Palmer Drought Severity Index (PDSI) from 1870 to 2002 is derived using historical precipitation and temperature data for global land areas on a 2.58 grid. Over Illinois, Mongolia, and parts of China and the former Soviet Union, where soil moisture data are available, the PDSI is significantly correlated ( r = 0.5 to 0.7) with observed soil moisture content within the top 1-m depth during warm-season months. The strongest correlation is in late summer and autumn, and the weakest correlation is in spring, when snowmelt plays an important role. Basin-averaged annual PDSI covary closely ( r = 0.6 to 0.8) with streamflow for seven of world's largest rivers and several smaller rivers examined. The results suggest that the PDSI is a good proxy of both surface moisture conditions and streamflow. An empirical orthogonal function (EOF) analysis of the PDSI reveals a fairly linear trend resulting from trends in precipitation and surface temperature and an El Nino Southern Oscillation (ENSO)-induced mode of mostly interannual variations as the two leading patterns. The global very dry areas, defined as PDSI < -3.0, have more than doubled since the 1970s, with a large jump in the early 1980s due to an ENSO-induced precipitation decrease and a subsequent expansion primarily due to surface warming, while global very wet areas (PDSI > +3.0) declined slightly during the 1980s. Together, the global land areas in either very dry or very wet conditions have increased from; 20% to 38% since 1972, with surface warming as the primary cause after the mid-1980s. These results provide observational evidence for the increasing risk of droughts as anthropogenic global warming progresses and produces both increased temperatures and increased drying.