Interannual variability of surface evaporative moisture sources of warm‐season precipitation in the Mississippi River basin
Interannual variability of surface evaporative moisture sources of warm‐season precipitation in the Mississippi River basin
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密西西比河流域暖季降水地表蒸发水源的年际变化
DOI：
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发表时间：
2003
期刊：
影响因子：
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通讯作者：
P. Dirmeyer
中科院分区：
文献类型：
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作者：
A. Sudradjat;K. Brubaker;P. Dirmeyer
[1]研究了密西西比河流域降水蒸发源的变化模式。在密西西比及其次流域的选定区域的蒸发贡献的暖季降水的时间序列产生的15天的基础上，1963年至1998年。源区的贡献是通过后向轨迹分析来估计的，后向轨迹分析是在时间上从凝结点到蒸发点追踪水汽。所需的大气动力学资料和NCEP气候预报中心降水观测资料均采用NCEP再分析资料。源贡献和降水异常时间序列的相关性和主成分分析揭示了由内部（密苏里州，红/阿肯色州，下密西西比）和外部（得克萨斯州/墨西哥和加勒比海）的来源，这解释了统计上的暖季降水的年际变化的空间格局。进一步分析表明，在降水异常中，外源的作用大于内源。检查一个子集的时期，从1979年到1998年，水分通量分析证实了外部来源的作用，通过显示降水异常和通量之间的强关联跨越南部边界的盆地（其中包括得克萨斯州/墨西哥和加勒比海地区的贡献）。介绍了一个指数，根据可测量的表面压力之间的差异中心在大西洋和美国中部（密西西比流域）。该指数在预测流域降水供应缓慢变化方面具有潜在的实用价值。
[1] Patterns of variability of the evaporative sources of Mississippi River basin precipitation are investigated. Time series of selected regions' evaporative contributions to warm-season precipitation in the Mississippi and its subbasins are produced on a 15-day basis for the years 1963 to 1998. Source region contributions are estimated by backward-trajectory analysis, which tracks water vapor backward in time from its site of condensation to its point of evaporation. The National Centers for Environmental Prediction (NCEP) reanalyses are used for the required atmospheric dynamics and observed data from NCEP Climate Prediction Center for precipitation. Correlation and principal component analyses of the source contribution and precipitation anomaly time series reveal a spatial pattern consisting of internal (Missouri, Red/Arkansas, and Lower Mississippi) and external (Texas/Mexico and Caribbean) sources, which explains statistically much of the interannual variability in warm-season precipitation. Further analysis of the pattern reveals that the external sources play a more important role than internal sources in the anomalies of precipitation. Examining a subset of the period, from 1979 to 1998, moisture flux analysis confirms the role of the external sources by showing the strong association between the precipitation anomalies and flux across the southern boundaries of the basin (which includes the contributions from Texas/Mexico and Caribbean). An index is introduced, based on measurable surface pressure differences between centers over the Atlantic Ocean and central United States (Mississippi watershed). The index is potentially useful in forecasting slow variations of precipitation supply in the basin.