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Evaluation of hydrological balance and its variability in arid and semi‐arid regions of Eurasia from ECMWF 15 year reanalysis
Author(s) -
Yatagai Akiyo
Publication year - 2003
Publication title -
hydrological processes
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.222
H-Index - 161
eISSN - 1099-1085
pISSN - 0885-6087
DOI - 10.1002/hyp.1439
Subject(s) - precipitation , arid , evapotranspiration , water balance , moisture , climatology , environmental science , hydrometeorology , plateau (mathematics) , cru , geography , geology , meteorology , paleontology , ecology , mathematical analysis , geotechnical engineering , mathematics , biology
Hydrometeorological cycles over arid and semi‐arid regions in mid‐latitude Eurasia (the Silk Road region) were investigated using meteorological reanalysis data for the period 1979–93, available from the European Centre for Medium‐range Weather Forecasts (ECMWF). Results show that seasonal changes of moisture balance in Turkey and central Asia, hereafter referred to as the western region, differ from those in the Taklimakan Desert and Loess Plateau, hereafter referred to as the eastern region. Here, we equate evaporation minus precipitation with the divergence field of the vertically integrated water vapour flux. In the western region, precipitation and positive convergence C of moisture primarily occurs during October–March. In contrast, the eastern region receives precipitation and has its positive C occurring during June–August. As a result, the eastern region has nearly simultaneous seasonal peaks in precipitation P and evapotranspiration E , whereas the western region has minimum P and maximum E in summer. The main annual moisture route for the Silk Road region is from the west to east; however, moisture also comes from the north in July. Over Turkey, moisture arrives from the west and south. In central Asia, however, most of the moisture comes from the west, the convergence peaks in March, and moisture from the south and west is also greater during this month. In the Loess Plateau, moisture enters from the west, the north, and the south, and exits to the east. In July, the peak precipitation and convergence season, all moisture flows are greater for the entire region, and a large influx of moisture from the south occurs during the summer season. The moisture from the south, the monsoonal flow, has a large interannual variability. Copyright © 2003 John Wiley & Sons, Ltd.