长江中下游1998年夏季梅雨期降水再循环研究

改进了Eltahir的降水再循环率计算模式,引入水汽变化量,使其可用于小于月际时间尺度的降水再循环评估。并利用1998年6~8月间长江中下游162个测站的旬蒸发和降水资料,结合NCEP/NCAR的高空逐日再分析资料,对长江中下游1998年梅雨期的降水再循环率做了计算。分析发现:1998年夏季暴雨时期长江中下游的降水平均约有三成来自当地的蒸发。区域蒸发的水汽在安徽南部和湖北东部对降水的贡献最大。区域平均再循环率的旬变化强烈,最高可达67.8%,最小只有0.8%。表明地表水文敏感,地-气相互作用不稳定。

Research on Precipitation Recycling during Meiyu Season over Middle-Lower Reaches of Changjiang River in 1998

The Eltahir calculation model is improved by considering the derivatives of water vapor to adapt to the under-monthly scale assessment of precipitation recycling ratio.By using the ten-day precipitation and evaporation data and NCEP/NCAR daily pressure level reanalysis data,the precipitation recycling ratio over the middle-lower reaches of the Changjiang River during Meiyu season in 1998 is estimated.It is found out that about 30% of precipitation in the research area is contributed by local evaporation during continual heavy rainfall summer in 1998.The greatest contribution is over the southern Anhui and eastern Hubei provinces.The ten-day precipitation recycling ratio varies frequently. The highest value is 67.8%,while the lowest is just 0.8%.That indicates the high sensibility of land surface hydrology and the instability of land-atmosphere interaction.