地基GPS反演泥石流流域局地降水水汽特征——以云南东川蒋家沟为例

Precipitable Water Vapor in the Debris-Flow Watershed Inversed by Ground-based GPS——A Case Study of the Jiangjia Valley in Yunnan Province

在暴雨型泥石流预警预报中,如何准确获取有效的降水信息是关键问题。基于蒋家沟流域内布设的地基GPS观测站和流域内3个雨量站点,对比分析大气可降水量(PWV)和站点实际降水,发现PWV变化趋势与降水的发生有较好的对应关系,降水一般发生在PWV的峰值处或滞后于峰值发生;根据PWV过程中的极小值将长序列PWV过程划分为数组短序列PWV过程,引入前期PWV和有效PWV,通过有降水的前期累积PWV和有效累积PWV的散点函数拟合确定降水发生时的PWV临界线,PWV临界线将为泥石流流域的降水预警提供依据,同时可证明地基GPS反演PWV对泥石流流域尺度下的降水预警具有重要价值,其反演得到的PWV不仅是降水预报中的重要因子,PWV临界线的确定亦为降水的准确性和时效性提供参考。

Accurate and effective precipitation information is crucial for forecast of rainstorm debris-flow. The value of the water vapor, which has indicative significance for the occurrence and continual of the precipitation, has be- come the key factor of rainfall prediction. This study was aimed to interpret the process of Precipitable Water Vapor （PWV） being translated into the observed precipitation and analyze the characteristic of PWV when the precipitation trigger debris-flow. Based on the data from ground-based GPS station and three rainfall stations in the Jiangjia val- ley, a relationship between the trend of PWV and the occurrence of precipitation was found. Precipitation always occurred in or after the peak of PWV curve. The long PWV curve was divided into several short PWV curves by the minimum value of PWV. Then the preliminary PWV and effective PWV were defined. The critical PWV line was de- termined by fitting function of the preliminary PWV and effective PWV, which made a contribution to precipitation forecast. It was proved that the PWV inversed by ground-based GPS is of great significance to forecast of precipitati- on in the debris-flow watershed.