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联合GNSS大气可降水量与实测降水的气象干旱监测:以湖北省GNSS站为例

Meteorological drought monitoring combined with GNSS precipitable water vapor and measured precipitation: a case study of GNSS stations in Hubei Province

  • 摘要: 全球导航卫星系统(Global Navigation Satellite System, GNSS)反演的大气可降水量(Precipitable Water Vapor, PWV)为暴雨等气象灾害监测提供了新的数据。本文从大气水汽和降水的综合角度,联合2011—2022年湖北省陆态网5个GNSS台站的PWV和中国逐日降水数据构建了月尺度降水效率(Precipitation Efficiency, PE)气象干旱指数,并通过与常用的标准化降水指数(Standardized Precipitation Index, SPI)、气象干旱综合监测指数(Meteorological Drought Composite Index, MCI)和标准化降水蒸散发指数(Standardized Precipitation Evapotranspiration Index, SPEI)进行对比,分析PE气象干旱指数的特点和优势。结果表明:(1) 5个GNSS站点大气水汽变化具有较好的空间一致性,而降水则具有较强的局地变化特征,站点间PWV的相关系数均大于0.98,降水量相关系数在0.66~0.90之间。二者的融合将能同时反映干旱期间大范围水汽和局地降水的综合变化特征。(2) PE气象干旱指数与SPI、MCI、SPEI具有较强的相关性,相关系数在0.56~0.85之间,表明PE监测干旱的有效性,但在反映干旱严重程度和空间分布特征方面表现出一定的差异。(3) GNSS站点间PE的相关系数(0.50~0.81)是四种指数中最小的,说明PE气象干旱指数具备反映局地干旱特征差异的能力。采用PE气象干旱指数对湖北省GNSS站点干旱事件的监测结果显示,2011—2022年间襄樊站发生严重干旱的频次最高,而武汉站伏秋旱发生次数多且持续时间较长。研究结果证实了PE气象干旱指数监测干旱演变过程及干旱空间分布特征的有效性和优势。

     

    Abstract: The atmospheric precipitable water vapor (PWV) derived from Global Navigation Satellite System (GNSS) provides new data for monitoring meteorological disasters such as heavy rainfall. In this study, we constructed the monthly Precipitation Efficiency (PE) meteorological drought index from a comprehensive perspective of atmospheric water vapor and precipitation, based on daily PWV and precipitation data from five GNSS stations in Hubei Province during 2011-2022. The characteristics and advantages of the index was verified using Standardized Precipitation Index (SPI), Meteorological Drought Composite Index (MCI) and Standardized Precipitation Evapotranspiration Index (SPEI). The results are as follows. (1) The variation of atmospheric water vapor in Hubei Province has good spatial consistency, while precipitation has strong local variation characteristics. The correlation coefficients of PWV at five GNSS stations are all greater than 0.98, and the correlation coefficients of rainfall are between 0.66 and 0.90. A combination of these two factors could reflect the comprehensive variations in large-scale PWV and local precipitation. (2) PE index was well correlated with SPI, MCI and SPEI (correlations ranging from 0.56 to 0.85), indicating the effectiveness of PE. (3) The correlation coefficient of PE between GNSS stations (0.50~0.81) is the smallest among the four indexes, indicating that the PE meteorological drought index has the ability to reflect the difference of local drought characteristics. PE index indicates that Xiangfan was a high-frequency site of severe drought during 2011-2022. Drought events in Wuhan site frequently occurred in autumn season and lasted a long time. Results confirmed the effectiveness and advantages of the drought indices constructed from GNSS PWV in characterizing drought evolution and spatial distribution.

     

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