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A Meteorological Drought Index Accounting for the Lagged Response between Precipitable Water Vapor and Precipitation
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DOI：10.1016/j.asr.2026.05.022.png)
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Abstract
En 中文
Global Navigation Satellite System (GNSS)-derived Precipitable Water Vapor (PWV) provides high-precision, high-temporal-resolution atmospheric water vapor data, offering a physically grounded basis for developing meteorological drought indices. Building on this advantage, this study proposes a Standardized Lagged Precipitation–PWV Conversion Index (SLPCI) tailored to the Poyang Lake Basin, explicitly accounting for the empirically identified lagged hydroclimatic response between PWV and precipitation. To enable basin-scale drought characterization, we further develop an Area-Weighted SLPCI (ASLPCI) using spatially explicit areal weighting. Results reveal a consistent 1–2 month lag in the PWV response relative to precipitation across the basin—i.e., precipitation peaks precede PWV peaks by 1–2 months. At the station level, SLPCI demonstrates strong agreement with three established benchmarks: the Standardized Precipitation–PWV Conversion Index (SPCI), Standardized Precipitation Index (SPI), and Standardized Precipitation Evapotranspiration Index (SPEI). Across 1-, 3-, and 6-month accumulation scales, SLPCI achieves 7.9%–35.1% higher Pearson correlation coefficients (PCCs) with SPI and SPEI—and 26.8%–30.1% lower root mean square errors (RMSEs)—relative to SPCI. At the regional scale, ASLPCI significantly outperforms the Area-Weighted SPCI (ASPCI) in consistency with the Area-Weighted SPI (ASPI) and Area-Weighted SPEI (ASPEI): PCCs improve by 23.90%–58.50%, and RMSEs decrease by 29.70%–44.20% across all three time scales. Crucially, run theory–based drought identification shows that ASLPCI detects more frequent and longer-lasting drought events than both ASPI and ASPEI—indicating superior sensitivity to sustained moisture deficits. Collectively, these findings demonstrate that ASLPCI delivers robust, physically informed, and spatially representative drought monitoring capability for the Poyang Lake Basin, thereby supporting timely and evidence-based drought risk management.
Keywords:
Precipitable Water Vapor
Meteorological Drought Index
Lagged Response
Area-Weighted Index
Drought Monitoring
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