School of Geography and Information Engineering, China University of Geosciences (Wuhan), Wuhan 430078, China; Artificial Intelligence School, Wuchang University of Technology, Wuhan 430223, China.
School of Geography and Information Engineering, China University of Geosciences (Wuhan), Wuhan 430078, China.
Sci Total Environ. 2023 Jul 20;883:163403. doi: 10.1016/j.scitotenv.2023.163403. Epub 2023 Apr 12.
Drought is a prolonged dry period in the natural climate cycle, and is one of the most costly weather events. The Gravity Recovery and Climate Experiment (GRACE) derived terrestrial water storage anomalies (TWSA) have been widely used to assess drought severity. However, the relatively short cover period of GRACE and GRACE Follow-On limit our knowledge about the characterization and evolution of drought over decades time scale. This study proposes a standardized GRACE reconstructed TWSA index (SGRTI) to assess the drought severity based on a statistical reconstruction method calibrated by GRACE observations. Results show that the SGRTI correlates well with 6-month scale SPI and SPEI, with correlation coefficients reaching 0.79 and 0.81 in the YRB from 1981 to 2019. Soil moisture can capture drought condition like the SGRTI, while cannot further reflect deeper water storage depletion. The SGRTI is also comparable to the SRI and in-situ water level. As a case study for the Yangtze River Basin, its three sub-basins experience more frequent droughts, shorter drought duration, and lower severity drought, as identified by SGRTI during 1992-2019 relative to 1963-1991. The presented SGRTI in this study can provide a valuable supplement to the drought index before the GRACE era.
干旱是自然气候周期中一段长时间的干燥期，是最昂贵的天气事件之一。地球重力恢复和气候实验（GRACE）得出的陆地水储量异常（TWSA）已被广泛用于评估干旱严重程度。然而，GRACE 和 GRACE Follow-On 的相对较短的覆盖周期限制了我们对几十年时间尺度上干旱特征和演变的了解。本研究提出了一种标准化的 GRACE 重建 TWSA 指数（SGRTI），通过 GRACE 观测校准的统计重建方法来评估干旱严重程度。结果表明，SGRTI 与 6 个月尺度的 SPI 和 SPEI 高度相关，在 1981 年至 2019 年的 YRB 中，相关系数分别达到 0.79 和 0.81。土壤湿度可以像 SGRTI 一样捕捉干旱状况，但不能进一步反映更深层次的储水耗竭情况。SGRTI 与 SRI 和原位水位也相当。作为长江流域的案例研究，在 1992 年至 2019 年期间，与 1963 年至 1991 年相比，该流域三个子流域的干旱更频繁、干旱持续时间更短、干旱严重程度更低，这是由 SGRTI 识别的。本研究中提出的 SGRTI 可以为 GRACE 时代之前的干旱指数提供有价值的补充。
