Division of Earth Environmental System Science (Major of Environmental Engineering), Pukyong National University, Busan 48513, Republic of Korea.
Department of Environmental Engineering, Pukyong National University, Busan 48513, Republic of Korea.
Sci Total Environ. 2020 Nov 20;744:140701. doi: 10.1016/j.scitotenv.2020.140701. Epub 2020 Jul 9.
The drought index, which mainly focuses on the moisture supply side of the atmosphere, which has been mainly used in the field of drought monitoring, has limitations that cannot reflect drought caused by changes in various climate variables such as an increase in surface air temperature due to global warming. To overcome these limitations, various evaporation demand-based drought indices have been proposed, focusing on the aspect of atmospheric moisture demand. However, drought indices that consider only precipitation or the demand for atmospheric evaporation are difficult to comprehensively interpret drought caused by various climatic factors. The novelty of this study is to propose a new drought index to simultaneously monitor droughts occurring in terms of atmospheric moisture supply and demand. The proposed Copula-based Joint Drought Index (CJDI) combines the Standardized Precipitation Index and the Evaporative Demand Drought Index using copula. Since CJDI reflects the correlation between the two drought indices, it is shown that CJDI can better monitor Korea's past droughts than other drought indices. It is found that quantification of past drought using CJDI can be used to objectively recognize the level of drought currently in progress by combining with drought severity-duration-frequency curves derived from partial duration series. As a result of analyzing the future drought pattern in Korea, it was revealed that the drought would be alleviated by about 11% in the case of SPI and SPEI, but the drought would intensify by about 89% in the case of EDDI. In the case of CJDI, it is projected that the drought is likely to intensify to about 17%. From the perspective of better reproducing past droughts and projecting a more convincing future drought than other drought indices, CJDI is expected to be fully utilized as a drought index to monitor droughts and establish climate change adaptation policies.
干旱指数主要关注大气的水分供应侧，主要用于干旱监测领域，但存在无法反映因全球变暖导致地面气温升高而引起的干旱等各种气候变量变化的局限性。为了克服这些局限性，已经提出了各种基于蒸发需求的干旱指数，主要关注大气水分需求方面。但是，只考虑降水或大气蒸发需求的干旱指数很难全面解释各种气候因素引起的干旱。本研究的新颖之处在于提出了一种新的干旱指数，以同时监测大气水分供应和需求方面发生的干旱。提出的基于 Copula 的联合干旱指数 (CJDI) 使用 Copula 将标准化降水指数和蒸发需求干旱指数结合起来。由于 CJDI 反映了两个干旱指数之间的相关性，因此表明 CJDI 可以比其他干旱指数更好地监测韩国过去的干旱。通过与从部分持续时间序列得出的干旱严重程度-持续时间-频率曲线相结合，利用 CJDI 对过去干旱的量化可以用于客观地认识当前正在进行的干旱水平。通过分析韩国未来的干旱模式，结果表明 SPI 和 SPEI 的情况下干旱将减轻约 11%，而 EDDI 的情况下干旱将加剧约 89%。在 CJDI 的情况下，预计干旱可能会加剧到约 17%。从更好地再现过去干旱和比其他干旱指数更有说服力地预测未来干旱的角度来看，预计 CJDI 将被充分用作监测干旱和制定气候变化适应政策的干旱指数。
