Regional downscaling of Mediterranean droughts under past and future climatic conditions
Regional downscaling of Mediterranean droughts under past and future climatic conditions
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DOI：
10.1016/j.gloplacha.2016.10.015
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发表时间：
2017-04-01
影响因子：
3.9
通讯作者：
Tramblay, Yves
中科院分区：
文献类型：
--
作者：
Hertig, Elke;Tramblay, Yves
地中海气候的复杂性、降水量的高度多变性以及季节分布的不均衡性（大约10月至4月为雨季，夏季为旱季），为地中海地区极易遭受干旱创造了一般条件。在过去几十年中，由于气温上升加上降水减少，地中海地区发生干旱的风险似乎有所增加。这种向更温暖和更干燥条件的普遍变化预计将在未来继续。在本研究中，干旱是由标准化降水指数（SPI），在114个站位于整个地中海地区。SPI是相对于特定位置的干旱严重程度的标准化度量，从不同时间段的降雨总量中获得。这允许比较不同的位置和具有类似SPI变化的同质区域的描绘。已确定13个区域。利用基于位势高度和相对湿度的环流类型作为预报因子，建立了一种降尺度方法，对不同地区的SPI时间序列进行降尺度处理。使用运行21年的验证期的降尺度方法进行了验证，以评估在不同的气候条件下的方法的技能，并检测可能的非平稳性的预测和预测的关系。结果表明，降尺度方法提供了令人满意的结果，除了最干旱的地区。根据情景RCP 8.5，MPI-ESM-LR模型的三个成员集合提供的未来预测表明，2070-2100年期间整个地中海地区的干旱严重程度和发生率将增加。(C)2016爱思唯尔B. V.保留所有权利。
The complexity of the Mediterranean climate with its high precipitation variability and its unequal seasonal distribution with a wet season from approximately October to April and a dry season in summer set general conditions for a high vulnerability of the Mediterranean area to droughts. In the last few decades the risk of drought episodes appears to be enhanced in the Mediterranean area due to temperature increases combined with precipitation decreases. This general change towards warmer and dryer conditions is expected to continue in the future. In the present study droughts are represented by the Standardized Precipitation Index (SPI), at 114 stations located across the Mediterranean area. The SPI is a normalized measure of drought severity relative to a specific location, obtained from rainfall totals aggregated over different time periods. This allows a comparison of different locations and the delineation of homogeneous regions with similar SPI variability. 13 regions have been identified. A downscaling approach using circulation types based on geopotential heights and relative humidity as predictors has been set up to downscale the SPI time series in the different regions. The downscaling approach has been validated using running 21 years validation periods, in order to assess the skill of the method during different climatic conditions and to detect possible non-stationarities in the predictors-predictand relationships. Results show that the downscaling method provided satisfactory results, except for the most arid regions. Future projections, provided from a three member ensemble of the MPI-ESM-LR model under scenario RCP 8.5, indicate an increase in the drought severity and occurrence for the whole Mediterranean region for the period 2070-2100. (C) 2016 Elsevier B.V. All rights reserved.