Abstract The Fertile Crescent (FC) region comprises the east coast of the Mediterranean Sea and the northern part of the Arabian Peninsula. The FC suffered two severe drought episodes separated by a 7-year period, in 1998–2000 and 2007–2009, which are considered the most severe episodes to hit the region in the last 50 years. A Lagrangian model (FLEXPART) and ERA-Interim data (with a 1° × 1° lat-long resolution) were used to identify for the first time the climatological sources of moisture for the FC and their characteristics. Variability and the source-receptor relationships, concerning their contribution to the precipitation, and the implications regarding the transport of moisture changes over the FC, during the wet season (October-May) from 1980 to 2014 were analysed. The main climatological moisture sources during this period were determined to be the FC itself, the eastern Mediterranean Sea, the Red Sea, the Persian Gulf, the Arabian Sea, the Caspian and Black Seas, and the central and western parts of the Mediterranean Sea. The analysis showed higher anomalous conditions in the moisture transport from some moisture sources during the two outstanding drought episodes. The key feature of the wet seasons during these episodes was a deficit in the moisture losses over the studied area related to the FC itself, the Red and Arabian Seas sources, followed and to a lesser extent by the eastern Mediterranean Sea over the northern part of the FC region. Nevertheless, the moisture supply deficit from the sources was much greater during the 2007–2009 drought event. The SPEI index at large scales (24 months) showed that the 2007–2009 episode was part of longer-term drought conditions that had been developing over the previous months, reinforcing the drought severity given recycling processes attributed to the FC. During the two extreme drought episodes, the mountainous terrain over the northern and eastern FC suffered the highest precipitation deficits, and these areas are, precisely, the most influenced by two of the major moisture sources, namely, the FC and eastern Mediterranean Sea. The decreased moisture contribution from these main sources led to more intense droughts over the region. As a result, both regions should be considered as hotspots to signal severe or extreme droughts in the region.

中文翻译：

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两次严重干旱期间新月沃土上水分收支的拉格朗日分析

摘要 新月沃地 (FC) 地区包括地中海东海岸和阿拉伯半岛北部。FC 在 1998-2000 年和 2007-2009 年遭受了两次间隔 7 年的严重干旱，这被认为是过去 50 年来该地区遭受的最严重的干旱。拉格朗日模型 (FLEXPART) 和 ERA-Interim 数据（具有 1° × 1° 经纬度分辨率）首次用于确定 FC 的气候学水分来源及其特征。分析了 1980 年至 2014 年雨季（10 月至 5 月）期间的变异性和源 - 受体关系，关于它们对降水的贡献，以及对 FC 上水分传输的影响。这一时期的主要气候湿源被确定为 FC 本身、东地中海、红海、波斯湾、阿拉伯海、里海和黑海以及地中海中西部。分析表明，在两次突出的干旱事件期间，来自某些水分源的水分输送出现了更高的异常情况。这些事件中雨季的主要特征是与 FC 本身、红海和阿拉伯海源相关的研究区域的水分损失不足，其次是地中海东部和北部FC 地区。然而，在 2007-2009 年干旱事件期间，来自源头的水分供应缺口要大得多。大规模（24 个月）的 SPEI 指数表明，2007-2009 年的事件是前几个月发展起来的长期干旱条件的一部分，鉴于 FC 的再循环过程，加剧了干旱的严重程度。在两次极端干旱期间，FC 北部和东部的山区遭受了最大的降水亏缺，而这些地区恰恰是受两个主要水分来源，即 FC 和地中海东部的影响最大的地区。这些主要来源的水分贡献减少导致该地区更加严重的干旱。因此，这两个地区都应被视为该地区严重或极端干旱信号的热点。