Links between circulation and changes in the characteristics of Iberian rainfall
Links between circulation and changes in the characteristics of Iberian rainfall
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DOI：
10.1002/joc.810
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发表时间：
2002-11-15
期刊：
影响因子：
--
通讯作者：
Jones, PD
中科院分区：
文献类型：
--
作者：
Goodess, CM;Jones, PD
研究大气环流模式和降雨量之间的联系对于了解气候变化和发展基于经验环流的降尺度方法很重要。本文利用一个自动环流分类方案和18个测站的日降雨量，研究了1958-1997年期间伊比利亚半岛环流-降水关系的时空变化。环流分类方案与北大西洋涛动(NAO)之间的联系以及降水与NAO之间的直接联系也被考虑在内。探讨了降雨量和环流型频率的趋势。除地中海东南部海岸外，半岛平均季节降雨量减少的总体趋势掩盖了雨日数量和降雨概率的较大变化。伊比利亚大部分地区的降雨日有增加和减少的趋势，地中海东南部沿海的降雨日有增加和减少的趋势，这两者都反映在降雨量分位数的变化上。初步分析表明，这些变化可能在所有环流类型中发生了系统的变化。对降雨量和环流类型频率的趋势进行比较，发现了可能的联系。这些联系得到了线性回归分析的支持，线性回归分析使用环流类型频率作为预测变量，并以冬季月份的降雨量总数作为预测变量。选定的预报变量反映了影响整个半岛冬季降水的主要环流特征，即在半岛大部分地区受到大西洋西风和西南风气团的强烈影响，在西班牙北部/西北部和葡萄牙北部受到北风和西北风地面气流的强烈影响，以及在西班牙东南部受到地中海而不是大西洋影响的较强影响。然而，观测到的降雨量变化不能仅用环流变化来解释。版权所有(C)2002年皇家气象学会。
Investigation of the links between atmospheric circulation patterns and rainfall is important for the understanding of climatic variability and for the development of empirical circulation-based downscaling methods. Here, spatial and temporal variations in circulation-rainfall relationships over the Iberian Peninsula during the period 1958-97 are explored using an automated circulation classification scheme and daily rainfall totals for 18 stations. Links between the circulation classification scheme and the North Atlantic oscillation (NAO) are also considered, as are the direct links between rainfall and the NAO. Trends in rainfall and circulation-type frequency are explored. A general tendency towards decreasing mean seasonal rainfall over the peninsula, with the exception of the southeastern Mediterranean coast, hides larger changes in wet day amount and rainfall probability. There is a tendency towards more, less-intensive rain days across much of Iberia, with a tendency towards more, more-intensive rain days along the southeastern Mediterranean coast, both of which are reflected in changes in rainfall amount quantiles. A preliminary analysis indicates that these changes may have occurred systematically across all circulation types. Comparison of the trends in rainfall and in circulation-type frequency suggests possible links. These links are supported by linear regression analyses using circulation-type frequencies as predictor variables and rainfall totals for winter months as the predictands. The selected predictor variables reflect the main circulation features influencing winter rainfall across the peninsula, i.e. the strong influence of Atlantic westerly and southwesterly airmasses over much of the peninsula, of northerly and northwesterly surface flow over northern/northwestern Spain and northern Portugal and the stronger effect of Mediterranean rather than Atlantic influences in southeastern Spain. The observed rainfall changes cannot, however, be explained by changes in circulation alone. Copyright (C) 2002 Royal Meteorological Society.