On using a generalized linear model to downscale daily precipitation for the center of Portugal: an analysis of trends and extremes
On using a generalized linear model to downscale daily precipitation for the center of Portugal: an analysis of trends and extremes
复制标题
使用广义线性模型降低葡萄牙中部的日降水量：趋势和极端值分析
DOI：
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发表时间：
2015
影响因子：
3.4
通讯作者：
M. J. Cruz
中科院分区：
文献类型：
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作者：
M. Pulquério;P. Garrett;F. Santos;M. J. Cruz
葡萄牙是气候变化的热点地区，预计降水将减少，对未来的水资源供应产生重要影响。作为过去几十年受干旱影响较大的欧洲国家之一，为了研究其对水资源的影响，评估未来降水制度将如何变化是很重要的。由于全球环流模式的尺度较粗，通常需要使用统计和/或动力技术将气候变量降尺度到区域或局部尺度。在本研究中，我们测试了在GLIMCLIM程序中实现的广义线性模型的使用，以降低塔古斯盆地所在的葡萄牙中部的降水尺度。对该方法的性能进行了分析，并对21世纪未来的降水趋势和极值进行了评估。此外，我们还首次利用标准化降水指数对气候变化情景下研究区干旱的演变进行了分析。结果表明，GLIMCLIM能够准确地捕捉降水的年际变化和季节特征。然而，夏季降水被大大高估了。此外，极端降水通常可以很好地恢复，但高日降雨量可能被高估，并且模式不能正确地恢复干旱期长度。按比例缩小的预估显示，本世纪末降水将减少19%至28%。结果表明，与1961-1990年相比，极端降水将减少，干旱强度可能增加3倍，并对生态、社会和经济产生强烈影响。
Portugal is on a climate change hot spot region, where precipitation is expected to decrease with important impacts regarding future water availability. As one of the European countries affected more by droughts in the last decades, it is important to assess how future precipitation regimes will change in order to study its impacts on water resources. Due to the coarse scale of global circulation models, it is often needed to downscale climate variables to the regional or local scale using statistical and/or dynamical techniques. In this study, we tested the use of a generalized linear model, as implemented in the program GLIMCLIM, to downscale precipitation for the center of Portugal where the Tagus basin is located. An analysis of the method performance is done as well as an evaluation of future precipitation trends and extremes for the twenty-first century. Additionally, we perform the first analysis of the evolution of droughts in climate change scenarios by the Standardized Precipitation Index in the study area. Results show that GLIMCLIM is able to capture the precipitation’s interannual variation and seasonality correctly. However, summer precipitation is considerably overestimated. Additionally, precipitation extremes are in general well recovered, but high daily rainfall may be overestimated, and dry spell lengths are not correctly recovered by the model. Downscaled projections show a reduction in precipitation between 19 and 28 % at the end of the century. Results indicate that precipitation extremes will decrease and the magnitude of droughts can increase up to three times in relation to the 1961–1990 period which can have strong ecological, social, and economic impacts.