Generating rainfall and temperature scenarios at multiple sites: Examples from the Mediterranean
Generating rainfall and temperature scenarios at multiple sites: Examples from the Mediterranean
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在多个地点生成降雨量和温度情景：来自地中海的示例
DOI：
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发表时间：
2002
期刊：
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通讯作者：
T. Holt
中科院分区：
文献类型：
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作者：
J. Palutikof;C. Goodess;S. Watkins;T. Holt
采用了一种统计降尺度方法，根据大气环流模型的输出，生成集水区内各点温度和降雨量的每日时间序列。降雨情景由两个阶段的过程构建。首先，对于一个单一的站，一个有条件的一阶马尔可夫链被用来产生湿，干日序列。然后，多站点的情况下，从基准文件中包含的多个站点的观测，按季节，环流天气类型，以及一天是潮湿还是干燥的基准站分类的每日时间序列进行采样。温度情景是使用由自由大气变量初始化的确定性传递函数构建的。温度和降雨情景之间的关系是建立在两种方式。首先，海平面气压场定义了支撑降雨情景的环流天气类型，并用于构建温度情景中的预测变量。第二，单独的温度传递函数开发的潮湿和干燥的日子。在两个地中海流域的方法进行了评价。降雨情景总是过于干燥，尽管应用蒙特卡罗技术试图克服这个问题。温度情景通常过于凉爽。这些假设情景被用来探讨极端事件的发生，以及以温度为例预测的应对气候变化的变化。平均值的变化和极端值的变化之间的非线性关系得到了清楚的证明。
A statistical downscaling methodology was implemented to generate daily time series of temperature and rainfall for point locations within a catchment, based on the output from general circulation models. The rainfall scenarios were constructed by a two-stage process. First, for a single station, a conditional first-order Markov chain was used to generate wet and dry day successions. Then, the multisite scenarios were constructed by sampling from a benchmark file containing a daily time series of multiple-site observations, classified by season, circulation weather type, and whether the day is wet or dry at the reference station. The temperature scenarios were constructed using deterministic transfer functions initialized by free atmosphere variables. The relationship between the temperature and rainfall scenarios is established in two ways. First, sea level pressure fields define the circulation weather types underpinning the rainfall scenarios and are used to construct predictor variables in the temperature scenarios. Second, separate temperature transfer functions are developed for wet and dry days. The methods were evaluated in two Mediterranean catchments. The rainfall scenarios were always too dry, despite the application of Monte Carlo techniques in an attempt to overcome the problem. The temperature scenarios were generally too cool. The scenarios were used to explore the occurrence of extreme events, and the changes predicted in response to climate change, taking the example of temperature. The nonlinear relationship between changes in the mean and changes at the extremes was clearly demonstrated.