The annual cycle of heavy precipitation across the United Kingdom: a model based on extreme value statistics
The annual cycle of heavy precipitation across the United Kingdom: a model based on extreme value statistics
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DOI：
10.1002/joc.1811
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发表时间：
2009-10-01
期刊：
影响因子：
--
通讯作者：
Osborn, T. J.
中科院分区：
文献类型：
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作者：
Maraun, D.;Rust, H. W.;Osborn, T. J.
通过建立统计模型并将其与689个雨量计的资料进行拟合，研究了英国极端i日降水事件的年周期。广义超值分布(GeV)同时适用于一年中所有月份的月极大值时间序列，通过用调和函数逼近位置和尺度参数的年周期，同时保持形状参数全年不变，我们对相邻雨量计的形状参数进行平均，以减少不确定性。并且还内插所有模型参数的值以给出(Lie UK)的完整覆盖。模型显示出明显的空间格局，估计参数、位置和尺度参数的年平均值与地形高度相关。位置参数的年周期在英国西北部(在晚秋或冬季达到峰值)和东安格利亚(在夏末达到峰值)较强，而在中部地区较低。尺度参数的年周期表现出类似的模式，在东安格利亚幅度最大。年周期位相的空间型表明，它们与锋面降水的优势有关，在英国的西部产生极端降水，在英国东南部产生对流降水。形状参数显示出从东部的正值到西部一些地区的负值的梯度。我们还估计了每个雨量计的10年和100年回归水平。并在英国版权所有(C)2008皇家气象学会
The annual cycle of extreme I-day precipitation events across the UK is investigated by developing a statistical model and fitting it to data from 689 rain gauges A generalized extrerne-value distribution (GEV) is fit to the time series of monthly maxima, across all months of the year simultaneously, by approximating, the annual cycles of the location and scale parameters by harmonic functions, while keeping the shape parameter constant throughout the year We average the shape parameter of neighbouring rain gauges to decrease uncertainties. and also Interpolate values of all model parameters to give complete coverage of (lie UK. The model reveals distinct spatial patterns the estimated parameters The annual mean of the location and scale parameter is highly correlated with orography. The annual cycle of the location parameter is strong in the northwest UK (peaking in late autumn or winter) and in East Anglia (where it peaks HI late summer), and low in the Midlands The annual cycle of the scale parameter exhibits a similar pattern with strongest amplitudes in East Anglia The spatial patterns of the annual cycle phase suggest that they are linked to the dominance of frontal precipitation for generating extreme precipitation in the west and convective precipitation in the southeast of the UK The shape parameter shows a gradient from Positive Values in the east to negative values in some areas of the west We also estimate 10-year and 100-year return levels at each rain gauge, and interpolated across the UK Copyright (C) 2008 Royal Meteorological Society