北半球从冬到夏季节急变的共轭敏感性分析

根据共轭敏感性理论,用共轭模式对1983～1987年北半球从冬到夏的季节急变,包括这5a平均情况及1983年和1987年异常偏早或偏晚的个例进行分析,分别得出这些急变影响最大的初始扰动分布。从年平均的资料来看,在4月前后季节急变所对应的最敏感扰动与海洋的作用有关;而6月前后的季节急变所对应的最敏感扰动与海洋的作用延伸到陆地后受到大地形的影响有关。1983年和1987年的个例分析表明:4月份大陆上出现最敏感扰动中心,造成4月急变偏早或偏晚发生;6月份海洋上出现最敏感扰动中心,造成6月急变的异常;4月急变偏早时6月急变偏晚;4月急变偏晚时6月急变偏早。

Adjoint sensitivity analyses on seasonal rapid change of circulation over the Northern Hemisphere

According to statistical test of ECMWF daily data from winter to summer, the seasonal rapid change (SRC) is found separately in April and June over the Northern Hemisphere. The features of April SRC and June SRC, including the distributions of optimal sensitivity perturbation(DOSP), the early or late anomaly and the DOSP for each of them are studied based on adjoint sensitivity analysis theory. The results provide us with some new insight into the most significant influential factors of SRC. It also demonstrates the great potential of further applications of this method in oceanic and atmospheric circulation diagnostics.