异物理模态法物理量差异对集合预报的影响

Influence of the Physical Quantity Differences of Different Physical Mode Method on the Ensemble Forecast

利用异物理模态法的数学计算方案,选择积分12h的500hPa水汽通量散度(湿位涡)预报离差构造初值扰动的归一化初值扰动模态,进而构造扰动初值,对一次川东北大暴雨个例进行集合预报试验,从扰动初值水平结构、集合预报平均、大于50mm降水量概率、降水离散度、区域预报离差、Talagrand分布、Brier评分、集合预报系统对控制预报的逐时方差演变等多个方面对两种物理量处理方法所得结果进行对比分析,认为两种处理方法所得结果总体上非常相似,不存在显著差异。两种处理方法产生的扰动初值差异并没有引起大尺度环流明显差异,但对中尺度动力场、热力场产生了一定影响。就Brier评分、雨带位置而言,水汽通量散度处理方法略优于湿位涡处理方法,而强降水区范围而言则是湿位涡处理方法略占优。另外,区域预报离差显示,湿位涡处理方法的集合预报系统发散度要大一些。

Using the math calculate program of Different Physical Mode Method （ DPMM）, choosing water - vapour flux di- vergence （ moist potential vorticity） forecast deviations integraled 48h on 500hPa to construct normalization initial value disturbance mode of initial value disturbance, and it constructs disturbance initial value, makes a ensemble forecast test on a heavy rain case in Northeast, gives comparative analysis on the results of two kinds of physical quantity approaches from horizontal structure of disturbance initial value, ensemble forecast average, precipitation rate over 50mm, precipitation dispersion, region forecast deviations, Talagrand probability distribution, Brier Score, hourly variance evolution of ensemble forecast system on control forecast, and other aspects. It considers that the results of two kinds of approaches are similar in general, and there is no significant difference. The initial value disturbance differences produced from two kinds of approaches do not cause the difference of large - scale circulation, but affect the mesoscale dynamic field and thermodynamic field. On Brier Score and rain belt location, the water - vapour flux divergence approach is slightly better than moist potential vorticity approach, but on heavy precipitation range, the moist potential vorticity approach is slightly better. Besides, the forecast deviations show that the dispersion of ensemble forecast system of moist potential vorticity approach is bigger.