摘要:
为了揭示云迹风资料同化对于东亚海域内各层模拟风场的影响,采用由日本GMS卫星红外和水汽通道资料反演得到的1999年6月底至7月初的云迹风资料,首先对这些云迹风资料进行质量评估,评估结果表明云迹风u,v分量的均方根误差和偏差都在所容许的误差范围之内.然后针对10个个例进行5种不同的四维同化模拟试验,多种同化试验和无同化控制试验的检验对比表明:在经过初始12 h常规高空地面资料和云迹风资料同化过程以后,模拟结果质量有了比较明显的提升;各种同化试验与控制试验间的最大差异发生在12h,也即同化结束的时刻,此后随着模拟时间的增长,两者间的差异逐渐变小;但24~36h同化试验对控制试验的改进效果又开始提升,36h后效果再次下降.由于海面上缺少常规测站,因此无法实现海面部分的测站同化,而这必将影响到海面部分的模拟质量,而云迹风资料恰可以祢补这个不足.试验表明云迹风资料对u,v风场的改进则主要集中在对流层高层(300~200hPa),对中低层的影响不很明显,这与云迹风资料主要集中在高层是相一致的.另外,敏感性试验表明经过质量控制的云迹风同化模拟的性能相对不采用质量控制的同化模拟有了一定程度的提高.
Abstract:
In order to explore the impact of cloud motion wind(CMW) data on the numerical simulation of wind fields from upper to lower levels in the sea area of eastern asia,the CMW data retrieved from infrared and water vapor channels of Japan GMS satellite from late June to early July in 1999 is adopted. First the quality of the CMW data is evaluated and the results indicate that the root square meanerror and bias of the CMW's u &v components are in the permmited ranges. Then five different four assimilation simulation experiments are performed for each of ten cases. Mutifold comparisions between the assimilation experiments and non-assimilation ones indicate that after initial 12 h assimilation of regular upper air and surface obser vation and CMW data,it is much evident that the quality of the simulation results is promoted. The maximum difference between assimilation experiments and control ones occurs at 12 h which is also the end hour of assimilation,after this it minishes along with the increasing simulation time. But during 24~36 h the effects that the assimilation experiments are better than the control ones begin to increase,after 36 h it dropsagain. Because of absence of regular observation in sea area,it is impossible to implement observation assimilation on sea part and it is certain that this will influence the simulation quality of sea part. Experiments indicate that the CMW data improves u & v wind fields mainly on the upper troposphere(300~200 hPa) and it has lillte impacton middle-lowlevel,which is consistent with the fact that the CMW data distributes on upper levels. The performance of the CMW assimilation experiments using the quality control is,to some extent,better than that of ones not usingit.
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