Integration of Chemical Transport Model and Field Observations based on the Four Dimensional Variational Method

建立了一个区域化学输运模式的四维变分（4D-Var）数据同化系统，并将其应用于2007年3月30日至4月4日东亚地区的一次重沙尘事件。直接同化了5个NIES激光雷达观测点尘埃消光系数的垂直剖面。同化后的模型粉尘消光系数有较大提高。同化结果显著增加了戈壁沙漠和蒙古地区的沙尘排放量；特别是在3月29日至30日期间。这次沙尘事件是由于这几天戈壁沙漠和蒙古地区沙尘抬升通量过大造成的。优化后的总粉尘排放量为57.9 Tg，比同化前增加57.8%。同化后的模式结果与OMI气溶胶指数和WMO SYNOP报告一致，Lidar-4DVAR系统具有提高亚洲扬尘排放/输送模式精度的潜力。

A four-dimensional variational (4D-Var) data assimilation system for a regional chemical transport model was developed and then applied to a heavy dust event which occurred between 30 March to 4 April 2007 over eastern Asia. The vertical profiles of the dust extinction coefficients derived from 5 NIES LIDAR observation sites are directly assimilated. The modeled dust extinction coefficients are improved considerably after assimilation. Assimilation results increase dust emissions over the Gobi Desert and Mongolia considerably; especially between 29 and 30 March. The heavy dust event is caused by the heavy dust uplift flux over the Gobi Desert and Mongolia during those days. We obtain the total optimized dust emissions of 57.9 Tg (57.8% larger than before assimilation). We also confirmed that the assimilated model results agreed with OMI aerosol index and WMO SYNOP report, and Lidar-4DVAR system has a potential to improve the accuracy of Asian dust emission/transport model.