基于高度再指定的FY-2C双通道云导风同化及预报试验

Numerical experiments of assimilation and forecasts by using dualchannels AMV products of FY-2C based on height reassignment

为了探求FY-2C双通道云导风在实际预报中的可用性,先对双通道云导风进行合并,并利用T511模式12h预报场对云导风进行高度再指定,使得云导风资料的空间密度和质量明显提高。进而利用WRF模式及其变分同化系统WRFDA对高度再指定前、后的云导风在同化及预报中的影响进行了研究,结果表明:同化原始云导风使初估风场的统计误差增大,而同化高度再指定后的云导风对初估风场有明显的改善作用;同化原始云导风会导致压、温、湿的初估场误差增加,但同化高度再定位后的云导风效果明显好于同化原始云导风;同化高度再定位后的云导风对48h内的风场预报有改善作用,随着预报时效的延伸,风场的改善带动了其他要素场从负影响到正影响的转变。

To study the practicability of dual-channel atmospheric motion vectors（AMVs） of FY-2C in operational forecast, the dual-channel AMVs were merged firstly, and then the merged AMVs were reassigned to the new heights with the 12 h wind fields forecasted by the T511 System as a reference, which could both increase the spa- tial density and improve the quality of AMVs obviously. On this basis, the impact of the AMVs without and with height reassignment on assimilation and forecasts by using the WRF model and its three-dimensional system were studied. Ifs found that the assimilation of the original AMVs enhanced the statistical errors of the initial wind field. However, the assimilation of the reassigned AMVs improved the quality of the initial wind field. Further more, the assimilation of either the original or the reassigned AMVs led to increasing errors of the initial field of height, temperature and humidity. However, the assimilation of the reassigned AMVs was much better than that of the original AMVs. The 48 h forecasts of the wind field were improved by assimilating the reassigned AMVs. With the extension of the validity period, the better wind field could drive the impact of assimilating the reassigned AMVs on other from a negative element fields to translate initial pattern to a positive forecasting pattern.