两种OI陆面同化方法在GRAPES_Meso模式中的初步应用试验

初始土壤湿度和土壤温度,对陆面模式以及数值模式的模拟结果都有很大影响。OI(Optimal Interpolation)方法,是考虑观测和预报误差的客观统计方法,能够给出一个修正后的土壤湿度和土壤温度。在OI方法基础上发展的OI_EC和OI_MF方法,已经在欧洲中期天气预报中心、法国气象局等业务应用。现在的GRAPES_Meso模式还未引入陆面同化技术,所以本文将OI_EC和OI_MF两种陆面同化方法在GRAPES_Meso中进行初步应用。通过夏、冬两个季节的试验结果发现:两种陆面同化方法均能有效地提高模式对2m气温模拟效果,对于降水模拟结果没有明显变化。对比两种OI陆面同化方法结果,OI_EC方法得到的系数更为合理,OI_MF方法不适合模拟植被覆盖较低的区域。

Application of Two OI Land Surface Assimilation Techniques in GRAPES_Meso

The initial soil water content and temperature significantly influence numerical weather forecasts. The Optimal Interpolation (OI) technique takes into account observation and forecast errors in an objective statistical way and can produce the analyzed soil water content and temperature. The OI_EC and OI_MF, which were developed from the original OI technique, have been used in the operational systems in European Centre for Medium Range Weather Forecasts and in Météo France, but not in the GRAPES_Meso of China. So, we tried to apply the two OI techniques in the GRAPES_Meso. The experiment results of the two seasons in summer and winter show that the accuracy of the simulated 2 m temperature is improved by the use of the two OI techniques, and there is no obvious change in precipitation simulation results. Comparing the results of two OI techniques, we find that the OI_EC coefficients are more reasonable, and the OI_MF method is not suitable for simulating in the low vegetation coverage area.