Application of Lightning Observations of TRMM Satellite to the Mesoscale Numerical Model by a New Nudging Assimilation Adjustment Technique

A new nudging assimilation adjustment technique is proposed, which may be used to assimilate the lightning observations of TRMM satellite into the initial fields of the mesoscale numerical model. The technique combines the physical initialization technology with the nudging technology. According to the observed lightning intensity and spatial location, the assimilation technique adjusts the content and spatial distribution of water vapor and five cloud hydrometeors in the initial fields of the numerical model, and thereby improves the initial condition of model and increases the accuracy of 0－6-hour short-term rainfall forecast of the mesoscale numerical model. The nudging assimilation adjustment technique is further used to assimilate the lightning observations of TRMM satellite into the initial conditions of three short-term precipitation events simulated by the ARPS model. The results show that, the assimilation of observational lightning data may increase water vapor and cloud hydrometeors in the initial condition and reasonably rearrange the spatial distribution of water substances. The short-term forecast of precipitation and cloud hydrometeors by the mesoscale numerical model is effectively enhanced.