The impact of satellite temperature and moisture profiles on simulating and understanding tropical cyclone genesis

Forecast of tropical cyclone (TC) genesis is a challenging problem in numerical weather prediction (NWP), partly because of the mechanisms that control the TC genesis are not well understood. In addition, numerical weather model could fail to predict the TC genesis due to uncertainties in the initial conditions. The available satellite observations, such as these temperature and moisture profiles derived from the AIRS and NPP/CrIS, offer a very good data source that could be assimilated into the numerical models to improving the numerical simulations of TC genesis. In addition, through diagnosing the data impacts to the numerical simulations, they could also lead to a better understanding of the processes associated with the TC genesis.

In this study, we first demonstrated the impact of AIRS derived atmospheric temperature profiles on numerical simulation of Typhoon Nuri (2008) over the Western Pacific Ocean. The mesoscale community Weather research and forecasting (WRF) model at three-level nested domains of 36/12/4km horizontal resolution and a unified Gridpoint Statistical Interpolation (GSI) data assimilation system were used. Results indicated that assimilation of AIRS derived temperature profiles results in more accurate prediction of Nuri's genesis, whereas without the AIRS data assimilation, the model fails predicting Nuri's genesis. More importantly, data assimilation results imply that the upper level warming contributes to Nuri's genesis. Assimilation of AIRS data enhances the representation of upper level warming in the WRF model.

Additional experiments are being conducted emphasized on assimilating AIRS moisture profiles and also examining the impact of the new NPP satellite temperature and moisture profiles with more case studies. Results will be presented at the symposium.