Performance of temperature and dew point data based on Collection 5 algorithm of MODIS and their applications in numerical modelling of tropical cyclones

The latest algorithm for the retrieval of thermodynamic profiles of the atmosphere from MODIS satellite data, namely, Collection 5, has been used to obtain temperature and dew point data. The quality of the data so obtained is studied by comparison with the measurements from a ground-based microwave radiometer in Hong Kong. Given the limited dataset, it appears that the quality of the temperature data is reasonable. On the other hand, the MODIS-based dew point in general deviates significantly from the radiometer measurements. The application of the MODIS-derived temperature and dew point profiles is then studied in the forecasting of the movement of tropical cyclones. The numerical weather prediction model used is Weather Research and Forecasting (WRF) version 2.2 and the MODIS data are assimilated using WRF VAR version 2.1. Three tropical cyclone cases in 2009 are considered. In general, it is found that the inclusion of temperature profiles from MODIS helps improve the forecast of the movement of the tropical cyclones. On the other hand, if dew point data are also assimilated, the track forecast generally deteriorates, which may be due to the rather unsatisfactory quality of the dew point profiles. The model simulation results will be discussed in the present paper.