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This study determined the accuracy and biases associated with retrieved Moderate Resolution Imaging Spectroradiometer (MODIS) total precipitable water (TPW) data, and it investigated the impact of these data on severe weather simulations using the Weather Research and Forecast (WRF) model. Comparisons of MODIS TPW with the global positioning system (GPS) TPW and radiosonde-derived TPW were carried out. The comparison with GPS TPW over the United States showed that the root-mean-square (RMS) differences between these two datasets were about 5.2 and 3.3 mm for infrared (IR) and near-infrared (nIR) TPW, respectively. MODIS IR TPW data were overestimated in a dry atmosphere but underestimated in a moist atmosphere, whereas the nIR values were slightly underestimated in a dry atmosphere but overestimated in a moist atmosphere. Two cases, a severe thunderstorm system (2004) over land and Hurricane Isidore (2002) over ocean, as well as conventional observations and Special Sensor Microwave Imager (SSM/I) retrievals were used to assess the impact of MODIS nIR TPW data on severe weather simulations. The assimilation of MODIS data has a slightly positive impact on the simulated rainfall over Oklahoma for the thunderstorm case, and it was able to enhance Isidore’s intensity when the storm track was reasonably simulated. The use of original and bias-corrected MODIS nIR TPW did not show significant differences from both case studies. In addition, SSM/I data were found to have a positive impact on both severe weather simulations, and the impact was comparable to or slightly better than that of MODIS data.

A coupled atmosphere‐ocean single-column model has been developed for testing tropical ocean‐atmosphere feedbacks. The model is evaluated against observational data (both in situ and satellite) during the Tropical Ocean Global Atmosphere Coupled Ocean‐Atmosphere Response Experiment (TOGA COARE) intensive observation period. The coupled model is able to successfully reproduce variations in cloud parameters and surface fluxes; the model also overestimates the latent and sensible heat fluxes compared to observations. The overestimation is most likely due to errors in the atmospheric surface layer temperature and specific humidity. The sea surface temperatures produced by the model are reasonable. The mean bias in sea surface temperature as compared to buoy data is 08C; the maximum deviation from the observed temperature is 0.48C. This model is then used to investigate the sensitivity of the ocean and the ocean‐atmosphere system to variations in the included interfacial parameterization in the tropical Pacific. The sensitivity of the model results to the turbulent flux model used in the coupled version is shown to produce daily averaged sea surface temperature variations of over 0.58C. Of equal significance is the variation in model response to temperatures from different depths in the water column. Use of the typically cooler skin temperature as the interfacial temperature rather than the temperature at depth results in strong differences in the atmospheric profiles of heat, moisture, and cloud properties. These differences are not caused solely by the difference in temperature, but are also due to the much-reduced diurnal variation in sea surface temperature at depth. The extent to which a daily averaged sea surface temperature changes the resulting atmospheric profiles depends on whether the diurnal variability was strong; under low-wind conditions the differences are the most dramatic.