Satellite-Based Insights into Precipitation Formation Processes in Continental and Maritime Convective Clouds at Nighttime

Nighttime microphysical retrievals can be obtained to a much lesser accuracy than those of the daytime, because of lack of the solar radiation. However, a proper treatment of the brightness temperature difference (BTD) between a thermal IR channel (11 μm) and a mid-IR channel (3.7 μm) reveals information about the microstructure and precipitation potential of clouds at nighttime. The two factors that contribute to large BTD are the particle size at cloud top and the optical depth of the cloud layer. These two factors have contradictory effects on precipitation. The respective contributions were simulated and compared with observations of the Tropical Rainfall Measuring Mission. Based on that, a method was developed to use the distribution of BTD with cloud-top temperature for retrieving cloud microstructure and precipitation properties.