Difference Between Cloud Top Height and Storm Height for Heavy Rainfall Using TRMM Measurements

抄録

 This study compares the regional characteristics of heavy rain clouds in terms of Cloud Top Height (CTH) and Storm Height (SH) from long-term Tropical Rainfall Measuring Mission (TRMM) observations. The SH is derived from Precipitation Radar reflectivity and the CTH is estimated using Visible and InfraRed Scanner brightness temperature (10.8 μm) and reanalysis temperature profiles. As the rain rate increases, the average CTH and average SH increase, but by different degrees in different regions. Heavy rainfall in continental rainfall regimes such as Central Africa and the United States is characterized by high SH, in contrast to oceanic rainfall regions such as the northwestern Pacific, Korea, and Japan; the increase of atmospheric instability in dry environments is interpreted as a mechanism of continental floods. Conversely, heavy rain events in Korea and Japan occur in a thermodynamically near-neutral environment with large amounts of water vapor; these are characterized by the lowest CTH, SH, and ice water content. The northwestern Pacific exhibits the lowest SH in humid environments, similar to Korea and Japan; however, this region also characteristically exhibits the highest convective instability condition as well as high CTH and CTH–SH values, in contrast to Korea and Japan. The observed CTH and SH characteristics of heavy rain clouds are expected to be useful for the evaluation and improvement of satellite-based precipitation estimation and numerical model cloud parameterization.