Retrieval of Latent Heating Profiles from TRMM Radar Data

The latent heating profiles in cloud systems have an important role in not only global circulation and climate but also meso- and cloud-scale circulation. Although the TRMM precipitation radar (PR) is a superior instrument to observe the three-dimensional precipitation structure of cloud systems, it is difficult to retrieve the latent heating profile from the precipitation structure. To obtain the exact latent heating profile, both cloud-physical and dynamic structures in a cloud system have to be known because the latent heating is a result of the phase change of water.

In this study, a new method to retrieve latent heating profiles from TRMM PR data is proposed. Since the method is based on thermodynamic retrieval technique assuming the steady condition, a vertical velocity profile is required. In the method, the vertical velocity is estimated by a cubic function, the coefficients of which depend on the cloud top height, the cloud type (convective/stratiform), and the bright band height. All the data are obtained from TRMM PR and VIRS observation data. The application of the method to an observed squall line system provides suitable results of latent heating profile. At least, a horizontal distribution of the vertically-integarated heating agrees with that another latent heating distribution derived from surface rainfall rate. In addition, the retrieved latent heating structure is compared with a result of a numerical model simulation.