A STUDY ON IMPACTS OF DIFFERENT RADIATIVE TRANSFER SCHEMES ON MESOSCALE PRECIPITATIONS

A radiative transfer scheme based on delta-4 stream, correlated-k distribution and with relative detailed cloud water, rain water, ice crystal and graupel radiative properties description, is employed into PSU/NCAR MM5. A study on impacts of different radiative transfer schemes on mesoscale precipitations is carried out using a case of South China Severe Storm in 1998. The calculations show that radiation process plays an important role in the mesoscale precipitations. The cloud radiative properties descriptive accuracy in the radiative transfer schemes in influences the surface rainfall obviously. Different radiative transfer schemes result in different precipitation processes and the disagreement among the schemes in the daytime is much bigger than that at night. Radiative processes have distinct effect on the maximum rainfall centers, while little on the surface rainfall geographic distribution. The difference of the solar radiation calculation among the radiative transfer schemes causes more notable surface precipitation varieties than that on the longwave radiation. The employment of new radiative transfer scheme is successful and it improves the mesoscale precipitation simulation ability to a certain extent.