Geophysical Research Letters

Statistical properties of precipitation as observed by the TRMM precipitation radar

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Abstract

The statistical properties of tropic-subtropic precipitation are revealed with 13 years of Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) measurements. About 3% of PR observations are raining pixels. The average daily rainfall over 37.5°N–37.5°S is 1.28, 1.18, and 2.46 mm d−1 for convective, stratiform, and total rain, respectively, indicating 51.85% from convective rain and 48.09% from stratiform rain. The related values are 1.300, 1.272, and 2.573 mm d−1 over ocean and 1.22, 0.97, and 2.19 mm d−1 over land, indicating a convective rain fraction of 50.51% over ocean and 55.77% over land. The 92% (93%) and 73% (55%) of rain events over ocean (land) are from stratiform and convective rain <5 mm h−1, respectively, while the associated rainfall contributions in stratiform and convective rain are 62% (68%) and 27% (15%) over ocean (land). Results demonstrate that contributions from large rain intensity events are very importation in total precipitation, especially over land. The rainfall missed by TRMM PR is mostly light rain and does not significantly impact large-scale statistics of convective and stratiform rain amount. Light rain will increase the total precipitation by about 10% and, if considered a separate category, decrease the observed convective and stratiform rain contributions about 10% over the PR domain. These statistical properties of precipitation could be utilized as a baseline in the assessment of precipitation from operational numerical weather prediction and climate models.

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