|Coverage||Global tropics (40N-40S, 0-360E)|
|Time Period||December 1997 - Present|
|Resolution||5 x 5 degree, monthly|
A number of climate rainfall products are produced from the passive microwave (TMI) and precipitation radar (PR) sensors on board the Tropical Rainfall Measuring Mission (TRMM) satellite, which was launched in November of 1997. The TRMM monthly or climate rainfall products, referred to as the level 3 products, are derived primarily from accumulations of the TRMM level 2 products, or instantaneous rainfall estimates corresponding to the original satellite snapshot views. The availability of multiple rainfall products from the various TRMM rainfall sensors is due to the fact that each one has various strengths and weaknesses. As a result, the "best" rainfall estimate is application dependent. The TRMM PR provides the highest spatial resolution (~4 km), most information content, the best vertical resolution (80 levels), and the most directly measured surface rainfall estimates for many application. The swath width of the PR, however, is around 1/3 of the TMI swath width resulting is significantly poorer sampling for many climate applications.
The current version is version 6
The 3B31 is a monthly accumulation of the 2B31 dataset. It is based on the 2B31 retrieval algorithm, which combines information from both the PR and TMI data. This dataset contains monthly mean values of the surface rainfall rate as well as 14 layer vertical profiles of rain water. In addition, the 3B31 dataset contains the 3A12 rain accumulations as there is no 3A12 dataset. The 2B31 retrieval algorithm used for this product is based on the technique by Haddad et al. [1997a, 1997b].