What are the caveats in using TRMM Multi-satellite Precipitation Analysis (TMPA) products?

[GES DISC - igarcias]

Answer:

The following are some caveats in using TMPA:

The key caveat is that all of the TMPA products are research products, not "operational" in the sense of hot spares, contingency plans, and backup machines waiting to take over in the event of a failure. Looking back through the RT news, the prospective user should get the sense that the system could run for months at a time, but if there's a network failure or a disk crash, it might take days to fix, particularly over weekends or holidays.

The TMPA is a gridded product, which is different from the point rain gauge data more familiar to some users. On the other hand, grid values might be more appropriate for certain applications than are point values from rain gauges.
Although the TMPA analysis scheme is consistent for the time period of a given version, the suite of input data varies. For example, there is less of the (higher-quality) microwave data before 2001 or so; the infrared data are on a coarser grid in 1998-1999; gauge sites report individually, and, therefore, are subject to availability issues, particularly in developing countries.
Occurrence of precipitation over land tends to be underestimated, because satellite schemes tend to miss light precipitation and precipitation that is enhanced by flow lifting over mountains.
Occurrence and amount of precipitation in some, but not all, coastal areas tend to be underestimated. Conversely, arid coastal areas (oceans and lakes) sometimes show persistent artifacts. Both effects are due to issues in the input microwave estimates.
The RT amounts tend to be biased high in warm-season convective weather due to biases in the input microwave estimates.