SORTING OUT THE VARIETY OF PRECIPITATION DATASETS

For the non-expert user, the variety of precipitation datasets can be confusing. The range of publicly available, quasi-global, long-term precipitation data sets is summarized, based on the International Precipitation Working Group listing of such data sets at http://www.isac.cnr.it/~ipwg/data/datasets.html. One important concept is the distinction between a Climate Data Record (CDR) and a High-Resolution Precipitation Product (HRPP). The CDR emphasizes homogeneity over time, while the HRPP focuses on providing the best snapshot quality, although each strives for the other goal as well.

The poster also summarizes specific precipitation products for which the author has responsibilities as examples of these data sets. The Global Precipitation Climatology Project suite of products is a state-of-the-art example of CDR precipitation data sets. The Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis is a mature HRPP, while the successor Integrated Multi-satellitE Retrievals for the Global Precipitation Measurement (GPM) mission (IMERG) is being developed currently. Although still in its first version, IMERG provides 0.1°x0.1° half-hourly data that are competitive with other modern HRPP’s. It provides successive runs at 6 hours, 16 hours, and 3.5 months after observation time, referred to as the Early, Late, and Final Runs, respectively over the latitude band 60°N-S, for the period March 2014 to the present. In Spring 2016 IMERG will be retrospectively processed for the GPM era with fully GPM-based calibrations. Then, in early 2017 IMERG will be extended to cover the period 1998 to the present, and later expanded to fully global. One of the key goals in the joint NASA-Japan Aerospace Exploration Agency GPM mission is to facilitate use of the precipitation data in applications by non-expert users. All of the products described are freely available, with access summarized at http://pmm.nasa.gov/ under the “get data” button.