University of MarylandCMNS-Earth System Science Interdisciplinary Center
Variations and trends in global total precipitation and patterns of change are described using the Global Precipitation Climatology Project (GPCP) monthly product, a globally complete precipitation analysis based on satellite and gauge information for the period 1979 to the present. The planetary mean GPCP (Version 2.3) number is 2.69 mm/d (+/- 5%) and is generally confirmed by comparisons with TRMM and GPM estimates in the tropics and CloudSat estimates at higher latitudes, and by global water budget analyses.
Although the global total precipitation shows a very small increase (~1%/K) over the 1979-2017 period of global warming, the tropics show a significant increase centered on the latitude of the ITCZ, with mid-latitudes in the northern hemisphere showing a decrease. The global map of observed trends shows general correspondence with that indicated by climate models (both CMIP and AMIP) under a warming climate, but there are significant remaining differences.
The GPCP Monthly analysis is also used to examine trends and variations in precipitation intensity in the tropics (30oN-30oS) and compared to AMIP and CMIP climate models. Significant trends in intensity at the monthly time scale are noted with the GPCP analyses, with larger rainfall magnitudes increasing, moderate rainfall values decreasing and dry areas expanding. Similar variations in daily rainfall intensity are seen on ENSO time scales using the TRMM Multi-satellite Precipitation Analysis (TMPA) for the shorter 1998-2017 period.
Dr. Robert Adler of University of Maryland has several decades' experience in developing and analyzing global precipitation data sets. He was a project scientist for NASA Tropical Rainfall Measurement Mission (TRMM) for several years and has been a key developer of the Global Precipitation Climatology Project (GPCP) and the TRMM Composite Climatology (TCC) products. He has also led efforts for estimation of climatological uncertainties for the GPCP dataset and has led efforts for global flood monitoring.
People interested in meeting Dr. Bob Adler please contact HAS associate professor Ali Behrangi (firstname.lastname@example.org). There are only limited availabilities to meet Dr. Adler in person (most likely between 12:30-2:30 on Friday).