H24E-02
CMORPH Global High-Resolution Precipitation Estimates: Reprocessing, Bias Correction, and Error Quantification

Tuesday, 15 December 2015: 16:15
3022 (Moscone West)
Pingping Xie, NOAA/NCEP Climate Prediction Center, College Park, MD, United States, Robert Joyce, NOAA/NCEP/CPC, Boca Raton, FL, United States and Shaorong Wu, Wyle-CPC/NCEP/NOAA, College Park, MD, United States
Abstract:
CMORPH global high-resolution satellite precipitation estimates have been reprocessed and bias-corrected for an 18-year period from January 1998 to the present to cover the entire TRMM/GPM era. As the first step of this project, the CMORPH estimates have been reprocessed with a frozen algorithm and with input PMW retrievals and IR observations of identical versions throughout the data period.

Bias correction is then performed for the reprocessed CMORPH over the entire data period from 1998 to the present. Over land, the bias in the raw CMORPH is removed by matching the probability density function (PDF) of the CMORPH with that of the CPC unified daily gauge analysis. Over ocean, the raw CMORPH satellite estimates are calibrated against a long-term precipitation analysis (pentad GPCP) to ensure temporal homogeneity for climate applications. The reprocessed, bias-corrected CMORPH estimates present an 18-year homogeneous record of high-resolution precipitation on an 8kmx8km and 30-min resolution covering the globe from 60oS-60oN.

Accuracy of the reprocessed, bias corrected CMORPH is examined through comparison against gauge based analysis over land and against buoy measurements over ocean. Overall, the bias corrected CMORPH exhibited improved performance upon the raw CMORPH, with bias removed almost completely over the tropics and extra-tropical regions during warm seasons. Caused by shortcomings in the input PMW retrievals, CMORPH tends to miss precipitation over cold surfaces. Quantitative accuracy of bias corrected CMORPH is a function of season, location, precipitation intensity, and the availability of satellite retrievals.

Bias corrected CMORPH is applied to examine the large-scale precipitation variations over the globe. In particular, diurnal variations of precipitation is investigated and compared with those determined by the three new generation reanalyses (CFSR, MERRA, and ERA-Interim). A comprehensive description and diagnostic discussions will be given at the AGU meetings.

<< Previous Abstract | Next Abstract >>