Comparative Ground Validation of IMERG and TMPA at Variable Spatiotemporal Scales in the Tropical Andes

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Title: Comparative Ground Validation of IMERG and TMPA at Variable Spatiotemporal Scales in the Tropical Andes
Authors: Manz, B
Paez-Bimos, S
Horna, N
Buytaert, W
Ochoa-Tocachi, B
Lavado-Casimiro, W
Willems, B
Item Type: Journal Article
Abstract: An initial ground validation of the Integrated Multisatellite Retrievals for GPM (IMERG) Day-1 product from March 2014 to August 2015 is presented for the tropical Andes. IMERG was evaluated along with the Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis (TMPA) against 302 quality-controlled rain gauges across Ecuador and Peru. Detection, quantitative estimation statistics, and probability distribution functions are calculated at different spatial (0.1°, 0.25°) and temporal (1 h, 3 h, daily) scales. Precipitation products are analyzed for hydrometeorologically distinct subregions. Results show that IMERG has a superior detection and quantitative rainfall intensity estimation ability than TMPA, particularly in the high Andes. Despite slightly weaker agreement of mean rainfall fields, IMERG shows better characterization of gauge observations when separating rainfall detection and rainfall rate estimation. At corresponding space–time scales, IMERG shows better estimation of gauge rainfall probability distributions than TMPA. However, IMERG shows no improvement in both rainfall detection and rainfall rate estimation along the dry Peruvian coastline, where major random and systematic errors persist. Further research is required to identify which rainfall intensities are missed or falsely detected and how errors can be attributed to specific satellite sensor retrievals. The satellite–gauge difference was associated with the point-area difference in spatial support between gauges and satellite precipitation products, particularly in areas with low and irregular gauge network coverage. Future satellite–gauge evaluations need to identify such locations and investigate more closely interpixel point-area differences before attributing uncertainties to satellite products.
Issue Date: 15-Sep-2017
Date of Acceptance: 7-Jul-2017
ISSN: 1525-7541
Publisher: American Meteorological Society
Start Page: 2469
End Page: 2489
Journal / Book Title: Journal of Hydrometeorology
Volume: Sept 2017
Copyright Statement: © 2017 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (
Sponsor/Funder: Natural Environment Research Council (NERC)
Natural Environment Research Council [2006-2012]
British Council (UK)
Funder's Grant Number: NE/K010239/1
Keywords: 0401 Atmospheric Sciences
Meteorology & Atmospheric Sciences
Publication Status: Published
Appears in Collections:Faculty of Engineering
Civil and Environmental Engineering
Centre for Environmental Policy
Faculty of Natural Sciences

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