Comparative Ground Validation of IMERG and TMPA at Variable Spatiotemporal Scales in the Tropical Andes
File(s)
Published version
Author(s)
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.
Date Issued
2017-09-15
Date Acceptance
2017-07-07
Citation
Journal of Hydrometeorology, 2017, Sept 2017, pp.2469-2489
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 (www.ametsoc.org/PUBSReuseLicenses).
Sponsor
Natural Environment Research Council (NERC)
Natural Environment Research Council [2006-2012]
British Council (UK)
Grant Number
NE/K010239/1
NE/L002515/1
211956441
Subjects
0401 Atmospheric Sciences
Meteorology & Atmospheric Sciences
Publication Status
Published