Validation of TRMM and FEWS Satellite Rainfall Estimates with Rain Gauge Measurement over Ashanti Region, Ghana
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Date
2016-10-28
Journal Title
Journal ISSN
Volume Title
Publisher
Atmospheric and Climate Sciences
Abstract
Satellite rainfall estimates have predominantly been used for climate impact studies
due to poor rain gauge network in sub-Saharan Africa. However, there are limited
microscale studies within the sub-region that have assessed the performance of these
satellite products, which is the focus of the present study. This paper therefore considers validation of Tropical Rainfall Measuring Mission (TRMM) and Famine Early
Warning System (FEWS) satellite estimates with rain gauge measurements over
Ashanti region of Ghana. First, a consistency assessment of the two gauge data
products, the Automatic Rain Gauge (ARG) and Ghana Meteorological Agency
(GMet) Standard Rain Gauge (SRG) measurements, was performed. This showed a
very good agreement with correlation coefficient of 0.99. Secondly, satellite rainfall
products from TRMM and FEWS were validated with the two gauge measurements.
Validation results showed good agreement with correlation coefficients of 0.6 and 0.7
for TRMM and FEWS with SRG, and 0.87 and 0.86 for TRMM and FEWS with ARG
respectively. Probability Of Detection (POD) and Volumetric Hit Index (VHI) were
found to be greater than 0.9. Volumetric Critical Success Index (VCSI) was 0.9 and
0.8 for TRMM and FEWS respectively with low False Alarm Ratio (FAR) and insignificant Volumetric Miss Index (VMI). In general, relatively low biases and RMSE
values were observed. The biases were less than 1.3 and 0.8 for TRMM and FEWSRFE respectively. These indicate high rainfall detection capabilities of both satellite
products. In addition, both TRMM and FEWS were able to capture the onset, peak
and cessation of the rainy season, as well as the dry spells. Although TRMM and
FEWS sometimes under/overestimated rainfall, they have the potential to be used for
agricultural and other hydro-climatic impact studies over the region. The Dynamic Aerosol-Cloud-Chemistry Interactions in West Africa (DACCIWA) project will provide an improved spatial gauge network database over the study area to enhance future validation and other climate impact studies.
Description
An article published by Atmospheric and Climate Sciences, 2016, 6, 500-518 and available at DOI: 10.4236/acs.2016.64040
Keywords
Rain Gauge, Validation, TRMM and FEWS-RFE, DACCIWA Project, Ashanti Region
Citation
Atmospheric and Climate Sciences, 2016, 6, 500-518