Precipitation variability and trends in Ghana: An intercomparison of observational and reanalysis products
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Date
2014
Journal Title
Journal ISSN
Volume Title
Publisher
Climatic Change
Abstract
Inter-annual variability and trends of annual/seasonal precipitation totals in
Ghana are analyzed considering different gridded observational (gauge- and/or satellitebased) and reanalysis products. A quality-controlled dataset formed by fourteen gauges
from the Ghana Meteorological Agency (GMet) is used as reference for the period
1961–2010. Firstly, a good agreement is found between GMet and all the observational
products in terms of variability, with better results for the gauge-based products—
correlations in the range of 0.7–1.0 and nearly null biases—than for the satellite-gauge
merged and satellite-derived products. In contrast, reanalyses exhibit a very poor performance, with correlations below 0.4 and large biases in most of the cases. Secondly, a
Mann-Kendall trend analysis is carried out. In most cases, GMet data reveal the existence of
predominant decreasing (increasing) trends for the first (second) half of the period of study,
1961–1985 (1986–2010). Again, observational products are shown to reproduce well the
observed trends—with worst results for purely satellite-derived data—whereas reanalyses
lead in general to unrealistic stronger than observed trends, with contradictory results (opposite signs for different reanalyses) in some cases. Similar inconsistencies are also found
when analyzing trends of extreme precipitation indicators. Therefore, this study provides a
warning concerning the use of reanalysis data as pseudo-observations in Ghana.
Description
An article published by Climatic Change (2014) 124:805–819 and available at
DOI 10.1007/s10584-014-1100-9
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Citation
Climatic Change (2014) 124:805–819