Variability of seasonal and annual rainfall in the River Nile riparian countries and possible linkages to ocean–atmosphere interactions
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Date
2016
Authors
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Journal ISSN
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Publisher
Hydrology Research
Abstract
Variability analyses for the rainfall over the Nile Basin have been confined mostly to sub-basins and
the annual mean of the hydroclimatic variable based on observed short-term data from a few
meteorological stations. In this paper, long-term country-wide rainfall over the period 1901–2011 was
used to assess variability in the seasonal and annual rainfall volumes in all the River Nile countries in
Africa. Temporal variability was determined through temporal aggregation of series rescaled
nonparametrically in terms of the difference between the exceedance and non-exceedance counts
of data points such that the long-term average (taken as the reference) was zero. The co-occurrence
of the variability of rainfall with those of the large-scale ocean–atmosphere interactions was
analyzed. Between 2000 and 2012, while the rainfall in the equatorial region was increasing, that for
the countries in the northern part of the River Nile was below the reference. Generally, the variability
in the rainfall of the countries in the equatorial (northern) part of the River Nile was found to be
significantly linked to occurrences in the Indian and Atlantic (Pacific and Atlantic) Oceans. Significant
linkages to Niño 4 regarding the variability of both the seasonal and annual rainfall of some countries
were also evident.
Description
Keywords
Climate indices, Climate variability, Nonparametric anomaly indicator method, Ocean–atmosphere interactions, Rainfall variability, River Nile
Citation
Onyutha, C. (2016). Variability of seasonal and annual rainfall in the River Nile riparian countries and possible linkages to ocean–atmosphere interactions. Hydrology Research, 47(1), 171-184. doi: 10.2166/nh.2015.164