Precipitation Products’ Inter–Comparison over East and Southern Africa 1983–2017

Elsa Cattani,Olivia Ferguglia,Andrés Merino,Vincenzo Levizzani

doi:10.3390/rs13214419

Abstract

During recent decades East Africa (EA) and Southern Africa (SA) have experienced an intensification of hydrological hazards, such as floods and droughts, which have dramatically affected the population, making these areas two of the regions of the African continent most vulnerable to these hazards. Thus, precipitation monitoring and the evaluation of its variability have become fundamentally important actions through the analysis of long-term data records. In particular, satellite-based precipitation products are often used because they counterbalance the sparsity of the rain gauge networks which often characterize these areas. The aim of this work is to compare and contrast the capabilities of three daily satellite-based products in EA and SA from 1983 to 2017. The selected products are two daily rainfall datasets based on high-resolution thermal infrared observations, TAMSAT version 3 and CHIRPS, and a relatively new global product, MSWEP version 2.2, which merges satellite-based, rain gauge and re-analysis precipitation data. The datasets have been directly intercompared, avoiding the traditional rain gauge validation. This is done by means of pairwise comparison statistics at 0.25° spatial resolution and daily time scale to assess rain–detection and quantitative estimate capabilities. Monthly climatology and spatial distribution of seasonality are analyzed as well. The time evolution of the statistical indexes has been evaluated in order to analyze the stability of the rain detection and estimation performances. Considerable agreement among the precipitation products emerged from the analysis, in spite of the differences occurring in specific situations over complex terrain, such as mountainous and coastal regions and deserts. Moreover, the temporal evolution of the statistical indices has demonstrated that the agreement between the products improved over time, with more stable capabilities in identifying precipitating days and estimating daily precipitation starting in the second half of the 1990s.

Highlights

The African continent is one of the most vulnerable places in the world; its population is over a billion people, most of whom live in semi–arid regions heavily prone to droughts, while other regions are plagued by floods
Analogies and differences among TAMSAT3, CHIRPS and MSWEP data sets were evaluated in East Africa (EA) and Southern Africa (SA) during the period 1983–2017 in terms of precipitation detection and estimation at the daily scale, as well as precipitation monthly climatology and seasonality
Unlike the numerous validation studies available in the literature, in this work we opted for direct pairwise comparisons between the three satellite products, without a rain gaugebased product as reference

Summary

Introduction

The African continent is one of the most vulnerable places in the world; its population is over a billion people, most of whom live in semi–arid regions heavily prone to droughts, while other regions are plagued by floods. It is an economically and politically unstable continent, where most of the people live below the poverty threshold and social inequalities often make life precarious. Climate change will amplify the existing stress on water availability, affecting agricultural production and food security. This scenario, characterized by a high dependence on agriculture and a low Remote Sens.

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