Towards a historical precipitation database for West Africa: Overview, quality control and harmonization

Abstract

Reliable long‐term observations from precipitation stations are often required for climatological studies but are strongly limited in many regions of the world. To improve this limitation for West Africa, we compiled daily and monthly observations from more than 20 national, continental and global databases, to establish a historical precipitation archive with a focus on four countries (Burkina Faso, Ghana, Benin and Togo). The new archive contains long‐term daily and monthly precipitation measurements from 1819 to 2013 for more than 1,000 sites. It is, therefore, the most comprehensive historical dataset with daily and monthly precipitation observations for this region. To produce a quality‐controlled and harmonized precipitation dataset for the focal region, various statistical algorithms have been implemented. These algorithms rely on straightforward geostatistical approaches (e.g., spatial correlograms) and corresponding statistical tests for identification and elimination of unreliable time series, in addition to various standard approaches used by global data centers. Although the quality control revealed various data errors and uncertainties for measurements and meta‐information (e.g., unit conversion errors, temporal offsets, frequent and long data gaps), a spatial interpolation using the quality‐controlled and harmonized dataset produced relatively reliable precipitation patterns for different target variables (e.g., monthly precipitation amount and daily precipitation probability). A major remaining challenge is providing free access to this database for research and other noncommercial purposes, due to national data protection regulations. However, several further tasks have been initiated and implemented (e.g., free provision of gridded precipitation datasets and point statistics) to improve the access and availability of station‐based precipitation observations and related data products for this climatologically challenging region.

Regionalization of the Onset and Offset of the Rainy Season in Senegal Using Kohonen Self-Organizing Maps

“…The database of the National Hydrological and Meteorological Services (NHMS) consists of four national datasets (Burkina Faso, Ghana, Benin, and Senegal), covering the period from 1960 to 2010, with data availability between 1970 and 2010 reaching approximately 85% [38]. The largest subset of the NHMS database is Burkina Faso's subset (NHMS-BF), which includes 142 chronological series of precipitation.…”

Present and Future of Heavy Rain Events in the Sahel and West Africa

“…The data set consists of historical daily accumulated rainfall recorded by standard and tipping bucket gauges spread over the Sahel and covering 1960 to 2016 (Figure 1). This dataset is quality checked and used extensively for different research purposes [1,34,35]. It was made available through a strong collaboration between the West African Science Service Center on Climate Change and Adapted Land Use (WASCAL, www.wascal.org) and the National Meteorological and Hydrological Services (NMHS) of the member countries, as described by Salack et al [3].…”

Atmospheric circulation patterns that trigger heavy rainfall in West Africa

“…The daily rainfall data used in this study comes from a dataset established within the WASCAL (West African Science Service Centre on Climate Change and Adapted Land Use) project. A description of the rainfall dataset, with data sources and applied quality algorithms, is given in Bliefernicht et al, (2021). The rainfall dataset was also the source of information used in several other studies for this region, for example, for groundwater reconstruction using hydrological models (Ascott et al, 2020) or validation of regional climate model simulations (Dieng et al, 2017).…”