ECMWF Subseasonal to Seasonal Precipitation Forecast for Use as a Climate Adaptation Tool Over Nigeria

Ugbah Paul Akeh,Olumide A Olaniyan,Steve Woolnough

doi:10.1007/978-3-030-45106-6_97

Ugbah Paul Akeh, Olumide A Olaniyan + Show 1 more

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https://doi.org/10.1007/978-3-030-45106-6_97

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Abstract

AbstractFarmers in most parts of Africa and Asia still practice subsistence farming which relies minly on seasonal rainfall for Agricultural production. A timely and accurate prediction of the rainfall onset, cessation, expected rainfall amount, and its intra-seasonal variability is very likely to reduce losses and risk of extreme weather as well as maximize agricultural output to ensure food security.Based on this, a study was carried out to evaluate the performance of the European Centre for Medium-range Weather Forecast (ECMWF) numerical Weather Prediction Model and its Subseasonal to Seasonal (S2S) precipitation forecast to ascertain its usefulness as a climate change adaptation tool over Nigeria. Observed daily and monthly CHIRPS reanalysis precipitation amount and the ECMWF subseasonal weekly precipitation forecast data for the period 1995–2015 was used. The forecast and observed precipitation were analyzed from May to September while El Nino and La Nina years were identified using the Oceanic Nino Index. Skill of the forecast was determined from standard metrics: Bias, Root Mean Square Error (RMSE), and Anomaly Correlation Coefficient (ACC).The Bias, RMSE, and ACC scores reveal that the ECMWF model is capable of predicting precipitation over Southern Nigeria, with the best skill at one week lead time and poorest skills at lead time of 4 weeks. Results also show that the model is more reliable during El Nino years than La-Nina. However, some improvement in the model by ECMWF can give better results and make this tool a more dependable tool for disaster risk preparedness, reduction and prevention of possible damages and losses from extreme rainfall during the wet season, thus enhancing climate change adaptation.

Highlights

BackgroundWeather and climate affect man in diverse ways which greatly impact agriculture, food security, housing, transportation, health, engineering structures, water resources, military operations, oil exploration and exploitation, environment, livelihoods, etc. (Ugbah 2016)
At initial start dates up to June11 and towards the end of the season in September, the precipitation values all seem to be in close agreement, having only small differences, but beyond the week starting June 11, the forecasts start to deviate significantly from the observed with the largest differences around the period of the little dry season after which the lines begin to converge until the end of the season (Fig. 3)
It can be seen that the differences in precipitation amount increase with increasing lead time as depicted by lead 1 forecast which lies closest to the observation throughout the season

Summary

Introduction

BackgroundWeather and climate affect man in diverse ways which greatly impact agriculture, food security, housing, transportation, health, engineering structures, water resources, military operations, oil exploration and exploitation, environment, livelihoods, etc. (Ugbah 2016). These impacts are usually associated with extreme weather and seasonal hazards such as tropical cyclones, heavy rainfall, flooding, etc., which occur more frequently (IPCC 2018) For these reasons, scientists have continued to invest great time and resources in trying to understand and predict the processes that lead to changes in the atmosphere associated with these hazards. A timely and accurate prediction of the onset, cessation, expected rainfall of the monsoon season, and its intra-seasonal variability is very likely to reduce losses and risk of extreme weather (Vitart et al 2016) as well as maximize agricultural output to ensure food security This is one of the purposes for which the S2S project was set up

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