Nyssen, Jan

Termonia, Piet

Van Ginderachter, Michiel

Van Schaeybroeck, Bert

Van Vooren, Sander

Ghent University Academic Bibliography

Geophysical Research AbstractsVol. 21, EGU2019-6612, 2019EGU General Assembly 2019© Author(s) 2019. CC Attribution 4.0 license.Validation of CORDEX Rainfall in the northwest Ethiopian highlandsand the role of the model orographyBert Van Schaeybroeck (1), Jan Nyssen (2), Piet Termonia (1,3), Michiel Van Ginderachter (1,3), and Sander VanVooren (2)(1) Royal Meteorological Institute of Belgium, Research and development, Brussels, Belgium, (2) Ghent University,Department of Geography, Ghent, Belgium, (3) Ghent University, Department of Physics and Astronomy, Ghent, BelgiumPrecipitation patterns over the Ethiopian highlands are known to be very complex but are of strong socio-economicimportance due to a high population density. Unfortunately, the region suffers from a lack of reliable observationaldatasets. A better understanding of the spatio-temporal rainfall variability could therefore be accomplished byrunning climate models. Precipitation modelling, however, is challenging in this region because of the complexorography including the Simien mountains peaking at 4550 m, the presence of Lake Tana and the seasonalconvective rainfalls. Also, observations are still required for model validation to gain confidence in climateprojections that assess how global climate change affects precipitation and associated impacts, for example, onagriculture.In this work, model precipitation from the CORDEX project is evaluated for northwest Ethiopia againstmultiple sets of gridded observational data sets (Van Vooren et al. 2018). Thereby the role of the model orographyis highlighted. Despite the model overestimation, observations generally lie within the range of the modelensemble. The climate models overestimate the elevational sensitivity, i.e. rainfall is too large for high elevationsand too small for low elevations. Surprisingly, the models that use the most smoothened representation of themodel orography are closest to observations but these positive results could be a mere consequence of their verypoor orographic representation or an underestimation of orographic rainfall in the observational datasets. A secondgroup of six models also has a poor orographic representation but provides the largest ensemble contribution tothe overestimation of rainfall at high elevations. Given their strong elevation–precipitation correlation even largerbiases could be expected in case these models incorporate a correct orography.Van Vooren, S., Van Schaeybroeck, B., Nyssen, J., Van Ginderachter, M., & Termonia, P. (2019). Evalua-tion of CORDEX rainfall in northwest Ethiopia: sensitivity to the model representation of the orography.International Journal of Climatology, Online Early View.

Validation of CORDEX rainfall in the northwest Ethiopian highlands and the role of the model orography

https://biblio.ugent.be/publication/8605324/file/8605325

Validation of CORDEX rainfall in the northwest Ethiopian highlands and the role of the model orography

Abstract

Similar works

Full text

Available Versions

Ghent University Academic Bibliography