Evaluation of simulations with the regional climate model REMO over Central Africa and the effect of increased spatial resolution

Abstract

Simulations of the regional climate model REMO at 25 and 50 km (0.44° and 0.22°, respectively) grid spacing are evaluated over Central Africa for the period 1998–2010. The model's ability to simulate various aspects of the observed climate is assessed with a main focus on precipitation characteristics. The results show that the REMO model has a good skill to reproduce the main regional features of the mean climate fields as well as seasonal and annual cycles, although some biases still exist. The model captures the variability in precipitation anomalies between different events associated with El Niño/Southern Oscillation. Generally, the findings remain largely insensitive to the refinement of the horizontal resolution, especially when considering the regional scale. This points the fact that the model dynamical and physical setup may have to be adjusted when setting a focus on the Central African region, in order to better represent the climate mechanisms. It is further found that REMO is capable of capturing the basic features of climatic extremes and accurately represents the shape of the frequency distribution of daily precipitation data. Daily characteristics of precipitation are simulated much better by REMO at 25 km.

CORDEX Multi‐RCM Hindcast Over Central Africa: Evaluation Within Observational Uncertainty

“…The annual overestimation of rainfall in ERAINT over the above countries, coupled with the improvement of ERAINT by RCMs is also observed at the seasonal scale (see supporting information, Figures S1–S8). These features, which are generally induced by topography, are also associated to pressure gradient between CA land and the Atlantic Ocean surface (Vondou & Haensler, ; Vondou et al, ). Thus, the wet biases found here highlight the challenge for ERA‐Interim reanalysis to adequately simulate low‐level clouds and precipitation in CA as recently shown by Dommo et al ().…”

“…In MPI‐REMO, the first phase is strongly overestimated and the second phase is underestimated. This can be related to a misrepresentation of precipitation over the coastal region (Moufouma‐Okia & Jones, ; Vondou & Haensler, ). The spatial correlation values ( ) between each data sets and the observations ensemble mean is also presented on Figure .…”

“…Globally, there has been a marked increase in the analyses of CORDEX simulations across Africa (Abiodun et al, ; Akinsanola et al, ; Coppola et al, ; Diallo et al, ; Dosio, ; Endris et al, ; Favre et al, ; Gbobaniyi et al, ; Hernández‐Díaz et al, ; Kalognomou et al, ; Kim et al, ; Klutse et al, ; Moufouma‐Okia & Jones, ; Nikulin et al, ; Pinto et al, ; Pokam et al, ; Russo et al, ). However, very few RCMs assessments have been performed with a focus over CA and in addition, most of these works have used only one RCM (Fotso‐Nguemo et al, ; Tamoffo et al, ; Vondou & Haensler, ).…”

An evaluation of COSMO‐CLM regional climate model in simulating precipitation over Central Africa

“…Overall, this analysis shows that CCLM succeeds to reasonably capture the precipitation climatology as well as the patterns of the associated low‐level circulation over CA, though some deficiencies are still evident. Moreover, biases in precipitation obtained here are generally a problem common to RCMs, but are consistent to those found in other studies with either CCLM (Panitz et al ., ; Dosio et al ., ; Dieng et al ., ) or different RCMs (e.g., Tchotchou and Kamga, ; Gbobaniyi et al ., ; Diallo et al ., ; Mbienda et al ., ; Fotso‐Nguemo et al ., ; Vondou and Haensler, ; Tamoffo et al ., ). Majority of these studies suggested that these biases are mostly linked to the models failure to resolve convective processes and topography than to errors inherited from the lateral boundary conditions.…”

“…() with CCLM over the whole African domain, also those of Crétat et al . () and Vondou and Haensler () with WRF and REMO, respectively, over their different regions of interest. In addition, they mentioned that CCLM fails to fully transport the atmospheric moisture from the ocean to the inland regions, in particular over the Guinean Gulf.…”