Selection of the Optimum Global Circulation Model that Mimics the Circumstances of Egypt
Authors:   Ph.D., PE, Professor, Director of Coastal Research Institute and Former Director of Environment and Climate changes Research Institute, National Water Research Center, Cairo, Egypt,, Kheireldin* Khaled , Roushdi* Mahmoud ,   Ph.D., Associated Professor, Environment and Climate changes Research Institute, National Water Research Center, Cairo, Egypt,, Aboelkhear Mostafa ,   M.Sc., Assistant Researcher, Environment and Climate changes Research Institute, National Water Research Center, Cairo, Egypt,
Published: June 2020

Egyptian researchers in the field of climatic changes and their effects on various sectors, such as agriculture, water resources, health and social usually operate one of the Global Circulation Models (GCMs) and rely on its results. They considered its results as facts and real and they study the impact without reference to the uncertainty in their results. This is a major drawback to study the effect of climate changes on different sectors since there is a persuasive variation in the results of different models. Therefore, the impact analysis may result in building policies and develop alternatives in a way that is related to the real situation of the area under study. It has been found that the best global model or recycling models for the case of Egypt must be neutralized. It is an imperative component for building future policies to study the impact of climate change properly. The current study focuses on assessing the results of GCMs in Egypt. Previous reviews showed that there is no study to address this issue on Egypt. Thus, the following methodology was followed. Forty GCMs in Coupled Model Inter-comparing Project (CMIP5), are analyzed for the variable’s precipitation and temperature. These GCMs were Evaluated for Egypt for the climate variable precipitation rate through dividing the entire Egypt area to 110 cells each cell is square 100 km x 100 km. The precipitation and temperature were evaluated through applying five performance indicators. These indicators are listed as follow: i) coefficient of correlation (CoC) , ii) normalized root mean (NRMSE), absolute normalized mean bias error (ANMBE), average absolute relative error (AARE) and skill score (SS).The Payoff matrix (40 GCMs versus 5 indicators) is developed and then the entropy technique for determination of the performance indicators’ weights is applied. The Normalization technique was applied for each season out of 4 seasons that are winter, spring, summer and autumn on the performance indicators. These weights are applied to assist for ranking the 40 GCMs. The Ranking of these GCMs were obtained through a multi-criterion decision-making outranking method (PROMETHEE-2). Finally, it is proven that the “MPI-ESM-LR” GCM is found to be the best model for predicting the climate change parameters, (precipitation and temperature), all over Egypt compared to the other 39 models. The MPI-ESM-LR GCM model is developed by the Max Planck Institute for Meteorology in Germany. It is recommended that the results of climate change projects for Egypt up until year 2100 has to apply the output results of the GCM named MPI-ESM-LR rather than other GCMs as long as it gives the most proper results for climate change projection of Egypt.