Identification of Water Vapor Flux Convergence Layers and Estimation of Precipitation over Ethiopia

Abstract

Abstract This paper aimed to investigate the most important moisture-bearing layers in VIWVF among different monthly intervals over the Ethiopian atmosphere based European Centre for Medium-Range Weather Forecasts (ECMWF) averaged reanalysis zonal and meridional wind data and specific humidity data with the time coverage from 1991-2019 with 0.25° by 0.25° spatial resolution in various types of pressure levels from 1000hpa to 300hpa and ERA5-Land monthly averaged reanalysis data for precipitation. The Ethiopian troposphere is classified into four layers clustering by the Euclidean Distance method. VIWVF and specific humidity are higher in the lower pressure levels and decrease at higher altitudes. The moisture source during the Belg season is the Indian Ocean and the Arabian Sea are the main sources; the ML1 and ML2 are the interesting layers and good moisture convergence cores for Belg season rainfall, especially in March and April. During the Kiremt season, VIWVF sources are from the South Indian Ocean and the Mediterranean Sea through the Red Sea, with high moisture flux convergence observed in Lr. L and ML1 tropospheric layers (1000hpa-850hpa and 825hpa-750hpa), in July and August. Significant positive correlations between Belg VIWVF and precipitation were recognized in the layer 700hpa-600hpa over Northeastern highlands, Bale, Harar, and Yirgacheffe, whereas significant positive correlation with Kiremt rainfall over central-western to northwestern Ethiopia in July and August at 1000-850hpa and 825-750hpa. This research targeted to identify the most important moisture-centered layers, especially in the Summer(main) and Spring (second) rainy seasons through VIWVF and its association with precipitation in order to forecast climate and weather impacts over Ethiopia’s atmosphere.