AbstractsEarth & Environmental Science

Regional Sources of Precipitation in the Ethiopian Highlands

by Elnaz Ashkriz

Institution: Uppsala University
Year: 2015
Keywords: Ethiopian highlands; precipitation; moisture transport; wind; Natural Sciences; Naturvetenskap; Natural Sciences; Earth and Related Environmental Sciences; Oceanography, Hydrology, Water Resources; Naturvetenskap; Geovetenskap och miljövetenskap; Oceanografi, hydrologi, vattenresurser; Kandidatprogram i geovetenskap; Bachelor Programme in Earth Science
Record ID: 1357645
Full text PDF: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-252771


The purpose of this essay is to investigate the origin of the large amount of precipitation that is present in the northern Ethiopian Highlands. With Moisture transport into the Ethiopian Highlands by Ellen Viste and Asgeir Sorteberg as a base, this essays intents to compare the same data but by focusing on a much smaller time scale. This frame was chosen to see if the data would deviate (i.e. a small and specific time scale versus a large and general time scale). Whilst the investigation by Viste and Sorteberg focuses on the two most rain rich months, July and August during 1998-2008, this essay focuses on only July during 2008.                       To investigate where the precipitation originates from, this essay has analyzed different meteorological parameters such as horizontal and vertical winds at different altitudes and the moisture content of these winds.                       This essay has like Viste’s and Sorteberg’s paper used ERA-Interim data as a basis. However the course of action has differed. This essay has made conclusions by visually drawing conclusions by studying the data images while Viste and Asgeir have drawn their conclusions by backtracking the wind to its origin.                       This investigations results showed that great amounts of moisture were transported into the highlands from the south-west, and to some extent also from the north. While the moisture transport from the south-west was large due to the level of moist in the air, these winds where fairly small and at low altitudes. The winds from the north were visible at higher altitudes and were stronger, however they carried much less water vapor. However, exactly how much each of these winds actually contributed to producing rain is more difficult to say.                       The results from Viste and Asgeir (2011) showed that the amount of moist that was transported into the highlands were about 46 percent more from the north compared to from the south. The contribution to moisture release within the area was however almost equally great from north and south.                       Both investigations thus showed that the largest amount of moist was transported from the south and north. What this study did however not address was how large amount of the entire moist that had contributed to rain.                       One anomaly of large amounts of precipitation was registered on the 20<sup>th</sup> of July 2008. This study looked closer into this which showed that large winds were registered this date as well as an upwind cell. One can presume that these winds carried large amounts of moisture, which previous results has shown, and that this might be an explanation to the large amount of precipitation that was measured on the 20<sup>th</sup> of July.