ASSESSMENT OF OUTGOING RADIATION VARIABILITY OVER SELECTED TOWNS OF AMHARA REGION, ETHIOPIA

GETANEH, WASSIE

dc.contributor.author	GETANEH, WASSIE
dc.date.accessioned	2017-12-19T04:13:48Z
dc.date.available	2017-12-19T04:13:48Z
dc.date.issued	2017-12-19
dc.identifier.uri	http://hdl.handle.net/123456789/8277
dc.description.abstract	Net radiation plays an essential role in determining the thermal conditions of the Earth’s surface and is an important parameter for the study of land-surface processes and global climate change. The estimated monthly net outgoing radiation values were validated against ground data for 12 months from (1997-2016) period of observation at eight stations with different underlying surface types. The long-wave radiation to space decreases with increasing cloud cover and cloud height because cloud temperatures are considerably lower than the earth’s surface and they decrease with cloud elevation. Moreover, clouds are good reflectors of solar radiation and consequently the global albedo increases and the absorbed solar energy decreases with increasing cloud cover. Gases absorb certain wavelengths of outgoing long wave radiation (OLR) which contributes by adding heat to the atmosphere. An increase in the concentration of a greenhouse gas would contribute to global warming by increasing the amount of radiation that is absorbed and emitted by these atmospheric constituents. The OLR is dependent on the temperature of the radiating body. It is affected by the Earth's skin temperature, skin surface emissivity, atmospheric temperature, water vapor profile, and cloud cover. In this study we assessed the characteristics of OLR over selected cities of Amhara region, Ethiopia, which helps to understand the existing relationship among different variables of climate. The result shows, the outgoing long wave radiation is maximum in winter than summer in all candidate cities due to clouds forcing effect. In addition the annual outgoing longwave radiation of the study area is estimated using simple models, for Bahir dar, Motta, Debre markos, Gondar, Metemma, Dangila, Nefas mewcha and Debre tabor is (7.076, 8.213, 7.1960, 7.05995, 6.628, 6.360, 6.234, 6.7450) MJ 𝑚 −2 respectively. 𝑑𝑎𝑦 −1 Key Words: Outgoing longwave radiation, evapotranspiration, clearness index, Shortwave radiation, net short wave radiation, albedo, actual vapor pressure, relative humidity, Cloud cover , sunshine hour duration , energy balance and greenhouse effect.	en_US
dc.language.iso	en_US	en_US
dc.subject	physics	en_US
dc.title	ASSESSMENT OF OUTGOING RADIATION VARIABILITY OVER SELECTED TOWNS OF AMHARA REGION, ETHIOPIA	en_US
dc.type	Thesis	en_US