Radiative forcing determination depending on MISR data and Fu-Liou Model

Abstract

Atmospheric aerosols particles exert significant direct radiative forcing and this plays an important rule of climate and climate change. Aerosols particles can affect the radiation budget and the temperature by changing the energy balance and distribution of solar and terrestrial radiation in the atmosphere. This paper discusses aerosols distribution over Middle East and North Africa and their influences on Radiative Forcing (RF) which consequently affect the radiation budget and try to find out an alternative method to obtain data of AOD else that obtained from Aeronet with acceptable error. These data can be used as input for RTM model (Fu-Liou) to determine RF. Thus RF can be calculated anywhere over the study area and not only at Aeronet stations. For this purpose Aerosol properties data from several Aeronet stations and corresponding data from MISR satellite in the focused region for long term have been retrieved and analyzed to verify MISR data; then data of Aeronet used to feed Fu-Liou model to simulate irradiances in the shortwave range under cloud-free conditions. Radiative Forcing estimated from Fu-Liou model have been compared with daily RF data of year 2015 over Egypt from Aeronet. As well as, average seasonal RF outputs from Fu-Liou model over North Africa and Middle East have been compared with the Aeronet RF at the surface and top of atmosphere for the different four seasons. The results illustrated that data from MISR satellite is coincide with Aeronat data with acceptable error while the average error of RF values from the Fu-Liou model and Aeront at wavelength 550nm is 10 % on surface and 7 % at top of atmosphere relative to Aeront when the prevailing type of aerosols is dust. While this ratio, increases to be from 14 to 19% on surface and from 17 to 22% at top of atmosphere for the different cases of aerosol types. This study is considered as an important attempt to find out method to determine RF at any where over the focused area and not only at Aeronet stations also this paper addressed the percentage of different types of aerosols during different situations and it documented the horizontal distribution of aerosols optical properties and its radiative forcing over the selected region.