Modification of radiative transfer model for estimating solar irradiance over Peninsular Malaysia

The availability of atmospheric parameters is important in estimating solar irradiance using Radiative Transfer Model. Atmospheric data such as temperature, relative humidity, pressure and atmospheric trace constituent in the function of altitude are the basic requirement for estimating solar irradiance and it is very limited. Static atmospheric model such as Air Force Geophysics Laboratory Atmospheric Constituent Profiles does provide the required parameter however it is outdated and does not reflect the local atmospheric condition. A Local Static Atmospheric Model for Malaysia was built in this study to provide the needed atmospheric parameters. The model was built based on monthly data from Atmospheric InfraRed Sounder in a period of ten years at peninsular Malaysia and validated with local meteorological data. Along with the atmospheric model, simple model of the atmospheric radiative transfer of sunshine was rewritten in MATLAB environment with some minor modification that allows the local atmospheric model to be integrated into the radiative transfer model. The modified radiative transfer model takes five parameters for the calculation of the solar irradiance which are, date, time, longitude, latitude and altitude. It reduces the parameter needed by the conventional radiative transfer model such as the inputs of atmospheric parameter, pressure, zenith angle, path length, and earth-sun distance. The modified the radiative transfer model was design to include the local atmospheric model as the main atmospheric input which improve its accuracy and suitable to be used locally. The results of the study were compared with the solar flux data from Aerosol Robotic Network which return an overall correlation of 97% with 4.8% root mean square error for zenith angle below 60°

AERONET Remotely Sensed Measurements and Retrievals of Biomass Burning Aerosol Optical Properties During the 2015 Indonesian Burning Season

An extreme biomass burning event occurred in Indonesia from September through October 2015 due to severe drought conditions, partially caused by a major El Niño event, thereby allowing for significant burning of peatland that had been previously drained. This event had the highest sustained aerosol optical depths (AODs) ever monitored by the global Aerosol Robotic Network (AERONET). The newly developed AERONET Version 3 algorithms retain high AOD at the longer wavelengths when associated with high Ångström exponents (AEs), which thereby allowed for measurements of AOD at 675 nm as high as approximately 7, the upper limit of Sun photometry. Measured AEs at the highest monitored AOD levels were subsequently utilized to estimate instantaneous values of AOD at 550 nm in the range of 11 to 13, well beyond the upper measurement limit. Additionally, retrievals of complex refractive indices, size distributions, and single scattering albedos (SSAs) were obtained at much higher AOD levels than possible from almucantar scans due to the ability to perform retrievals at smaller solar zenith angles with new hybrid sky radiance scans. For retrievals made at the highest AOD levels the fine‐mode volume median radii were ~0.25–0.30 micron, which are very large particles for biomass burning. Very high SSA values (~0.975 from 440 to 1,020 nm) are consistent with the domination by smoldering combustion of peat burning. Estimates of the percentage peat contribution to total biomass burning aerosol based on retrieved SSA and laboratory measured peat SSA were ~80–85%, in excellent agreement with independent estimates