Radiation and microphysical data are employed to deduce the bulk radiative and microphysical characteristics of the aerosol layer over the Saudi Arabian Peninsula and the adjacent Arabian Sea. Observed particle size distributions, total mass loading, and vertical distributions of the dust are presented for five analysis periods. There is a large daily variability of the dust mass loading over the desert. The broadband radiative characteristics of the dust are inferred by comparing calculations for a dust free atmosphere with in situ broadband radiative measurements. The dust had no detectable effect on the longwave radiative fluxes, while it approximately doubled the clear sky shortwave absorption. The total shortwave absorption by the dust is dependent on the underlying surface albedo. The solar absorptance of the dust is expressed in terms of the dust mass loading and is incorporated into a broadband shortwave radiative transfer model to assess the surface and tropospheric energy budgets. For the desert cases the dust is largely responsible for a net 24 hour radiative energy convergence between 530 and 800 mbar. A 24-hour radiative energy convergence is also found over the ocean; however, the layer depth is shallower than the desert case, being limited to the top of the dust layer. The thermodynamic structure of the heat low is presented. Calculations of temperature advection from the Saudi Arabian Peninsula to the Arabian Sea, suggest that horizontal advection aids in offsetting a net 24 hour tropospheric energy convergence over the desert. This warm air advection along with the transport of dust over the Arabian Sea, may assist in maintaining the low level inversion and shallow most layer observed over the western and central Arabian Sea.