SRAD sky view factor modelled using the 1" DEM-S

Mean monthly solar radiation was modelled across Australia using topography from the 1 second resolution SRTM-derived DEM-S and climatic and land surface data. The SRAD model (Wilson and Gallant, 2000) was used to derive:
• Incoming short-wave radiation on a sloping surface
• Short-wave radiation ratio (shortwave on sloping surface / shortwave on horizontal surface)
• Incoming long-wave radiation
• Outgoing long-wave radiation
• Net long-wave radiation
• Net radiation
• Sky view factor
All radiation values are in MJ/m2/day except for short-wave radiation ratio which has no units. The sky view factor is the fraction of the sky visible from a grid cell relative to a horizontal plane.

The radiation values are determined for the middle day of each month (14th or 15th) using long-term average atmospheric conditions (such as cloudiness and atmospheric transmittance) and surface conditions (albedo and vegetation cover). They include the effect of terrain slope, aspect and shadowing (for sun positions at 5 minute intervals from sunrise to sunset), direct and diffuse radiation and sky view.

The 3 arc-second resolution versions of these radiation surfaces have been produced from the 1 arc-second resolution surfaces, by aggregating the cells in a 3x3 window and taking the mean value.