Mean monthly net longwave radiation 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.

本研究采用1秒分辨率的航天飞机雷达地形测绘任务（Shuttle Radar Topography Mission，SRTM）衍生的DEM-S数字高程模型地形数据，结合气候与地表数据集，对澳大利亚全域的月均太阳辐射开展建模。本研究使用SRAD模型（Wilson与Gallant，2000）推导得到以下参数：
• 倾斜地表入射短波辐射
• 短波辐射比（倾斜地表短波辐射/水平地表短波辐射）
• 入射长波辐射
• 出射长波辐射
• 净长波辐射
• 净辐射
• 天空视野因子

所有辐射值的单位均为MJ/m²/天，仅短波辐射比无单位。天空视野因子指某网格单元相对于水平面的可见天空占比。

本数据集以每月中旬（14日或15日）为代表日，基于长期平均大气条件（如云量、大气透射率）与地表条件（反照率与植被覆盖度）计算得出辐射值，涵盖地形坡度、坡向与阴影效应（日出至日落期间以5分钟间隔模拟太阳位置），并包含直接辐射、散射辐射与天空视野影响。

本研究通过对1角秒分辨率的辐射栅格进行3×3窗口像元均值聚合，生成了3角秒分辨率的辐射表面数据集。