Winter solar radiation data layer used in the creation of Land Environments of New Zealand (LENZ) classification. The classification layers have been made publicly available by the Ministry for the Environment (see https://data.mfe.govt.nz/layers/?q=LENZ for to access these layers).

Winter solar radiation reaches a minimum in June, the month when the sun is lowest in the sky and day lengths are at their shortest, hence the layer is the monthly average solar radiation layer calculated for the month of June. Estimates of winter solar radiation across New Zealand were derived from a surface fitted to monthly solar radiation estimates for 98 sites as described for mean annual solar radiation.

Data describing monthly humidity was used as a surrogate measure of cloudiness to improve the fit of the surface to the underlying data. This also increases the local accuracy of the surface predictions, as the number of meteorological stations used to fit the humidity surface is more than three times greater than the number of sites used to fit the solar radiation surface. For more details on the creation of these layers see the mean annual solar radiation layer.

The units for this layer are in MJ/m2/day, higher values signify areas that have higher levels of solar radiation. This layer has been multiplied by a factor of 10 (i.e. converted into an integer grid) to save space and make the grids more responsive. A value of 53 is actually 5.3 MJ/m2/day.

Additional details such as the climate station locations used in the creation of the layer and error maps are defined in the attached LENZ Technical Guide.