What is downscaling?
Forecast models work on a grid system, predicting values for fixed, regularly spaced points throughout the atmosphere. Where a forecast is presented as being for a named location, for example a town or city, then the forecast data must first be interpolated from the grid to the intermediate location. This is done by applying weightings to the adjacent four grid points to produce a single value for the site. Corrections for varying orography and land type are taken into account in this process. E.g. where a site has forecast grid points adjacent that are located over the ocean, the weighting will be biased towards those remaining two points that lie over land. Such downscaled forecasts are a vital tool when trading site specific weather Indices such as those traded through the CME.
