However, if there is a large difference between the actual surface site elevation and the grid box average elevation, then one might review as to whether an altitude correction is needed. So, if your surface site has a surface elevation within about 100 m of the grid box average, then you should be able to use the provided values for the estimated parameter. The surface elevation provided is that of the 1/2 x 1/2 degree area grid box. For meteorological parameters like temperature and relative humidity this value is representative of the 1/2 x 1/2 degree area for solar the irradiance is determined using cloud statistics from a 1x1 degree area.

The data sets provided through POWER are 'gridded' in the sense that the value of the parameter you request is effective for the entire area of the grid box. Please see our documentation pages for more information on the data source. Regardless, the value is given is for the grid box average and that is why it doesn't correspond exactly to elevation of a particular location.

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