GRAS
Satellite Application Facility

Error-Covariance Products

The error covariance matrix is a dataset that specifies the correlations in the observation errors between all possible pairs of vertical levels. It is given as a two-dimensional array, of size NxN , where N is the number of vertical levels in the sounding data products.

There are two basic error-covariance matrix products:

• Covariance matrix for NRT sounding data products
• Covariance matrix for off-line sounding data products

Each matrix can be provided in several versions reflecting variations with geographical areas (e.g. latitude) and with season.