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 (GRM-07)
- Covariance matrix for Offline sounding data products (GRM-15)
Each matrix can be provided in several versions reflecting variations with geographical areas (e.g. latitude) and with season.