Monitoring of NRT Products: Desroziers plots

This page displays monthly RO Desroziers observation uncertainty estimates provided by MetOffice and ECMWF. Plots and data can also be downloaded from next demonstration products: Desroziers (MetOffice) and RO error stats (ECMWF). Click on the plot for a more detailed description.

Note that the Desroziers diagnostics are a consistency check on the input covariances provided to the data assimilation. They can be used to provide updated estimates of observation-, background- and analysis-error covariance matrices. However, these estimates depend upon the matrices which are provided as input, so should be carefully considered before being used.

Interpretation of diagnosed errors:
It is important to note that the diagnosed and prescribed observation errors should not be interpreted as pure measurement uncertainties. They represent the effective errors seen by a specific data assimilation system and may include contributions from forward-model error, representativeness error, and other sources of mismatch between the observations and models. Consequently, different NWP centres may diagnose different error estimates for the same GNSS-RO observations owing to differences in their models, observation operators, and assimilation systems.