A new hybrid formulation for the background error covariance in the IFS: evaluation
Title | A new hybrid formulation for the background error covariance in the IFS: evaluation
|
Technical memorandum
|
|
Date Published |
12/2019
|
Secondary Title |
ECMWF Technical Memoranda
|
Number |
856
|
Author | |
Publisher |
ECMWF
|
Abstract |
A new hybrid formulation for the background errors in the European Centre for Medium-Range Weather Forecasts (ECMWF) 4D-Var was proposed in Massart (2018) and tested in simple configurations. In the following document, we evaluate this new formulation in a more realistic configuration. In order to perform the evaluation, the new formulation had to be adapted to the current implementation of ECMWF
Overall, the results show that the new hybrid formulation of the background errors provides better forecast scores than when using static background errors. Yet, it currently fails to compete with the current formulation for medium-range forecasts. Nonetheless, the results also show that the current formulation could be improved. For example, the wind forecast is better for all forecast ranges in the southern hemisphere and tropics when it is derived from the a -Bh experiment. The relative humidity forecast fromthe a -Bh experiment is also in general the best. These results encourage us to further develop the new hybrid formulation. |
URL | https://www.ecmwf.int/en/elibrary/81147-new-hybrid-formulation-background-error-covariance-ifs-evaluation |
DOI | 10.21957/3ad31a1ey |
Download citation |