Cycle 23r4 summary of changes

12 June 2001 Introduction of Cy23r4. This version includes the following modifications:

1. several changes in the use of satellite data over land and sea ice (more AMSU data and use of skin temperature rather than upper-layer soil temperature in processing radiances);

2. radiation parametrization routines are called on an hourly (instead of 3-hourly) basis during the data assimilation;

3. the time integration of the surface skin temperature over land has been improved;

4. the horizontal diffusion on vorticity has been increased to bring it in line with that applied to divergence and temperature without any noticeable impact on the forecast fields;

5. an improved ozone model developed by Meteo France has been introduced with a new parametrization of the destruction of ozone by heterogeneous chemical processes.

Cycle changes

Please note

Prior to 2006 information on cycle upgrades has been migrated from the old website to the new website "as is". The information has not been reviewed during the migration.