15 April 2022
New URL, updated contents, and addiotional ALERA2 data
The URL is changed, contents are updated, and data of ALERA2 is added.
01 Oct 2008
Additions to ens
All 40 members from 22 Aug 2006 to 16 Jan 2007 are copied in ens directory and now available online.
01 Jul 2008
As of 2 July 2008, the URL of ALERA is changed as follows: http://www.jamstec.go.jp/esc/afes/alera/
18 January 2008
Several surface pressure data rejected unexpectedly
BUG REPORT: A bug has been found in the observation file conversion program. As a result, several surface pressure observations (out of about 5000) per analysis have been rejected unexpectedly. The impact is expected to be small.
ALERA posted
ALERA (AFES–LETKF experimental reanalysis) is posted on this server. It is accessible with an OPeNDAP client, such as GrADS and nco. Visit the ALERA page for details. Enjoy.
System update on 1 June 2005
An updated version of LETKF is used after 1 June 2005. In this update, vertical localization is introduced for surface pressure observations. The update has positive impact on the analysis performance evidenced by the reduced difference from CDAS (NCEP/NCAR Reanalysis).
ALERA Publications
A list of publications related to ALERA has been created.
Spin-up period
The first month (May 2005, or at least first ten days) is considered to be a spin-up period. Although the shock is very small, the second month (June 2005) could also be considered as a spin-up period for the updated system introduced on 1 June 2005. The data in early days are available for those who are interested in the spin-up process of LETKF.
Discontinuity of ensemble spread
There is a discontinuity of the ensemble spread around North America. The discontinuity appears at 0 and 12 UTC. The specific reason for the discontinuity has not been identified. Similar discontinuities are sporadically found other parts of the world as well.