Implementation of 3DVAR for the Met Office Stratospheric Analyses ================================================================= The Middle Atmospheric Group at the Met Office has "been working on the development of a 3D variational (3DVAR) data assimilation system to replace the Analysis Correction (AC) data assimilation system. The stratospheric analyses were produced by a research data assimilation from October 1991, and from October 1995 the research system was replaced by a similar system which was run as part of the operational suite. " The new 3DVAR assimilation went operational on 14th November this year. Output from the new system is now available at the BADC for scientific research, in the same format as output from the current system. "The major changes are: * The introduction of the 3D variational data assimilation scheme. This is described by the recent paper by Lorenc et al, 2000 (Quart. J. Roy. Meteor. Soc., 126, 2992-3012). * The assimilation of radiances, rather than temperature retrievals, from polar orbiter satellites. * The use of a new model configuration, with 40 (rather than 42) levels; this is closer to what is used in the standard global forecast model. Preliminary trials of the new data assimilation system have indicated that the analysed fields in the troposphere and lower stratosphere are similar to those from the current system. Objective forecast verification scores have indicated significant benefit from the change from AC (with assimilation of retrievals) to the use of 3DVAR (with radiance assimilation). In the upper stratosphere the changes are more marked: the stratopause is typically 10 K warmer than in the current system, with the uppermost levels cooler. These latter changes are are largely a reversal of biases that were introduced inadvertently in January 1999 when the ozone climatology file was changed incorrectly." A new filename convention has been adopted to differentiate the output files from the new 3DVAR assimilation scheme and the data files from the previous AC data assimilation system. Hence ppassm_operf_y.._m.._d.._h...pp becomes ppassm_operg_y.._m.._d.._h...pp At the BADC, the new data files can be found in the current year assimilated data directory: /badc/ukmo-assim/data/standard/2000/ The Assimilated data documentation on the BADC Web pages will be updated shortly. BADC Support 15th November 2000

ACSOE data monthly release ========================== Some data archived in the framework of the ACSOE project have been released to the public domain: * data from the FREETEX campaign of 1996 (FREETEX-96); * data from the FREETEX campaign of 1998 (FREETEX-98); * ozone profiles (OZPROF) collected in April 1998. Data directories: * [/badc/acsoe/data/freetex-96/jungfrau/](/cgi-bin/data_browser/data_browser/badc/acsoe/data/freetex-96/jungfrau/) * [/badc/acsoe/data/freetex-98/jungfrau/](/cgi-bin/data_browser/data_browser/badc/acsoe/data/freetex-98/jungfrau/) * [/badc/acsoe/data/ozprof/aberystwyth/98/](/cgi-bin/data_browser/data_browser/badc/acsoe/data/ozprof/aberystwyth/98/) ______________ BADC Support 1/11/2000

ACSOE data monthly release ========================== Some data archived in the framework of the ACSOE project have been released to the public domain: * ozone profile data (OZPROF) collected in March 1998. Data directory: [/badc/acsoe/data/ozprof/aberystwyth/98/](/cgi-bin/data_browser/data_browser/badc/acsoe/data/ozprof/aberystwyth/98/) ______________ BADC Support 2/10/2000

The BADC has made available a new service allowing registered users to download selected UKMO surface station data from multiple stations and multiple years. To access this new service, proceed as follows: ...

ACSOE data monthly release ========================== Some data archived in the framework of the ACSOE project have been released to the public domain: * ozone profile data (OZPROF) collected in February 1998. Data directory: [/badc/acsoe/data/ozprof/aberystwyth/98/](/cgi-bin/data_browser/data_browser/badc/acsoe/data/ozprof/aberystwyth/98/) ______________ BADC Support 1/9/2000

Delays in setting up new BADC user accounts =========================================== Due to the Royal Mail Strike in Oxfordshire, no mail has been delivered to the BADC for the past 7 days. This unfortunately implies that no applications for new BADC Accounts have been delivered to the BADC for the past 7 days and nobody knows how long it will last. Consequently there will be delays in setting up accounts for new BADC users. However, if you wish to access restricted data in earnest, please contact the BADC Support at badc@rl.ac.uk . We are sorry for the inconvenience this may cause. BADC Support 15/08/00.

ACSOE data monthly release ========================== Some data archived in the framework of the ACSOE project have been released to the public domain: * ozone profile data (OZPROF) collected in December 1997 and January 1998; * data from the HILLCLOUD campaigns of June-July 1996 and June-July 1997. Data directories: * [/badc/acsoe/data/ozprof/aberystwyth/97/](/cgi-bin/data_browser/data_browser/badc/acsoe/data/ozprof/aberystwyth/97/) * [/badc/acsoe/data/ozprof/aberystwyth/98/](/cgi-bin/data_browser/data_browser/badc/acsoe/data/ozprof/aberystwyth/98/) * [/badc/acsoe/data/hillcloud-96/](/cgi-bin/data_browser/data_browser/badc/acsoe/data/hillcloud-96/) * [/badc/acsoe/data/hillcloud-97/](/cgi-bin/data_browser/data_browser/badc/acsoe/data/hillcloud-97/) ______________ BADC Support 1/8/2000

Haloe Level 3A version 19 data now publically available from the BADC ==================================================================== The BADC has recently acquired the HALOE Level 3A version 19 data. This dataset covers the time period from 11-OCT-1991 through 30-APR-2000. The HALOE level 3A data are vertical profiles of methane (CH4), hydrogen chloride (HCl), hydrogen fluoride (HF), nitric oxide (NO), nitrogen dioxide (NO2), water vapor (H2O), ozone (O3), temperature (TEMP), and aerosol extinction (AEXTCH4, AEXTHCL, AEXTHF and AEXTNO). More information about this dataset is available at BADC Support 24/07/00.

GISST2.3 Data have had to be replaced ===================================== The UK Met. Office has recently discovered an error in their reformat-to-send-out program which has made a difference of 1 in the second decimal place of the GISST dataset we hold. The difference is negligible but to be consistent, the BADC replaced all the GISST files with the correct version 2.3 provided by the UK Met. Office. 10 years gzipped data files as provided by the UK Met. Office have also been made available. Note that the GICE data are unaffected. We are sorry for the inconvenience this may cause. BADC Support 12/07/00.