For example, “C” variables (such as precipitation and surface fluxes) are completely determined by the model during the data assimilation and should be used with caution. Output variables are classified into four classes, depending on the degree to which they are influenced by the observations and/or the model. A special CDROM, containing 13 years of selected observed, daily, monthly, and climatological data from the NCEP/NCAR Reanalysis, is included with this issue. Reanalysis information and selected output is also available on-line via the Internet ( http//::8000). Different types of output archives are being created to satisfy different user needs, including a “quick look” CD-ROM (one per year) with six tropospheric and stratospheric fields available twice daily, as well as surface, top-of-the-atmosphere, and isentropic fields. The system has been designed with advanced quality control and monitoring components, and can produce 1 mon of reanalysis per day on a Cray YMP/8 supercomputer. The database has been enhanced with many sources of observations not available in real time for operations, provided by different countries and organizations. The data assimilation and the model used are identical to the global system implemented operationally at the NCEP on 11 January 1995, except that the horizontal resolution is T62 (about 210 km). The NCEP/NCAR 40-yr reanalysis uses a frozen state-of-the-art global data assimilation system and a database as complete as possible. This eliminates perceived climate jumps associated with changes in the data assimilation system. This effort involves the recovery of land surface, ship, rawinsonde, pibal, aircraft, satellite, and other data quality controlling and assimilating these data with a data assimilation system that is kept unchanged over the reanalysis period 1957–96. The NCEP and NCAR are cooperating in a project (denoted “reanalysis”) to produce a 40-year record of global analyses of atmospheric fields in support of the needs of the research and climate monitoring communities.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |