Meteorology / Analysis Data FTP / NOAA Reanalysis

Global NOAA-NCEP/NCAR pressure level reanalysis data archives were reprocessed into the HYSPLIT compatible format and are available on ARL's web site for 1948 through 2003. The global data files are on their native latitude-longitude grid (2.5 degree) and are archived as one file (122 Mb) per month. The GUI menu tab accesses the correct directory with the proper file name using anonymous ftp after the desired year and month have been selected.

The NCEP/NCAR Reanalysis Project is a joint project between the National Centers for Environmental Prediction (NCEP, formerly "NMC") and the National Center for Atmospheric Research (NCAR). The goal of this joint effort is to produce new atmospheric analyses using historical data (1948 onwards) and as well to produce analyses of the current atmospheric state (Climate Data Assimilation System, CDAS). Until recently, the meteorological community has had to use analyses that supported the real-time weather forecasting. More information about the reanalysis project and data can be found at the NCEP and CDC web sites.

A subset of this data (global pressure level only) is available from ARL in a format suitable for transport and dispersion calculations using HYSPLIT through the GUI. Both the global pressure-level data and a sigma-level regional extract over the U.S. are available through the web for on-line calculations using READY by selecting "Reanalysis" in the meteorological data set selection pull-down menu. Each directory contains data files with the following syntax: R{S|P}{YEAR}{MONTH}.{gbl|usa|tbd}, where R indicates "Reanalysis", S or P indicates that the data are on Sigma or Pressure surfaces, YEAR is a four digit year, and MONTH is a two digit month. The file suffix identifies the projection as either the 2.5 degree global latitude-longitude projection (gbl), or a regional conformal map projection (such as over the "usa"). Other regional projections are "to be determined (tbd)" later. The projection details are encoded in the file's index record and are processed by HYSPLIT during trajectory or dispersion computations. Note conformal regional projections (usa) are currently available only from READY's research directory pull-down menu.

A comparable data set is also available from ECMWF's 40 year reanalysis project. The GRIB files must be downloaded independently from the GUI, but may be converted through the GUI to the ARL format.



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