******************************************************************************* * * * Welcome to the NCEP/NCAR Reanalysis CD-ROM. This CD-ROM contains forty-one* * (1958-98) years of selected monthly mean fields from the NCEP/NCAR * * Reanalysis Project. Several levels of monthly mean heights, temperatures, * * winds, specific humidity and vertical velocity are included, together * * with precipitation, surface and top of the atmosphere fluxes, and * * near-surface fields. A monthly climatology of these fields averaged over * * 1979-1998 is included. For some fields (500 and 700 mb heights, 700 mb * * temperatures, 200 and 850 mb winds, sea level pressure and surface * * temperatures (SST)) we have included fifty-one years (1948-98). Independent* * estimates of precipitation and olr globally (1979-98) and precipitation and* * surface air temperature over the U.S. (1948-98) are included, as are grids * * of the number of different types of observation by month (1946-98). A * * comprehensive interactive menu is provided to plot the fields on the CD-ROM* * * * The model's land-sea mask and orography are also included. * * * * Problems and questions should be directed to: * * * * Dr. Glenn H. White * * Environmental Modeling Center * * W/NP23, WWB, Rm. 207 * * National Centers for Environmental Prediction * * 5200 Auth Rd. * * Camp Springs, MD 20746 * * USA * * * * email: Glenn.White@Noaa.Gov * * * * * * * * * * ************************************************************************* * * * To run the demo from Windows95, enter E:\DEMO.BAT at the RUN * * * * option from the START menu, assuming the cd-rom is device E:. * * * * To run the demo from MS-DOS or the MS-DOS prompt, enter * * * * E: * * * * DEMO * * * * * * * * To run the demo from Windows98, * * * * a) click on "MyComputer", * * * * b) click on your cdrom drive, * * * * c) click on "demo.bat" * * * * * * * * To run grads directly, * * * * a) click on "MyComputer", * * * * b) click on your cdrom drive, * * * * c) click on "start.bat", * * * * d) click on "Programs" directory, * * * * e) click on "PCGRADS" directory, * * * * f) click on "grads.exe" * * * * g) press the enter key (to select landscape format) * * * * h) type in the the control file you wish to open * * * * for example "open /data/monthly/hgt.ctl" will * * * * open the file containing 51 years of monthly mean * * * * heights * * * * * * * * It is possible to run the demo on some workstations. See the end * * * * of "README.UNX". I successfully ran it on my LINUX box which had * * * * GrADS already on it. * ************************************************************************* * * * * To run grads, enter E:START E:, assuming the cdrom is device E:, or * * simply type in start and follow directions. * * * * ******************************************************************************* TABLE OF CONTENTS ----- -- -------- I) Introduction II) Data Organization and Access Software III) The 30-Second Plot IV) Other Important CD-ROM Documents V) Changes I. INTRODUCTION This CD-ROM contains forty-one years of selected fields (fifty-one for a few fields) from the NCEP/NCAR Reanalysis Project. The goal of this reanalysis project is to provide the climate research, monitoring, and modeling communities with analyses that span the last 51 years that have been generated from a stable, invariant analysis system. Before the reanalyses, there was little choice but to use analyses that supported real-time weather forecasting; changes in these systems introduced inhomogeneities that could be erroneously interpreted as changes in the 'climate'. The quality of these analyses should be superior to earlier 'operational' analyses because: o a state-of-the-art data assimilation system is used, o more observations (later data cut-off time) are used, o quality control has been improved, and o the model/data assimilation procedure remains essentially unchanged during the entire NCEP/NCAR Reanalysis project (1948-1995) and for the ongoing CDAS (Climate Diagnostics Assimilation System). (Of course there will be some changes as the types and numbers of observations change over the years.) More comprehensive descriptions of the NCEP/NCAR Reanalysis Project can be found in file "TEXT\INTRO\REANAL.INF" (published BAMS, March 1996) and in file "TEXT\CLOSE\REANCLOS1.HTML (submitted to BAMS, June 1999). The main source of inhomogeneities in the NCEP/NCAR reanalysis is probably changes in the observing system. We have included on this CD-ROM monthly totals of 7 types of observations on a 2.5 deg. grib for 1946-98; the demo includes programs to plot the observations and to maskout in any monthly mean field regions where no observations are available for that month. This is intended to let users of the CD-ROM examine changes in the observing system and to warn the users of the reanalysis about deficiencies in the observing system, especially before the use of satellite data, which began in 1975. II DATA ORGANIZATION and ACCESS SOFTWARE The reanalysis products on this CD were written in GRIdded Binary (GRIB), which is a self-documenting, international standard. For those who desire more information about GRIB, see documentation in file "TEXT\GRIB\GUIDE.TXT". However, since GRIB can be difficult to read without the proper software, we have provided two methods for accessing the GRIB data on this CD. First, the PC version of "Grid Analysis and Display System" (GrADS) is included. GrADS is an extremely powerful, useful, and easy-to-use data manipulation and display package that was developed by Brian Doty of the Center for Ocean-Land-Atmosphere Studies in Calverton, Maryland. The Unix versions of GrADS are available at no charge (see PROGRAMS\GRADS.DOC). The PC version of GrADS is in the "PROGRAMS\PCGRADS" directory. This version requires a PC with a 386 with a math co-processor, 486DX or a Pentium CPU. For more information on GrADS, including instructions on obtaining the latest version of pc-GrADS, see the file "PROGRAMS\GRADS.DOC". The second method to access GRIB data is through the use of a C language program developed at NCEP by Wesley Ebisuzaki called 'wgrib', which is also provided on this CD. This program requires a C compiler and a 32-bit (or more) computer and was written expressly for support of the NCEP/NCAR Reanalysis project. Complete documentation for 'wgrib' appears in file "PROGRAMS\WGRIB\README" on this CD. More up-to-date documentation can be found on the internet at http://wesley.wwb.noaa.gov/wgrib.html'. 'wgrib' performs the following functions: o inventories files, o deletes records, o rearranges records, o converts GRIB to IEEE, binary and text. The data is stored in the following format. 'Horizontal' fields (maps) are stored in GRIB on a 144 x 73, 2.5 x 2.5 degree grid. The first data point is for the northern-most point at 0E. The second point is is slightly east of the first point. For more information, see TEXT\TABLE.IDS. III The 30-Second Plot One goal in the design of this CD-ROM was to make if fast to use. Suppose you happen to be interested in the monthly mean 500 mb geopotential height for February 1962. You should be able to take this CD-ROM put it into your computer, and be looking at the 500 mb heights in half a minute. 0) GrADS must be installed. A version of GrADS for the PC is on the CD-ROM, see README.DOS. Workstation versions are available from Brian Doty, COLA (see PROGRAMS\GRADS.MSG). 1) Insert CD-ROM into PC, or workstation (10 seconds) 2) On a workstation, you must mount the cd-rom (system specific) (6 seconds) Assume the cd-rom is mounted at /cdrom (Unix) or e: (MS-DOS). 3) Start GrADS (4 seconds) 4) Open a control file (5 seconds) example: ga> open /cdrom/data/monthly/hgt.ctl (UNIX, lower-case cd-rom file names) example: ga> open /cdrom/DATA/MONTHLY/HGT.CTU (UNIX, upper-case cd-rom file names) example: ga> open /cdrom/DATA/MONTHLY/HGT.CTS;1 (UNIX, upper-case with semicolon cd-rom file names) example: ga> open /data/monthly/hgt.ctl (MS-DOS, assuming you were at the e: prompt before starting grads) Note: to check the contents of the file, type ga> query file 5) Display a plot (5 seconds) example: ga> set time feb1962 ga> set lev 500 ga> d hgt Note: The 30-second plot will only work on PC's and certain UNIX workstations (see README.UNX). A complete listing of the data files and contents can be found in TEXT\LISTS\FILELIST and TEXT\TABLE.IDS. IV) Other Important CD-ROM Documents See file(s) ___________ 1) About the NCEP/NCAR Reanalysis Project .... TEXT\INTRO\REANAL.INF TEXT\CLOSE\REANCLOS1.HTML 2) Directory structure of this CD ............ CD.ORG 3) Data organization, access information ..... README.DOS, README.UNX, CD.ORG 4) Table of data fields on this CD ........... WHEREIS.IT, TEXT\TABLE.IDS (units, filename interpretation, i.e., Rosetta stone) (list of data files) TEXT\LISTS\FILELIST 5) About GRIB (GRIdded Binary) ............... TEXT\GRIB\GUIDE.TXT 6) Details about the Reanalysis Project ...... TEXT\DETAILS\*.* 7) Data Access Software ...................... - Analysis & Display ("GrADS") ........... PROGRAMS\GRADS.MSG, README.DOS PROGRAMS\PCGRADS\GRADSCRU.TXT - Read/inventory/convert ("wgrib")......... PROGRAMS\WGRIB\README