******************************************************************************* * * * Welcome to the NCEP/NCAR Reanalysis Global Synoptic CD-ROM. This CD-ROM * * contains once-daily global time series of 1000 and 500 heights, 850 and * * 200 winds and 500 mb vertical velocity for 1979-96 together with a daily * * climatology of these fields averaged over 1979-95 from the NCEP/NCAR * * Reanalysis Project. * * * * The CD-ROM contains a "demo" with examples of plots that can be made * * with GrADS and with an interactive option ( "d" ) that lets the user * * produce plots over any geographical area for any day or a series of * * days of any of the fields included here and their anomalies from * * the daily climatology. * * * * Problems and questions should be directed to: * * * * Dr. Glenn White * * Environmental Modeling Center * * 5200 Auth Road Room 204 * * Camp Springs, MD 20746 USA * * * * email:Glenn.White@Noaa.Gov * * * * phone:(301)763-8302 ext 7238 * * * * ************************************************************************* * * * 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 * * * ************************************************************************* * * * * * ******************************************************************************* TABLE OF CONTENTS ----- -- -------- I) Introduction II) Data Organization and Access Software III) The 30-Second Plot IV) Other Important CD-ROM Documents V) Changes VI) Calculating an anomaly from climatology I. INTRODUCTION This CD-ROM contains 18 years of selected 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 40 years that have been generated from a stable, invariant analysis system. To date, there has been little choice but to use analyses that supported real-time weather forecasting, and 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 will remain essentially unchanged during the entire NCEP/NCAR Reanalysis project (1957-1995) and for the CDAS (Climate Diagnostics Assimilation System). (Of course there will be some changes as the types and numbers of observations changes over the years.) A more comprehensive description of the NCEP/NCAR Reanalysis Project can be found in file "TEXT\INTRO\REANAL.INF" (published BAMS, March 1996). 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 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. '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 formats. '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. A program, PROGRAMS\X2GRAD\X2GRAD.C can be used to make the files GrADS compatible. 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 weather on February 2, 1982 at 000 GMT. 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 in to 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/series/hgt500.ctl (UNIX, lower-case cd-rom file names) example: ga> open /cdrom/DATA/SERIES/HGT500.CUC (UNIX, upper-case cd-rom file names) example: ga> open /cdrom/DATA/SERIES/HGT500.CSC:1 (UNIX, upper-case with semicolon cd-rom file names) example: ga> open e:/data/series/hgt500.ctl (MS-DOS, assuming cd-rom is device e:) Note: to check the contents of the file, type ga> query file 5) Display a plot (5 seconds) example: ga> set time 00z2feb1982 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. Plots of any field or its anomaly from climatology can be made through the option "d" (Interactive Display of Daily Fields) in the demo program. IV) Other Important CD-ROM Documents See file(s) ___________ 1) About the NCEP/NCAR Reanalysis Project .... TEXT\INTRO\REANAL.INF 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 ........... 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 V) Changes Data for 1979 and for Oct. 1992-Feb. 1993 was rerun recently by R. Kistler and contains three corrections from the other years included here. Paobs were used correctly, the correct snow cover was used and several radiosonde stations were included that were erroneously omitted in an earlier version of the reanalysis. During 1979 these radiosondes were over Antarctica. The TOGA-COARE period (Oct. 1992- Feb. 1993) was rerun correcting an error in data processing that affected the tropical west Pacific. The climatology included here was prepared by J. E. Schemm and J. Huang. For each day they calculated the mean for 1979-95 from the NCEP/NCAR reanalysis at each point, then applied harmonic analysis. They kept the annual mean and the first 4 harmonics of the annual cycle. They used an earlier version of 1979 and of Oct. 1992-Feb. 1993 than the one included here. VI) Calculating an anomaly from climatology To calculate the anomaly from climatology in 1000 mb height for 000GMT 11 March 1993, 1) start GrADS 2) open the relevant control files: ga> open /cdrom/data/series/hgt1000.ctl ga> open /cdrom/data/series/chgt1000.ctl 3) retrieve the climatology for March 11 ga> set time 00z11mar1980 ga> define z=hgtprs.2 4) calculate and plot the anomaly for March 11, 1993 ga> set time 00z11mar93 ga> d hgt-z Anomalies from the daily climatology for any field for any day or a series of days can be plotted through option "d" in the Demo program.