README -- Contents of GEOS_1x1/SST_200508 directory 13 Jul 2009 Bob Yantosca, Philippe Le Sager, and Claire Carouge geos-chem-support@g.harvard.edu This directory contains monthly-mean ground/sea-surface temperatures obtained from NOAA (see README to original data below) on the GEOS-CHEM 1x1 grid. The file naming convention is: SST.geos.1x1.YYYY where YYYY = 1985 .. 2008. Other years can be added as the data become available. NOTES: =============================================================================== (1) The raw SST data from NOAA was converted into binary punch (bpch) file format by Rokjin Park (rjp@io.harvard.edu). Rokjin Park also regridded these files to the GEOS 1x1 grid. (2) Bob Yantosca now maintains the IDL code that was used for the regridding. (see below) (3) Bpch files were created for each year (1985-2004), with each file containing 12 months of monthly-mean data. (4) Files are on the GEOS 1x1 grid (halfpolar boxes, 1st box centered on -180), and the GEOS-Chem code will regrid "on-the-fly" to other grids. Bob Yantosca 13 July 2009 %%%%%%%%%%%%%% README for IDL processing code from Rokjin Park %%%%%%%%%%%%%%% Files: ------ (1) lstags.onedeg,dat -- data file (2) rd_sst.pro -- IDL program Procedure: ---------- 1. Place these two files in any main directory including SST data. 2. Monthly SST data for each year should be in individual subdirectories under the main directory. 3. The subdirectory name should be just individual years (2005, 2006, etc) 3. Execute IDL 4. at the idl prompt, type ".r rd_sst" %%%%%%%%%%%%%% README for "raw" SST data from NOAA begins here: %%%%%%%%%%%%%%% Description of the OI.v2 Monthly SST Analysis (v2 indicates version 2) The NOAA OI.v2 SST monthly fields are derived by a linear interpolation of the weekly optimum interpolation (OI) version 2 fields to daily fields then averaging the daily values over a month. The monthly fields are in the same format and spatial resolution as the weekly fields. The OI.v2 analysis is described in Reynolds, R.W., N.A. Rayner, T.M. Smith, D.C. Stokes, and W. Wang, 2001: An Improved In Situ and Satellite SST Analysis for Climate, J. Climate, submitted. The paper has been accepted by the Journal of Climate subject to minor revisions. A preprint of the paper can be obtained in the directory: ftp://ftp.ncep.noaa.gov/pub/cmb/People/reynolds/oiv2pap/ The paper is presently in two word perfect files (oiv2_text.wpd and oiv2_figs.wpd) and two word files (oiv2_text.doc and oiv2_figs.doc). The first file is the text, the second is the figures.) These fields are available in individual monthly files. Each file is named oiv2mon.{YYYYMM}, where {YYYYMM} is the year and month of the field. Files in this directory ending with the extension '.gz' have been compressed using the gzip utility. An interim file with just the most recent month or partial month is available in oiv2mon.month. This file will be re-written each week if we have sufficient weekly fields to linearly interpolate to the 15th of the month or beyond. The files were written in IEEE binary (big-endian). Each file contains three records described as follows: rec 1: date and version number (8 4-byte integer words) rec 2: gridded sst values in degC (360*180 4-byte real words) rec 3: gridded ice concentration (360*180 1-byte integer words) The ice field shows the approximate monthly average of the ice concentration values input to the SST analysis. Ice concentration is stored as the percentage of are of area covered. For the ice fields, the value 122 represents land or coast. Note, the ice land mask is a function of the ice analysis and may change periodically. The sst and ice fields are on a 1-degree (360 lon by 180 lat) grid. The first gridbox of each array is centered on 0.5E, 89.5S. The points move eastward to 359.5E, then northward to 89.5N. The OI analysis is done over all ocean areas and the Great Lakes. There is no analysis over land. The land values are filled by a Cressman interpolation to produce a complete grid for possible interpolation to other grids. The ocean and land areas are defined by a land sea mask. This data set is a binary, direct access file, lstags.ondeg.dat, which is included in the same directory. The spatial grid is defined identically to the grid for the SST arrays. The values in ls.dat are set to 1 over the ocean and 0 over land. It can be read by the following fortran code: REAL*4 TAGLS(360,180) c c NOTE, recl definition below depends on compiler c (number of 4-byte words OR number of bytes) c choose one of following krecl definitintions c parameter(krecl=360*180) ! number of 4-byte words parameter(krecl=360*180*4) ! number of bytes open (24,file='lstags.onedeg.dat',form='unformatted', 1 access='direct',recl=krecl) c c Read in land sea tags (1 for ocean; 0 for land) c READ (24,rec=1) TAGLS STOP 1 END The following sample fortran program reads the data and prints out sample values: c-------------- start of code ----------------------------------------- program rdoimonv2 c read OI.v2 SST file and land mask and print selected values. c sst - sea surface temperature array (deg C) c ice - ice concentration array (%) (0-100, >100 = land or coast) c iyrst - year of start date of analysis c imst - month of start date of analysis c idst - day of start date of analysis c iyrnd - year of end date of analysis c imnd - month of end date of analysis c idnd - day of end date of analysis c ndays - number of days in analysis (start date thru enddate) c index - analysis version for reference c xlon - longitude of center of grid square c xlat - latitude of center of grid square c tagls - land/sea tag array (0=land, 1=water) c NOTES: c - land values for sst do not necessarily coincide with land values c from ice analysis c - recl definition for the direct access open depends on the compiler c (number of 4-byte words OR number of bytes). c Choose the appropiate parameter statement for krecl c implicit none c integer krecl parameter(krecl=360*180) ! number of 4-byte words c parameter(krecl=360*180*4) ! number of bytes real*4 sst(360,180),xlon,xlat integer*4 iyrst,imst,idst,iyrnd,imnd,idnd,ndays,index,i,j integer*4 ice(360,180) character*1 cice(360,180) real*4 tagls(360,180) open (24,file='lstags.onedeg.dat',form='unformatted', 1 access='direct',recl=krecl) c c Read in land sea tags (1 for ocean; 0 for land) c read (24,rec=1) tagls c date string used in filename represents the mid-week date c weeks prior 1990 are centered on Sunday c weeks in 1990 and onward are centered on Wednesday open(11,file='oiv2mon.199308',form='unformatted') read(11) iyrst,imst,idst,iyrnd,imnd,idnd,ndays,index read(11) ((sst(i,j),i=1,360),j=1,180) read(11) ((cice(i,j),i=1,360),j=1,180) print '(a,i4,1x,i2,1x,i2)', 'start date: ',iyrst,imst,idst print '(a,i4,1x,i2,1x,i2)', ' end date: ',iyrnd, imnd,idnd print '(a,i2)', ' num days: ',ndays print '(a,i10,/)', ' index: ',index c ...choosing one longitude i = 181 c ... determine longitude of middle of grid boxes with this index xlon = float(i) - 0.5 c .... loop thru several latitudes (decrementing to run North->South) do j = 180,150,-1 ice(i,j)=ichar(cice(i,j)) xlat = float(j) - 90.5 print 125, 'lon = ',xlon,'lat = ',xlat,'sst = ',sst(i,j), 1 'ice = ',ice(i,j),'tagls= ',tagls(i,j) 125 format(a,f5.1,4x,a,f5.1,4x,a,f5.1,4xa,i3,4x,a,f2.0) enddo stop end c-------------- end of code ----------------------------------------- Following are the results of the above code when reading the file for August 1993. If your 'index' does not match the one shown below, you have a newer analysis version and your SST and ice values likely will not match either. Please feel free to request the correct output for your version to ensure you are reading the data correctly. --- Start Output start date: 1993 8 1 end date: 1993 8 31 num days: 31 index: 1141070244 lon = 180.5 lat = 89.5 sst = -1.8 ice = 100 tagls= 1. lon = 180.5 lat = 88.5 sst = -1.8 ice = 96 tagls= 1. lon = 180.5 lat = 87.5 sst = -1.7 ice = 96 tagls= 1. lon = 180.5 lat = 86.5 sst = -1.7 ice = 94 tagls= 1. lon = 180.5 lat = 85.5 sst = -1.6 ice = 92 tagls= 1. lon = 180.5 lat = 84.5 sst = -1.5 ice = 92 tagls= 1. lon = 180.5 lat = 83.5 sst = -1.4 ice = 89 tagls= 1. lon = 180.5 lat = 82.5 sst = -1.4 ice = 89 tagls= 1. lon = 180.5 lat = 81.5 sst = -1.5 ice = 88 tagls= 1. lon = 180.5 lat = 80.5 sst = -1.5 ice = 88 tagls= 1. lon = 180.5 lat = 79.5 sst = -1.6 ice = 91 tagls= 1. lon = 180.5 lat = 78.5 sst = -1.6 ice = 91 tagls= 1. lon = 180.5 lat = 77.5 sst = -1.5 ice = 92 tagls= 1. lon = 180.5 lat = 76.5 sst = -1.3 ice = 92 tagls= 1. lon = 180.5 lat = 75.5 sst = -0.4 ice = 89 tagls= 1. lon = 180.5 lat = 74.5 sst = 1.0 ice = 61 tagls= 1. lon = 180.5 lat = 73.5 sst = 2.3 ice = 9 tagls= 1. lon = 180.5 lat = 72.5 sst = 3.0 ice = 4 tagls= 1. lon = 180.5 lat = 71.5 sst = 2.8 ice = 3 tagls= 1. lon = 180.5 lat = 70.5 sst = 2.5 ice = 1 tagls= 1. lon = 180.5 lat = 69.5 sst = 2.2 ice = 0 tagls= 1. lon = 180.5 lat = 68.5 sst = 2.7 ice = 122 tagls= 0. lon = 180.5 lat = 67.5 sst = 4.6 ice = 122 tagls= 0. lon = 180.5 lat = 66.5 sst = 8.1 ice = 122 tagls= 0. lon = 180.5 lat = 65.5 sst = 9.1 ice = 0 tagls= 1. lon = 180.5 lat = 64.5 sst = 8.5 ice = 0 tagls= 1. lon = 180.5 lat = 63.5 sst = 8.1 ice = 0 tagls= 1. lon = 180.5 lat = 62.5 sst = 8.1 ice = 0 tagls= 1. lon = 180.5 lat = 61.5 sst = 8.3 ice = 0 tagls= 1. lon = 180.5 lat = 60.5 sst = 8.8 ice = 0 tagls= 1. lon = 180.5 lat = 59.5 sst = 9.6 ice = 0 tagls= 1. --- End Output Please note, a new climatology based on these fields was derived by Yan Xue of NCEPs Climate Prediction Center following the technique of Reynolds and Smith (1995) and Smith and Reynolds (1998). The new climatology is available in: ftp://ftp.ncep.noaa.gov/pub/cpc/wd52yx/sstclim/ For further information, contact: Diane C. Stokes email: Diane.Stokes@noaa.gov Voice: (301) 763-8000 extension 7581 FAX: (301) 763-8125 Postal Address: Climate Modeling Branch W/NP24 Environmental Modeling Center National Centers for Environmental Prediction World Weather Building, Room 807 5200 Auth Road Camp Springs, MD 20746 USA UPDATED: 20 December 2001