The Objective FSU Tropical Pacific Winds - a description Version 1.1 7 October 2002 updated: 14 October 2003 The Center for Ocean-Atmospheric Prediction studies at FSU is pleased to announce version 1.1 of our objectively analyzed fields of tropical Pacific pseudo-stress. The data are available for 1978-2002 on this ftp site. The netcdf files are self describing, while the ascii files are outlined below. If you are interested in using the netCDF files you either need to download the software (http://www.unidata.ucar.edu/Software.html) or have access to programs that can read netCDF files (e.g., Matlab, IDL). NOTE FOR USERS OF THE OLD SUBJECTIVE FSU WINDS: please note that the objective product is on an 85 by 30 grid. We added values centered on 122E to bridge the gap between our tropical Pacific and tropical Indian ocean products. IMPROVEMENTS SINCE VERSION 1.0: 1. Improvements have been made to the land mask to address known problem 2 below. 2. Buoy data have been added to the background field. Earlier version only used ship data. 3. Weighting function for the background has been modified. KNOWN PROBLEMS: 1. Sampling-related issue cause the uncertainty (to be provided in a future release) to be non-uniform across the field. Note that this is true of any other publicly available product of which we are aware. Greater caution should be applied when drawing conclusions about data-void areas, such as the south eastern Pacific Ocean. 2. The improved land mask still results in a small number of relatively poor vectors in regions with many islands (e.g., Indonesia). This is a consequence of not averaging across land (which usually results in more accurate winds). The problem is related to poor sampling and will be addressed in a later update. The netCDF (.nc) and ASCII (.asc) files contain Pacific Ocean pseudostress from ship and buoy reports on an 85x30 grid, 1 grid/month. All monthly grids are included in one netCDF file: FSU_obj_psv_pac19782002v11.nc, while ASCII files are separated by year: FSU_obj_psv_pacYYYYv11.asc. Also included are twelve- month climatologies covering the period 1978-2001 (*v11c.asc and *v11c.nc). The analyses are a Research-Quality product based on surface marine observations from COADS LMRF6 for the period 1978-1997 and the National Climatic Data Center (NCDC) TD-1129 archive for 1998-2002. Also included in the analyses are observations from the TAO Buoy array (1980-2002). The pseudostress (tau x, tau y below) are in (meters/sec)**2 with east = positive and north = positive. Further information on conversion to other units is available via the web (http://www.coaps.fsu.edu/~bourassa/scat_html/ forcing_tut/forcing_tutorial.html#pseudostress). Any tau x and tau y with a value of 999.0 is fully over land. The data are on a 2 by 2 degree grid, with 85 points e-w and 30 points n-s. The designation of cells as sea or land is based on the ElTopo5 topography. Any grid cells with eltopo cell elevations (from a twelfth of a degree grid) less than mean sea level are treated as water. The few inland points that meet this condition are treated as land. Observations from land cell do not contribute to our gridded product. NOTE: THE NEW OBJECTIVE PRODUCT IS AVAILABLE FROM 122E TO 70W LONGITUDE, WHEREAS THE OLD SUBJECTIVE FSU WIND GRID WAS FROM 124E TO 70W LONGITUDE. tau x( 1, 1) and tau y( 1, 1) are centered at 122e and 29s tau x( 2, 1) " " are centered at 124e and 29s . . tau x(84, 1) " " are centered at 72w and 29s tau x(85, 1) " " are centered at 70w and 29s tau x( 1, 2) " " are centered at 122e and 27s tau x( 1, 3) " " are centered at 122e and 25s . . tau x( 1,29) " " are centered at 122e and 27n tau x( 1,30) " " are centered at 122e and 29n The following FORTRAN code is an example of how to read the ASCII (*.asc) versions of the data files. Note: the data in the files are scaled up by a factor of 10, and that using this format will scale them to the proper numbers. program readwd dimension taux(85,30),tauy(85,30) c read 1 month wind stress grid read (1,10) month,iyear,taux,tauy 10 format (2i5,14f5.1,/(16f5.1)) . . . . . end We acknowledge the support of NOAA Office of Global Programs and the National Science Foundation for funding this project. REFERENCE: Bourassa, M. A., S. R. Smith, and J. J. O'Brien, 2001: A new FSU winds and flux climatology. 11th Conference on Interations of the Sea and Atmosphere, San Diego, CA, Amer. Meteor. Soc., 912. CONTACT: Shawn R. Smith COAPS The Florida State University Tallahassee, FL 32306-2840 Voice: (850) 644-6918 Fax: (850) 644-4841 Internet:winds@coaps.fsu.edu