A subset of WOCE RV data for surface flux studies WOCE Surface Meteorology DAC/Surface Fluxes SAC Center for Ocean-Atmospheric Prediction Studies The Florida State University 1. Overview and file description A subset of the WOCE surface meteorology data collected on research vessels (RV) has been compiled for use in surface flux studies. The data were selected based upon availability of both necessary parameters for turbulent flux calculations and instrument heights. In addition, a minimum of the values must pass automated and visual quality evaluation (described in Smith et al. 1996). The selected data files are from global oceanographic cruises during the period 1990-1998. The data are provided in compressed tar files. The naming convention is RVcall_sign.tar.Z. Each tar file contains one or more netCDF files of surface meteorology data and a RVcall_sign.vars file. The *.vars file lists all netCDF files in the tar file. In addition the *.vars file contains the time resolution of the data and notes the existence of moisture (RH, Q, TD, or TW)and radiation (RAD, RAD2) variables in each data file. Note that the user must check the radiation variable type on RAD and RAD2 to determine the radiation parameter (e.g., shortwave, longwave, uv) stored in each variable. As an example, the following line from the DBBH.vars file: DBBH.900126001v200.nc 1 TD RH RAD RAD2 denotes that the data are nominally reported every minute and that dewpoint temperature, relative humidity, and two radiation parameters are available from the file DBBH.900126001v200.nc. Data are provided for 15 vessels: Call Research sign vessel ---- ------------------- 7JWN Takuyo DBBH Meteor DBCK Heincke DBLK Polarstern DFCG Sonne FNGB Marion Dufrense JDSS Hakuho Maru JGAW Bosei Maru 2 JGZK Ryofu Maru JRPG Kaiyo KCEJ Knorr UBNZ Akademik Shuleykin UNAA Aurora Australis WSRY Thomas G. Thompson Y3CW A. von Humboldt 2. Documentation Documentation, including file formats, file naming conventions, and quality control procedures can be downloaded from our web page: http://www.coaps.fsu.edu/woce/ Important documents include: File naming convention: http://www.coaps.fsu.edu/woce/html/wcdnames.htm NetCDF format documentation: http://www.coaps.fsu.edu/woce/html/wcdpubnc.htm Quality control methods (Smith et al. 1996): http://www.coaps.fsu.edu/woce/docs/qchbook/qchbook.htm Quality control flag descriptions: http://www.coaps.fsu.edu/woce/html/wcdflags.htm 3. File selection process The selection process was completed on a file by file basis. Note that the files contain a maximum of 1440 records (equal to the number of minutes in a day). This means that the minimum file sizes are daily; however, when the RV data are recorded less frequently (i.e., hourly, 6-hourly) the files may contain multiple days of data. Each data file was tested independent of neighboring files. The selection criterion begins with the identification of data files that contain: Atmospheric pressure Air temperature Sea temperature True (earth-relative) wind direction and speed Moisture (at least one parameter: relative humidity, specific humidity, dewpoint or wet-bulb temperatures) The second selection criterion is that each of the above values, with the exception of sea temperature, have a known instrument height. These heights are typically measured in meters above the mean water line. Note: Atmospheric pressure (P) has both instrument height and pressure 'type' variable attributes. The height is the physical height of the barometer above the mean water line of the vessel. In some cases the pressure data are adjusted to sea level (prior to arrival at the data center) resulting in the 'type' attribute being set to one. When the pressure type is equal to one, data users should assign the pressure data a height equal to zero (even though the height in the data file may be missing or greater than zero). All ships recording sea-level pressure (type = 1) are included regardless of their recorded barometer height. A final test evaluates the quality flags placed upon the individual data records. The flags are described in Smith et al. (1996). Data files are retained when greater than 90% of the available ship position (latitude and longitude), air temperature, atmospheric pressure, winds, and moisture (at least one variable) are deemed to be of good quality. Data that are of good quality are flagged: A - units determined by WOCE data center G - value > 4 standard deviation from climatology (These values are often extreme, but they may be of interest to some scientists). I - Interesting feature in data (e.g., hurricane, frontal passage, sharp sea temperature gradient). R - Value is an interpolated value (interpolation done prior to the data arrival at the data center) Z - Data passed all evaluation All other assigned flags mark suspect or erroneous values. 4. Questions All inquiries about this dataset should be made to wocemet@coaps.fsu.edu. 5. Reference Smith, S.R., C. Harvey, and D.M. Legler, 1996: Handbook of Quality Control Procedures and Methods for Surface Meteorology Data. COAPS Report No. 96-1, WOCE Data Assembly Center for Surface Meteorology, Center for Ocean Atmospheric Prediction Studies, Florida State University, Tallahassee, Florida, 49pp.