README FILE for Sounding-Derived Parameters for Planetary Boundary Layer (PBL) Studies -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- I. DOWNLOAD QUICK START Start by downloading "derived-stations.txt", which has metadata for all stations in the dataset. You can find this file in the same location where this README file resides, i.e., by going to directory pub/data/igra/derived at ftp.ncdc.noaa.gov or pointing your browser to http://www1.ncdc.noaa.gov/pub/data/igra/derived . Then, to find and download the data for a specific station, proceed as follows: - Find the station's name in "derived-stations.txt" and note its station identification code (e.g., Key West is "72201"); - From the subdirectory "data-por", download the GZIP-compressed data file (i.e., ".dat.gz" file) that corresponds to this code (e.g., "72201.dat.gz" has the data for Key West ); and - Uncompress the downloaded file using the Winzip program under Windows or the "gunzip" command under Linux. -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- II. CONTENTS OF ftp://ftp.ncdc.noaa.gov/pub/data/igra/derived data-por: Directory with all ".dat.gz" files derived-countries.txt: List of country codes and names derived-stations.txt: List of stations and their metadata readme.txt: This file status.txt: Notes on the current status of the PBL data -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- III. FORMAT OF DATA FILES (".dat.gz" FILES) Each ".dat.gz" file contains data for one station. The name of the file corresponds to a station's World Meteorological Organization (WMO) identification number (e.g., "72201.dat.gz" contains the data for the station with the identification number 72201). Each file contains a series of multiline sounding records, each of which consists of a header record followed by one line of data for each pressure level in the sounding. The variables in each header record include the following: --------------------------------- Variable Columns Type --------------------------------- HEADREC 1- 1 Character ID 2- 6 Integer YEAR 7-10 Integer MONTH 11-12 Integer DAY 13-14 Integer HOUR 15-16 Integer RELTIME 17-20 Integer NUMLEV 21-24 Integer --------------------------------- These variables have the following definitions: HEADREC is the header record indicator (always set to "#"). ID is the station identification code. Please see "derived-stations.txt" for a complete list of stations and their metadata. YEAR is the year of the sounding. MONTH is the month of the sounding. DAY is the day of the sounding. HOUR is the hour of the sounding. RELTIME is the release time of the sounding (format HHMM, missing=9999). NUMLEV is the number of levels in the sounding (i.e., the number of data records that follow). In the subsequent data records, the first record always represents the surface level. The variables in each data record include the following: ------------------------------- Variable Columns Type ------------------------------- PRESS 1- 7 Integer OBSGPH 9- 15 Integer CALCGPH 17- 23 Integer TEMP 25- 31 Integer TEMPGRAD 33- 39 Integer PTEMP 41- 47 Integer PTEMPGRAD 49- 55 Integer VAPPRESS 57- 63 Integer SATVAP 65- 71 Integer RH 73- 79 Integer RHGRAD 81- 87 Integer UWND 89- 95 Integer UWDGRAD 97-103 Integer VWND 105-111 Integer VWNDGRAD 113-119 Integer ------------------------------- All missing values are coded as -99999. The variables have the following definitions: PRESS is the observed pressure (pascal or mb * 100). OBSGPH is the observed geopotential height (meters). This value is often not available at significant levels. CALCGPH is the calculated geopotential height (meters). The geopotential height has been estimated by applying the hydrostatic balance to the atmospheric layer between the next lower level with an observed geopotential height and the current level. TEMP is the observed temperature (Kelvin * 10). TEMPGRAD is the the temperature gradient between the current level and the next higher level with a temperature (K/km * 10, positive if temperature increases with height). PTEMP is the potential temperature (K * 10). PTEMPGRAD is the potential temperature gradient between the current level and the next higher level with a potential temperature (K/km * 10, positive if potential temperature increases with height). VAPPRESS is the vapor pressure (mb * 1000) as computed from temperature, pressure, and dewpoint depression at the same level. SATVAP is the saturation vapor pressure (mb * 1000) as computed from pressure and temperature at the same level. RH is the relative humidity (Percent * 10) as calculated from vapor pressure, saturation vapor pressure, and pressure at the same level. RHGRAD is the relative humidity gradient between the current level and the next higher level with temperature and dewpoint depression (%/km * 10, positive if relative humidity increases with height). UWND is the zonal wind component (m/s * 10) as computed from the observed wind speed and direction. UWDGRAD is the vertical gradient of the zonal wind between the current level and the next higher level with a wind observation [(m/s per km) * 10, positive if zonal wind becomes more positive with height]. VWND is the meridional wind component (m/s * 10) as computed from the observed wind speed and direction. VWNDGRAD is the vertical gradient of the meridional wind component between the current level and the next higher level with a wind observation [(m/s per km) * 10, positive if the meridional wind becomes more positive with height]. -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- IV. FORMAT OF "derived-stations.txt" ------------------------------ Variable Columns Type ------------------------------ FIPS 1- 2 Character ID 5- 9 Integer NAME 12-46 Character LATITUDE 48-53 Real LONGITUDE 55-61 Real ELEVATION 63-66 Integer GUANFLAG 68-68 Character LKSFLAG 69-69 Character COMPFLag 70-70 Character FSTYEAR 73-76 Integer LSTYEAR 78-81 Integer ---------------------------------- These variables have the following definitions: FIPS is the FIPS country code. Please see "derived-countries.txt" for a complete list of country codes. ID is the WMO station identification number. NAME is the name of the station. LATITUDE is the latitude of the station (in decimal degrees). LONGITUDE is the longitude of the station (in decimal degrees). ELEVATION is the elevation of the station (in meters). GUANFLAG is a flag that indicates whether the station is part of the GCOS Upper Air Network (GUAN). There are three possible values: Blank = non-GUAN station F = Former GUAN station G = GUAN station LKSFLAG is a flag that indicates whether the station is part of the Lanzante-Klein-Seidel (LKS) station network. There are two possible values: Blank = non-LKS station L = LKS station COMPFLAG is a flag that indicates whether a station's record is a composite of two or more original station records. There are two possible values: Blank = Composite station C = Composite station FSTYEAR is the first year of record at the station in the PBL data. LSTYEAR is the last year of record at the station in the PBL data. -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- V. FORMAT OF "derived-countries.txt" ------------------------------ Variable Columns Type ------------------------------ FIPS 1-2 Character NAME 5-44 Character ------------------------------ These variables have the following definitions: FIPS is the FIPS country code. NAME is the name of the country. -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- For additional information, please send an e-mail to imke.durre@noaa.gov or xungang.yin@noaa.gov.