------------------------------------------------------------------------- Addendum for Planetary Climate Book: This is the readme file for the original IGRA dataset. Subsamples of the original data files are contained in the Original subdirectory of this directory. The ProcessIRGR.py script there reads a station file, extracts the data, and puts it into separate files (one for each sounding) that are easier to read than the raw data. This script can be used to process additional data files downloaded from the IGRA web site http://www.ncdc.noaa.gov/oa/climate/igra/index.php Only a few of the many stations have been downloaded, and in most cases, only a few years of the total data record for each station are retained, so as to keep the data volume down. The processed file haves names in the form nnnnnn.yy.mm.dd.hh.txt where nnnnnnn is the station number. See the file "stations.txt" for the location of the station. ------------------------------------------------------------------------- Integrated Global Radiosonde Archive (IGRA) v1.20 Readme File (July 2007) I. General Information This file lists the contents of the IGRA ftp directory and describes the format of the various sounding, monthly-mean, and station inventory files available. Changes since July 2006 (see status.txt for details): 1. A change in the beginning date of the year-to-date files to 01/01/2006. 2. A period-of-record reprocessing for data through 2006. 3. A change from .Z to .gz compressed files (see status.txt). 4. The addition of a subdirectory "derived" which contains some sounding-derived variables (e.g., relative humidity, vertical temperature gradient, u and v wind componens). See the separate documentation in the subdirectory for details. Imke Durre (imke.durre@noaa.gov) - (last updated July 2007) II. Contents of ftp://ftp.ncdc.noaa.gov/pub/data/igra --------------------------------- Directories: --------------------------------- data-por Period of record data files (base version through 2006 + daily updates; one file per station) data-y2d Daily updates since January 1, 2007 (replaced daily; one file per station) derived Parameters derived from IGRA (includes period-of-record station files and documentation). monthly-por Period of record monthly-mean files (updated monthly) monthly-upd Files of monthly means for the last month only (replaced monthly) --------------------------------- Files: --------------------------------- igra-composites.txt IGRA stations with composited records igra-countries.txt List of country codes used in the station list igra-metadata20090527.txt IGRA station history and metadata inventory igra-metadata-description.txt Description and format of igra-metadata.txt igra-qc.pdf Paper describing IGRA quality-control for temperature (J. Climate, in press) igra-overview.pdf Paper describing IGRA (J. Climate, 2006) igra-stations.txt List of stations in IGRA readme.txt This file status.txt Notes on the current status of IGRA's online files III. Format Description of IGRA Data Files --------------------- Notes: --------------------- 1. There is one file per station, named #####.dat, where ##### is the station number. 2. Each sounding consists of one header record and n data records, where n (given in the header record) is the number of levels in the sounding. 3. For all variables in the data record except the level type indicators, -8888 indicates that the original value has been removed by one of the IGRA quality assurance procedures, while -9999 means that the data value was never present. 4. For each pressure, geoppotential height, and temperature value, a one-character quality assurance flag indicates whether the corresponding value was checked by procedures based on climatological means and standard deviations. Possible flag values are: blank = no climatological check applied due to an insufficient number of data values for computing the relevant statistics, A = value falls within "tier-1" climatological limits based on all days of the year and all times of day at the station, and B = value passes checks based on both the tier-1 climatology and a "tier-2" climatology specific to the time of year and time of day of the data value. --------------------- Header Record Format: --------------------- Variable Name Columns Description ----------------------- ------- ----------- Header Record Indicator 1- 1 # character Station Number 2- 6 WMO station number Year 7- 10 Month 11- 12 Day 13- 14 Observation Hour 15- 16 00-23 UTC Release Time 17- 20 0000-2359 UTC, 9999 = missing Number of levels 21- 24 number of subsequent data records --------------------- Data Record Format: --------------------- Variable Name Columns Description ----------------------- ------- ----------- Major Level Type 1- 1 1 = standard pressure level 2 = significant thermodynamic level 3 = additional wind level Minor Level Type 2- 2 1 = surface, 2 = tropopause, 0 = other Pressure 3- 8 units of Pa (mb * 100) Pressure Flag 9- 9 A, B, or blank (see note 4 above) Geopotential Height 10- 14 units of meters Geopotential Height Flag 15- 15 A, B, or blank (see note 4 above) Temperature 16- 20 units of degrees C * 10 Temperature Flag 21- 21 A, B, or blank (see note 4 above) Dewpoint Depression 22- 26 units of degrees C * 10 Wind Direction 27- 31 units of degrees (0-360, inclusive) Wind Speed 32- 36 units of (m/s)*10 IV. Format of IGRA Monthly-Mean Files --------------------------------- Notes: --------------------------------- 1. File names are of the form VVVV_HHz.mly, where VVVV = variable and HH = nominal hour. Possible values for VVVV: ghgt = geopotential height, temp = temperature, uwnd = zonal wind component, vwnd = meridional wind component. Possible values for HH: 00, 12. 2. Monthly means are computed for the surface and mandatory levels at the nominal times of 00 and 12 UTC, considering data within two hours of each nominal time. 3. A mean is provided only if there are at least 10 values for a particular station, month, nominal time, and level. 4. Means are given in units of meters for geopotential height, degrees C * 10 for temperature, and (m/s) * 10 for zonal and meridional wind. --------------------------- File Format (VVVV_HHz.mly): --------------------------- Variable Name Columns Description ------------------------ ------- ----------- Station Number 1- 5 WMO station number Year 7- 10 Month 12- 13 Pressure Level 15- 18 units of HPa (mb), 9999 = Surface level Mean Value 20- 24 see Note 4 above for units Number of Values in Mean 26- 27 V. Format Description of IGRA Station Inventory Files --------------------------------- Station List (igra-stations.txt): --------------------------------- Notes: ------ In the station list, stations are identified as GUAN, former GUAN, Lanzante-Klein-Seidel, or composite stations if applicable. The following notes apply to these identifications: 1. GUAN stands for Global Climate Observing System Upper Air Network, see http://www.wmo.ch/web/gcos/gcoshome.html 2. The Lanzante-Klein-Seidel network is described in the following paper: Lanzante, J.R., S.A. Klein, D.J. Seidel, 2003: Temporal homogenization of monthly radiosonde temperature data. Part I: Methodology. Journal of Climate, 16, 224-240. See http://ams.allenpress.com/ amsonline/?request=get-toc&issn=1520-0442&volume=016&issue=02 3. Composite means that the data from two or more source stations have been combined into one IGRA station. See igra.composite.stations for a list of these stations. Variable Name Columns Description ----------------------- ------- ----------- Country Code (FIPS) 1- 2 see igra-countries.txt Station Number 5- 9 WMO station number Station Name 12- 46 Latitude 48- 53 units of decimal degrees Longitude 55- 61 units of decimal degrees Elevation 63- 66 units of meters above sea level GUAN Code 68- 68 G = current GUAN station F = former GUAN station blank = other (see Note 1) LKS Network Code 69- 69 L = Lanzante-Klein-Seidel station blank = other (see Note 2) Composite Station Code 70- 70 C = Composite station blank = other (see Note 3) First Year of Record 73- 76 Last Year of Record 78- 81 --------------------------------------- Country Code List (igra-countries.txt): --------------------------------------- Note: ------ Country codes are taken from Federal Information Processing Standard (FIPS) Publication 10-4 (http://www.cia.gov/cia/publications/factbook/appendix/appendix-d.html). Variable Name Columns Description ----------------------- ------- ----------- Country Code 1- 2 2-character FIPS code used in igra-stations.txt Country Name 5- 44 ----------------------------------------------------- List of Composite Stations (igra-composites.txt): ----------------------------------------------------- Note: ------ The compositing was performed using data through the end of 2006. Consequently, the dates provided in the composite station list do not extend beyond 2006. Nevertheless, like all other stations, composite stations are continuously updated with data received under the corresponding current station number. Variable Name Columns Description ----------------------- ------- ----------- Composite Station Info: Station Number 1- 5 WMO number of composite station Date of First Record: Year 7- 10 Month 11- 12 Day 13- 14 Hour 15- 16 Date of Last Record: Year 18- 21 Month 22- 23 Day 24- 25 Hour 26- 27 Source Station 1: Station Number 30- 34 WMO number of source station 1 Date of First Record: Year 36- 39 Month 40- 41 Day 42- 43 Hour 44- 45 Date of Last Record: Year 47- 50 Month 51- 52 Day 53- 54 Hour 55- 56 Source Station 2: Station Number 59- 63 WMO number of source station 2 Date of First Record: Year 65- 68 Month 69- 70 Day 71- 72 Hour 73- 74 Date of Last Record: Year 76- 79 Month 80- 81 Day 82- 83 Hour 84- 85