Format Description of IGRA 2 Sounding Data Files --------------------- Notes: --------------------- 2. Both types of files are updated once a day in the early morning Eastern Time. The latest observations usually become available within two calendar days of when they were taken. 2. Data files are available for two different time spans: In subdirectory data-por, data files contain the full period of record. In subdirectory data-y2d, files only contain soundings from the current (or current and previous) year. For example, as of August 2016, the files in the data-y2d subdirectory begin with January 1, 2016. 3. Each file in the data-por and data-y2d subdirectories contains the sounding data for one station. The name of the file corresponds to a station's IGRA 2 identifier (e.g., "USM00072201-data.txt.zip" contains the data for the station with the identifier USM00072201). 3. 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. --------------------- Header Record Format: --------------------- --------------------------------- Variable Columns Type --------------------------------- HEADREC 1- 1 Character ID 2- 12 Character YEAR 14- 17 Integer MONTH 19- 20 Integer DAY 22- 23 Integer HOUR 25- 26 Integer RELTIME 28- 31 Integer NUMLEV 33- 36 Integer P_SRC 38- 45 Character NP_SRC 47- 54 Character LAT 56- 62 Integer LON 64- 71 Integer --------------------------------- These variables have the following definitions: HEADREC is the header record indicator (always set to "#"). ID is the station identification code. See "igra2-stations.txt" for a complete list of stations and their names and locations. YEAR is the year of the sounding. MONTH is the month of the sounding. DAY is the day of the sounding. HOUR is the nominal or observation hour of the sounding (in UTC on the date indicated in the YEAR/MONTH/DAY fields). Possible valid hours are 00 through 23, and 99 = missing. Hours are given as provided by the data provider, and the relationship between this hour and the release time varies by data provider, over time, and among stations. RELTIME is the release time of the sounding in UTC. The format is HHMM, where HH is the hour and MM is the minute. Possible are 0000 through 2359, 0099 through 2399 when only the release hour is available, and 9999 when both hour and minute are missing. NUMLEV is the number of levels in the sounding (i.e., the number of data records that follow). P_SRC is the data source code for pressure levels in the sounding. It has 25 possible values: bas-data = British Antarctic Survey READER Upper-Air Data cdmp-amr = African Monthly Radiosonde Forms digitized by the U.S. Climate Data Modernization Program cdmp-awc = "African Wind Component Data" digitized from Monthly Forms by the U.S. Climate Data Modernization Program cdmp-mgr = "WMO-Coded Messages" for Malawi, digitized from "Computer-Generated Forms" by the U.S. Climate Data Modernization Program cdmp-zdm = Zambian "Daily UA MB Ascent Sheets" digitized by the U.S. Climate Data Modernization Program chuan101 = Comprehensive Historical Upper Air Network (v1.01) erac-hud = ERA-CLIM Historical Upper Air Data iorgc-id = IORGC/JAMSTEC-Digitized data for Indonesia mfwa-ptu = West African Temperature-Humidity Soundings digitized by Meteo-France ncar-ccd = C-Cards Radiosonde Data Set from NCAR ncar-mit = MIT Global Upper Air Data from NCAR ncdc6210 = NCDC Marine Upper Air Data (NCDC DSI-6210) ncdc6301 = NCDC U.S. Rawindsonde Data (NCDC DSI-6301) ncdc6309 = NCDC "NCAR-NMC Upper Air" (NCDC DSI-6309) ncdc6310 = NCDC "Global U/A Cards" (NCDC DSI-6310) ncdc6314 = Global Telecommunications System messages received and processed at Roshydromet and archived at NCDC (NCDC DSI-6314) ncdc6315 = NCDC "People's Republic of China Data" (NCDC DSI-6315) ncdc6316 = NCDC "Argentina National Upper Air Data" (NCDC DSI-6316) ncdc6319 = NCDC "Korea National Upper Air Data" (NCDC DSI-6319) ncdc6322 = Global Telecommunications System messages received at the Australian Bureau of Meteorology and archived at NCDC (NCDC DSI-6322) ncdc6323 = NCDC "Australian U/A Thermo/Winds Merged" (NCDC DSI-6323) ncdc6324 = NCDC "Brazil National Upper Air Data" (NCDC DSI-6324) ncdc6326 = NCDC "Global Upper Air Cards" (NCDC DSI-6326) ncdc6355 = Russian Ice Island upper air data processed by NCAR and archived at NCDC ncdc-gts = Global Telecommunications System (GTS) messages received at NCDC from the National Centers for Environmental Prediction ncdc-nws = U.S. National Weather Service upper air data received at NCDC in real-time ngdc-har = Historical Arctic radiosonde archive from the National Geophysical Data Center usaf-ds3 = U.S. Air Force 14th Weather Squadron Upper Air Data Set ( received in DS3 format) NP_SRC is the data source code for non-pressure levels in the sounding. These include levels whose vertical coordinate is only identified by height as well as surface levels without either pressure or height. NP_SRC has 15 possible values: cdmp-adp = "African Daily Pilot Balloon Ascent Sheets" digitized by the U.S. Climate Data Modernization Program cdmp-awc = "African Wind Component Data" digitized from "Monthly Forms" by the U.S. Climate Data Modernization Program cdmp-us2 = "U.S. Winds Aloft digitized from "Daily Computation Sheets" by the U.S. Climate Data Modernization Program cdmp-us3 = "U.S. Winds Aloft" digitized from "Military Daily Computation Sheets" by the U.S. Climate Data Modernization Program cdmp-usm = U.S. pilot balloon observations digitized from "Monthly Forms" by the U.S. Climate Data Modernization Program chuan101 = Comprehensive Historical Upper Air Network (v1.01) erac-hud = ERA-CLIM Historical Upper Air Data mfwa-wnd = West African Winds Aloft digitized by Meteo-France ncdc6301 = NCDC U.S. Rawindsonde Data (NCDC DSI-6301) ncdc6309 = NCDC "NCAR-NMC Upper Air" (NCDC DSI-6309) ncdc6314 = Global Telecommunications System messages received and processed at Roshydromet and archived at NCDC (NCDC DSI-6314) ncdc-gts = Global Telecommunications System (GTS) messages received at NCDC from the National Centers for Environmental Prediction ncdc-nws = U.S. National Weather Service upper air data received at NCDC in real-time ngdc-har = Historical Arctic radiosonde archive from the National Geophysical Data Center usaf-ds3 = U.S. Air Force 14th Weather Squadron Upper Air Data Set (received in DS3 format) LAT is the Latitude at which the sounding was taken. For mobile stations, it is the latitude at the time of observation. For fixed stations, it is the same as the latitude shown in the IGRA station list regardless of the date of the sounding since no attempt was made to reconstruct the sounding-by-sounding location history of these stations. LON is the longitude at which the sounding was taken. For mobile stations, it is the longitude at the time of observation. For fixed stations, it is the same as the longitude shown in the IGRA station list regardless of the date of the sounding since no attempt was made to reconstruct the sounding-by-sounding location history of these stations. --------------------- Data Record Format: --------------------- ------------------------------- Variable Columns Type ------------------------------- LVLTYP1 1- 1 Integer LVLTYP2 2- 2 Integer ETIME 4- 8 Integer PRESS 10- 15 Integer PFLAG 16- 16 Character GPH 17- 21 Integer ZFLAG 22- 22 Character TEMP 23- 27 Integer TFLAG 28- 28 Character RH 29- 33 Integer DPDP 35- 39 Integer WDIR 41- 45 Integer WSPD 47- 51 Integer ------------------------------- These variables have the following definitions: LVLŪTYP1 is the major level type indicator. It has the following three possible values: 1 = Standard pressure level (for levels at 1000, 925, 850, 700, 500, 400, 300, 250, 200, 150, 100, 70, 50, 30, 20, 10, 7, 5, 3, 2, and 1 hPa) 2 = Other pressure level 3 = Non-pressure level LVLŪTYP2 is the minor level type indicator. It has the following three possible values: 1 = Surface 2 = Tropopause 0 = Other ETIME is the elapsed time since launch. The format is MMMSS, where MMM represents minutes and SS represents seconds, though values are not left-padded with zeros. The following special values are used: -8888 = Value removed by IGRA quality assurance, but valid data remain at the same level. -9999 = Value missing prior to quality assurance. PRESS is the reported pressure (Pa or mb * 100, e.g., 100000 = 1000 hPa or 1000 mb). -9999 = missing. PFLAG is the pressure processing flag indicating what level of climatology-based quality assurance checks were applied. It has three possible values: blank = Not checked by any climatology checks. If data value not equal to -9999, it passed all other applicable checks. A = Value falls within "tier-1" climatological limits based on all days of the year and all times of day at the station, but not checked by "tier-2" climatology checks due to insufficient data. 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. GPH is the reported geopotential height (meters above sea level). This value is often not available at variable-pressure levels. The following special values are used: -8888 = Value removed by IGRA quality assurance, but valid data remain at the same level. -9999 = Value missing prior to quality assurance. ZFLAG is the geopotential height processing flag indicating what level of climatology-based quality assurance checks were applied. It has three possible values: blank = Not checked by any climatology checks or flag not applicable. If data value not equal to -8888 or -9999, it passed all other applicable checks. A = Value falls within "tier-1" climatological limits based on all days of the year and all times of day at the station, but not checked by "tier-2" climatology checks due to insufficient data. 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. TEMP is the reported temperature (degrees C to tenths, e.g., 11 = 1.1°C). The following special values are used: -8888 = Value removed by IGRA quality assurance, but valid data remain at the same level. -9999 = Value missing prior to quality assurance. TFLAG is the temperature processing flag indicating what level of climatology-based quality assurance checks were applied. It has three possible values: blank = Not checked by any climatology checks or flag not applicable. If data value not equal to -8888 or -9999, it passed all other applicable checks. A = Value falls within "tier-1" climatological limits based on all days of the year and all times of day at the station, but not checked by "tier-2" climatology checks due to insufficient data. 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. RH is the reported relative humidity (Percent to tenths, e.g., 11 = 1.1%). The following special values are used: -8888 = Value removed by IGRA quality assurance, but valid data remain at the same level. -9999 = Value missing prior to quality assurance. DPDP is the reported dewpoint depression (degrees C to tenths, e.g., 11 = 1.1°C). The following special values are used: -8888 = Value removed by IGRA quality assurance, but valid data remain at the same level. -9999 = Value missing prior to quality assurance. WDIR is the reported wind direction (degrees from north, 90 = east). The following special values are used: -8888 = Value removed by IGRA quality assurance, but valid data remain at the same level. -9999 = Value missing prior to quality assurance. WSPD is the reported wind speed (meters per second to tenths, e.g., 11 = 1.1 m/s). The following special values are used: -8888 = Value removed by IGRA quality assurance, but valid data remain at the same level. -9999 = Value missing prior to quality assurance.