IHOP 2002 Soundings Rawinsonde Homestead Integrated Sounding System(ISS) [NCAR/ATD] 1.0 General Description This is one of the upper air data sets developed for the International H2O Project 2002 (IHOP 2002). This dataset contains high resolution sounding data from the Homestead site located in the Oklahoma Panhandle at 100 36.36'W longitude, 36 33.54'N latitude and an elevation of 862 meters. Rawinsondes were released from May 12th, 2002 to June 25th, 2002. Release frequencies ranged between daily during normal operations up to hourly during Intensive Observing Periods (IOPs). The Homestead site employed the National Center for Atmospheric Research Atmospheric Technology Divison (NCAR/ATD) Integrated Sounding System (ISS) which utilized Vaisala Rawinsondes. More information about Homestead's ISS can be obtained from the following url:http://www.atd.ucar.edu/rtf/projects/ihop_2002/iss/. 1.1 ATD Information Contacts/PIs: Dave Parsons parsons@ucar.edu Tammy Weckwerth tammy@ucar.edu William Brown wbrown@ucar.edu Mailing Address: NCAR/Atmospheric Technology Division P.O. Box 3000 1850 Table Mesa Drive Boulder, CO 80307; USA Phone: (303)-497-8833 Fax: (303)-487-8770 Data Inquiry Contacts: William Brown wbrown@ucar.edu Kathryn Beierle kbeierle@ucar.edu 2.0 Detailed Data Description 2.1 Detailed Format Description All upper air soundings were converted to University Corporation for Atmospheric Research/Joint Office for Science Support (UCAR/JOSS) Cross Chain LORAN Atmospheric Sounding System (CLASS) Format (JCF). JCF is a version of the National Center for Atmospheric Research (NCAR) CLASS format and is an ASCII format consisting of 15 header records for each sounding followed by the data records with associated QC information. Header Records The header records (15 total records) contain data type, project ID, site ID, site location, release time, sonde type, meteorological and wind data processors, and the operator's name and comments. The first five header lines contain information identifying the sounding, and have a rigidly defined form. The following 7 header lines are used for auxiliary information and comments about the sounding, and may vary from dataset to dataset. The last 3 header records contain header information for the data columns. Line 13 holds the field names, line 14 the field units, and line 15 contains dashes ('-' characters) delineating the extent of the field. The five standard header lines are as follows: Line Label (padded to 35 char) Contents 1 Data Type: Description of type and resolution of data. 2 Project ID: ID of weather project. 3 Release Site Type/Site ID: Description of launch site. 4 Release Location (lon,lat,alt): Position of launch site, in format described below. 5 UTC Release Time (y,m,d,h,m,s): Time of release, in format: yyyy, mm, dd, hh:mm:ss The release location is given as: lon (deg min), lat (deg min), lon (dec. deg), lat (dec. deg), alt (m) Longitude in deg min is in the format: ddd mm.mm'W where ddd is the number of degrees from True North (with leading zeros if necessary), mm.mm is the decimal number of minutes, and W represents W or E for west or east longitude, respectively. Latitude has the same format as longitude, except there are only two digits for degrees and N or S for north/south latitude. The decimal equivalent of longitude and latitude and station elevation follow. The seven non-standard header lines may contain any label and contents. The labels are padded to 35 characters to match the standard header lines. Data Records The data records each contain time from release, pressure, temperature, dewpoint, relative humidity, U and V wind components, wind speed and direction, ascent rate, balloon position data, altitude, and quality control flags (see the QC code description). Each data line contains 21 fields, separated by spaces, with a total width of 130 characters. The data are right-justified within the fields. All fields have one decimal place of precision, with the exception of latitude and longitude, which have three decimal places of precision. The contents and sizes of the 21 fields that appear in each data record are as follows: Field Format No. Width Parameter Units Missing Value ------------------------------------------------------------------------ 1 6 F6.1 Time Seconds 9999.0 2 6 F6.1 Pressure Millibars 9999.0 3 5 F5.1 Dry-bulb Temperature Degrees C 999.0 4 5 F5.1 Dew Point Temperature Degrees C 999.0 5 5 F5.1 Relative Humidity Percent 999.0 6 6 F6.1 U Wind Component Meters / Second 9999.0 7 6 F6.1 V Wind Component Meters / Second 9999.0 8 5 F5.1 Wind Speed Meters / Second 999.0 9 5 F5.1 Wind Direction Degrees 999.0 10 5 F5.1 Ascension Rate Meters / Second 999.0 11 8 F8.3 Longitude Degrees 9999.0 12 7 F7.3 Latitude Degrees 999.0 13 5 F5.1 Range Kilometers 999.0 14 5 F5.1 Azimuth Degrees 999.0 15 7 F7.1 Altitude Meters 99999.0 16 4 F4.1 QC for Pressure Code (see below) 99.0 17 4 F4.1 QC for Temperature Code (see below) 99.0 18 4 F4.1 QC for Humidity Code (see below) 99.0 19 4 F4.1 QC for U Component Code (see below) 99.0 20 4 F4.1 QC for V Component Code (see below) 99.0 21 4 F4.1 QC for Ascension Rate Code (see below) 99.0 Fields 16 through 21 contain the Quality Control information derived at the UCAR Joint Office for Science Support (UCAR/JOSS). Any QC information from the original sounding is replaced by the following JOSS codes: Code Description 99.0 Unchecked (QC information is "missing.") ("UNCHECKED") 1.0 Checked, datum seems physically reasonable. ("GOOD") 2.0 Checked, datum seems questionable on physical basis.("MAYBE") 3.0 Checked, datum seems to be in error. ("BAD") 4.0 Checked, datum is interpolated. ("ESTIMATED") 9.0 Checked, datum was missing in original file. ("MISSING") Sample Data The following is a sample record of the IHOP 2002 NCAR-ISS Homestead data in JOSS CLASS format. The data portion is much longer than 80 characters and therefore wraps around to a second line. See section 2.1 for an exact format specification Data Type: Sounding Project ID: IHOP_2002 NCAR-ISS Sndings Release Site Type/Site ID: Fixed NCAR-ISS/Homestead HOM Release Location (lon,lat,alt): 100 36.36'W, 36 33.54'N, -100.61, 36.56, 862.0 UTC Release Time (y,m,d,h,m,s): 2002, 05, 12, 20:28:03 Sonde Type/ID/Sensor ID/Tx Freq: NCAR GLASS RS80-15GH VAISALA System Operator/Comments: LOUtest,,test flight Radiosonde Serial Number: 213308408 Input File: y5122028.hom / / Nominal Release Time (y,m,d,h,m,s):2002, 05, 12, 20:28:03 Time Press Temp Dewpt RH Uwind Vwind Wspd Dir dZ Lon Lat Elev Azim Alt Qp Qt Qh Qu Qv Qdz sec mb C C % m/s m/s m/s deg m/s deg deg deg deg m code code code code code code ------ ------ ----- ----- ----- ------ ------ ----- ----- ----- -------- ------- ----- ----- ------- ---- ---- ---- ---- ---- ---- -1.0 920.6 12.3 4.3 57.7 2.0 -7.4 7.7 345.0 999.0 -100.606 36.559 999.0 999.0 862.0 3.0 3.0 3.0 99.0 99.0 9.0 0.0 918.7 11.2 3.1 57.1 9999.0 9999.0 999.0 999.0 17.5 -100.606 36.559 999.0 999.0 879.5 3.0 3.0 3.0 9.0 9.0 99.0 1.0 918.3 11.1 3.1 57.3 9999.0 9999.0 999.0 999.0 3.6 -100.606 36.559 999.0 999.0 883.1 3.0 99.0 99.0 9.0 9.0 99.0 2.0 917.9 11.1 3.0 57.5 9999.0 9999.0 999.0 999.0 3.5 -100.606 36.559 999.0 999.0 886.6 99.0 99.0 99.0 9.0 9.0 99.0 3.0 917.5 11.0 3.0 57.8 9999.0 9999.0 999.0 999.0 3.3 -100.606 36.559 999.0 999.0 889.9 99.0 99.0 99.0 9.0 9.0 99.0 2.2. Data File Specifics from ATD These files contain data calculated at one-second intervals . The variables pressure, temperature, and relative humidity are calibrated values from measurements made by the sonde. The dew point is calculated from the relative humidity. The altitude value is calculated from the hydostatic equation using pressure, temperature, and dew point. The rate of ascent is obtained from the altitude difference between two successive time steps. The position(lat, lon), angle and range come from the GPS and altitude data. This data is interpolated to one second in order to match the wind data. All wind data are computed from GPS navigation signals received from the sonde. The raw wind values are calculated at a one half second data rate by a commercial processing card. These raw values are subjected to a digital filter to remove low frequency oscillations due to the sonde pendulum motion beneath the balloon. The resolution of the data is reduced to one second. This time record is used in the interpolation of the pressure, temperature, and humidity data. 3.0 Quality Control 3.1 ATD Data Quality Control The raw soundings are first run through the Atmospheric Sounding Processing ENvironment (ASPEN), which analyzes the data, performs smoothing, and removes suspect data points. The soundings are then visually evaluated for outliers, or any other obvious problems. Finally, the prelaunch PTU radiosonde data are compared with surface data measured by independent surface sensors to check for problems that may have gone undetected by the first two quality control procedures. By performing the QC measures outlined above on the data from IHOP 2002, it was found that in some cases the prelaunch sonde data are drier than the surface data during the day, and that the dry bias increases with the solar angle, and reaches its maximum around noon. This dry bias in the prelaunch sonde humidity data corresponds to warmer prelaunch temperature data. Whether the drier, warmer prelaunch data is due to sensor arm heating, or some other problem, is not clear. For this reason, no corrections have been applied to the data. 3.2 JOSS Quality Control Processing This dataset underwent am automated QC process. The dataset underwent internal consistency checks which included two types of checks,gross limit checks on all parameters and rate-of-change checks on temperature, pressure and ascension rate. Some further information on the QC processing conducted by JOSS can be found in Loehrer et al. (1996) and Loehrer et al. (1998). 3.2.1 Gross Limit Checks These checks were conducted on each sounding and data were automatically flagged as appropriate. Only the data point under examination was flagged. JOSS conducted the following gross limit checks on the 1996 sounding dataset. In the table P = pressure, T = temperature, RH = relative humidity, U = U wind component, V = V wind component, B = bad, and Q = questionable. __________________________________________________________________ Parameter(s) Flag Parameter Gross Limit Check Flagged Applied __________________________________________________________________ Pressure < 0 mb or > 1030 mb P B Altitude < 0 m or > 35000 m P, T, RH Q Temperature < -80C or > 45C T Q Dew Point < -99.9C or > 30C RH Q > Temperature T, RH Q Relative Humidity < 0% or > 100% RH B Wind Speed < 0 m/s or > 100 m/s U, V Q > 150 m/s U, V B U Wind Component < 0 m/s or > 100 m/s U Q > 150 m/s U B V Wind Component < 0 m/s or > 100 m/s V Q > 150 m/s V B Wind Direction < 0 deg or > 360 deg U, V B Ascent Rate < -10 m/s or > 10 m/s P, T, RH Q _________________________________________________________________ 3.2.2 Vertical Consistency Checks These checks were conducted on each sounding and data were automatically flagged as appropriate. These checks were started at the lowest level of the sounding and compared neighboring 1-sec data points. In the case of checks ensuring that the values increased/decreased as expected, only the data point under examination was flagged. However, for the other checks, all of the data points used in the examination were flagged. All items within the table are as previously defined. _____________________________________________________________________ Vertical Consistency Parameter(s) Flag Parameter Check Flagged Applied _____________________________________________________________________ Time decreasing/equal None None Altitude decreasing/equal P, T, RH Q Pressure increasing/equal P, T, RH Q > 1 mb/s or < -1 mb/s P, T, RH Q > 2 mb/s or < -2 mb/s P, T, RH B Temperature < -15 C/km P, T, RH Q < -30 C/km P, T, RH B > 5 C/km (not applied at p , 150mb) P, T, RH Q < 30 C/km (not applied at p , 150mb) P, T, RH B Ascent Rate change of > 3 m/s or < -3 m/s P Q change of > 5 m/s or < -5 m/s P B _____________________________________________________________________ 4.0 References Loehrer, S. M., T. A. Edmands, and J. A. Moore, 1996: TOGA COARE upper-air sounding data archive: development and quality control procedures. Bull. Amer. Meteor. Soc., 77, 2651-2671. Loehrer, S. M., S. F. Williams, and J. A. Moore, 1998: Results from UCAR/JOSS quality control of atmospheric soundings from field projects. Preprints, Tenth Symposium on Meteorological Observations and Instrumentation, Phoenix, AZ, Amer. Meteor. Soc., 1-6.