Charleston (US) FASTEX High-Resolution Sounding Dataset ------------------------------------------------------- 1.0 Site Information Location: 80.00 Deg W Longitude 32.90 Deg N Latitude Station Elevation: 15 m Typical Launch Times: 00 12 UTC (and during selected IOPs 06 and 18 UTC) Dates Available: 1 January 1997 - 28 February 1997 (scattered missing files: see Section 8.0) Site WMO Code: 72208 Source Agency: National Weather Service (US) Country Code: US `Native Vertical Resolution': 6 seconds Total Launches Available in `Native Resolution': 146 2.0 Radiosonde Information Radiosonde Type: VIZ Windfinding System: Radiotheodolite 3.0 Parameters in Raw Dataset Parameters Units -------------------------------------- Time Seconds Temperature Deg C Relative Humidity % Altitude Geopotential Meters Pressure Millibars Elevation Angle Deg Azimuth Angle Deg -------------------------------------- 4.0 Conversion to JOSS CLASS format (ASCII text) 4.1 The raw 6 s vertical resolution time, temperature, relative humidity, altitude, and pressure were kept without change. 4.2 The ascension rate was calculated for each data point (excluding the surface, where it was given a missing value) based on the altitude and time at two levels, the current 6 s level and the previous 6 s level. If the data point for which the ascension rate was being calculated had missing time or altitude, the ascension rate was not calculated at that level and was flagged as missing. If the data point prior to that for which the ascension rate was being calculated had a missing time or altitude, then the data point two data points prior to the present one was used, and so on until one with non-missing time and altitude was found. If there are no non-missing previous data points the ascension rate is set to missing. 4.3 Dew points were calculated via the equations from Bolton (1980). Due to CLASS format constraints, Dew Points less than -99.9 Deg C were given a value of -99.9 Deg C and were flagged as being questionable. 4.4 In past derivation of winds using the raw 6-sec resolution elevation and azimuth angle data containing elevation angle oscillations occasionally led to large oscillations in wind velocity, specifically at low elevation angles (Williams 1993). The general approach to correct this problem was to remove the outlier radiosonde position data before computing the wind components. This process required fitting a ninth order polynomial to the azimuth and elevation angle data from 360 seconds to the end of the sounding, then comparing the calculated residuals and observed values, and finally removing the outliers when present. Applying some additional smoothing helped rectify the more extensive problem occurring when low elevation angles were within 10 degrees of the limiting angles (LA). When the elevation angle was between (LA + 7.5) and (LA + 10), the new elevation angle was computed using a 2 min linear fit. When the elevation angle was between (LA + 5) and (LA + 7.5), the new elevation angle was computed using a 3 min linear fit. When the elevation angle was less than (LA + 5), the new elevation angle was calculated employing a 4 min linear fit. No frequency smoothing occurred when the number of low elevation angle observations was greater than 20% of the total number of observations. A Finite Fourier Series analysis performed using the elevation angle's residuals allowed removal of 90-190 second periods and smoothing periods below 30 seconds. Obtaining the u and v wind components entailed fitting a 2 min second order polynomial to the position except for the beginning and end minute (or 1.5 minutes if over 50 mb) which used a 3 min fit. A linear fit was used when there were less than 15% of the total number of points, not including the beginning or end of the flight, on one side of the point under going the wind value calculation. 4.5 The latitude and longitude position of the radiosonde was calculated based on (Snyder, 1987). See Snyder page 159 equations 20-14, 20-15, 20-18, and 21-15. 5.0 JOSS CLASS Format (ASCII text) Description 5.1 Header records The header records (15 total records) contain data type, project ID, site ID, site location, actual release time, nominal release time, and possibly other specialized information. The first five header lines contain information identifying the sounding, and have a rigidly defined form. The following 6 header lines are used for auxiliary information and comments about the sounding, and they vary significantly from dataset to dataset (For Charleston these lines are empty). The next line (line 12) contains the Nominal date and time of the release. 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 six standard header lines are as follows: Line Label (fixed to 35 char in length) Contents 1 Data Type: Description of type and resolution of data. 2 Project ID: ID of weather project. 3 Launch Site Type/Site ID: Description of launch site. 4 Launch Location (lon,lat,alt): Position of launch site, in format described below. 5 UTC Launch Time: Time of release, in format: yyyy, mm, dd, hh:mm:ss 12 UTC Nominal Launch Time: Nominal release time. The launch site type/site ID has the format: site ID (three or four letter code), the full site name, the country code (specified in Section 1.0) and the WMO code for the site. 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 six non-standard header lines may contain any label and contents. The label is fixed to 35 characters to match the standard header lines. Again, for Charleston soundings, these lines have been left empty. Sample header records are provided in the sample data file in section 5.3. 5.2 Data records The data records each contain time from release, pressure, temperature, dew point, relative humidity, U and V wind components, wind speed and direction, ascent rate, balloon position data, altitude, and quality control flags (see 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 Missing No. Width Parameter Units 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 Variable (see below) 999.0 14 5 F5.1 Variable (see below) 999.0 15 7 F7.1 Altitude Meters 99999.0 16 4 F4.1 QC flag for Pressure Code (see below) 99.0 17 4 F4.1 QC flag for Temperature Code (see below) 99.0 18 4 F4.1 QC flag for Humidity Code (see below) 99.0 19 4 F4.1 QC flag for U Component Code (see below) 99.0 20 4 F4.1 QC flag for V Component Code (see below) 99.0 21 4 F4.1 QC flag for Ascension Rate Code (see below) 99.0 ---------------------------------------------------------------------- Fields 13 and 14 are `variable' because depending on the sounding system the variables used in these positions can vary. For the Charleston soundings, these fields have been set to missing. Fields 16 through 21 contain the Quality Control information (flags) generated locally at JOSS. These flags are based on the automatic or visual checks made. See Sections 6.0 and 7.0 for further information. The JOSS QC flags are as follows: 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') ---------------------------------------------------------------------- 5.3 Sample data The following is a sample portion of a JOSS CLASS format file including header records. The data portion is much longer than 80 characters and, therefore, wraps around to a second line. Data Type: NWS Project ID: FASTEX class format 6 sec sounding Launch Site Type/Site ID: CHS Charleston, US, 72208 Launch Location (lon,lat,alt): 080 0.00'W, 32 54.00'N, -80.00, 32.90, 15.0 GMT Launch Time (y,m,d,h,m,s): 1997, 02, 24, 17:05:00 Ascension No: 1134 / / / / / Nominal Launch Time (y,m,d,h,m,s): 1997, 02, 24, 18:00:00 Time Press Temp Dewpt RH Uwind Vwind Wspd Dir dZ Lon Lat Rng Ang Alt Qp Qt Qh Qu Qv Qdz sec mb C C % m/s m/s m/s deg m/s deg deg km deg m code code code code code code ------ ------ ----- ----- ----- ------ ------ ----- ----- ----- -------- ------- ----- ----- ------- ---- ---- ---- ---- ---- ---- 0.0 1032.8 15.0 -3.4 28.0 -4.7 -4.0 6.2 50.0 999.0 -80.000 32.900 999.0 999.0 15.0 2.0 2.0 2.0 1.0 1.0 99.0 6.0 1028.2 14.3 -7.9 20.7 -4.9 -3.1 5.8 58.0 6.3 -80.000 32.900 999.0 999.0 53.0 2.0 2.0 2.0 1.0 1.0 99.0 12.0 1023.7 13.6 -7.4 22.5 -4.5 -3.2 5.5 55.0 6.2 -80.001 32.900 999.0 999.0 90.0 2.0 2.0 2.0 1.0 1.0 99.0 6.0 Quality Control Procedures This dataset underwent the JOSS QC process which consisted of internal consistency checks and visual quality control. The internal consistency checks included gross limit checks on all parameters and vertical consistency checks on temperature, pressure, and ascension rate. JOSS then visually examined each sounding. 6.1 Automated Quality Control Procedures 6.1.1 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 Charleston FASTEX 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 > 1050 mb P B Altitude < 0 m or > 40000 m P, T, RH Q Temperature < -80C or > 30C T Q Dew Point < -99.9C or > 25C 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 ---------------------------------------------------------------- 6.1.2 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 values. 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. Above 100 mb, 30 sec averages were used for the checks. 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 from surface to 800 mb: > 25 C/km (not applied at p < 275mb) P, T, RH Q > 40 C/km (not applied at p < 275mb) P, T, RH B for pressures < 800 mb: > 5 C/km (not applied at p < 275mb) P, T, RH Q > 30 C/km (not applied at p < 275mb) 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 ---------------------------------------------------------------- 6.2 Visual Quality Control Procedures Each sounding was then visually examined for problems that were not able to be captured via the automated checks described in item 6.1 above. These problems typically included oddities in the dew point and wind profiles. These two parameters can be highly variable, and hence, the automated checking is more difficult. The visual checking procedure has two main purposes: First, as a check on the results provided by the automatic checks, and second, as a more stringent check on the more variable parameters. 7.0 Dataset Availability Datasets Available Online ---------------------------------------------------------------- Quality Controlled Data File in Native Resolution (available in Bufr, EBufr, and OFPS QCF (ASCII) formats) Site-by-site processing and QC documentation (including special spatial QC and general QC documents) ---------------------------------------------------------------- Datasets Available Offline ---------------------------------------------------------------- Non-Quality Controlled, Raw Format File in Native Resolution Automatically generated Error Files (see item 6.0 above) ---------------------------------------------------------------- 8.0 Dataset Remarks 8.1 Missing Files The following expected soundings were missing: 2 January 1200 6 January 1200 14 January 1200 18 January 0000 1200 19 January 0000 1200 20 January 0000 1200 21 January 0000 1200 22 January 0000 1200 23 January 0000 1200 27 January 0000 8.2 Significant Problems These soundings were of generally good quality. 9.0 FASTEX Data Use According to the FASTEX data policy, the use of these data is unrestricted for research and educational purposes. Proper acknowledgements should be given in publications that utilize this data to specific scientists and institutions that made the collection of data possible. Where appropriate, all authors considering publication of FASTEX related research results should offer co-authorship to investigators that had a primary role in the collection of data utilized in the study. 10.0 Upper-Air Sounding Data Providers Country Name Address -------- ---------------- -------------------------------------------------- Canada Dave Steenbergen AES 4905 Dufferin Street Downsview Ontario M3H 5T4 Denmark Klaus Hedegaard DMI Lyngbyveg 100 DK-2100 France Michel Rochas Meteo-France Instrumentation Dept. 7,rue Teisserenc de Bort BP202 78195 Trappes Iceland Flosi Sigurosson Meteorological Office Technical and Obs. Dept Bustadavegur 9 IS-140 Reykjavik Ireland Liam Burke Meteorological Office Instrumentation and Environmental Division Glasnevin Hill Dublin 9 Portugal Renato Carvalho INMG Rua C. Aeroporto de Lisboa 1700 Lisboa Spain Cesar Belandia INM Servicio de Observacion, Camino de la Moreras s/n Ciudad Universitaria 28071 MADRID United John Stancombe UK Met Office Upper Air Network Kingdom London Road Bracknell, Berkshire RG12 2SZ USA Robert Thomas NOAA W/OSO14 SSMC/2 1325 East West Highway Silver Spring,MD 20910 FASTEX Principal Investigators and Data Providers for the FASTEX Ships Ships Name Address -------- ------------------ -------------------------------------- AEGIR Alain Joly Meteo-France/CNRM 42 Av.G.Coriolis 31057 Toulouse Cedex France (alain.joly@meteo.fr) V.BUGAEV Pierre Bessemoulin Meteo-France/CNRM 42 Av.G.Coriolis 31057 Toulouse Cedex France (pierre.bessemoulin@meteo.fr) KNORR Ola Persson NOAA/ETL CIRES, Univ. of Colorado Campus Box 216 Boulder, CO 80309 USA (pogp@etl.noaa.gov) SUROIT Alain Joly Meteo-France/CNRM 42 Av.G.Coriolis 31057 Toulouse Cedex France (alain.joly@meteo.fr) The FASTEX enhanced radiosounding program was supported by AES (Canada), CNRS/INSU (France), DMI (Denmark), the Icelandic Met. Office, Meteo-France, Met Eireann (Ireland), NCAR/MMM (USA), the UK Met. Office, WMO/COSNA. The FASTEX ships were supported by CNRS/INSU (France), The European Commission, IFREMER (France), Meteo-France, NOAA (USA), NSF (USA). 11.0 References Bolton, D., 1980: The Computation of Equivalent Potential Temperature. Mon. Wea. Rev., 108, 171-180. Snyder, J. P., 1987: Map Projections - A Working Manual. United States Geological Survey Professional Paper 1395, 383 pp. Williams, S.F., C.G. Wade, and C. Morel, 1993: A comparison of high resolution radiosonde winds: 6-second Micro-ART winds versus 10-second CLASS LORAN winds. Preprints, Eighth Symposium on Meteorological Observations and Instrumentation, Anaheim, California, Amer. Meteor. Soc., 60-65.