NOAA P-3 (N42) FASTEX High-Resolution Dropsonde Data Set -------------------------------------------------------- 1.0 Site Information Location: Variable Station Elevation: Variable Typical Launch Times: Variable Dates Available: 2, 4, 23 February 1997 Source Agency: National Oceanic and Atmospheric Administration (NOAA) `Native Vertical Resolution': 0.5 seconds Final Dataset Resolution: 2 seconds Total Launches Available in `Native Resolution': 36 Total Launches Available in Final Resolution: 31 (see section 4.6 to see why there are fewer here) 2.0 Radiosonde Information Radiosonde Type: Vaisala RSS903 Uses heated humidity sensor Windfinding System: GPS 3.0 Parameters in Raw Dataset Parameters Units -------------------------------------- Time Seconds Pressure Millibars Temperature Deg C Relative Humidity % Wind Direction Deg Wind Speed m/s Ascencion Rate m/s Latitude Deg Longitude Deg Altitude Geopotential Meters -------------------------------------- 4.0 Conversion to JOSS CLASS format (ASCII text) 4.1 These soundings include the correction applied by NCAR/SSSF to correct for the incorrect usage of the internal radiosonde temperature rather than the ambient temperature to correct the reported relative humidity values. For further information on this correction please contact Hal Cole (cole@ucar.edu). 4.2 These files arrived at JOSS in ascii format and were converted to a high resolution JOSS CLASS format (section 5.0) using JOSS developed software. JOSS implemented Quality Control procedures (described below) in an attempt to remove any noise contained in the raw 0.5 s ascii files. These procedures are in addition to typical JOSS Quality Control procedures detailed in section 6.0. The high resolution class files are of varying resolution but consist of the raw 0.5 s data minus the 'BAD' data points. These files then were linearly interpolated to 2 s resolution JOSS CLASS files. The pressures and times in the original ascii files were increasing. JOSS reversed the pressures and times in the high resolution CLASS files and in the final 2 s resolution interpolated CLASS files. 4.3 For files containing a launch time, JOSS processing entailed using the data point whose time was the closest to the launch time plus 20 seconds in an attempt to prevent recording data while the dropsonde was still in the launch bay and/or during the dropsonde's environmental acclimation. In addition, JOSS processing required that the launch pressure be less than 600 mb and the launch dry bulb temperature be less than 30 deg C. Furthermore, JOSS processing checked the initial data points near the launch point to insure that only the most suitable data points were used. Picking a bad launch point would cause the unnecessary removal of many good points due to the rate of change checks (section 4.3). Only data points whose times occurred after the launch time were written to the high resolution class file. Files not containing launch times or containing many bad data points needed special processing in order to 'force' the JOSS processing software to chose quality launch points. 4.4 The raw 0.5 s vertical resolution time, temperature, relative humidity, altitude, pressure, dew point, latitude, longitude, wind direction and wind speed were kept without change. However, JOSS implemented rate of change quality control checks which determined whether a data point was written to the high resolution class file. These quality control checks included checks for excessive lapse rates, pressure changes, and ascension rates between successive points. 4.5 The lapse rate was calculated for each data point based on the altitude and dry bulb temperature at two levels, the current 0.5 s level and the previous 0.5 s level. If the absolute value of the calculated lapse rate exceeded 75 deg C/km, then the data point was not written to the high resolution class file. If the current data point contained a missing altitude, but not a missing dry bulb temperature, a -10 m/s ascension rate was assumed and based on this assumption, a lapse rate was then calculated. If the absolute value of this assumed lapse rate exceeded 75 deg C/km then the current data point was not written to the high resolution class file. 4.6 If a data point's pressure and altitude were missing, that point was not kept. This explains why the number of soundings in the 2 s data set is lower than in the 0.5 sec data set. Some soundings had no pressure or altitude information within them. Furthermore, if the absolute value of the pressure change between the current time and the previous time was greater than or equal to 5 mb/sec, than that data point was not written to the high resolution class file. 4.7 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 0.5 s level and the previous 0.5 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. Raw 0.5 s data was not written to the high resolution class file if the ascension rate was less than or equal to -40 m/s or greater than or equal to 10 m/s. 4.8 The U and V wind components were calculated based on the wind speed and direction at the 0.5 s level. 4.9 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. 4.10 A 2 s vertical resolution file was created using existing 2 second interval data points from the high resolution CLASS file beginning with 0 s. Pressure, dry bulb temperature, relative humidity, U and V wind components, latitude and longitude, were linearly interpolated if no original 2 second interval data point existed within the high resolution class file. Dew point temperature, total wind speed and wind direction, ascension rate and altitude were calculated. The altitude was calculated by assuming that the final data point within the sounding was the surface and since the surface was the ocean surface, the altitude at this point was assumed to be 0 m, as long as the pressure at this point was >= 960 mb. If the pressure was < 960 mb the altitudes were not recalculated. If the altitudes were not recalculated the altitudes within the files are those reported by the dropsonde. For those that were recalculated from the bottom-up using a version of the hypsometric equation (Holton 1979, Hess 1959, Herzegh 1988). The ascension rate recalculation followed the procedure detailed in section 4.7 minus the rate of change condition and for 2 s vertical resolution data points. The altitude recalculation utilized the hypsometric equation and used the virtual temperature if the relative humidity was not missing. Otherwise the dry bulb temperature was employed. To determine whether a file had recalculated altitudes, just see if the first data point within the file (the "surface") has a zero altitude, if so, the altitudes WERE recalculated. If not, the altitudes WERE NOT recalculated. Missing 2 s variables were interpolated using the closest high resolution points surrounding the variable to be interpolated. The distance between these points determined the Quality Control flags written in the CLASS file's QC fields detailed below in section 5.2. If the data points used in the interpolation were less than 20 seconds apart, the interpolated datum was flagged "UNCHECKED", between 20 s and 40 s, the datum was flagged "QUESTIONABLE", and for points greater than 40 s apart , the interpolated point was flagged "BAD". Thus it is important to examine the flags within this dataset as data may have been interpolated over large intervals. 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 the NOAA P-3 these lines contained significant information). 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 the NOAA P-3 soundings, these lines contain significant information on the pre-launch conditions. 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 NOAA P-3 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: Dropsonde Project ID: FASTEX class format high resolution AVAPS dropsonde Launch Site Type/Site ID: P-3 Orion, N42RF Launch Location (lon,lat,alt): 019 17.18'W, 53 31.40'N, -19.29, 53.52, 5782.0 GMT Launch Time (y,m,d,h,m,s): 1997, 02, 23, 13:30:56 Pre-launch Obs Data System/time: NOAA\RAMS, 13:33:22.0 Pre-launch Obs (p,t,d,h): 445.6 mb, -38.5 C, -62.7 C, 15.6 % Pre-launch Obs (wd,ws): 253.0 deg, 21.9 m/s System Operator: Offutt Comments: Drop #7 fast fall / Nominal Launch Time (y,m,d,h,m,s): 1997, 02, 23, 13:30:56 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 ------ ------ ----- ----- ----- ------ ------ ----- ----- ----- -------- ------- ----- ----- ------- ---- ---- ---- ---- ---- ---- 222.0 963.8 2.5 -3.3 65.3 13.7 16.3 21.3 220.0 999.0 -19.172 53.549 999.0 999.0 99999.0 1.0 1.0 1.0 1.0 1.0 99.0 220.0 961.1 2.2 -4.9 59.5 13.9 16.6 21.7 220.0 999.0 -19.172 53.549 999.0 999.0 66.7 1.0 1.0 1.0 1.0 1.0 99.0 218.0 958.7 2.0 -5.1 59.7 14.3 17.0 22.2 220.0 -10.1 -19.172 53.548 999.0 999.0 86.9 1.0 1.0 1.0 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. These checks are different from the checks described in section 4.0. in that the 4.0 checks were point to point checks between adjacent times and were only vertical consistency checks while the Automatic Quality Control software employed six second averaging in its checking procedure and included gross limit checks. In addition, the Auto QC used a different set of parameters during its vertical consistency checks. More importantly, the Auto QC DID NOT REMOVE data points. It only changed QC flags. 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 NOAA P-3 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 < -30 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. The Auto QC software employed six-second averaging for these checks. These checks were started at the lowest level of the sounding and compared the end points of a six second interval. In the case of checks ensuring that the values increased/decreased as expected, only the data points under examination were flagged. However, for the other checks, all four 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 increasing/equal None None Altitude increasing/equal P, T, RH Q Pressure decreasing/equal P, T, RH Q > 3 mb/s or < -3 mb/s P, T, RH Q > 4 mb/s or < -4 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 > 5 m/s or < -5 m/s P Q change of > 9 m/s or < -9 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 Relative Humidity Issues UCAR/JOSS has conducted intercomparisons of the relative humidity measurements of the various dropsonde systems and the FASTEX ships. For information on these intercomparisons please contact Jim Moore (moore@ucar.edu). 8.2 Wind Problems There are some files with significant problems with the winds. This includes problems such as drastic speed and directional changes, wind speeds that are too high, and winds that are erratic in their speed and/or direction. 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 FASTEX Land-Based 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 Aircraft Dropsonde Data Providers Aircraft Name Address -------- -------------- ---------------------------------- LEAR36 Dean Lauritsen NCAR/ATD P.O. Box 300 Boulder,CO 80307 USA (lauritsn@ucar.edu) US-C1307 Jon Talbot 53rd Weather Reconnaissance Squadron, US-C1308 Keelser Air Force Base Mississippi, USA (info@hurricanehunters.com) NOAA-GIV John Daugherty NOAA/NSSL 325 Broadway Boulder,CO 80303 USA (johnd@ncar.ucar.edu) NOAA-P3 David Jorgensen NOAA/NSSL 325 Broadway Boulder,CO 80303 USA (davej@ncar.ucar.edu) UK-C130 Sid Clough Joint Centre for Mesoscale Meteorology (JCMM) Department of Meteorology, University of Reading PO Box 243 Earley Gate Reading Berkshire RG6 6BB UK (saclough@meto.gov.uk) 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) FASTEX Principal Investigators for the FASTEX Aircraft Aircraft Name Address --------- ------------- ---------------------------------------- LEAR36 Kerry Emanuel Center for Meteorology and Physical Oceanography Room 54-1620 Massachsetts Inst. of Technology Cambridge,MA 02139 USA (emanuel@texmex.mit.edu) Chris Snyder NCAR/MMM P.O.Box 3000 Boulder,CO 80307 USA (chriss@ncar.ucar.edu) US-C1307 Zoltan Toth NOAA/NCEP Mail code: W/NMC2 US-C1308 5200 AUTH RD Rm 207 Camp Springs,MD 20746 USA (wdzozt@sun1.wwb.noaa.gov) NOAA-GIV Melvyn Shapiro NOAA/ETL 325 Broadway Boulder,CO 80303 USA mshapiro@etl.noaa.gov Jean-Pierre Cammas Laboratoire d'Aerologie Obs. Midi-Pyrenees 14 Avenue Edouard Belin 31400 Toulouse France (camjp@aero.obs-mip.fr) Alain Joly Meteo-France/CNRM 42 Av.G.Coriolis 31057 Toulouse Cedex France (alain.joly@meteo.fr) Rolf Langland Naval Research Laboratory 7 Grace Hopper Ave. Monterey,CA 93943-5502 (langland@nrlmry.navy.mil) NOAA-P3 David Jorgensen NOAA/NSSL 325 Broadway Boulder,CO 80303 USA (davej@ncar.ucar.edu) UK-C130 Sid Clough Joint Centre for Mesoscale Meteorology (JCMM) Department of Meteorology University of Reading PO Box 243 Earley Gate Reading Berkshire RG6 6BB UK (saclough@meto.gov.uk) 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 Herzegh, P. H., 1988: Formulation of output parameters for PAM II CMF data. Field Observing Facility, National Center for Atmospheric Research, Boulder, CO. Hess, S. L., 1959: Introduction to Theoretical Meteorology. Holt, Rinehart and Winston, 362 pp. Holton, J.R., 1979: An Introduction to Dynamic Meteorology. Academic Press, 391 pp. Snyder, J. P., 1987: Map Projections - A Working Manual. United States Geological Survey Professional Paper 1395, 383 pp.