Dropsonde (NOAA and NASA) TOGA-COARE High-Resolution Sounding Dataset 1.0 Site Information Location: Variable Station Elevation: Variable Typical Launch Times: Events of Opportunity Dates Available: 22 Oct 1992 - 24 Feb 1993 Total Launches Available in `Native Resolution': 106 Total Launches Available in GTS Format Only: 0 2.0 Radiosonde Information Radiosonde Type: NCAR Lightweight Omega Digital Dropsonde (LOD2). Radiation Correction Applied?: No Ground Equipment: CLASS Windfinding System: OMEGA Windfinding Equipment: OMEGA Resolution of Raw Data: 10 s 3.0 Parameters in Raw Dataset Parameters Units -------------------------------------- Time Seconds Altitude Geopotential Meters Pressure Millibars Temperature Deg C Relative Humidity % Dew Point Deg C Wind Direction Deg Wind Speed Meters/Second U Wind Component Meters/Second V Wind Component Meters/Second Ascension Rate Meters/Second Longitude Degrees Latitude Degrees Range Kilometers Azimuth Angle Degrees -------------------------------------- 4.0 Conversion to OFPS CLASS 4.1 The altitudes in many of the original files appeared to be off by significant amounts at the surface, which should have a near zero altitude. There are two sources of potential error in the altitudes. First, the aircraft altitude may be off. Second, the use of all data in the calculation of the altitude (i.e. no outlier removal) may lead to significant errors. In order to correct as much of this problem as possible, OFPS first attempted to remove some outlier data and recalculate the altitudes from the top-down. In most cases, only two data points were removed as outliers, the 10 and 20 sec data points. Then, the remaining error in altitude can be assumed to be due to the aircraft aircraft altitude being incorrect, so we set the surface altitude to 0 m and recalculated the altitudes from the bottom-up. Not all files were able to pass through all of the processing. First, several files had the data cut off prior to reaching the surface. These had outliers removed and altitudes recalculated from the top-down, but did not go through the second pass of bottom-up recalculation. These files include: 2042113.d8a 2061604.d8a 2172300.d8b 2222317.d8a mddtttt aircraft Second, many files had problems that did not allow any altitude recalculation. These problems included large data gaps and the radiosonde data becoming unreliable for extended periods of time, often around the surface. These files went through NO altitude reprocessing, and hence ALL altitudes within these files are highly questionable. These files include: 1120204.d8a 1120224.d8a 1190450.d8a 1190607.d8a 1190629.d8b 1260026.d8a 2041729.d8b 2041838.d8b 2041939.d8b 2042028.d8b 2061347.p3a 2061459.p3a 2061652.d8b 2062016.d8b 2062038.d8a 2062225.p3a 2082130.d8a 2102248.d8a 2102344.d8a 2172110.d8a 2222138.d8a 2222218.d8b a221801.n43 c132123.p3b 4.2 All other raw 10 s vertical resolution data, except the ascension rate, were kept without change. 4.3 The ascension rate was recalculated 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 10 s level and the previous 10 s level. If any time or altitude values were missing, at either of the levels, the ascension rate was not calculated at the current 10 s level and it was flagged as missing. This was necessary since the CLASS software treats all layers as ten-second layers, even when there is missing data in between. 4.4 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 estimated. 5.0 Automatic Quality Control Procedures Internal quality control procedures were applied to each sounding individually. These checks included two general types: `Reasonable limit' checks on all parameters and `Rate-of-Change'' checks on pressure, temperature, and ascension rate. These checks led to the development of automatically generated quality control flags in the OFPS CLASS format file. Also, files were generated that contain descriptions of the problems found in each sounding. For further information on the OFPS automatic quality control procedures used for the TOGA-COARE project see Loehrer et al (1996). 6.0 Visual Quality Control Procedures Each sounding was then visually examined for problems that are not able to be captured via the automatic checks described in item 5.0 above. These problems typically included oddities in the dew point and wind profiles. These two parameters can be highly variable, and hence, the automatic 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. For further information on this procedure, see Loehrer et al (1996). 7.0 Spatial Quality Control Procedures Basic statistics are generated indicating whether a given station performed consistently with respect to its neighbors and the network as a whole. The first set of statistics are level-by-level checks versus neighboring stations. The neighbors are those stations in a constricted latitude band. The general methodology used by OFPS is a simple distance weighted averaging scheme comparing the observed values to those expected by the averaging scheme. Tests are applied to altitude, temperature, dew point, wind speed and direction at 14 standard pressure levels. The second set of statistics are level-by-level checks versus network-wide averages. For these all of the data from the network at a particular level and time is averaged and each site is compared to the average. For more information on the procedures used for the spatial consistency checks see Loehrer et al (1996). For general findings from the spatial QC see the OFPS spatial QC overview and findings document. The statistics from both checks are also available online. -----------------NOTE------------------NOTE------------------ Due to the nature of this data set, no spatial QC procedures will be applied. -----------------NOTE------------------NOTE------------------ 8.0 Derived Sounding Parameters The NCAR SUDS (System for User-editing and Display of Soundings; Burghart 1993) software was used to calculate common wind, thermodynamic and stability parameters using the procedures of Weisman and Klemp (1982). Any data points flagged as BAD by the automatic or visual checks are not used in the calculation of these parameters. These parameters will be online, with a separate file for each sounding. The parameters calculated by this routine include: SUDS Derived Parameters ---------------------------------------------- Surface Potential Temperature Surface Virtual Potential Temperature Surface Mixing Ratio 500 mb Potential Temperature 500 mb Virtual Temperature 500 mb Virtual Potential Temperature Lifted Condensation Level (LCL) Lifted Index Level of Free Convection (LFC) Positive Area Below the LFC Negative Area Below the LFC Convective Available Potential Energy (CAPE) Negative Area Above the LFC Shear over the Lowest 6 km Bulk Richardson Number (Ri) Mean Layer Vector Wind between 1000 and 700 mb ---------------------------------------------- -----------------NOTE------------------NOTE------------------ Due to the nature of these soundings, no sounding parameter files were created. -----------------NOTE------------------NOTE------------------ 9.0 JOSS CLASS Format (ASCII text) Description 9.1 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 data set to data set. 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 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. Sample header records are provided in the sample data file later in this section. 9.2 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. Fields 16 through 21 contain the Quality Control information (flags) generated locally at JOSS. These flags are based on the automated or visual checks made. 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') ---------------------------------------------------------------------- 9.3 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: Project ID: TOGA-COARE Dropsonde Hi-Res soundings. Release Site Type/Site ID: LOCKHEED WP-3D, P3A Release Location (lon,lat,alt): 160 0.00'E, 06 0.00'S, 160.00, -6.00, 5680.0 UTC Release Time (y,m,d,h,m,s): 1992, 11, 06, 14:47:24 Sonde Type/ID/Sensor ID/Tx Freq: NCAR LOD2 (OMEGA) 328, 120, 405.5 Winds Type/Processor/Smoothing: OMEGA, TRIMBLE MINI-OMEGA, 240 SECONDS Pre-launch Met Obs Source: MANUAL ENTRY System Operator/Comments: T. HOCK, (REPROCESSED),1ST COARE FLIGHT, DUAL SYSTEM TRACKED, TURN MAD IN MIDDLE OF FLIGHT. OFPS Comment: These data have been reprocessed by OFPS. SEE Documentation. / Nominal Release Time (y,m,d,h,m,s):1992, 11, 06, 14:47:24 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 ------ ------ ----- ----- ----- ------ ------ ----- ----- ----- -------- ------- ----- ----- ------- ---- ---- ---- ---- ---- ---- 0.0 504.9 -5.9 -8.3 83.3 6.5 1.5 6.7 257.0 999.0 160.000 -6.000 999.0 999.0 5747.5 1.0 1.0 1.0 2.0 2.0 9.0 10.0 9999.0 999.0 999.0 999.0 9999.0 9999.0 999.0 999.0 999.0 9999.000 999.000 999.0 999.0 99999.0 9.0 9.0 9.0 9.0 9.0 9.0 20.0 9999.0 999.0 999.0 999.0 9999.0 9999.0 999.0 999.0 999.0 9999.000 999.000 999.0 999.0 99999.0 9.0 9.0 9.0 9.0 9.0 9.0 10.0 Usage of GTS Messages No GTS messages were available for the missing soundings. 11.0 Dataset Availability Datasets Available Online ---------------------------------------------------------------- Quality Controlled Data File in Native Resolution (available in Bufr, EBufr, and OFPS QCF (ASCII) formats) Statistics generated from the Horizontal Checks (see item 7.0 above) Derived Sounding Parameters (see item 8.0 above) Interpolated 5 mb Vertical Resolution Files (see item 9.0 above) 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 5.0 above) ---------------------------------------------------------------- 12.0 Dataset Remarks No remarks. 13.0 References Burghart, C., 1993: SUDS: The system for user-editing and display of soundings. Research Data Program, National Center for Atmospheric Research, Boulder, CO. 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. Weisman, M.L., and J.B. Klemp, 1982: The dependence of numerically simulated convective storms on vertical wind shear and buoyancy. Mon. Wea. Rev., 110, 504-520.