Co-Principal Investigator: Dr Simon Vosper Manager, Orography Group Met Office Fitzroy Road Exeter EX1 3PB UK Tel: +44 1392 884584 Fax: +44 1392 885681 E-mail: simon.vosper@metoffice.gov.uk Co-Principal Investigator: Mr Philip Brown Manager, Cloud Physics Research Met Office Fitzroy Road Exeter EX1 3PB UK Tel: +44 1392 886740 Fax: +44 1392 885681 E-mail: phil.brown@metoffice.gov.uk Co-Principal Investigator Prof. Stephen Mobbs Director, NCAS School of Earth & Environment University of Leeds LS2 9JT UK Tel: +44 113 3435158 Fax: +44 113 3436716 E-mail: stephen@env.leeds.ac.uk
This is one of the upper air data sets developed for the Terrain-induced Rotor Experiment (T-REX). It includes 72 high vertical resolution (0.5 second) dropsondes from the UK FAAM BAE-146 aircraft. Soundings were released from 17 Mar to 8 Apr 2006.
All upper air soundings were converted to National Center for Atmospheric Research/Earth Observing Laboratory (NCAR/EOL) Sounding Composite Format (ESC). ESC 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.
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 the release site. |
| 4 | Release Location (lon,lat,alt): | Position of release site in the format described below. |
| 5 | UTC Release Time (y,m,d,h,m,s): | Time of release, in the 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. Records for this dataset include the following three non-standard header lines.
| Line | Label (padded to 35 char) | Contents |
|---|---|---|
| 6 | Radiosonde Serial Number: | Sounding identification number |
| 7 | Wind Finding Methodology: | Loran-C |
| 12 | Nominal Release Time (y,m,d,h,m,s): | Nominal time of release, in the format: yyyy, mm, dd, hh:mm:ss |
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 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 No. | Width | Format | 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 | Ascent 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 | Elevation Angle | Degrees | 999.0 |
| 14 | 5 | F5.1 | Azimuth Angle | 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 Wind Component | Code (see below) | 99.0 |
| 20 | 4 | F4.1 | QC for V Wind 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 NCAR Earth Observing Laboratory (NCAR/EOL). Any QC information from the original sounding is replaced by the following EOL 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") |
The following is a sample record of BAE-146 T-REX high resolution dropsonde data in ESC 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: B176/Bae146-301, G-LUXE Dropsonde/Descending Project ID: T-REX Release Site Type/Site ID: Bae146-301, G-LUXE B176 Release Location (lon,lat,alt): 118 14.90'W, 36 46.82'N, -118.248, 36.780, 8545.0 UTC Release Time (y,m,d,h,m,s): 2006, 03, 17, 18:08:49 Sonde Id: 024415369 / / / / / Nominal Release Time (y,m,d,h,m,s): 2006, 03, 17, 18:08:49 Time Press Temp Dewpt RH Ucmp Vcmp spd dir Wcmp Lon Lat Ele Azi Alt Qp Qt Qrh 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 ------ ------ ----- ----- ----- ------ ------ ----- ----- ----- -------- ------- ----- ----- ------- ---- ---- ---- ---- ---- ---- -1.0 328.8 -48.5 -50.4 81.4 19.4 22.7 29.9 220.5 999.0 -118.248 36.780 999.0 999.0 8545.0 9.0 99.0 99.0 99.0 99.0 9.0 0.4 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 0.9 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 1.4 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 1.9 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 2.4 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 2.9 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
| ID | SITE | STATE | LONG | LAT | ELEV (m) |
|---|---|---|---|---|---|
| G-LUXE | BAE-146 | CA | -999.000 | -99.000 | -9999.0 |
This data set underwent two sets of QC procedures. The raw "D" data files were passed through the Atmospheric Sounding Processing ENvironment (ASPEN) software, which performs smoothing and removes bad data points. Note that bad surface measurements, collected after the dropsondes have hit the ground, have NOT been removed from this dataset.
Additionally, NCAR/EOL conducted the following QC procedures:
This dataset underwent an 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 EOL can be found in Loehrer et al. (1996) and Loehrer et al. (1998).
These checks were conducted on each sounding and data were automatically flagged as appropriate. Only the data point under examination was flagged. EOL conducted the following gross limit checks on the T-REX BAE-146 dropsoude 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 | Gross Limit Check | Parameter(s) Flagged | Flag Applied |
|---|---|---|---|
| Pressure | < 0 mb or > 1050 mb | P | B |
| Altitude | < 0 m or > 40000 m | P, T, RH | Q |
| Temperature | < -90 °C or > 45 °C | T | T |
| Dew Point | < -99.9 °C or > 33 °C > Temperature |
RH T, RH | Q Q |
| Relative Humidity | < 0% or > 100% | RH | B |
| Wind Speed | < 0 m/s or > 100 m/s > 150 m/s |
U, V U, V | Q B |
| U Wind Component | < 0 m/s or > 100 m/s > 150 m/s |
U U | Q B |
| V Wind Component | < 0 m/s or > 100 m/s > 150 m/s |
V V | Q B |
| Wind Direction | < 0° or > 360° | U, V | B |
| Ascent Rate | < -10 m/s or > 10 m/s | P, T, RH | Q |
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 2-sec data points (except at pressures less than 100 mb where 30-sec average values were used. 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.
| Parameter | Vertical Consitency Check | Parameter(s) Flagged | Flag Applied |
|---|---|---|---|
| Time | decreasing / equal | None | None |
| Altitude | decreasing / equal | P, T, RH | Q |
| Pressure | increasing / equal > 1 mb/s or < -1 mb/s > 2 mb/s or < -2 mb/s |
P, T, RH P, T, RH P, T, RH | Q Q B |
| Temperature | < -15 °C/km < -30 °C/km > 50 °C/km (not applied at p < 250 mb) >100 °C/km (not applied at p < 250 mb) |
P, T, RH P, T, RH P, T, RH P, T, RH |
Q B Q B |
| Ascent Rate | change of > 3 m/s or & lt; -3 m/s change of > 5 m/s or < -5 m/s |
P P | Q B |
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.