This is one of the upper air data sets developed for the Dynamics of the Madden-Julian Oscillation (DYNAMO) 2011-2012 project. This data set includes 365 high vertical resolution (2 second) soundings from Singapore taken by the Meteorological Service Singapore from 1 October 2011 through 31 March 2012. These data were initially processed by NCAR/EOL into the EOL Sounding Composite format and passed through a series of automated and visual checks. No data were changed during this part of the processing. The L3 version of the data had the NCAR dry bias correction applied to the Vaisala radiosondes. The Graw radiosondes had a procedure applied to make adjustments to the near-surface radiosonde data due to a change in the release procudures. See section 2.2 for more information.
Scot Loehrer
NCAR/EOL
loehrer@ucar.edu
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, and meteorological and wind data processors. 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 non-standard header lines.
| Line | Label (padded to 35 char) | Contents |
|---|---|---|
| 6 | Sonde Id/Sonde Type: | 937046/Graw DFM-97 |
| 7 | ||
| 8 | ||
| 9 | ||
| 10 | ||
| 11 | ||
| 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 DYNAMO Singapore high resolution sounding 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: Meteorological Service Singapore Radiosonde/Ascending Project ID: DYNAMO Release Site Type/Site ID: WSSS Singapore/Changi / 48698 Release Location (lon,lat,alt): 103 48.00'E, 01 20.00'N, 103.800, 1.333, 14.0 UTC Release Time (y,m,d,h,m,s): 2011, 10, 01, 00:00:00 Radiosonde Type: Vaisala RS92-SGP / / / / / Nominal Release Time (y,m,d,h,m,s):2011, 10, 01, 00:00:00 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 ------ ------ ----- ----- ----- ------ ------ ----- ----- ----- -------- ------- ----- ----- ------- ---- ---- ---- ---- ---- ---- 0.0 1008.5 27.9 25.5 87.0 -0.5 2.6 2.6 170.0 999.0 103.800 1.333 999.0 999.0 14.0 99.0 99.0 99.0 99.0 99.0 9.0 2.0 1007.3 27.8 22.8 74.0 -1.1 1.9 2.2 149.0 5.5 9999.000 999.000 999.0 999.0 25.0 99.0 99.0 99.0 99.0 99.0 99.0 4.0 1005.8 27.8 22.8 74.0 -1.3 1.6 2.0 141.0 6.5 9999.000 999.000 999.0 999.0 38.0 99.0 99.0 99.0 99.0 99.0 99.0 6.0 1004.4 27.7 22.9 75.0 -1.3 1.4 1.9 137.0 6.5 9999.000 999.000 999.0 999.0 51.0 99.0 99.0 99.0 99.0 99.0 99.0 8.0 1003.1 27.6 22.8 75.0 -1.4 1.3 1.9 134.0 5.5 9999.000 999.000 999.0 999.0 62.0 99.0 99.0 99.0 99.0 99.0 99.0 10.0 1001.9 27.5 22.9 76.0 -1.3 1.2 1.8 133.0 5.5 9999.000 999.000 999.0 999.0 73.0 99.0 99.0 99.0 99.0 99.0 99.0 12.0 1000.4 27.4 23.0 77.0 -1.3 1.2 1.8 132.0 6.5 9999.000 999.000 999.0 999.0 86.0 99.0 99.0 99.0 99.0 99.0 99.0 14.0 998.7 27.2 22.9 77.0 -1.4 1.2 1.9 131.0 7.5 9999.000 999.000 999.0 999.0 101.0 99.0 99.0 99.0 99.0 99.0 99.0 16.0 997.3 27.2 22.8 77.0 -1.5 1.3 2.0 130.0 6.5 9999.000 999.000 999.0 999.0 114.0 99.0 99.0 99.0 99.0 99.0 99.0 18.0 995.8 27.0 22.9 78.0 -1.6 1.3 2.1 129.0 6.5 9999.000 999.000 999.0 999.0 127.0 99.0 99.0 99.0 99.0 99.0 99.0 20.0 994.6 26.9 23.0 79.0 -1.7 1.4 2.2 129.0 5.5 9999.000 999.000 999.0 999.0 138.0 99.0 99.0 99.0 99.0 99.0 99.0 22.0 993.4 26.8 22.9 79.0 -1.8 1.5 2.3 130.0 5.5 9999.000 999.000 999.0 999.0 149.0 99.0 99.0 99.0 99.0 99.0 99.0 24.0 991.9 26.7 22.8 79.0 -1.9 1.6 2.5 131.0 6.5 9999.000 999.000 999.0 999.0 162.0 99.0 99.0 99.0 99.0 99.0 99.0 26.0 990.7 26.6 22.9 80.0 -1.9 1.7 2.6 132.0 5.0 9999.000 999.000 999.0 999.0 172.0 99.0 99.0 99.0 99.0 99.0 99.0 28.0 989.5 26.5 22.8 80.0 -1.9 1.9 2.7 134.0 5.5 9999.000 999.000 999.0 999.0 183.0 99.0 99.0 99.0 99.0 99.0 99.0 30.0 988.3 26.4 22.7 80.0 -1.9 2.0 2.8 137.0 5.5 9999.000 999.000 999.0 999.0 194.0 99.0 99.0 99.0 99.0 99.0 99.0 32.0 987.1 26.2 22.8 81.0 -1.9 2.2 2.9 140.0 5.5 9999.000 999.000 999.0 999.0 205.0 99.0 99.0 99.0 99.0 99.0 99.0 34.0 985.7 26.2 22.7 81.0 -1.8 2.4 3.0 143.0 6.5 9999.000 999.000 999.0 999.0 218.0 99.0 99.0 99.0 99.0 99.0 99.0 36.0 984.5 26.1 22.6 81.0 -1.8 2.5 3.1 145.0 5.5 9999.000 999.000 999.0 999.0 229.0 99.0 99.0 99.0 99.0 99.0 99.0 38.0 983.3 26.0 22.7 82.0 -1.6 2.6 3.1 148.0 5.0 9999.000 999.000 999.0 999.0 239.0 99.0 99.0 99.0 99.0 99.0 99.0 40.0 982.1 25.8 22.5 82.0 -1.6 2.7 3.1 149.0 5.5 9999.000 999.000 999.0 999.0 250.0 99.0 99.0 99.0 99.0 99.0 99.0 42.0 980.9 25.7 22.6 83.0 -1.5 2.7 3.1 150.0 5.5 9999.000 999.000 999.0 999.0 261.0 99.0 99.0 99.0 99.0 99.0 99.0 44.0 979.9 25.6 22.5 83.0 -1.5 2.7 3.1 151.0 4.5 9999.000 999.000 999.0 999.0 270.0 99.0 99.0 99.0 99.0 99.0 99.0 46.0 978.7 25.6 22.5 83.0 -1.5 2.7 3.1 151.0 5.0 9999.000 999.000 999.0 999.0 280.0 99.0 99.0 99.0 99.0 99.0 99.0 48.0 977.5 25.5 22.6 84.0 -1.5 2.6 3.0 150.0 5.5 9999.000 999.000 999.0 999.0 291.0 99.0 99.0 99.0 99.0 99.0 99.0 50.0 976.3 25.4 22.2 83.0 -1.5 2.5 2.9 149.0 5.5 9999.000 999.000 999.0 999.0 302.0 99.0 99.0 99.0 99.0 99.0 99.0
The L3 version had the following corrections applied by Colorado State University:
For the Vaisala RS92 radiosondes (prior to 21 Decemeber 2011) the RH data were corrected using the NCAR dry bias correction (Wang et al. 2013).
When the switch was made from Vaisala to Graw sonde on 21 Dec. 10Z 2011, their launching procedure also changed to launching from inside a building. This resulted in suspicious low-level (lowest 15-20 hPa or about 40 seconds after launch) T and Td data in about 90% of the sondes. In most cases, the surface data which came from a source indepedent of the sonde was correct.
To mitigate this questionable data the following procedure was delevoped. A visual editor was used to mark questionable low-level data. If surface data was good, new data was generated by linearly interpolating from the surface point to the first good data value. If surface data was questionable, the lowest three good data points were used to determine a gradient which was used to extrapolate the data down to the surface.
This procedure effectively removed the questionable low-level data.
| ID | SITE | LONG | LAT | ELEV (m) |
|---|---|---|---|---|
| WSSS Singapore/Changi | 48698 | 103.80000 | 1.33300 | 14.0 |
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 NCAR/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. NCAR/EOL conducted the following gross limit checks on the DYNAMO Singapore 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 | 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 < 2 50 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 |
Each sounding was visually examined for data quality issues. Any issues found were flagged in the data file and/or noted in Section 3.4.
Also in the GRAW data many soundings have a very dry RH layer just above the surface. These have also been flagged as questionable.
The 201201221000 sounding has bad temperature values from ~445-385mb.
The soundings at 201201242300 and 201202251000 appear to have the radiosonde sitting at the surface for a period of time after data collection has started. These data have been flagged as questionable.
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.
Wang, J., L. Zhang, A. Dai, F. Immler, M. Sommer and H. Voemel, 2013: Radiation dry bias correction of Vaisala RS92 humidity data and its impacts on historical radiosonde data. J. Atmos. Oceanic Technol., accepted.