PLOWS Sounding Composite Highest Resolution Upper-Air Data Set

1.0 General Description

This dataset contains the highest possible resolution (i.e., the 'native' resolution) upper-air sounding data in the National Center for Atmospheric Research (NCAR) Earth Observing Laboratory (EOL) Sounding Composite Format from stations in the following networks in the Profiling of Winter Storms (PLOWS) domain:

• National Center for Atmospheric Research (NCAR) Earth Observing Laboratory (EOL) Mobile Integrated Sounding System (MISS) GPS Advanced Upper-Air Sounding System (GAUS) Rawinsonde Data (2008-2009 field season),
• NCAR/EOL MISS GAUS Rawinsonde Data (2009-2010 field season),
• National Weather Service (NWS) Rawinsonde Data (2008-2009 and 2009-2010 field seasons),
• University of Missouri Rawinsonde Data (2008-2009 and 2009-2010 field seasons)
• NCAR/EOL C-130 Dropsonde Data (2009-2010 field season)

Data for the PLOWS domain (37°N to 46°N and 88°W to 99°W) are contained within this dataset and for the 2009-2010 field season soundings from additional NWS stations are available during certain PLOWS IOPs. The dataset covers the time period 1 February 2009 through 31 March 2009 and 1 November 2009 through 10 March 2010. This PLOWS Sounding Composite Highest Resolution Upper-Air Dataset contains 979 soundings from 3 platforms for the time period 1 February 2009 through 31 March 2009 and 2432 soundings from 4 platforms during 1 November 2009 through 10 March 2010. Version 2 of this data set was released in February 2017. See Section 3.3 for details on the changes.

Data from the NWS stations are typically available every 12 hours (00 and 12 UTC) with occasional special releases. The NCAR MISS data are available at variable intervals during PLOWS 2008-2009 IOP-3 (26 February) and IOP-4 (8 March) and for PLOWS 2009-2010 IOP-7 (15-17 November 2009), IOP-8 (23-25 November 2009), IOP-9 (2-3 December 2009), IOP-10 (8-9 December 2009), IOP-14 (24 January 2010), IOP-15 (29-30 January 2010), IOP-17 (4-6 February 2010), IOP-18 (8-10 February 2010), IOP-19 (14-15 February 2010), IOP-21 (22 Febraury 2010), IOP-23 (1-3 March 2010), and IOP-24 (8-9 March 2010). The University of Missouri data are available at variable intervals during PLOWS 2008-2009 IOP-1 (11-12 February), IOP-2 (18 February), and IOP-5 (28 -29 March) and for PLOWS 2009-2010 IOP-7 (15-17 November 2009), IOP-8 (23-25 November 2009), IOP-9 (2-3 December 2009), IOP-10 (8-9 December 2009), IOP-13 (16-17 January 2010), IOP-14 (24 January 2010), and IOP-21 (22 Febraury 2010). The NSF/NCAR C-130 dropsondes were deployed only for the 2009-2010 field season and are available during IOP-6 (13 November 2009), IOP-8 (23-25 November 2009), IOP-10 (8-9 December 2009), IOP-11 (14-15 December 2009) and IOP-18 (8-10 February 2010).

Complete information on the PLOWS IOPs are available from the PLOWS field catalog: http://catalog.eol.ucar.edu/plows_09-10/missions/missions.html

Section 2.1 contains a detailed description of the format of the composite dataset. See Section 3.0 below for the quality control processing performed by NCAR/EOL on this dataset. Section 4.0 contains references.

2.0 Detailed Data Description

2.1 Detailed Format Description

All upper air soundings were converted to National Center for Atmospheric Research/Earth Observing Laboratory (NCAR/EOL) Sounding Composite (ESC) format. 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.

Header Records

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:

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 nonstandard 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 nonstandard header lines.

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 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:

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 Sounding Composite Format codes:

Sample Data

The following is a sample record of a PLOWS high resolution rawinsonde data in EOL Sounding Composite 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:                         GAUS SOUNDING DATA/Ascending
Project ID:                        PLOWS_2008-2009
Release Site Type/Site ID:         IOP 3
Release Location (lon,lat,alt):    090 29.58'W, 44 01.32'N, -90.493, 44.022, 305.3
UTC Release Time (y,m,d,h,m,s):    2009, 02, 26, 19:07:08
Sonde Id/Sonde Type:               082033957/Vaisala RS92-SGP (ccGPS)
Reference Launch Data Source/Time: Campbell Scientific CR10/19:07:26.00
System Operator/Comments:          lou/lost everything at approx 675mb, No PTH
Post Processing Comments:          Aspen Version 2.8.1.8, Configuration upsonde-1s
/
/
Nominal Release Time (y,m,d,h,m,s):2009, 02, 26, 19:07:08
 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  973.7   2.4  -3.2  66.5   -2.2   -0.9   2.4  68.0 999.0  -90.493  44.022 999.0 999.0   310.9  1.0  1.0  1.0  1.0  1.0  9.0
   0.0  973.4 999.0 999.0  66.8   -2.7   -1.0   2.9  69.7   4.4  -90.493  44.022 999.0 999.0   313.8  1.0  9.0  1.0  1.0  1.0 99.0
   1.0  972.8   2.3  -3.2  66.9   -3.4   -1.1   3.6  71.9   4.8  -90.493  44.022 999.0 999.0   318.4  1.0  1.0  1.0  1.0  1.0 99.0
   2.0  972.2   2.2  -3.3  67.1   -4.0   -1.2   4.2  73.4   5.3  -90.493  44.022 999.0 999.0   323.6  1.0  1.0  1.0  1.0  1.0 99.0

2.2 Station List

The NSF/NCAR C-130 dropsondes were deployed only for the 2009-2010 field season and are available during IOP-6, 8, 10, 11 and 18.

The NCAR/EOL MISS radiosondes are available during IOP-3, 4, 7-10, 14-15, 17-19, 21, and 23-24.

The University of Missouri radiosondes are available during IOP-1, 2, 5, 7-10, 13-14 and 21.

The NWS stations outside of the core PLOWS domain are only included for specific IOP time periods:

13-15 December 2009 (IOP-11) - International Falls, MN (INL).

17-19 December 2009 (IOP-12) and 16 -17 January 2010 (IOP-13) - Birmingham, AL (BMX) and Nashville, TN (OHX).

28-30 January 2010 (IOP-15) - Little Rock, AR (LZK)

3-6 February 2010 (IOP-17) - Shreveport, LA (SHV), Jackson, MS (JAN) and Little Rock, AR (LZK)

26-27 February 2010 (IOP-22) - Little Rock, AR (LZK), Norman, OK (OUN), Dallas, TX (FWD) and Shreveport, LA (SHV)

1-3 March 2010 (IOP-23) - Norman, OK (OUN), Little Rock, AR (LZK), Dallas, TX (FWD), Charleston, SC (CHS), Peachtree City, AL (FFC)

8-9 March 2010 (IOP-24) - North Platte, NE (LBF), Rapid City, SD (UNR)

Complete information on the PLOWS IOPs are available from the PLOWS field catalog: http://catalog.eol.ucar.edu/plows_09-10/missions/missions.html

3.0 Quality Control Processing

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).

3.1 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. EOL conducted the following gross limit checks on the PLOWS sounding datasets. In the table P = pressure, T = temperature, RH = relative humidity, U = U wind component, V = V wind component, B = bad, and Q = questionable.

3.2 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 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.

3.3 Data Quality Issues

Version 2.0 of this data set was released in February 2017. In this version a dry bias in the RD94 relative humidity measurements was corrected. The dry bias was strongly temperature dependent, being considered quite small at warm temperature and more substantial at cold temperatures. More complete information on the origin, magnitude, and impact of the bias is available in an NCAR Technical Note (Voemel, et al 2016):
http://dx.doi.org/10.5065/D6XS5SGX

Complete information on the processing and data quality of each network can be found in their respective documentation files:

University of Missouri (both field seasons)

NCAR/EOL MISS (2008-2009 field season)

NCAR/EOL MISS (2009-2010 field season)

National Weather Service (both field seasons)

NCAR/EOL C-130 Dropsondes (2009-2010 field season)

4.0 References

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.

NWS, 1991: Micro-ART Observation and Rework Programs Technical Document, National Weather Service, National Oceanic and Atmospheric Administration, Washington, D.C., March 1991.

Wade, C. G., 1995: Calibration and data reduction problems affecting National Weather Service radiosonde humidity measurements. Preprints, Ninth Symposium on Meteorological Observations and Instrumentation, Charlotte, NC, Amer. Meteor. Soc., 37-42.

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.

Williams, S. F., S. M. Loehrer, and D. R. Gallant, 1998: Computation of high-resolution National Weather Service rawinsonde winds. Preprints, Tenth Symposium on Meteorological Observations and Instrumentation, Phoenix, AZ, Amer. Meteor. Soc., 387-391.