BAMEX Soundings Dropsonde WMI Learjet Profiles Data [JOSS]
1.0 General Description
This is one of the upper air data sets developed for the
Bow Echo and Mesoscale Convection Vortex Experiment (BAMEX).
This data set contains 438 soundings launched between 5/24/2003
and 7/06/2003, during 18 missions, from the Weather Modification Inc.
(WMI) Learjet 35. The dropsonde data was provided by the National
Center for Atmospheric Research Atmospheric Technology Divison
(NCAR/ATD).
For more information on the NCAR GPS Dropsonde System please visit
the following site:
NCAR GPS Dropsonde System
1.1 ATD Contacts and Mailing Address
Contacts: Terry Hock
hock@ucar.edu
Junhong Wang
junhong@ucar.edu
Kate Beierle
kbeierle@ucar.edu
Mailing Address: NCAR/Atmospheric Technology Division
P.O. Box 3000
1850 Table Mesa Drive
Boulder, CO 80307; USA
2.0 Detailed Data Description
2.1 Detailed Format Description
All upper air soundings were converted to University Corporation
for Atmospheric Research/Joint Office for Science Support (UCAR/JOSS)
Cross Chain LORAN Atmospheric Sounding System (CLASS) Format
(JCF). JCF 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:
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 launch site.
4 Release Location (lon,lat,alt): Position of launch site,
in format described below.
5 UTC Release Time (y,m,d,h,m,s): Time of release, in 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 label is padded to 35 characters to match the standard
header lines.
Line Label (padded to 35 char) Contents
6 Sonde Type/ID/Sensor ID/Tx Freq: Vaisala RD93 GPS Dropsonde Serial Number
YYWWDSSSS, where YY last two digits
of year, WW - week number (1-52),
D - day of the week (1-7,Monday=1), and
SSSS is the sequence number
7 System Operator/Comments: Comments recorded by operator during
flight. This line is often blank.
8 Input File: Original file from ATD.
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:
Field Format
No. Width 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 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 Range Kilometers 999.0
14 5 F5.1 Azimuth 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 Component Code (see below) 99.0
20 4 F4.1 QC for V 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 UCAR Joint Office for Science Support (UCAR/JOSS).
Any QC information from the original sounding is replaced by the
following JOSS 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")
Sample Data
The following are sample records for the BAMEX Soundings
Dropsonde WMI Learjet Profile Data in JOSS CLASS 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: Sounding
Project ID: BAMEX 2003 Class Format Dropsonde
Sounding from Lear
Release Site Type/Site ID: WMI Lear 35A , N425AS
Release Location (lon,lat,alt): 094 19.68'W, 41 50.82'N, -94.33,
41.85, 12861.0
UTC Release Time (y,m,d,h,m,s): 2003, 06, 10, 05:39:51
Sonde Type/ID/Sensor ID/Tx Freq: 031335040
System Operator/Comments: ,
Input File: D20030610_053951QC.cls
/
/
/
Nominal Release Time (y,m,d,h,m,s):2003, 06, 10, 05:39:51
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
------ ------ ----- ----- ----- ------ ------ ----- ----- ----- --------
------- ----- ----- ------- ---- ---- ---- ---- ---- ----
702.6 968.6 16.9 15.9 94.0 9999.0 9999.0 999.0 999.0 999.0 9999.000
999.000 999.0 999.0 217.1 99.0 99.0 99.0 9.0 9.0 9.0
702.1 967.9 16.9 15.9 94.0 9999.0 9999.0 999.0 999.0 -11.8 9999.000
999.000 999.0 999.0 223.0 99.0 99.0 99.0 9.0 9.0 99.0
701.6 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
701.1 966.7 16.9 15.9 93.8 9999.0 9999.0 999.0 999.0 999.0 9999.000
999.000 999.0 999.0 233.5 99.0 99.0 99.0 9.0 9.0 9.0
700.6 966.1 16.9 15.9 93.7 9999.0 9999.0 999.0 999.0 -11.2 9999.000
999.000 999.0 999.0 239.1 99.0 99.0 99.0 9.0 9.0 99.0
2.2. Data File Specifics from ATD
The files contain data calculated at half-second intervals . The
variable pressure, temperature, and relative humidity are
calibrated values from measurements made by the sonde. The dew point
is calculated from the relative humidity. The altitude value is
calculated from the hydrostatic equation using pressure, temperature,
and dew point. For the dropsondes specifically, if the radiosonde is
launched over water, the height is calculated by integrating from
the surface (sea level) upward. However, if the radisonde is launched
over land, as was the case with BAMEX, we integrate from the flight
level down. The rate of ascent is obtained from the altitude
difference between two successive time steps. The position
(lat, lon), angle and range come from the GPS and altitude data.
All wind data are computed from GPS navigation signals received from
the sonde. The raw wind values are calculated at a one half second
data rate by a commercial processing card. These raw values are
subjected to a digital filter to remove low frequency oscillations
due to the sonde pendulum motion beneath the balloon. This time record
is used in the interpolation of the pressure, temperature, and humidity data.
3.0 Quality Control
3.1 ATD Data Quality Control
The raw soundings are first run through the Atmospheric Sounding Processing
ENvironment (ASPEN), which analyzes the data, performs smoothing, and removes
suspect data points. The soundings are then visually evaluated for
outliers, or any other obvious problems. Histograms of pressure, temperature,
relative humidity, wind speed and wind direction are then created to check the
range, and number of occurances of values and are derived from data at all
levels for all soundings. Finally, time series plots of temperature, relative
humidity, and wind speed and direction are created. They are used to both
examine the consistency of soundings launched from the same flight, and to
show the variablity of soundings from different missions.
Based on the QC procedures above, a couple of small problems with some of the
soundings were identified and corrected: incorrect flight-level pressure data,
problematic temperature data near the top of the profile, and bad data at the
surface. After minor corrections, the data are fine.
3.2 JOSS Quality Control Processing
This dataset underwent am 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 JOSS can be found in Loehrer et al.
(1996) and Loehrer et al. (1998).
3.2.1 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 BAMEX 2003 Soundings Dropsonde WMI Learjet Profile Data.
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 < -99.9C or > 45C T Q
Dew Point < -99.9C or > 30C 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 < -45 m/s or > 0 m/s P, T, RH B
----------------------------------------------------------------
3.2.2 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 values. 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.
----------------------------------------------------------------
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
> 5 mb/s or < -5 mb/s P, T, RH B
Temperature < -15 C/km P, T, RH Q
< -30 C/km P, T, RH B
from surface to 250 mb:
> 100 C/km (not applied
at p < 250mb) P, T, RH Q
> 200 C/km (not applied
at p < 250mb) P, T, RH B
for pressures < 250 mb:
> 100 C/km (not applied
at p > 150mb) P, T, RH Q
> 200 C/km (not applied
at p > 150mb) P, T, RH B
Ascent Rate change of > 3 m/s
or < -3 m/s P Q
change of > 5 m/s
or < -5 m/s P B
----------------------------------------------------------------
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.