Charleston (US) FASTEX High-Resolution Sounding Dataset
-------------------------------------------------------
1.0 Site Information
Location: 80.00 Deg W Longitude
32.90 Deg N Latitude
Station Elevation: 15 m
Typical Launch Times: 00 12 UTC
(and during selected IOPs 06 and 18 UTC)
Dates Available: 1 January 1997 - 28 February 1997
(scattered missing files: see Section 8.0)
Site WMO Code: 72208
Source Agency: National Weather Service (US)
Country Code: US
`Native Vertical
Resolution': 6 seconds
Total Launches Available
in `Native Resolution': 146
2.0 Radiosonde Information
Radiosonde Type: VIZ
Windfinding System: Radiotheodolite
3.0 Parameters in Raw Dataset
Parameters Units
--------------------------------------
Time Seconds
Temperature Deg C
Relative Humidity %
Altitude Geopotential Meters
Pressure Millibars
Elevation Angle Deg
Azimuth Angle Deg
--------------------------------------
4.0 Conversion to JOSS CLASS format (ASCII text)
4.1 The raw 6 s vertical resolution time, temperature,
relative humidity, altitude, and pressure were kept without change.
4.2 The ascension rate was calculated 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 6 s level and the previous 6 s level. If the
data point for which the ascension rate was being calculated
had missing time or altitude, the ascension rate was not
calculated at that level and was flagged as missing. If the
data point prior to that for which the ascension rate was
being calculated had a missing time or altitude, then the
data point two data points prior to the present one was
used, and so on until one with non-missing time and altitude
was found. If there are no non-missing previous data points
the ascension rate is set to missing.
4.3 Dew points were calculated via the equations from Bolton (1980).
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
questionable.
4.4 In past derivation of winds using the raw 6-sec resolution
elevation and azimuth angle data containing elevation angle
oscillations occasionally led to large oscillations in wind
velocity, specifically at low elevation angles (Williams 1993).
The general approach to correct this problem was to remove the
outlier radiosonde position data before computing the wind
components. This process required fitting a ninth order polynomial
to the azimuth and elevation angle data from 360 seconds to the
end of the sounding, then comparing the calculated residuals and
observed values, and finally removing the outliers when present.
Applying some additional smoothing helped rectify the more extensive
problem occurring when low elevation angles were within 10 degrees
of the limiting angles (LA). When the elevation angle was between
(LA + 7.5) and (LA + 10), the new elevation angle was computed using
a 2 min linear fit. When the elevation angle was between (LA + 5)
and (LA + 7.5), the new elevation angle was computed using a 3 min
linear fit. When the elevation angle was less than (LA + 5), the
new elevation angle was calculated employing a 4 min linear fit.
No frequency smoothing occurred when the number of low elevation
angle observations was greater than 20% of the total number of
observations. A Finite Fourier Series analysis performed using
the elevation angle's residuals allowed removal of 90-190 second
periods and smoothing periods below 30 seconds.
Obtaining the u and v wind components entailed fitting a 2 min
second order polynomial to the position except for the beginning
and end minute (or 1.5 minutes if over 50 mb) which used a 3 min
fit. A linear fit was used when there were less than 15% of the
total number of points, not including the beginning or end of the
flight, on one side of the point under going the wind value
calculation.
4.5 The latitude and longitude position of the radiosonde
was calculated based on (Snyder, 1987). See Snyder page 159
equations 20-14, 20-15, 20-18, and 21-15.
5.0 JOSS CLASS Format (ASCII text) Description
5.1 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 dataset to dataset (For Charleston
these lines are empty). 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 (specified in
Section 1.0) 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. Again, for Charleston soundings, these lines
have been left empty.
Sample header records are provided in the sample data file in
section 5.3.
5.2 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. For the
Charleston soundings, these fields have been set to missing.
Fields 16 through 21 contain the Quality Control information
(flags) generated locally at JOSS. These flags are based on the
automatic or visual checks made. See Sections 6.0 and 7.0 for
further information.
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')
----------------------------------------------------------------------
5.3 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: NWS
Project ID: FASTEX class format 6 sec sounding
Launch Site Type/Site ID: CHS Charleston, US, 72208
Launch Location (lon,lat,alt): 080 0.00'W, 32 54.00'N, -80.00, 32.90,
15.0
GMT Launch Time (y,m,d,h,m,s): 1997, 02, 24, 17:05:00
Ascension No: 1134
/
/
/
/
/
Nominal Launch Time (y,m,d,h,m,s): 1997, 02, 24, 18:00:00
Time Press Temp Dewpt RH Uwind Vwind Wspd Dir dZ Lon
Lat Rng Ang Alt Qp Qt Qh Qu Qv Qdz
sec mb C C % m/s m/s m/s deg m/s deg
deg km deg m code code code code code code
------ ------ ----- ----- ----- ------ ------ ----- ----- ----- --------
------- ----- ----- ------- ---- ---- ---- ---- ---- ----
0.0 1032.8 15.0 -3.4 28.0 -4.7 -4.0 6.2 50.0 999.0 -80.000
32.900 999.0 999.0 15.0 2.0 2.0 2.0 1.0 1.0 99.0
6.0 1028.2 14.3 -7.9 20.7 -4.9 -3.1 5.8 58.0 6.3 -80.000
32.900 999.0 999.0 53.0 2.0 2.0 2.0 1.0 1.0 99.0
12.0 1023.7 13.6 -7.4 22.5 -4.5 -3.2 5.5 55.0 6.2 -80.001
32.900 999.0 999.0 90.0 2.0 2.0 2.0 1.0 1.0 99.0
6.0 Quality Control Procedures
This dataset underwent the JOSS QC process which consisted of
internal consistency checks and visual quality control. The
internal consistency checks included gross limit checks on all
parameters and vertical consistency checks on temperature,
pressure, and ascension rate. JOSS then visually examined each
sounding.
6.1 Automated Quality Control Procedures
6.1.1 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 Charleston FASTEX
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(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 < -80C or > 30C T Q
Dew Point < -99.9C or > 25C 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 < -10 m/s or > 10 m/s P, T, RH Q
----------------------------------------------------------------
6.1.2 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. Above 100 mb, 30 sec averages were used for the
checks. All items within the table are as previously defined.
----------------------------------------------------------------
Vertical Consistency Parameter(s) Flag
Parameter Check Flagged Applied
----------------------------------------------------------------
Time decreasing/equal None None
Altitude decreasing/equal P, T, RH Q
Pressure increasing/equal P, T, RH Q
> 1 mb/s or < -1 mb/s P, T, RH Q
> 2 mb/s or < -2 mb/s P, T, RH B
Temperature < -15 C/km P, T, RH Q
< -30 C/km P, T, RH B
from surface to 800 mb:
> 25 C/km (not applied
at p < 275mb) P, T, RH Q
> 40 C/km (not applied
at p < 275mb) P, T, RH B
for pressures < 800 mb:
> 5 C/km (not applied
at p < 275mb) P, T, RH Q
> 30 C/km (not applied
at p < 275mb) 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
----------------------------------------------------------------
6.2 Visual Quality Control Procedures
Each sounding was then visually examined for problems that
were not able to be captured via the automated checks
described in item 6.1 above. These problems typically
included oddities in the dew point and wind profiles. These
two parameters can be highly variable, and hence, the
automated 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.
7.0 Dataset Availability
Datasets Available Online
----------------------------------------------------------------
Quality Controlled Data File in Native Resolution
(available in Bufr, EBufr, and OFPS QCF (ASCII) formats)
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 6.0 above)
----------------------------------------------------------------
8.0 Dataset Remarks
8.1 Missing Files
The following expected soundings were missing:
2 January 1200
6 January 1200
14 January 1200
18 January 0000 1200
19 January 0000 1200
20 January 0000 1200
21 January 0000 1200
22 January 0000 1200
23 January 0000 1200
27 January 0000
8.2 Significant Problems
These soundings were of generally good quality.
9.0 FASTEX Data Use
According to the FASTEX data policy, the use of these data is unrestricted
for research and educational purposes.
Proper acknowledgements should be given in publications that utilize this
data to specific scientists and institutions that made the collection of
data possible.
Where appropriate, all authors considering publication of FASTEX related
research results should offer co-authorship to investigators that had a
primary role in the collection of data utilized in the study.
10.0 Upper-Air Sounding Data Providers
Country Name Address
-------- ---------------- --------------------------------------------------
Canada Dave Steenbergen AES 4905 Dufferin Street Downsview Ontario M3H 5T4
Denmark Klaus Hedegaard DMI Lyngbyveg 100 DK-2100
France Michel Rochas Meteo-France Instrumentation Dept.
7,rue Teisserenc de Bort BP202 78195 Trappes
Iceland Flosi Sigurosson Meteorological Office Technical and Obs. Dept
Bustadavegur 9 IS-140 Reykjavik
Ireland Liam Burke Meteorological Office
Instrumentation and Environmental Division
Glasnevin Hill Dublin 9
Portugal Renato Carvalho INMG Rua C. Aeroporto de Lisboa 1700 Lisboa
Spain Cesar Belandia INM Servicio de Observacion,
Camino de la Moreras s/n
Ciudad Universitaria 28071 MADRID
United John Stancombe UK Met Office Upper Air Network
Kingdom London Road Bracknell, Berkshire RG12 2SZ
USA Robert Thomas NOAA W/OSO14 SSMC/2 1325 East West Highway
Silver Spring,MD 20910
FASTEX Principal Investigators and Data Providers for the FASTEX Ships
Ships Name Address
-------- ------------------ --------------------------------------
AEGIR Alain Joly Meteo-France/CNRM 42 Av.G.Coriolis
31057 Toulouse Cedex France
(alain.joly@meteo.fr)
V.BUGAEV Pierre Bessemoulin Meteo-France/CNRM 42 Av.G.Coriolis
31057 Toulouse Cedex France
(pierre.bessemoulin@meteo.fr)
KNORR Ola Persson NOAA/ETL CIRES, Univ. of Colorado
Campus Box 216 Boulder, CO 80309 USA
(pogp@etl.noaa.gov)
SUROIT Alain Joly Meteo-France/CNRM 42 Av.G.Coriolis
31057 Toulouse Cedex France
(alain.joly@meteo.fr)
The FASTEX enhanced radiosounding program was supported by AES (Canada),
CNRS/INSU (France), DMI (Denmark), the Icelandic Met. Office, Meteo-France,
Met Eireann (Ireland), NCAR/MMM (USA), the UK Met. Office, WMO/COSNA.
The FASTEX ships were supported by CNRS/INSU (France), The European
Commission, IFREMER (France), Meteo-France, NOAA (USA), NSF (USA).
11.0 References
Bolton, D., 1980: The Computation of Equivalent Potential
Temperature. Mon. Wea. Rev., 108, 171-180.
Snyder, J. P., 1987: Map Projections - A Working Manual. United States
Geological Survey Professional Paper 1395, 383 pp.
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.