High resolution radiosonde data
|
High resolution radiosonde data |
1 Format conversion procedures
1.1 Conversion to JOSS CLASS format (all datasets except 08508, 72208, 72402, 74494, KCEJ)
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1.1.1 The raw parameters, in their native resolution, were kept without
change
1.1.2 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 level and the previous
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.
1.1.3 The U and V wind components were calculated based on the wind
speed and direction at the wind data levels
1.1.4 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
1.1.5 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.
1.2 Lajes(08508) dataset conversion to JOSS CLASS format
--------------------------------------------------------
1.2.1 Meteo-France/CNRM received the high resolution data set from INMG.
Due to the lower resolution of these data in the upper levels,
Meteo-France/CNRM included data from the TEMP (GTS) messages
within the high resolution dataset.
1.2.2 This data set was hand entered at the site (Lajes), and contained
many typographical errors. Meteo-France/CNRM and UCAR/JOSS have
corrected such errors as have been found. Any remaining
typographical errors should be minimal, but caution should still
be used.
1.2.3 As the time from launch was not available in the original files, it
was estimated with a ascension rate of 5m/s (excluding at the surface,
where it was given a missing value).
1.2.4 Meteo-France/CNRM converted the data to a high resolution JOSS
CLASS format file, without quality control flags. These JOSS
CLASS format soundings were then passed along to UCAR/JOSS for
further processing and quality control procedures as described
below.
1.2.5 The raw variable vertical resolution temperature,
relative humidity, altitude, pressure, dew point,
wind direction, and wind speed were kept without change.
1.2.6 The ascension rate was not calculated for this data set due to
the lack of time information.
1.2.7 The U and V wind components were calculated based on
the wind speed and direction at the level.
1.2.8 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.
1.2.9 The latitude and longitude position of the radiosonde
was not calculated due to the lack of time information.
1.3 Charleston(72208) and Chatham(74494) datasets conversion
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1.3.1 The raw 6 s vertical resolution time, temperature,
relative humidity, altitude, and pressure were kept without change.
1.3.2 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.
1.3.3 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.
1.3.4 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.
1.3.5 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.
1.4 Wallops(72402) dataset conversion to JOSS CLASS format
------------------------------------------------------
1.4.1 These soundings arrived at JOSS in three seperate files, one
containing ~ 1.2 second vertical resolution PTH data, a second
file containing significant level PTH data, and a third file
containing one minute vertical resolution wind data.
1.4.2 The significant level files contained the independently measured
surface data point. The second data point in the significant level
file contains the time after release. The time difference between
these two points was saved. Since the 1.2 second data file did not
have any way of finding the release point we used the pressure,
temperature and RH from the second point (in the significant level
file) to search the 1.2 second PTH file for the sonde's release
point. This can be done since the data within the significant
level files was derived from data within the 1.2 second PTH files.
The 1.2 second PTH file was searched for the point matching the
second point's (again from the sig level file) pressure,
temperature, and relative humidity. When this matching point was
found , the 1.2 second file was then searched for the datum closest
to the matching point's time minus the time difference saved
previously. We then assumed that this matching point was the
release point and this became the zero point in the final file.
All the 1.2 second vertical resolution PTH data points whose times
occurred after this release point were written to the final file.
The release point usually occurred well beyond the zero time within
the 1.2 second PTH file. In order to make the release point's time
zero, its original time was subtracted from the remaining datum's
times. This is reflected in the final file's first point having
a negative time. This point is the independent surface
observation mentioned above and was saved for this reason.
1.4.3 Altitudes for the 1.2 second vertical resolution PTH data were
derived using the hypsometric equation using the virtual temperature.
Note, many times the launch point found in the 1.2 second vertical
resolution PTH file had altitudes unequal but close to 13 meters.
However this value was kept and all altitudes were calculated using
this surface height. If the dew point was missing, the dry
bulb temp was used in place of the virtual temperature.
1.4.4 Wind and 1.2 sec resolution PTH data points having the same times
were merged into one point except for the zero time. The zero time
wind was assumed to be an independent surface observation and
therefore was assigned to the significant level file's surface point,
the very first point in the final file. The wind for the zero time
within the final file remained missing. Otherwise, the wind data was
placed by altitude and its time was set to missing. If the wind and
1.2 sec vertical resolution PTH altitudes were sufficiently close,
the points were combined, using the calculated PTH altitude. If a
wind altitude was missing, it was placed in the final file by time,
with its time then set to missing.
1.4.5 The raw pressure, temperature, relative humidity, wind direction,
and wind speed were kept without change.
1.4.6 The ascension rate was calculated for each data point (excluding
the release point and the independent surface observation where it
was given a missing value) based on the altitude and time at two
levels, the current level and the previous 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.
1.4.7 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.
1.4.8 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.
1.4.9 The missing pressures for the one-minute winds not combined with
an exisiting 1.2 second vertical resolution PTH datum were linearly
interpolated using the pressures and altitudes from the times
immediately before and after the missing pressure's time. The
following equation details the procedure:
wind pressure = p1 + (p2 - p1)*[(Walt - h1)/(h2 - h1)], under the
conditions:h2 > Walt > h1 and p2 < p1, where hn is the height of
the nth pressure surface, pn is the nth pressure, and Walt is the
altitude of the wind data. If an altitude was missing, then the
equation became the following: wind pressure = [p1 + p2]/2.
These values were only calculated to make these wind values visible
for visual quality control (see below). These values should not
be used.
1.5 R/V KNORR dataset conversion to JOSS CLASS format
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1.5.1 FASTEX Experiment
-----------------
1.5.1.1 The raw 10 s vertical resolution time, temperature,
relative humidity, altitude, pressure, dew point,
wind direction, and wind speed were kept without change.
1.5.1.2 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 10 s level and the previous 10 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.
1.5.1.4 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.
1.5.1.5 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.
1.5.1.6 The quality codes from the source agency were ignored, except in
one case. The winds within the first 120 seconds were flagged as
questionable as they were in source data. This was due to these
winds being interpolated from the surface and the 120 sec data
point due to the 240 sec smoothing interval used by the source
agency to derive wind values.
1.5.2 LabSea Experiment
-----------------
1.5.2.1 The raw 10 s vertical resolution time, temperature,
relative humidity, altitude, pressure, dew point,
wind direction, and wind speed were kept without change.
1.5.2.2 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 10 s level and the previous 10 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
or if the ascension rate value was < 1 m/s or >12m/s the
ascension rate is set to the estimated value of 5 m/s.
1.5.2.4 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.
1.5.2.5 The latitude and longitude position of the radiosonde
was calculated based on the estimated trajectory of the
radiosonde. The trajectory of the radiosonde was calculated
based on altitude, ascension rate and wind values
at the current level and the prior calculated position. If the
wind is missing at the current level, the first previous wind
value is used. If there is no non-missing previous data points,
the estimated trajectory of the radiosonde is the vertical above
the launching point.
1.5.2.6 No quality code is set except when Dew Point are given a
value of -99.9 Deg C.
2 Quality Control Procedures
2.1 JOSS Quality Control Procedures
-------------------------------
These datasets 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.
2.1.1 Automated Quality Control Procedures
2.1.1.1 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 FASTEX 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.
----------------------------------------------------------------
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 < -30 m/s or > 10 m/s P, T, RH Q
----------------------------------------------------------------
2.1.1.2 Vertical Consistency Checks
These checks were conducted on each sounding and data were
automatically flagged as appropriate. The Auto QC software
employed six-second averaging for these checks. These checks
were started at the lowest level of the sounding and
compared neighboring six-second average 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 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
----------------------------------------------------------------
2.1.2 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 .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.
3 Additional quality control processing informations or dataset remarks:
Site
--------
03005 Dataset Remarks (from OFPS checking - September 1997)
-----------------------------------------------------
The VIZ winds had occasionally significant problems. As an example
of typical problems there is the 10 February release at 0300 UTC
which had a 100 mb layer centered around 800 mb with wind speeds
over 100 m/s and rapid directional shifts.
Additional quality control processing information
-------------------------------------------------
Timestamp Comment
--------- -------
30 May,1997: problem with the wind data launch time corrected on the
following dates:
19970219 14:16 19970206 14:22 19970206 17:25
19970117 05:27 19970209 05:21 19970224 02:19
19970118 05:28 19970219 20:17
03026 Dataset Remarks (from OFPS checking - September 1997)
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These soundings were of generally good quality.
03240 Dataset Remarks (from OFPS checking - September 1997)
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These soundings were of generally good quality.
03496 Dataset Remarks (from OFPS checking - September 1997)
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These soundings were of generally good quality.
03502 Dataset Remarks (from OFPS checking - September 1997)
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These soundings were of generally good quality.
03808 Dataset Remarks (from OFPS checking - September 1997)
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These soundings were of generally good quality.
03920 Dataset Remarks (from OFPS checking - September 1997)
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These soundings were of generally good quality.
03953 Dataset Remarks (from OFPS checking - September 1997)
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These soundings were of generally good quality.
04018 Dataset Remarks (from OFPS checking - September 1997)
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These soundings were of generally good quality.
04220 Dataset Remarks (from OFPS checking - September 1997)
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These soundings were of generally good quality.
04270 Dataset Remarks (from OFPS checking - September 1997)
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These soundings were of generally good quality.
04339 Dataset Remarks (from OFPS checking - September 1997)
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These soundings were of generally good quality.
04360 Dataset Remarks (from OFPS checking - September 1997)
-----------------------------------------------------
These soundings were of generally good quality.
Additional quality control processing information
-------------------------------------------------
Timestamp Comment
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01 Dec,1997: addition of radiosoundings at 06UTC and 18UTC
06011 Dataset Remarks (from OFPS checking - September 1997)
-----------------------------------------------------
These soundings were of generally good quality.
07110 Dataset Remarks (from OFPS checking - September 1997)
-----------------------------------------------------
The pressure levels above 100 mb, and especially those above 50 mb
were significantly affected by "bouncing". That is there is a data
point with a much higher than average ascension rate followed by a
data point with a much lower than average ascension rate. The
automated check that flags this type of error is from section 6.1.2
the ascension rate change check. Over 3.2% of all data points at
Brest were affected. The average rate over all FASTEX soundings
was only 0.28%. And for Brest, of those data points above 50 mb
about 40% were flagged as either questionable or bad due to this
problem.
The Loran-C chain receiving had intermitent significant problems
during FASTEX, this led to winds of uneven quality at Brest. At
lower and middle levels (up to 300 mb) about 5% of the winds were
either flagged as bad or questionable or were missing. At levels
above 300 mb this went up to 10-20%. An example of the significant
problems that are sometimes present is found in the 5 February
sounding taken at 0600 UTC. This sounding includes many drastic
wind speed changes of 10-40 m/s as well as drastic directional shifts.
Additional quality control processing information
-------------------------------------------------
Timestamp Comment
--------- -------
29 Jul,1997: Soundings dated 19970115:05:57 and 19970215:11:19
interpolated from middle resolution data
07145 Dataset Remarks (from OFPS checking - September 1997)
-----------------------------------------------------
The pressure levels above 100 mb, and especially those above 50 mb
were significantly affected by "bouncing". That is there is a data
point with a much higher than average ascension rate followed by a
data point with a much lower than average ascension rate. The
automated check that flags this type of error is from section 6.1.2
the ascension rate change check. Over 10.1% of all data points at
Trappes were affected. The average rate over all FASTEX soundings
was only 0.28%. And for Trappes, of those data points above 50 mb
about 43% were flagged as either questionable or bad due to this
problem. There was also a higher rate of above acceptable
ascension rates (> 10m/s) at Trappes (2.11%) versus the entire
FASTEX sounding dataset (0.36%).
The Loran-C chain receiving had intermitent significant problems
during FASTEX, this led to winds of uneven quality at Trappes. At
nearly all levels about 5-10% of the winds were either flagged as
bad or questionable or were missing. An example of the significant
The winds at Trappes were also of uneven quality. At nearly all
levels about 5-10% of the winds were either flagged as bad or
questionable or were missing.
Additional quality control processing information
-------------------------------------------------
Timestamp Comment
--------- -------
29 Jul,1997: Sounding dated 19970218:17:20
interpolated from middle resolution data
28 Aug,1997: Soundings dated 19970118:14:47 and 19970119:23:25
interpolated from middle resolution data
07510 Dataset Remarks (from OFPS checking - September 1997)
-----------------------------------------------------
The pressure levels above 100 mb, and especially those above 50 mb
were significantly affected by "bouncing". That is there is a data
point with a much higher than average ascension rate followed by a
data point with a much lower than average ascension rate. The
automated check that flags this type of error is from section 6.1.2
the ascension rate change check. Over 8.0% of all data points at
Bordeaux were affected. The average rate over all FASTEX soundings
was only 0.28%. And for Bordeaux, of those data points above 50 mb
about 50% were flagged as either questionable or bad due to this
problem. There was also a higher rate of above acceptable
ascension rates (> 10m/s) at Bordeaux (2.30%) versus the entire
FASTEX sounding dataset (0.36%).
The Loran-C chain receiving had intermitent significant problems
during FASTEX, this led to winds of uneven quality at Bordeaux. At
nearly all levels about 5-15% of the winds were either flagged as
bad or questionable or were missing. An example of the significant
problems that are sometimes present is found in the 24 January
sounding taken at 0600 UTC. This sounding includes wind speed
oscillations of 20 m/s, drastic speed and direction shifts among
other problems.
08001 Dataset Remarks (from OFPS checking - September 1997)
-----------------------------------------------------
These soundings were of generally good quality.
08508 Dataset Remarks (from OFPS checking - February 1998)
-----------------------------------------------------
Typograpical Errors
-------------------
As noted above, there were many typographical errors within this
data set that were corrected by Meteo-France and UCAR/JOSS. There
may be other typographical errors that were too small to have
been detected or had no obvious correction. Caution should be
used.
Humidity Values
---------------
Data from two different data sets were used in the development of
this data set by Meteo-France, the high resolution data set
provided by INMG and the TEMP messages. These data sources used
different methods in their treatments of very large dew point
depressions.
The high resolution data set (those data points within the sounding
the relative humidity as measured.
The TEMP messages (those data points within the sounding that are
at pressure levels that are not evenly divisible by 5) set any dew
point depression greater than 30 C to 30 C (i.e. leading to an
artificially high relative humidity value relative to that which
was measured).
The effect of this is that in very dry conditions at lower levels
the data points from the TEMP message have relative humidity
values that are higher than those at the surrounding high
resolution data points. This is really noticable only when the
relative humidity drops to 1-2% at pressure levels from the
surface to about 500-600 mb. Such data have been flagged as
questionable during the UCAR/JOSS viusal quality control
processing.
Additional quality control processing information
-------------------------------------------------
Timestamp Comment
--------- -------
18 Dec,1997: correction on data for the following dates:
19970208 11:16 19970209 23:24 19970216 23:26
30 Dec,1997: addition of radiosoundings from January
30 Jan,1998: minor corrections on dew point values and on launching
dates.
08522 Dataset Remarks (from OFPS checking - September 1997)
-----------------------------------------------------
These soundings were of generally good quality.
Additional quality control processing information
-------------------------------------------------
Timestamp Comment
--------- -------
10 Jun,1997: updating of quality flags for interpolated values
08579 Dataset Remarks (from OFPS checking - September 1997)
-----------------------------------------------------
These soundings were of generally good quality.
Additional quality control processing information
-------------------------------------------------
Timestamp Comment
--------- -------
10 Jun,1997: updating of quality flags for interpolated values
71600 Dataset Remarks (from OFPS checking - September 1997)
-----------------------------------------------------
These soundings were of generally good quality.
71801 Dataset Remarks (from OFPS checking - September 1997)
-----------------------------------------------------
Many of the soundings from St. Johns had significant low level
humidity problems. The first radiosonde humidity is much lower
than the independently measured surface humidity. The subsequent
radiosonde humidity values then return to the expected levels. An
example of this type of problem can be seen in the sounding from
1 January at 0000 UTC, a small portion of which is shown below:
Time Press Temp Dewpt RH
sec mb C C %
0.0 971.2 -7.2 -10.9 75.0
3.6 968.0 -7.2 -36.0 8.0
15.0 962.2 -7.9 -18.1 43.8
30.6 950.4 -8.7 -14.3 63.8
60.0 927.8 999.0 999.0 999.0
75.0 916.3 -11.4 -13.7 83.1
The surface RH is 75%, the first radiosonde RH is only 8%, the
radiosonde RH then recovers to more expected values.
Additional quality control processing information
-------------------------------------------------
Timestamp Comment
--------- -------
03 Jul,1997: data received in the FASTEX Central Archive: pressure,
height, temperature, dewpoint depression and relative
humidity at significant levels (no high resolution data
available for meteorological parameters); 1mn height and
wind data.
data calculated in the FASTEX Central Archive: U and V
wind components, ascension rate, latitude and longitude
position of the radiosonde .
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 estimated.
71816 Dataset Remarks (from OFPS checking - September 1997)
-----------------------------------------------------
These soundings were of generally good quality.
71906 Dataset Remarks (from OFPS checking - September 1997)
-----------------------------------------------------
These soundings were of generally good quality.
72208 Dataset Remarks (from OFPS checking - September 1997)
-----------------------------------------------------
These soundings were of generally good quality.
72402 Dataset Remarks (from OFPS checking - September 1997)
-----------------------------------------------------
These soundings were of generally good quality.
74494 Dataset Remarks (from OFPS checking - September 1997)
-----------------------------------------------------
These soundings were of generally good quality.
78016 Dataset Remarks (from OFPS checking - September 1997)
-----------------------------------------------------
Several of the soundings from Bermuda had significant problems.
As an example of the most severe problem there is the sounding
from 23 January at 0000 UTC. Below is a small section of that
sounding:
Time Press Temp Dewpt RH Uwind Vwind Wspd Dir
sec mb C C % m/s m/s m/s deg
1410.0 433.9 -23.5 -50.0 7.0 8.1 -1.0 8.2 277.0
1420.0 431.0 -23.9 -49.1 8.0 8.1 -1.1 8.2 278.0
1430.0 428.0 -24.3 -49.4 8.0 8.1 -1.1 8.2 278.0
1440.0 425.0 -24.8 -49.8 8.0 8.1 -1.1 8.2 278.0
1450.0 422.2 -25.2 -50.2 8.0 8.0 -1.1 8.1 278.0
1460.0 419.5 -17.7 -35.9 19.0 16.6 -0.6 16.6 272.0
1470.0 430.6 -18.1 -36.2 19.0 16.8 -0.9 16.8 273.0
1480.0 427.8 -18.5 -36.0 20.0 16.9 -1.2 16.9 274.0
1490.0 424.8 -19.0 -36.5 20.0 17.0 -1.5 17.1 275.0
1500.0 421.8 -19.5 -36.4 21.0 17.2 -1.8 17.3 276.0
1510.0 419.0 -19.9 -36.3 22.0 17.4 -2.1 17.5 277.0
Not the dramatic change in all parameters between 1450 and 1460
seconds. All data prior to 1450 seconds is consistent with the
1450 second data, while all data after 1460 seconds is consistent
with the 1460 second data. It appears as though this sounding
was either combined with another at some point in its processing
at Bermuda, or else, less likely, had measurement problems.
Other soundings that may also have this problem include:
8 January 0600 UTC and 1800 UTC
23 January 0000 UTC and 0600 UTC
5 February 0000 UTC
25 February 1200 UTC
Additional quality control processing information
-------------------------------------------------
Timestamp Comment
--------- -------
10 Jun,1997: updating of quality flags for interpolated values
EOGW Dataset Remarks (from OFPS checking - September 1997)
-----------------------------------------------------
There are a significant amount of missing winds in these files.
Up to 400 mb about 20% of the winds are missing, starting at
300 mb that increase to 25% and the amount of missing increase
such that above 100 mb about 50% of the winds are missing.
Many files have very little or no winds. Victor Bugaev used
the Vaisala Global Positioning System (GPS) windfinding system
which was in a development period during FASTEX. FASTEX was
the first operational use of the Vaisala GPS windfinding system
and some software problems were present that led to this
missing wind problem.
Additional quality control processing information
-------------------------------------------------
Timestamp Comment
--------- -------
16 Jul,1998: Ship position corrected for the sounding
dated 19970213 05:31 longitude=-34.92 not 34.81
FNOU Dataset Remarks (from OFPS checking - September 1997)
-----------------------------------------------------
The soundings from Fort Fleur D'Eppe appeared to be of generally good
quality.
FNPH Dataset Remarks (from OFPS checking - September 1997)
-----------------------------------------------------
The soundings from Fort Desaix appeared to be of generally good
quality.
Additional quality control processing information
-------------------------------------------------
Timestamp Comment
--------- -------
25 Jul,1997: Sounding dated 19970113:11:06
interpolated from middle resolution data
25 Aug,1997: Corrections at low levels ; soundings dated:
19970207:23:06 19970219:11:15 19970221:23:12
19970222:23:02 19970224:23:19
FZVN Dataset Remarks (from OFPS checking - September 1997)
-----------------------------------------------------
The winds at this site were often missing. About 25-30% of all
data point had missing winds. Le Suroit used the Vaisala Global
Positioning System (GPS) windfinding system which was in a
development period during FASTEX. FASTEX was the first
operational use of the Vaisala GPS windfinding system and some
software problems were present that led to this missing wind
problem.
KCEJ Dataset Remarks (from OFPS checking - September 1997)
-----------------------------------------------------
The winds within 200 mb of the surface were missing about 30% of
the time.
Additional quality control processing information
-------------------------------------------------
Timestamp Comment
--------- -------
07 Jul,1997: LABSEA experiment
data received in the FASTEX Central Archive: position of
the ship at launching date (decimal degrees); pressure
(hPa), geopotential (m), temperature (C), humidity (%),
dewpoint (C), wind speed (kt) and direction (deg); data
every 2 seconds for the first 300 seconds after launch,
every 5 seconds after.
data calculated in the FASTEX Central Archive: U and V
wind components, ascension rate, latitude and longitude
position of the radiosonde.
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 estimated.
08 Aug,1997: LABSEA experiment
addition of 5 soundings on the following dates:
19970202 23:03 19970213 22:25 19970215 20:09
19970220 14:15 19970227 10:05
OXTS2 Dataset Remarks (from OFPS checking - September 1997)
-----------------------------------------------------
The soundings from Irena Arctica appeared to be of generally good
quality with the following caveats.
First, Irena Arctica was among those most affected by a problem
of "bouncing". That is there is a data point with a much higher
than average ascension rate followed by a data point with a much
lower than average ascension rate. The automated check that flags
this type of error is from section 6.1.2 the ascension rate change
check. Over 2.5% of all data points at Irena Arctica were affected.
The average rate over all FASTEX soundings was only 0.28%. There
was also a higher rate of above acceptable ascension rates (> 10m/s)
at Irena Arctica (1.06%) versus the entire FASTEX sounding dataset
(0.36%).
Second, several soundings had a low level humidity problem in which
the first radiosonde humidity is much lower than the independently
measured surface humidity. The subsequent radiosonde humidity
values then return to the expected levels. An example of this
type of problem can be seen in the sounding from 16 January at
1200 UTC, a small protion of which is shown below:
Time Press Temp Dewpt RH
sec mb C C %
------ ------ ----- ----- -----
0.0 999.5 -0.7 -2.1 90.2
10.0 995.6 -0.7 -12.3 41.1
20.0 990.2 -0.8 -6.4 65.8
30.0 984.5 -1.4 -5.8 72.0
40.0 978.0 -1.9 -5.6 75.8
The surface RH is 90%, the first radiosonde RH is only 41%, the
radiosonde RH then recovers to more expected values.
Additional quality control processing information
-------------------------------------------------
Timestamp Comment
--------- -------
5 Sep,1997: correction on latitude and longitude on the following
date: 19970212 22:59
TFTA Dataset Remarks (from OFPS checking - September 1997)
-----------------------------------------------------
The winds at this site were often missing. About 25-30% of all
data point had missing winds. Aegir used the Vaisala Global
Positioning System (GPS) windfinding system which was in a
development period during FASTEX. FASTEX was the first
operational use of the Vaisala GPS windfinding system and some
software problems were present that led to this missing wind
problem.
Additional quality control processing information
-------------------------------------------------
Timestamp Comment
--------- -------
16 Jul,1998: Ship position corrected for the sounding
dated 19970212 05:53 latitude= 45.85 not 48.85
V2EZ Dataset Remarks (from OFPS checking - September 1997)
-----------------------------------------------------
The soundings from Godafoss appeared to be of generally good
quality with the following caveat.
There were two varieties of low level humidity problems observed
with the soundings from the Godafoss.
First, several soundings beginning on 18 February had very low
independently measured surface humidities. For example, the
18 February sounding taken at 18 UTC had an independently measured
surface RH of 1.0%, while the first radiosonde RH was 60.2% and
the radiosonde RH values above that point were consistant with that
value.
Second, several soundings had a low level humidity problem in which
the first radiosonde humidity is much lower than the independently
measured surface humidity. The subsequent radiosonde humidity
values then return to the expected levels. An example of this
type of problem can be seen in the sounding from 16 February at
0000 UTC, a small protion of which is shown below:
Time Press Temp Dewpt RH
sec mb C C %
------ ------ ----- ----- -----
0.0 991.5 1.8 0.3 89.8
10.0 986.4 1.4 -12.4 35.0
20.0 980.6 0.8 -6.1 59.9
30.0 975.1 0.2 -5.8 64.0
The surface RH is 90%, the first radiosonde RH is only 35%, the
radiosonde RH then recovers to more expected values.
Additional quality control processing information
-------------------------------------------------
Timestamp Comment
--------- -------
16 Jul,1998: Ship position corrected for the soundings dated:
19970105 23:40 longitude =-67 not -60.7
19970121 23:21 latitude = 52.33 not 55.33
19970219 23:00 longitude =-46.42 not -40.42
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Updated: 2 February 1999