Meteorology Data
from the
Marginal Ice Zone Experiments
(MIZEX-83, MIZEX-84 and MIZEX-87)
and the
Coordinated Eastern Arctic Experiment (CEAREX)
1. Introduction
1.1 Documentation structure
1. This introduction
2. Description of Data File Format on CD-ROM
2.1 Surface Data Files
2.2 Rawinsonde Profile Data
3. MIZEX-83
3.1 Overview of MIZEX-83 Meteorology
3.2 Instrumentation and Data Accuracy - POLARBJORN
4. MIZEX-84
4.1 Overview of MIZEX-84 Meteorology
4.2 Instrumentation and Data Accuracy - POLAR QUEEN
4.3 Instrumentation and Data Accuracy - HAAKON MOSBY
4.4 Instrumentation and Data Accuracy - POLARSTERN
4.5 Instrumentation and Data Accuracy - VALDIVIA
5. MIZEX-87
5.1 Overview of MIZEX-87 Meteorology
5.2 Instrumentation and Data Accuracy - POLAR CIRCLE
5.3 Instrumentation and Data Accuracy - HAAKON MOSBY
5.4 Instrumentation and Data Accuracy - VALDIVIA
6. CEAREX
6.1 Overview of CEAREX Meteorology
6.2 Instrumentation and Data Accuracy - POLARBJORN
6.3 Instrumentation and Data Accuracy - HAAKON MOSBY
6.4 Instrumentation and Data Accuracy - "O" Camp
6.5 Instrumentation and Data Accuracy - "A" Camp
7. Acknowledgments
8. References
9. Contact Information
1.2 Meteorology Documentation Overview
The data described here represent basic meteorological parameters
obtained during the Marginal Ice Zone Experiments in 1983, 1984, 1987
(MIZEX-83,84,87) and the Coordinated Eastern Arctic Experiment (CEAREX), in
September 1988 - May 1989. These were multi-national, interdisciplinary
projects which took place during various seasons in the seas around the
Svalbard archipelago.
Data files on this CD-ROM contain two types of meteorological data:
near-surface (also called surface) time series of wind, pressure, temperature,
and humidity; and rawinsonde (also called upper-air or sounding) profiles of
the same parameters. The format of these files is described in section 2.
This documentation is organized by field program. Each section
begins with an overview of the field operations that are pertinent to the
meteorological data. Following this, instrumentation and data accuracy are
described for each platform. The accuracies represent 95% confidence
intervals based on manufacturer's claims, field experience, and knowledge
of instrument location. In general, the sensitivity of the instruments was
at least one order of magnitude greater than the accuracy. Although
considerable effort has been made to remove erroneous data, it is likely
that a few bad data points remain.
Platform movement was vector subtracted from the measured wind
velocity (relative wind) to give the true wind speed and direction. The
velocities of the ship platforms were determined from bridge heading and
speed instruments.
Additional information and graphical plots of the data are contained
in hard-copy meteorological atlases (Lindsay, 1984; Lindsay, 1985; Lindsay,
1986; Guest and Davidson, 1988; Lackmann et al., 1989; Guest and Davidson,
1989; Frederickson, which are available upon request. See section 8 for the
complete citations. Information not presented here but contained in the atlases
includes maps of sea level pressure analyses, maps of platform and ice edge positions,
and radiation information in some cases.
All times in the data set and documentation are Universal Time
Convention, UTC.
Important Note: It was recently discovered that the humidity
measurements from the Coastal Climate WeatherPak meteorological stations
are highly suspect during cold conditions. Therefore, consider all the
humidity values from the MIZEX-87 and CEAREX surface data files to be
suspect when the air temperature is below -10 degrees C. Contact Peter
Guest (address in section 9) for details. The upper-air humidities are
not affected.
2. Description of Data File Format on CD ROM
The METEOR directory on this CD-ROM contains subdirectories for the
two types of data files, METEOR\SURFACE (12 surface data sets), and
METEOR\UPPER (10 upper-air sounding data sets). Files in the METEOR\
SURFACE subdirectory are ASCII coded 80 character records. Files in the
METEOR\UPPER subdirectory are ASCII coded 81 character records. The final
character in each record is a carriage-return. The variables within each
record are separated by at least one space.
2.1. Surface Data Files
These files contain time series of surface wind speed, wind direction,
air temperature, relative humidity and pressure values.
Filename
MIZ83PB.SFC : MIZEX83 -POLARBJORN. (5,796 RECORDS)
MIZ84HM.SFC : MIZEX84 HAAKON MOSBY. (1,641 RECORDS)
MIZ84PQ.SFC : MIZEX84- POLAR QUEEN. (6,311 RECORDS)
MIZ84PS.SFC : MIZEX84- POLARSTERN (3,599 RECORDS)
MIZ84VL.SFC : MIZEX84- VALDIVIA. (168 RECORDS)
MIZ87HM.SFC : MIZEX87- HAAKON MOSBY. (2,732 RECORDS)
MIZ87PC.SFC : MIZEX87- POLAR CIRCLE. (2,759 RECORDS)
MIZ87VL.SFC : MIZEX87- VALDIVIA. (105 RECORDS)
CRXACMP.SFC : CEAREX - A CAMP. (2,689 RECORDS)
CRXHM.SFC : CEAREX - HAAKON MOSBY. (3,431 RECORDS)
CRXOCMP.SFC : CEAREX - O CAMP. (3,580 RECORDS)
CRXPB.SFC : CEAREX - POLARBJORN. (34,913 RECORDS)
Every surface data record has the same format. The time on each
record represents the start of a ten-minute averaging period (except VALDIVIA,
see section 4.5 and section 5.4 of this documentation file). Missing data
have the value -99.0 for surface data.
The following FORTRAN program will read any of the surface data files:
INTEGER YEAR,MONTH,DAY,HOUR,MINUTE
1 READ(7,10,END=99)YEAR,MONTH,DAY,HOUR,MINUTE,UTR,WDT,TA,RH,PR
10 FORMAT(5(1X,I2),5(1X,E11.4)
GOTO 1
99 STOP
END
VARIABLE DEFINITIONS:
1. YEAR - Universal Time Convention (UTC)
2. MONTH -
3. DAY -
4. HOUR -
5. MINUTE -
6. UTR - TRUE WIND SPEED (m/s)
7. WDT - TRUE WIND DIRECTION (Degrees Azimuthal)
8. TA - AIR TEMPERATURE (C)
9. RH - RELATIVE HUMIDITY (%)
10. PR - SURFACE PRESSURE (mb)
2.2. Rawinsonde Profile Data
These files contain the rawinsonde profile data. Listed below are
the number of profiles and total records in each file.
Filename # Soundings # Records
MIZ84HM.AIR : MIZEX84 - HAAKON MOSBY 134 42069
MIZ84PQ.AIR : MIZEX84 - POLAR QUEEN 99 38208
MIZ84PS.AIR : MIZEX84 - POLARSTERN 217 73109
MIZ84VL.AIR : MIZEX84 - VALDIVIA 107 43916
MIZ87HM.AIR : MIZEX87 - HAAKON MOSBY 60 19085
MIZ87PC.AIR : MIZEX87 - POLAR CIRCLE 67 16398
MIZ87VL.AIR : MIZEX87 - VALDIVIA 53 13786
CRXHM.AIR : CEAREX - HAAKON MOSBY 93 27061
CRXOCMP.AIR : CEAREX - "O" CAMP 66 18797
CRXPB.AIR : CEAREX - POLARBJORN 467 128881
The rawinsonde profile data files contain two types of records: A
single header record at the beginning of each sounding, followed by several
data records with the profile information collected as the balloon goes up.
The header record contains:
1. LOC Platform label , i.e. MIZEX84HM, CEAREXPB etc.
2. XLAT Latitude (Degrees North)
3. XLON Longitude (Degrees East are positive, Degrees West are
negative)
4. IDATE Date (YYMMDD; i.e. Year, Month of Year, Day of Month)
5. ITIME Time at start of sounding (HHMM); i.e. Hour, Minute
6. IMAX Number of records in the sounding
The profile data records contain:
1. RCOUNT Record counter for sounding = 1.0 to IMAX
2. TA Air temperature (Degrees C)
3. TD Dewpoint temperature (Degrees C)
4. RH Relative humidity (%)
5. PR Pressure (mb)
6. WD Wind direction (azimuthal)
7. WS Wind speed (m/s)
8. Z Height (m)
If one of the above variables has a value of -999.0, then the value of
that quantity was not available or was invalid.
The following FORTRAN program will read any of the upper-air files.
CHARACTER*9 LOC
** READ HEADER **
5 READ(8,20,END=400) LOC,XLAT,XLON,IDATE,ITIME,IMAX
20 FORMAT(A9,2F10.4,3I10)
** READ THE DATA **
DO 200 I=1,IMAX
READ(8,30) RCOUNT,TA,TD,RH,PR,WD,WS,Z
30 FORMAT(8(F10.3))
200 CONTINUE
GO TO 5
400 STOP
END
3. MIZEX-83
3.1 Overview of MIZEX-83 Meteorology
The 1983 Marginal Ice Zone Experiment occurred in the East Greenland
Sea marginal ice zone (MIZ) during the summer. The data files presented
here contain values of surface meteorological parameters from the POLARBJORN,
an ice-strengthened vessel. Data collection began when the ship left the
port of Tromso at 1800 UTC 14 July 1983. The marginal ice zone (MIZ) was
entered at 600 UTC 18 July. The ship operated within the MIZ until 300
UTC 30 July with the exception of the following two breaks. From 1200 UTC
19 June to 2100 UTC 24 June the ship went to New Alesund, then to another
fjord in northern Svalbard and finally to and from Longyearbyen for
helicopter repairs. From 1700 UTC 11 July to 2000 UTC 12 July the ship
travelled to and from Longyearbyen for personnel rotation.
From 1200 UTC 27 June to 1730 UTC 8 July the POLARBJORN remained
moored to the same large floe. After 13 July the ship made stops at six
ice floes for periods of several hours. The rest of the time the ship was
usually in motion or undertaking oceanographic CTD measurements.
3.2 Instrumentation and Data Accuracy - MIZEX-83 POLARBJORN
3.2.1 Surface Measurements - POLARBJORN
The data on this CD-ROM represent averages from consecutive ten-minute
periods. The instruments were located on a bow mast, 16 meters above sea
level. The relative wind speed and direction were measured with a cup
anemometer and a vane. Temperature was obtained from an aspirated,
radiation-shielded, platinum-resistance thermometer (PRT). Humidity was
obtained from a cooled-mirror hygrometer. Pressure was not measured.
The temperature was accurate to within 0.5 degrees C and the humidity
to within 3% relative humidity. Wind speed and direction were usually
accurate to 0.3 m/s and 10 degrees respectively. There were some brief
periods when the wind measurements were less accurate due to ship-induced
air flow distortion.
3.2.2 Upper-Air Measurements - POLARBJORN
Rawinsonde measurements were obtained and summarized in "Radiosonde
Observations from the POLARBJORN, MIZEX 83" (Lindsay, R.W., 1984, Polar
Science Center, University of Washington, Technical Report, 280 pp.) They
are not contained on this CD-ROM. Inquire at NSIDC for current
availability of these data.
4. MIZEX-84
4.1 Overview of MIZEX-84 Meteorology
The 1984 Marginal Ice Zone Experiment (MIZEX-84) field program took
place in the East Greenland Sea during the summer of 1984. The MIZEX-84
meteorological program was much more extensive than MIZEX-83. This CD-ROM
contains surface and upper-air data from four ships: POLAR QUEEN, HAAKON
MOSBY, POLARSTERN and VALDIVIA. Identical Vaisala Upper Air Sounding
systems on all four ships measured upper-air parameters several times a
day.
The field program commenced on 3 June when the ice-strengthened POLAR
QUEEN left port, and was completed on 21 July. The POLAR QUEEN was usually
within the ice pack tens of kilometers from the edge. The normal-hulled
HAAKON MOSBY generally remained a few kilometers seaward of the ice edge.
The normal-hulled VALDIVIA operated in the open ocean, usually tens of
kilometers from the edge. The ice-breaker POLARSTERN operated deep within
the pack ice, along the ice edge and in the open ocean.
From 9 July to 13 July there was an intensive meteorological
measurement period when rawinsondes were launched every 3 hours from each
ship. The ships remained in the same position to form a diamond-shaped
pattern across the ice edge during this period.
4.2 Instrumentation and Data Accuracy - MIZEX 84 POLAR QUEEN
4.2.1 Surface Measurements - POLAR QUEEN
During most of MIZEX-84, the POLAR QUEEN was moored to a large ice
floe. Near-surface wind speed and air temperature were measured at four
levels from a 6.7 meter profile mast located on the floe 60 meters from the
ship. The profile enabled the wind speed to be measured with an accuracy
of 0.1 m/s. Temperature was accurate to 0.1 degree C.
When the profile mast was not deployed, during transit periods, or
when the profile mast had an upwind obstruction, the wind and temperature
was measured at 16 meters elevation from a bow mast on the ship. During
these times, the accuracies for wind speed and temperature were estimated
to be 0.3 m/s and 0.5 degree C. In all cases, the wind speed was adjusted to
the 10 meter value using standard flux-profile relationships. Both the ice
tower and bow mast locations had cup anemometers and radiation-shielded
aspirated platinum-resistance thermometers.
Wind direction was measured with a vane on the bow mast with an
accuracy of 5 degrees. The wind vane was not operational before 11 June,
therefore wind direction and wind speed, when the ship was moving, were not
available. Humidity was measured with a cooled-mirror hygrometer on the bow
mast and was accurate to 3% relative humidity. Pressure was measured in
the ship's laboratory with an accuracy of 2 mb. All values are ten-minute
averages.
A data set described in section II.B. of "MIZEX 84 Integrated Surface
Meteorological Data Set and Meteorological Atlas, 2nd edition" (Lindsay,
R.W., 1985, Polar Science Center, University of Washington, Technical
Report, 240 pp.), and available on 9-track tape from NSIDC, contains extra
variables that flag suspect values of wind speed, wind direction,
temperature and humidity. A future CD-ROM may include the data on this
tape; inquire at NSIDC for availability.
4.2.2 Upper-Air Measurements - POLAR QUEEN
Rawinsondes were launched from the ship at least twice a day under the
direction of R. Lindsay from the Polar Science Center, using a Vaisala Upper
Air Sounding system. The rawinsondes and initial processing of the data were
provided by the Alfred Wegener Institute for Polar Research (AWI) under the
direction of E. Augstein and M. Gube-Lenhardt.
The accuracy of the temperature and dewpoint temperature was 0.2
degree C and 1.0 degree C respectively, while height was accurate to 30 m.
Vector wind was accurate to 2.0 m/s. However, the reader should be
cautioned that rawinsonde measurements are instantaneous and do not
necessarily represent average conditions, particularly if strong secondary
circulations are present.
4.3 Instrumentation and Data Accuracy - MIZEX 84 HAAKON MOSBY
4.3.1 Surface Measurements
The surface data from the HAAKON MOSBY were obtained using instruments
similar to those on the POLAR QUEEN. The wind, air temperature and humidity
probes were mounted on a platform extending forward of the HAAKON MOSBY's
main mast at a height of 15 meters above sea level. Pressure was measured
in the ship's laboratory. The accuracies were: wind speed, 0.3 m/s; wind
direction, 10 degrees; air temperature, 0.5 degree C; relative humidity, 3%;
pressure, 2 mb. All observations were averaged over 10-minute intervals.
The accuracy of the wind measurements was worse when the winds were directly
from the stern.
4.3.2 Upper-Air Measurements - HAAKON MOSBY
Rawinsondes were launched four times a day or more under the direction
of K. Davidson. The processing of the data and the estimated accuracies
were identical to those for the POLAR QUEEN.
4.4 Instrumentation and Data Accuracy - MIZEX 84 POLARSTERN
4.4.1 Surface Measurements - POLARSTERN
The data were supplied by M. Gube-Lenhardt. The ship had two
anemometers, wind vanes, and temperature sensors. The set of sensors from
the side of the ship from which the wind was blowing was used. If the two
wind vanes could not agree on which side that was, the side with the higher
wind speed was used. The humidity was calculated from an Li-Cl sensor.
The values represent ten-minute averages. The accuracies are similar to
those quoted above for the HAAKON MOSBY data set.
4.4.2 Upper-Air Measurements - POLARSTERN
The rawinsondes were usually launched every three hours by personnel
from Alfred Wegener Institute for Polar Research. The processing of the
data and the estimated accuracies were identical to the POLAR QUEEN data
set.
4.5 Instrumentation and Data Accuracy - MIZEX 84 VALDIVIA
4.5.1 Surface Measurements - VALDIVIA
The data were supplied by M. Gube-Lenhardt. The data were based on
manually-recorded observations of the permanent ship instruments. The
observations were usually made every three hours and are based on averages
over a few seconds. Sometimes the wind speed was estimated from sea state.
Pressure was obtained from a barometer on the bridge. Humidity was not
measured. The accuracies were: wind speed, 2.0 m/s; wind direction,
15 degrees; air temperature, 1.0 degree C; pressure, 2 mb.
4.5.2 Upper-Air Measurements - VALDIVIA
The rawinsondes were usually launched every six hours. The processing
of the data and the estimated accuracies were identical to the POLAR QUEEN
data set.
5. MIZEX-87
5.1 Overview of MIZEX-87
The 1987 Marginal Ice Zone Experiment (MIZEX-87) was the third and
final of the MIZEX experiments. The field program occurred 19 March to 9
April in the Greenland Sea and 10 April to 11 April in the Barents Sea near
Bear Island. Surface and upper-air data were obtained from three ships:
POLAR CIRCLE, HAAKON MOSBY and VALDIVIA.
The ice-strengthened POLAR CIRCLE was usually within the ice a few
kilometers from the ice edge. The HAAKON MOSBY operated just seaward of
the ice edge. The VALDIVIA operated in the open ocean near the ice edge to
tens of kilometers from the edge.
5.2 Instrumentation and Data Accuracy - MIZEX 87 POLAR CIRCLE
5.2.1 Surface Measurements - POLAR CIRCLE
The POLAR CIRCLE collected data from 22 March through 11 April. A
Coastal Climate WeatherPak meteorological station was located on a platform
extending forward of the POLAR CIRCLE's bow mast at a height of 16 meters
above sea level. This instrument measured wind speed and direction,
temperature, and relative humidity. There was a bug in the WeatherPak
software in the wind speed calculation when the wind speed was greater than
9 m/s. During these periods, wind speed was measured from sonic
anemometers at the same location. There was excellent agreement (within
0.3 m/s) between these sensors at lower wind speeds; therefore reported
speeds should be accurate to at least this amount. The errors associated
with distortion of airflow by the ship were believed to be less than 5%
because the anemometer locations were well away from blocking structures.
An exception was when the wind was directly from the stern, when errors may
have been as great as 20%. The temperature was accurate to 1.0 degree C and
the relative humidity to within 5%.
Important Note: It was recently discovered that the humidity
measurements from the Coastal Climate WeatherPak meteorological stations
are highly suspect during cold conditions. Therefore, consider all the
humidity values in this file to be suspect when the air temperature is
below -10 degrees C. Contact Peter Guest (address in section 9) for
details. The upper-air humidities are not affected.
All the wind speed and direction values on this CD-ROM for all the
ships were corrected for ship motion based on the ship's speed and
heading. On the POLAR CIRCLE the ship's heading was obtained from a
compass on the WeatherPak and was routinely checked against the ship's
gyroscope. Unfortunately, the ship caused extreme magnetic distortion
for certain headings so that there were occasionally considerable errors
in the true wind directions between the times when the gyroscope heading
was recorded. When the POLAR CIRCLE was near the HAAKON MOSBY, the wind
direction from the latter should be used. Most of the time the wind
directions from the POLAR CIRCLE were accurate to within 20 degrees. This
problem did not affect the true wind speed calculations. The data were
averaged over ten-minute periods.
5.2.2 Upper-Air Measurements - POLAR CIRCLE
Vertical profiles of temperature, humidity and winds were obtained
using a rawinsonde system manufactured by the VIZ Corporation nominally
every six hours. The vector winds were determined from an Omega
navigation system on the rawinsondes and were usually accurate to 1.0 m/s.
[Omega is a world-wide radio navigation system providing navigational
parameters by phase comparison of very-low-frequency (10-14 KHz),
continuous-wave radio signals. (McGraw-Hill Dictionary of Scientific and
Technical Terms, 2nd edition, 1978.)] In regions of strong vertical shear,
errors may increase to 2.0 m/s. The temperature and dewpoint temperature
were accurate to 0.2 degree C and 1.0 degree C respectively, while the
heights were accurate to 30 meters. Note that rawinsonde measurements are
instantaneous and do not necessarily represent the average conditions,
particularly when strong secondary circulations are present.
5.3 Instrumentation and Data Accuracy - MIZEX 87 HAAKON MOSBY
5.3.1 Surface Measurements - HAAKON MOSBY
The HAAKON MOSBY had a Coastal Climate WeatherPak meteorological
station at 18 meters elevation with the same instruments and similar
accuracies as the POLAR CIRCLE for all parameters except wind direction.
At wind speeds above 11 m/s a miniature cup anemometer was used to measure
wind speed since the WeatherPak software had a bug in the calculation of
these wind speeds. Unlike the POLAR CIRCLE, there was no magnetic
distortion of the compass; therefore wind directions were usually accurate
to 5 degrees. During a few periods when air flow was from the stern of
the ship, flow distortion may have caused 20% errors in wind speed and
direction. Ten-minute averages were recorded.
Important Note: It was recently discovered that the humidity
measurements from the Coastal Climate WeatherPak meteorological stations
are highly suspect during cold conditions. Therefore, consider all the
humidity values in this file to be suspect when the air temperature is
below -10 degrees C. Contact Peter Guest (address in section 9) for
details. The upper-air humidities are not affected.
5.3.2 Upper-Air Measurements - HAAKON MOSBY
The rawinsondes launched from the HAAKON MOSBY were manufactured by
the Vaisala Corporation using a system developed by R. Helvey of the
Pacific Missile Test Center. The rawinsondes were usually launched every
six hours. The temperature data obtained from these rawinsondes have an
accuracy of 0.2 degree C and the dewpoint temperatures are accurate to
within 1.5 degrees C. Wind data were obtained using an Omega navigation
tracking system on each rawinsonde. The vector wind speeds were usually
accurate to 2 m/s. Winds in the lower 500 meters of the rawinsonde flights
had to be interpolated from surface and upper-level measurements and
therefore are likely to have larger errors. The heights are accurate to
within 30 meters.
5.4 Instrumentation and Data Accuracy - MIZEX 87 VALDIVIA
5.4.1 Surface Measurements - VALDIVIA
Instruments on the VALDIVIA measured all the basic parameters except
humidity. There was a problem recording the correct time; therefore this
CD-ROM contains data collected only during standard observation periods,
when the time was known. This was usually every three hours. The
accuracies of the values were the same as those from the HAAKON MOSBY.
Important Note: It was recently discovered that the humidity
measurements from the Coastal Climate WeatherPak meteorological stations
are highly suspect during cold conditions. Therefore, consider all the
humidity values in this file to be suspect when the air temperature is
below -10 degrees C. Contact Peter Guest (address in section 9) for
details. The upper-air humidities are not affected.
5.4.2 Upper-Air Measurements - VALDIVIA
The rawinsonde system on the VALDIVIA was virtually identical to the
POLAR CIRCLE system and had the same accuracies. Launches were usually
performed every six hours.
6. CEAREX
6.1 Overview of CEAREX Meteorology
The Coordinated Eastern Arctic Experiment began with the drift of the
R/V POLARBJORN on 17 September 1988 and ended on 19 May 1989 when the
POLARBJORN docked in Longyearbyen, Spitsbergen. In addition to the
POLARBJORN, the R/V HAAKON MOSBY and two ice camps were also used to
collect meteorological data.
6.1.1 CEAREX Drift Phase
The drift phase lasted from September 1988 until early January 1989.
During this period the POLARBJORN was moored to a large ice floe and was
relatively immobile. The POLARBJORN operated in the Fram Strait and
Barents Sea areas from late January until May 1989. The R/V HAAKON MOSBY
(University of Bergen, Norway) was active from 25 February until 25 March
1989.
During September 1988 the U.S. Coast Guard ice breaker NORTHWIND
escorted the R/V POLARBJORN (Rieber Shipping, Alesund, Norway) far into a
region of multiyear pack ice north of Svalbard. A large ice floe ("Alpha"
Floe) was selected, to which the POLARBJORN was moored on 17 September.
From this time until 15 November the POLARBJORN drifted slowly southward
with the ice pack; Alpha Floe was used as a drifting data collection
platform. Due to persistent northerly winds the POLARBJORN tracked east of
Spitsbergen, passing within a few kilometers of the island of Kvitoya. The
combination of strong northwesterly winds and the ship's location just
northwest of Kvitoya resulted in destruction of Alpha Floe on 15 November.
At this time equipment was brought aboard and an attempt was made to return
to Tromso, Norway. After several days of limited progress, 16 of the 20
scientists were airlifted to Spitsbergen on 12 December. One meteorologist
stayed aboard as the POLARBJORN worked slowly southward, maintaining data
acquisition systems and continuing the twice daily soundings. A strong
storm in early January allowed the POLARBJORN to break free and return to
Tromso on 9 January.
6.1.2 CEAREX Whaler's Bay / SIZEX Phase
The "Whaler's Bay" phase began on 13 January 1989, when the POLARBJORN
sailed from Tromso in route to operations in Fram Strait. The Seasonal Ice
Zone Experiment (SIZEX) phase contained two separate cruises, the first
lasting from 9 February until 5 March 1989, the second from 8 March until
2 April 1989. Bio-physical oceanographic operations commenced 4 April and
concluded 17 May 1989. The first SIZEX cruise concentrated on conditions
in the vicinity of Bjornoya, south of Svalbard; all subsequent cruises
were located in the Fram Strait region west of Svalbard.
The HAAKON MOSBY's participation in SIZEX began on 25 February 1989,
when the ship left Tromso, Norway, bound for regions in the Barents Sea.
From 26 February to 7 March 1989 the ship operated in the general area
between the Svalbard and the northern coast of Norway. On 7 March the
HAAKON MOSBY headed northwest toward regions in the Fram Strait west and
southwest of Svalbard, where the ship cruised seaward of the pack ice edge
from 11 to 19 March 1989. The HAAKON MOSBY then headed southeast into the
Barents Sea, finally returning to port on 23 March 1989. During the period
0800 UTC 25 February to 1400 UTC 23 March 1989, measurements of basic surface
meteorological parameters were taken every ten minutes. From 2 to 23 March
vertical soundings of the atmosphere were made approximately every six
hours, weather and equipment permitting, and more frequently during
interesting weather conditions.
6.1.3 Camp Operations Phase
The oceanography ice camp ("O" Camp) was active from 30 March until 24
April 1989; the acoustic ice camp ("A" Camp) operated from 30 March until
20 April 1989.
The "O" Camp and "A" Camp operations were located on the pack ice in
the Fram Strait. Most of the studies conducted at "O" Camp were related to
processes in the upper boundary layer of the ocean. The focus of "A" Camp
was acoustics in the ocean. Both camps were also the site of the
meteorological measurements described here.
Meteorological measurements were obtained in 1989 during the periods
1130 UTC 27 March - 1420 UTC 23 April and 1600 UTC 30 March - 0700 UTC 19
April for "O" Camp and "A" Camp, respectively. No rawinsondes were
launched from "A" Camp.
6.2 Instrumentation and Data Accuracy - CEAREX - POLARBJORN
6.2.1 Surface Measurements - POLARBJORN
A Coastal Climate WeatherPak meteorological station was located on a
platform extending forward of the POLARBJORN's bow mast at a height of 14
meters above sea level. This instrument measured wind speed and direction,
temperature, and relative humidity. Temperature data are accurate to
within 1.0 degree C and humidity to within 5%. Accuracy of wind speed and
direction depended on wind direction relative to the ship; a "sheltering"
effect was observed with winds directly from the stern. This situation
seldom occurred during the drift phase due to the ship's slowly varying
heading and persistent northerly winds. Wind speeds are accurate to within
0.3 m/s and direction to within 10 degrees, although during periods of
unfavorable wind direction, errors may have been larger.
Important Note: It was recently discovered that the humidity
measurements from the Coastal Climate WeatherPak meteorological stations
are highly suspect during cold conditions. Therefore, consider all the
humidity values in this file to be suspect when the air temperature is
below -10 degrees C. Contact Peter Guest (address in section 9) for
details. The upper-air humidities are not affected.
All winds were corrected for ship motion based on ship speed and
heading. Throughout most of the drift, ship and ice relative winds were
within 0.5 m/s. However, after 15 November when the POLARBJORN was mobile,
this correction was important.
6.2.2 Upper-Air Measurements - POLARBJORN
Vertical profiles of temperature, humidity, and wind speed and
direction were obtained twice daily throughout the experiment, with
additional launches during periods of extreme or unusual weather. The
system used rawinsondes and software developed by the VIZ Corporation. The
rawinsondes were equipped with thermistors that measured temperatures to
within 0.2 degree C. The humidity sensor consisted of a specially coated
glass plate, the resistance across which varies with humidity. Humidity
measurements generally agreed quite well with Coastal Climate WeatherPak
readings, although some overestimation was evident. Winds were measured
using Omega tracking and were therefore unavailable during periods of high
solar flare activity. [Omega is a world-wide radio navigation system
providing navigational parameters by phase comparison of very-low-frequency
(10-14 KHz), continuous-wave radio signals. (McGraw-Hill Dictionary of
Scientific and Technical Terms, 2nd edition, 1978.)]
A systematic underestimation of low-level winds occurred due to the
necessary 3-minute averaging of all wind data. Underestimation resulted
from inclusion of lighter inversion-layer winds in the average. Rawinsonde
wind directions were generally accurate to within 20 degrees. This data
set includes virtually all rawinsonde data with very little editing.
Spurious wind data take the form of shallow (100 meter) jets; the user of
the data files is cautioned to be skeptical of any soundings exhibiting
large vertical shear in the absence of a temperature inversion.
Altitude was measured with a baroswitch, occasionally yielding
spurious contacts, particularly at low levels. An effort was made to
remove spurious contacts, but success in this difficult task is a function
of operator experience, therefore inaccuracies may exist in some soundings.
Errors of this type are always largest at higher levels because of the
cumulative effect of erroneous contacts during the rawinsonde's ascent.
6.3 Instrumentation and Data Accuracy - CEAREX - HAAKON MOSBY
6.3.1 Surface Measurements - HAAKON MOSBY
A Coastal Climate WeatherPak meteorological station was used on board
the HAAKON MOSBY to measure air temperature, relative humidity, atmospheric
pressure, and wind speed and direction. This station was mounted on a
platform extending forward of the HAAKON MOSBY's bow mast at a height of 15
meters above sea level. All observations were averaged over ten-minute
intervals. The temperature data obtained from this instrument were
accurate to within 1.0 degree C and the relative humidity data to within 5%.
The accuracy of the wind measurements depended on the wind direction
relative to the ship; a "sheltering" effect was observed with winds blowing
directly from the stern. Wind speeds are accurate to within 0.3 m/s and
direction to within 10 degrees, although when winds were from the stern the
errors are likely to be larger. All wind data have been corrected for ship
motion based on ship speed and heading. The measurements of atmospheric
pressure are accurate to within 2 millibars.
Important Note: It was recently discovered that the humidity
measurements from the Coastal Climate WeatherPak meteorological stations
are highly suspect during cold conditions. Therefore, consider all the
humidity values in this file to be suspect when the air temperature is
below -10 degrees C. Contact Peter Guest (section 9) for details. The
upper-air humidities are not affected.
6.3.2 Upper-Air Measurements - HAAKON MOSBY
Vertical soundings of the atmosphere were routinely obtained roughly
every six hours, with rawinsonde flights at approximately 0000, 0600, 1200
and 1800 UTC every day, depending upon equipment or environmental
difficulties. During periods of unusual or exceptional weather conditions
soundings were made more frequently. The number of soundings made in a
single day varied from zero to as many as nine.
The vertical profiles of temperature, dew point temperature and wind
speed and direction were measured using rawinsondes manufactured by the
Vaisala Corporation and software developed by Roger Helvey. The
temperature data obtained from these rawinsondes have an accuracy of 0.2
degree C and the dewpoint temperatures are accurate to within 1.5 degrees
C. Wind data were obtained using an Omega navigation tracking system on
each rawinsonde. The vector wind speeds are considered to be accurate to
within 1 m/s. Winds in the lower 500 meters of the rawinsonde flights had
to be interpolated from surface and upper-level measurements and therefore
are likely to have larger errors. The heights are accurate to within 30
meters. Obvious errors in the profile data were removed but the data are
otherwise unedited.
6.4 Instrumentation and Data Accuracy - CEAREX - "O" Camp
6.4.1 Surface Measurements - "O" Camp
Wind speed, wind direction, temperature, humidity and pressure were
obtained from a Coastal Climate WeatherPak meteorological station and
recorded on Hewlett-Packard 200 series computers. The data were averaged
over ten-minute periods. The winds were measured at a height of 2.82 m
above the ice surface. Temperature, humidity and pressure were measured
at 2.24 m. The temperature was accurate to 0.5 degree C; relative humidity,
8.0%; wind speed, 0.2 m/s; wind direction, 5.0 degrees; and pressure,
2.0 mb. The pressure data show some high frequency fluctuations that are
not believed to be real.
Important Note: It was recently discovered that the humidity
measurements from the Coastal Climate WeatherPak meteorological stations
are highly suspect during cold conditions. Therefore, consider all the
humidity values in this file to be suspect when the air temperature is
below -10 degrees C. Contact Peter Guest (address in section 9) for
details. The upper-air humidities are not affected.
Computer and met station malfunctions created periods when data were
missing or obtained from other instruments. Considerable post-experiment
editing was required to provide the best estimates of the basic met
parameters. The periods and substitution measurements when problems
occurred will be described in the following paragraphs.
A computer malfunction on 27 March forced me to manually record the
met station data. Therefore, on this day, the values of all parameters are
based on 10-second average measurements with irregular intervals ranging
from 4 to 90 minutes between recorded measurements. No data were recorded
between 1730 and 2240 UTC. At 2240 UTC 27 March, the computer began
working and normal (ten-minute met station averages) data collection
occurred until 1710 UTC 28 March when computer failure again occurred.
Later, the computer was fixed but the met station failed. No data were
obtained until 1340 UTC 30 March.
At 1340 UTC 30 March a sonic anemometer was deployed at a height of
3.33 m. It measured average wind speed and direction, with an accuracy
of 0.3 m/s and 10 degrees, respectively, every ten minutes. Air temperature
was recorded manually at 1405 and 1425 UTC 30 March using an unshielded
alcohol thermometer located beside the hut 0.7 m above the surface. On
31 March and 1 April the alcohol thermometer was moved to a homemade box
shield located 1.7 m above the surface. The temperature was manually
recorded hourly during these days, except for sleep periods, and was accurate
to within 1.5 degrees C.
Beginning 2300 UTC 31 March, pressure from an altimeter in the camp
manager's hut was recorded two or three times a day. Starting at 1830 UTC
2 April, the sonic anemometer was used to determine ten-minute average
temperature.
The pressure and temperature sensors described in the previous two
paragraphs were calibrated later in the experiment when a replacement met
station was available for comparison. After adjusting for a bias, the
above sensors compared very well with the met station and the accuracies
were estimated to be at least as good as the met station accuracies, (2.0
mb and 0.5 degree C, respectively). It should be noted that temperature as
measured by a sonic anemometer is affected by humidity, but this is too
small an effect in the Arctic to alter the accuracy stated above.
At 1930 UTC 9 April, a replacement met station was deployed and
recorded average pressure, temperature, humidity and winds every ten
minutes. The heights and accuracies were the same as described earlier for
the met station. The values recorded by this instrument were used for
presentation in the atlas for the rest of the experiment, although the
other sensors were still operational and provided intercomparisons for the
post calibrations described above.
Therefore, with the exception of a gap from 1710 UTC 28 March to 1340
UTC 30 March, all basic met parameters were obtained by at least one sensor
throughout the experiment on "O" Camp. Humidity was the one exception; it
was available only when the met station was operational.
6.4.2 Upper-Air Measurements - "O" Camp
Upper-air measurements of the basic met parameters were obtained from
rawinsondes launched at "O" Camp. The rawinsondes were launched two or
more times each day. This system was manufactured by the VIZ Corporation.
The winds were measured by an Omega navigation tracking system on each
rawinsonde.
The accuracy of the temperature and dewpoint temperature was 0.2
degree C and 1.0 degree C respectively, while height was accurate to 30 m.
Vector wind speed was usually accurate to 1.0 m/s, although in shear
regions and near the surface errors may increase to 2.0 m/s. Sometimes,
the Omega tracking system had problems and errors were extreme. These bad
periods have not been removed from the data and can be identified by spikes
or false jets in the sounding data. A comparison of data obtained from two
profiles made within an hour confirmed the above accuracy estimates.
However, the reader should be cautioned that rawinsonde measurements are
instantaneous and do not necessarily represent the average conditions,
particularly if strong secondary circulations are present.
6.5 Instrumentation and Data Accuracy - CEAREX - "A" Camp
6.5.1 Surface Measurements - "A" Camp
Wind speed, wind direction, temperature, humidity and pressure were
obtained from a Coastal Climate WeatherPak meteorological station (met
station) and recorded on Hewlett-Packard 200 series computers. The data
were averaged over ten-minute periods. The winds were measured at a height
of 2.82 m above the ice surface. Temperature, humidity, and pressure were
measured at 2.24 m. The temperature was accurate to 0.5 degree C; relative
humidity, 8.0%; wind speed, 0.2 m/s; wind direction, 5.0 degrees; and
pressure, 2.0 mb. The pressure data show some high frequency fluctuations
which are not believed to be real.
Important Note: It was recently discovered that the humidity
measurements from the Coastal Climate WeatherPak meteorological stations
are highly suspect during cold conditions. Therefore, consider all the
humidity values in this file to be suspect when the air temperature is
below -10 degrees C. Contact Peter Guest (address in section 9) for
details. The upper-air humidities are not affected.
The "A" Camp data were obtained entirely from the met station and
contain no gaps larger than one-half hour. No editing of the data was
needed and the above accuracies and heights apply throughout the
measurement period.
6.5.2 Upper-Air Measurements - "A" Camp
There were no upper-air measurements taken at "A" Camp.
7. Acknowledgements
Unless otherwise noted, the data were collected and processed by
members of the Environmental Physics Group, Department of Meteorology,
Naval Postgraduate School (NPS). Other directly-contributing individuals
from other institutions are mentioned or referenced in the documentation.
This data compilation would not have been possible without the effort of
many other unmentioned individuals who were involved in planning, logistics,
data collection, data analyses and all the other tasks required to obtain
data in the Arctic.
The creation of this combined Arctic meteorological data base for
the CD-ROM was supported by the Office of Naval Research Arctic Program
(T. Curtin). The Direct Research Funding Program at the Naval Postgraduate
School and the Naval Oceanographic and Atmospheric Research Laboratory
supported the NPS scientific effort that acquired much of the data.
8. References
Frederickson, P.A. (1991) CEAREX/HAAKON MOSBY Meteorology Atlas.
Technical Note 82, Naval Oceanographic and Atmospheric Research Laboratory, 62 pp.
Guest, P.S. and K.L. Davidson (1989) CEAREX "O" and "A" Camp Meteorology
Atlas. Naval Postgraduate School, NPS-63-89-007, 64 pp.
Guest, P.S. and K.L. Davidson (1988) MIZEX 87 Meteorology Atlas. Naval
Postgraduate School, NPS-63-88-004, 140 pp.
Lackmann, G.M., P.S. Guest, K.L. Davidson, R.J. Lind and J. Gonzales (1989)
CEAREX/POLARBJOERN Meteorology Atlas. Naval Postgraduate School,
NPS-63-89-005, 545 pp.
Lindsay, R.W. (1986) MIZEX 84 Six Hourly Radiosondes: POLAR QUEEN,
POLARSTERN, HAAKON MOSBY, VALDIVIA. Polar Science Center, University
of Washington, Technical Report, 240 pp.
Lindsay, R.W. (1985) MIZEX 84 Integrated Surface Meteorological Data Set and
Meteorological Atlas, 2nd ed. Polar Science Center, University of
Washington, Technical Report, 240 pp.
Lindsay, R.W (1984) Radiosonde Observations from the POLARBJORN, MIZEX 83.
Polar Science Center, University of Washington. Technical Report,
280 pp.
9. Contact Information
Peter Guest
Naval Postgraduate School
Department of Meteorology, Code MR/Gs
Monterey, CA 93943-5000 USA
Phone: 408-646-2451
Telemail: K.DAVIDSON/Omnet
February 1991 (revised March 1991)
