Metadata Report for BODC Series Reference Number 45669
Metadata Summary
Problem Reports
Data Access Policy
Narrative Documents
Project Information
Data Activity or Cruise Information
Fixed Station Information
BODC Quality Flags
SeaDataNet Quality Flags
Metadata Summary
Data Description |
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Time Co-ordinates(UT) |
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Parameters |
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Problem Reports
No Problem Report Found in the Database
Data Access Policy
Public domain data
These data have no specific confidentiality restrictions for users. However, users must acknowledge data sources as it is not ethical to publish data without proper attribution. Any publication or other output resulting from usage of the data should include an acknowledgment.
The recommended acknowledgment is
"This study uses data from the data source/organisation/programme, provided by the British Oceanographic Data Centre and funded by the funding body."
Narrative Documents
IOS (Wormley) Processing of JASIN Surface Meteorological Data
Introduction
IOS initiated a programme to collate, analyse and intercalibrate as much of the JASIN meteorological data as possible to produce a unified high quality data set (covering sufficient time and space scales for comparison with SEASAT measurements). Particular emphasis was placed on measurements of wind speed and direction, sea surface temperature and integrated water vapour.
A large amount of effort was expended in the shipboard meteorological measurements - four -meteorological ships- (RV Meteor, HMS Hecla, RRS John Murray and Gardline Endurer) logged surface variables and launched radiosondes at the corners and, during Phase 2, centre of a 200km triangle. Two of the ships, RV Meteor and HMS Hecla, also flew tethered balloons. The meteorological ships had two independent sets of instruments for surface measurements - WMO (hourly, manual and including subjective observations and comments, logged to World Meteorological Organisation (WMO) standards) and automatically recorded data (1 minute sampling). Hr Ms Tydeman and RRS Discovery had autolog systems. The former was particularly useful because the ship roved over a large area enhancing the spatial coverage.
Several buoys carried meteorological sensors and a number of these were situated within a few kilometres of one another in the Fixed Intensive Array (FIA) - centred on 59° N, 12° 30' W. Several buoy instruments failed completely, including one system on H2 and all surface instruments on H1, H3 and P1.
Data Collection
Principal investigators were asked to provide data after carrying out initial reduction to meteorological quantities. Data were converted to a standard format and checked to ensure that all variables were present. For example, obtaining true winds from apparent winds and ship's velocity and conversion of components to speed and direction. Data were then plotted to standard scales and inspected for inconsistencies.
In the case of some of the autologged data from ships it was necessary to calibrate the data against the WMO values because of drift problems and incorrect pre-JASIN calibrations. Data obtained during intercomparison periods were used to identify instrument bias. For formal meteorological ship intercomparisons, the ships met for prearranged periods ranging from 3 hours to 12 hours and the frequency of the WMO measurements was increased to half-hourly.
The platforms within the FIA were close enough together for the entire measurement period to be considered as an intercomparison. Sub-periods were selected and consistency between the differences from one period to the next has been investigated. Systematic biases were noted, some of which were due to known calibration defects. When comparing wind speeds expected differences due to variations in sensor height have been allowed for by applying a stability-dependent model of the wind in a constant flux layer.
Careful inspection of the data and recognition that W2 was the longest continuous record available from a buoy (exposure superior to that of a ship) led to its selection as JASIN meteorological standard to which all other measurements were referred. On the basis of intercomparisons corrections have been deduced and applied to the data. Generally these are simple offsets because the range of conditions sampled was rarely large enough to yield meaningful statistics. Interplatform differences, which are not systematic or cannot be related to other variables, remain as uncertainties in the data set and represent the accuracy to which an internally consistent data set can be produced. These are as follows:
Wind Speed | ±0.5 m/s |
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Wind Direction | ±5° |
Atmospheric Pressure | ±0.2 mbar |
Dry Bulb Temperature | ±0.5°C |
Wet Bulb Temperature | ±0.5°C |
Sea Surface Temperature | ±0.1°C (cannot be derived from intercomparisons because of real spatial variability over short distances) |
All variations except wind speed biases are equally distributed about zero. For speed most biases are negative suggesting an overestimate of wind speed by the sensor on W2. This overestimate is small in magnitude, but some comparisons have been made using B1 as standard.
References
J.Businger, R.H.Stewart, T.Guymer, D.B.Lame, and G.H.Born (editors) (1980)
SEASAT - JASIN Workshop Report. Volume 1 Findings and Conclusions. JPL publication 80-62. Jet Propulsion Laboratory, Pasadena, California.
R.A.Weller, R.E.Payne, W.G.Large and W.Zenk (1983)
Wind Measurements From an Array of Oceanographic Moorings and F/S Meteor During JASIN 1978. Journal of Geophysical Research Vol. 88 p9689-9705
RRS Discovery JASIN Logged Meteorological Data
JASIN meteorological data - automatically logged data.
Ship | RRS Discovery |
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Location | Roving ship; generally within oceanographic intensive area centred on 59° N, 12° 13' W. Station keeping procedure - generally not head to wind. |
Instrumentation
Wind Speed and Direction
Wind speed and direction on starboard foremast 19.5m above sea level, true wind speed calculated and logged.
Air temperature
Dry and wet bulb temperatures measured by platinum resistance thermometers at 14m above sea level, in °C.
Sea surface temperature
Hull sensor at 2.5m below sea level on port side of ship.
Atmospheric pressure
Sensor located at 2.5m above sea level, connected to static head on foremast. Pressures are referenced to sea level.
The following corrections have been applied to the data using platform W2 as standard, except for wind speed where B1 was used as standard:
Parameter | Correction |
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Wind speed | +1.2m/s where relative wind direction greater than or equal to 0° and less than 20° +0.7 m/s where relative wind direction greater than or equal to 20° and less than 160° +2.0 m/s where relative wind direction greater than or equal to 160° and less than 200° +0.7 m/s where relative wind direction greater than or equal to 200° and less than 290° |
Atmospheric pressure | -0.23 mbar |
Dry bulb temperature | +0.15 °C |
Wet bulb temperature | +0.15 °C |
NB Correction is zero unless otherwise stated.
Data values are 2 minute means of 1 second samples.
Data sampling is non-uniform in places, for example:
Date | Sample Time | Comment |
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02 Aug 1978 | 0534 | |
0536 | Null cycle | |
0537 | ||
0539 | ||
0541 | ||
0543 | ||
0545 | Null cycle | |
0546 | ||
0548 | ||
06 Aug 1978 | 1540 | |
1542 | Null cycle | |
1543 | ||
1544 | ||
15 Aug 1978 | 0754 | |
0756 | Null cycle | |
0757 | ||
0759 | Null cycle | |
0800 |
Note: Spikes in the data may be due to interference by radio transmission during the cruise.
Project Information
Joint Air Sea Interaction Experiment (JASIN)
The JASIN Project was designed to study the interaction of the atmospheric and oceanic boundary layers with the larger scale motions of the sea and the air.
The primary aims may be summarized as follows:
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To observe and distinguish between the physical processes causing mixing in the atmospheric and oceanic boundary layers and relate them to the mean properties of the layers.
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To examine and quantify aspects of the momentum and heat budgets in the atmospheric and oceanic boundary layers and fluxes across and between them.
The multiplicity of processes to be sampled necessitated a large experiment and JASIN involved 14 ships and 3 aircraft with more than 50 teams of investigators from 9 countries. Altogether 35 mooring systems were deployed.
The experiment lasted for 2 months from mid-July to mid-September 1978 and comprised 2 intensive measuring periods preceded by a preparatory test period. The project took place in the north Rockall Trough, an area of deep water (1000m - 2000m) several hundred kilometres off the west coast of Scotland.
Data Activity or Cruise Information
Cruise
Cruise Name | D94_1 |
Departure Date | 1978-07-12 |
Arrival Date | 1978-07-24 |
Principal Scientist(s) | Peter M Saunders (Institute of Oceanographic Sciences Wormley Laboratory) |
Ship | RRS Discovery |
Complete Cruise Metadata Report is available here
Fixed Station Information
No Fixed Station Information held for the Series
BODC Quality Control Flags
The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:
Flag | Description |
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Blank | Unqualified |
< | Below detection limit |
> | In excess of quoted value |
A | Taxonomic flag for affinis (aff.) |
B | Beginning of CTD Down/Up Cast |
C | Taxonomic flag for confer (cf.) |
D | Thermometric depth |
E | End of CTD Down/Up Cast |
G | Non-taxonomic biological characteristic uncertainty |
H | Extrapolated value |
I | Taxonomic flag for single species (sp.) |
K | Improbable value - unknown quality control source |
L | Improbable value - originator's quality control |
M | Improbable value - BODC quality control |
N | Null value |
O | Improbable value - user quality control |
P | Trace/calm |
Q | Indeterminate |
R | Replacement value |
S | Estimated value |
T | Interpolated value |
U | Uncalibrated |
W | Control value |
X | Excessive difference |
SeaDataNet Quality Control Flags
The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:
Flag | Description |
---|---|
0 | no quality control |
1 | good value |
2 | probably good value |
3 | probably bad value |
4 | bad value |
5 | changed value |
6 | value below detection |
7 | value in excess |
8 | interpolated value |
9 | missing value |
A | value phenomenon uncertain |
B | nominal value |
Q | value below limit of quantification |