Metadata Report for BODC Series Reference Number 45725


Metadata Summary

Data Description

Data Category Meteorology -unspecified
Instrument Type Unspecified Instrumentation
Instrument Mounting research vessel
Originating Country United Kingdom
Originator -
Originating Organization Institute of Oceanographic Sciences Wormley Laboratory (now National Oceanography Centre, Southampton)
Processing Status banked
Project(s) JASIN
 

Data Identifiers

Originator's Identifier JOHN MURRAY
BODC Series Reference 45725
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 1978-07-27 18:23
End Time (yyyy-mm-dd hh:mm) 1978-08-10 16:42
Nominal Cycle Interval 60.0 seconds
 

Spatial Co-ordinates

Latitude 60.25000 N ( 60° 15.0' N )
Longitude 10.50000 W ( 10° 30.0' W )
Positional Uncertainty 1.0 to 5.0 n.miles
Minimum Sensor Depth -11.0 m
Maximum Sensor Depth 0.0 m
Minimum Sensor Height -
Maximum Sensor Height -
Sea Floor Depth -
Sensor Distribution Scattered at fixed depths - The sensors are scattered with respect to depth but each remains effectively at the same depth for the duration of the series
Sensor Depth Datum Unspecified -
Sea Floor Depth Datum -
 

Parameters

BODC CODE Rank Units Short Title Title
AADYAA01 1 Days Date(Loch_Day) Date (time from 00:00 01/01/1760 to 00:00 UT on day)
AAFDZZ01 1 Days Time(Day_Fract) Time (time between 00:00 UT and timestamp)
CAPHSL01 1 Millibars Air_press_SeaLvl Pressure (measured variable) exerted by the atmosphere by barometer and correction to sea level
CDTASS01 1 Degrees Celsius AirTemp Temperature of the atmosphere by dry bulb thermometer
CWETSS01 1 Degrees Celsius WetBulb_AirTemp Wet bulb temperature of the atmosphere by psychrometer
ERWDSS01 1 Degrees RelWindDirFrom_IS Wind direction (relative to moving platform) in the atmosphere by in-situ anemometer
ERWSSS01 1 Metres per second RelWindSpd Wind speed (relative to moving platform) in the atmosphere by in-situ anemometer
 

Definition of Rank

  • Rank 1 is a one-dimensional parameter
  • Rank 2 is a two-dimensional parameter
  • Rank 0 is a one-dimensional parameter describing the second dimension of a two-dimensional parameter (e.g. bin depths for moored ADCP data)

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
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 John Murray JASIN Logged Meteorological Data

JASIN meteorological data - automatically logged data.

Ship RRS John Murray
Location Northeast vertex or centre of JASIN meteorological triangle.
At northeast vertex ship steamed slowly upwind (at 0.5knots) until abreast of station, then steamed rapidly downwind (at 3knots) until limit of radar range of station was reached.
At centre ship steamed slowly upwind (at 0.5knots) until limit of radar range on station, then steamed rapidly downwind (at 3knots) past station until limit of radar range to station.

Instrumentation

Wind Speed

Porton Ship Meteorological System (PSMS) cup anemometer mounted on starboard side of meteorological yardarm, located 1m forward of the foremast at 11m above sea level. Relative wind speed recorded.

Wind Direction

PSMS wind vane on port side of meteorological yardarm, at 11m above sea level. Relative wind direction logged and referenced to the ships head. Original calibration invalid. Attempts to find a new calibration only partially successful, therefore wind directions should be used with caution. True wind speed will be affected if ship is steaming.

Air Temperature

Dry and wet bulb temperatures measured by Porton psychrometer on meteorological yardarm, at 11m above sea level, recorded in °C. Temperatures showed drift with time. This has been removed by calibration against WMO hourly data. Wet bulb temperatures were by far the worst.

Sea surface Temperature

PRT on float suspended from boom over side of ship. Sensor failed 19 July 1978.

Atmospheric Pressure

PSMS digiquartz pressure transducer at 0m above sea level, connected to static head on on the meteorological yardarm at 11m above sea level. All pressures were referenced to sea level. These data contain many spikes.


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:

  1. 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.

  2. 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 JM8/78
Departure Date 1978-07-12
Arrival Date 1978-09-01
Principal Scientist(s)Trevor H Guymer (Institute of Oceanographic Sciences Wormley Laboratory)
Ship RRS John Murray

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
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