Metadata Report for BODC Series Reference Number 45018

• 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

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

HMS Hecla JASIN Meteorological Data

JASIN meteorological data - manually logged hourly data to WMO standards

Instrumentation

Wind Speed

Munro cup anemometer on main mast 20m above sea level, true wind speed recorded to nearest knot. Corrected to a height of 10m above sea level.

Wind Direction

Munro wind vane on main mast 20m above sea level, true direction recorded to nearest 10deg and referenced to true north.

Air Temperature

Dry and wet bulb temperatures measured by Assman psychrometer on windward bridge wing, at 11m above sea level, in °C to nearest 0.1°C.

Sea Surface Temperature

Surface water collected by sea bucket and temperature measured by mercury-in-glass thermometer to nearest 0.1°C.

Atmospheric Pressure

Precision aneroid barometer (PAB) 1, at 11m above sea level, connected to static head on boom extending forward from main mast at 19m above sea level. PAB2 at 11m above sea level vented to bridge location. Porton ship meteorolgical system (PSMS) digiquartz autologging sensor at 2m above sea level, connected to boom static head; PAB3 at 2m above sea level connected to main mast static head at 22m above sea level. From 22 Jul 1978 to 28 Jul 1978 PAB3 logged instead of PSMS. PAB1, PAB2 corrected to sea level. Atmospheric pressures were measured to the nearest 0.1mb.

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:

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

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

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:

SeaDataNet Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle: