Metadata Report for BODC Series Reference Number 2014931

• 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

SBE56 thermistor secured to drifter during SMiLES cruise JR20150421: Data Quality Report

This is a data quality report for the SBE56 thermistors attached to a drogued drifter as part of Lagrangian Experiment 1 during SMiLES cruise JR20150421.

The first 49 and final 19 datacycles for each of the 12 thermistors were observed to have null latitudes and longitudes and therefore to represent pre-deployment and post-deployment periods of the drifter data. These datacycles were deleted.

Data Access Policy

Open Data supplied by Natural Environment Research Council (NERC)

You must always use the following attribution statement to acknowledge the source of the information: "Contains data supplied by Natural Environment Research Council."

Narrative Documents

JR20150421: BODC Data Processing of SBE56 temperature sensors secured to drifters

Data Processing

Data were submitted to BODC by FTP transfer with the originator placing data on BODC's internal site and following BODC's procedures; the data were subsequently archived. Data were provided for two experiments as both raw (.cnv files) and processed files (.mat files). The variables and series in the files differed depending on which experiment the data was from. The file containing data from Lagrangian Experiment 1 contained the temperature for 12 series and the following metadata: latitude, longitude and depth of the thermistor. The data from Lagrangian Experiment 3 were provided in three separate files, one for each drifter within the experiment. Each file contained temperature, latitude and longitude.

The processed matlab files were transferred to BODC internal format using standard BODC processing procedures. The originator's variable temperature was mapped to a BODC parameter code as follows:

Screening

Post transfer analysis and crosschecks were applied according to BODC procedures. This involved the screening of data using BODC's in house visualisation software where any suspect data were flagged but not removed.

JR20150421: Originator's Data Processing of SBE56 temperature sensors secured to drifters

Sampling Strategy

During cruise JR20150421, drogued drifters were deployed with the aim of tracking water movement during and beyond the length of the cruise. The drogues were used to ensure that the drifters followed the currents rather than the wind. The drogues consisted of a 10m holey sock (Pacific Gyre) with ten plastic hoops inside at intervals of 1 meter. The final hoop was weighted with lead in order to maintain a vertical orientation and to ensure that the drogue was stretched out in the water column. Sea-Bird SBE 56 temperature recorders were deployed on these drifters during Lagrangian Experiments 1 and 3.

As part of Lagrangian Experiment 1, a drogued drifter was deployed with two communication buoys, a 39cm satellite and radio communications buoy from Plymouth Marine Laboratory and a 46cm satellite only communications buoy from Plymouth University, each reporting the position of the drifter every ten minutes. The drogue was centred at a depth of 55m and additional weights were attached to the bottom of the drogue. Twenty SBE56 thermistors were secured to the drifter, which samples at 1 Hz. Three SBE37 CTDs were also secured, but the data is not included here. Only the top 50 m of the drifter setup were recovered as the jacket wire was severed at the 50m mark. This resulted in only 12 of the SBE56 thermistors being recovered.

Three drogued drifters, each attached with a SBE56 thermistor, were deployed during Lagrangian Experiment 3 in an eastward current (1 m s^-1) at the northern edge of a mesoscale eddy in the Antarctic Circumpolar Current (ACC), encountering the smaller features and to see how the speed of the drifters were affected. The drifters consisted of a SBE56 thermistor secured 1m below a pick-up buoy, a Plymouth University buoy containing a RockBLOCK satellite communications card and a drogue centred at 35 m water depth. As with Lagrangian Experiment 1, the thermistors were programmed to sample at 1 Hz.

Data Processing

After the drifters and SBE56 thermistors were recovered, data were downloaded and interpolated onto a time record. The position was also interpolated onto this record. For the Lagrangian Experiment 1, a 30 second time record was used. For the other three drifters, a 1 second time frame was used.

Project Information

Surface Mixed Layer Evolution at Submesoscales (SMILES)

Background

SMILES is a combined observational and numerical modelling experiment funded by the UK Natural Environment Research Council (NERC) from 01 July 2014 to 30 June 2017. The main aim of the project is to improve our understanding of the role played by submesoscale processes at the subantarctic front in the Southern Ocean.

Participants

The SMILES project is a collaboration between a team of researchers from the following institutions -

• Stanford University
• Plymouth University
• Cambridge University
• Plymouth Marine Laboratory
• British Antarctic Survey

Fieldwork and data collection

SMILES research is investigating the dynamics of submesoscales from two perspectives; numerical modelling and observational measurements.

RRS James Clark Ross 311 was the research cruise conducted as the observational element of the SMILES project which aims to improve our understanding of submesoscale dynamics in regions characterised by strong fronts and where they impact on water mass transformation. For this reason, the field site was chosen to be the subantarctic front (SAF) to the east of Drake Passage where the Antarctic Circumpolar Current generates a pronounced front between the warmer subantarctic water to the north and the subpolar water to the south. To the north of the SAF, subantarctic mode water is formed through a process previously considered to be governed by air-sea interaction alone. SMILES aims to investigate the extent to which submesoscale dynamics at the SAF and the surrounding region may impact on, and potentially govern, this process of water mass transformation.

The cruise departed Stanley, Falkland Islands on 21 April 2015 and returned on 22 May 2015 having collected data using several surveying techniques e.g. towed CTDs, Seasoar surveying and lagrangian surveys.

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: