Dataset: drifter_tracks
Deployment: AL9904

Drifter track data from Georges Bank, 1995-1999

Principal Investigator:

Richard Limeburner (Woods Hole Oceanographic Institution, WHOI)

BCO-DMO Data Manager:

Shannon Rauch (Woods Hole Oceanographic Institution, WHOI BCO-DMO)

Project:

U.S. GLOBEC Georges Bank (GB)

Current State:

Final no updates expected

Version:

01 June 2012

Version Date:

2012-06-01

Data URL:

https://www.bco-dmo.org/dataset-deployment/455278/data

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Description

Satellite-tracked drifters with holey sock drogues centered at 10, 15 and 40-m depths were deployed over Georges Bank during 1995-99 in support of the U.S. GLOBEC/Georges Bank Program.

References:
Christopher E. Naimie, Richard Limeburner, Charles G. Hannah and Robert C. Beardsley, 2001. On the geographic and seasonal patterns of the near-surface circulation on Georges Bank - from real and simulated drifters. Deep-Sea Research II: Topical Studies in Oceanography, vol 48, pp 501-518.

Methods & Sampling

Dataset acquisition description

The status of drogue presence is indicated by timing the submergence of the surface float. When the drogue is attached, its drag will cause the surface sphere to submerge occasionally as a wave passes. If the drogue has been lost, the surface sphere remains at the surface and is not buried by waves. When the surface float submerges, contacts on top of the sphere are shorted out by the seawater and the PTT controller starts counting the length of time (seconds) the contacts are shorted. Every 30 minutes the accumulated submergence time is scaled by 0.1 (for example, 1000 seconds is scaled to 100) and loaded into the first byte of the data string and a new submergence time is started. Typical submergence values are 10 to 100. Consistent submergence values of 0 indicate the drogue has been lost. The maximum submergence value is 180 and indicates the surface float is sinking, or heavily fouled.

Those drifters with identifications starting with a "g" were generally deployed in US territorial waters and those with an "n" deployed in Canadian waters by the Bedford Institute of Oceanography.

Data Processing Description

Dataset Processing Description

All drifters originally submitted by this investigator, regardless of year deployed, had a year day value beginning with January 1, 1995 (year day of 1.0000). Thus, a deployment in 1996 had a year day >365.0000 and a deployment in 1999 had a deployment year day value >1461.0000 (1996 was a leap year). BCO-DMO converted those original year day values to standard yrday_gmt values (0 to 365, or 0 to 366 for leap years).

Based on dates of deployment and recovery, a drifter file may span two calendar years. The 'year_start' parameter indicates the year the drifter was deployed.

BCO-DMO made the following modifications: Calculated actual 'yrday_gmt' values from the original 'yrday_special' column (yrday_special = number of days since January 1, 1995); Added argosid and cruiseid from the 'drifters_start'_positions' dataset; Re-formatted all values from scientific notation to integers; Changed incorrect year values for drifter g96; Corrected the year value in cases where yrday_special and year did not match (e.g. if yrday_special was 367, but year was 1995, changed year to 1996); Changed values of '999.00' to 'nd' to indicate 'no data'; Removed data for drifter g162 because it was undergoing gps testing locally.

BCO-DMO corrected unknown/missing cruise ID's for the following drifters:
g31- corrected to EN274. (Cruise report for EN274 documents the deployment of g31.)
g47- corrected to EN278. (Original data has EN278 listed.)
g84 and g85 - corrected to EN291. (EN291 cruise report documents the deployment of these drifters.)
g98 and g99 - corrected to EN294. (EN294 cruise report documents the deployment of these drifters.)
g140 and g142 - corrected to EN300. (EN300 cruise report documents the deployment of these drifters.)
g157 and g158 - corrected to OC315. (Original data has OC315 listed and Oceanus schedule confirms dates, locations, and investigators.)
g159 - corrected to OC316. (Original data has OC316 listed and cruise report confirms this.)
n6 to n10 - corrected to PAR98-078. (Cruise report for PAR-98-078 documents the deployment of these drifters.)

More information about this dataset deployment

Funding

Award Number	Funding Source
unknown GB NOAA	National Oceanic and Atmospheric Administration
unknown GB NSF	National Science Foundation

Instruments

Drifter Buoy

Supplied Description:

Instrument Type

Generic Name: Drifter Buoy

Generic Description:

Drifting buoys are free drifting platforms with a float or buoy that keep the drifter at the surface and underwater sails or socks that catch the current. These instruments sit at the surface of the ocean and are transported via near-surface ocean currents. They are not fixed to the ocean bottom, therefore they "drift" with the currents. For this reason, these instruments are referred to as drifters, or drifting buoys.

The surface float contains sensors that measure different parameters, such as sea surface temperature, barometric pressure, salinity, wave height, etc. Data collected from these sensors are transmitted to satellites passing overhead, which are then relayed to land-based data centers.

definition sources: https://mmisw.org/ont/ioos/platform/drifting_buoy and https://www.aoml.noaa.gov/phod/gdp/faq.php#drifter1

Parameters

Supplied Name	Supplied description	Supplied Units	Standard Name
year_start	Year that the drifter was initially deployed (e.g. 1995).	dimensionless	year_start
drifterid	Drifter identification number. 'g' = drifter initially deployed in US water; 'n' = drifter deployed in Canadian waters by the Bedford Institute of Oceanography.	dimensionless	drifterid
argosid	ARGOS drifter identification number.	dimensionless	argosid
cruiseid	Identification number of the cruise on which the drifter was initially deployed (e.g. OC302 = R/V Oceanus cruise number 302). 'nd' = cruiseid unknown.	dimensionless	cruiseid
lat	Latitude in decimal degrees; positive = North.	decimal degrees	lat
lon	Longitude in decimal degrees; negative = West.	decimal degrees	lon
temp	Water temperature.	degrees Celsius	temp
submergence	Tension value between surface float and drogue.	unknown	no_bcodmo_term
yrday_gmt	Day of the year and decimal time (01 to 366); calculated from the original column 'yrday_special' (year day since 01/01/95).	dimensionless	yrday_gmt
year	Year, in YYYY format (e.g. 1996).	dimensionless	year
day_gmt	Day of the month (0 to 30), in DD format.	dimensionless	day_gmt
month_gmt	Month of the year (01 to 12), in MM format.	dimensionless	month_gmt
time_gmt	Time of day (24 hour clock), including decimal minutes.	dimensionless	time_gmt
ISO_DateTime_UTC	Date and time (UTC) formatted to ISO8601 standard. T indicates start of time string; Z indicates UTC.	YYYY-mm-ddTHH:MM:SS.ssZ	ISO_DateTime_UTC

Database

Contribute Data

Dataset: drifter_tracks
Deployment: AL9904

Dataset acquisition description

Dataset Processing Description

Database

Contribute Data

Dataset: drifter_tracksDeployment: AL9904

Dataset acquisition description

Dataset Processing Description

Dataset: drifter_tracks
Deployment: AL9904