Global Drifter Center GDC Drifter Data Assembly Center DAC

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Global Drifter Center (GDC) / Drifter Data
Assembly Center (DAC) Mayra C. Pazos
(NOAA/AOML), Craig Engler (NOAA/AOML), Jessica
Redman (CIMAS) Satellite tracked surface
drifters have been deployed by the oceanographic
community since the 1970s, for both research and
operational purposes. The resulting data have
provided important information on the surface
currents of the global ocean as well as providing
critical sea surface temperature (SST) data for
the calibration of satellite SST sensors. This
is a joint project between AOML and Scripps
Institution of Oceanography, and coordinated with
international partners through the Data Buoy
Cooperation Panel (DBCP)
The GDC objective is to maintain a global 50 by
50 array of Argos tracked Lagrangian drifters to
meet the need for accurate and global in-situ
observations of SST and surface circulation.
These data support short-term climate predictions
satellite calibration and climate research and
monitoring.
The DAC objective for real time data is to
arrange for GTS distribution and removal as soon
as sensors fail.The objective for delayed mode
data is to provide uniform quality controlled
data of research quality for SST and surface
velocity measurements. The DAC receives,
processes and sends data to MEDS for archiving,
and makes data and products available through the
Web.
The GDC performs the following activities
The DAC performs the following activities
Pre-deployment Functions
Post-deployment Functions
Procurement and Distribution
Planning
GTS
Quality Control
Web access and Distribution
Performance Evaluation
Produce annual plan for global distribution and
deployment of 450-500 drifters through
interaction with international partners
Verify deployment status and communicate it to
VOS, research vessels, naval aircraft operators
and international partners
Request and distribute Argos PTT IDs from Service
Argos
Monitor procurement of drifters through Scripps
and vendors
Insertion and removal of buoy Ids from the GTS
Decode raw data received from Argos and apply
calibrations
Closely monitor drifter transmitter failure, SST
and drogue sensors
Insert interpolated data into the AOML database
for Web access
Monitor accuracy of data on the GTS in real time
Request specification sheets from manufacturers
and ensure buoys meet those specifications
Maintain master inventory of buoy locations prior
to deployments
Participate on international planning committee
and provide reports to DBCP
Identify drifters no longer in operation and
return their IDs to Service Argos in order to
save money and free up PTT ID numbers
Identify new drifters deployed and determine time
and position of first good transmission
Dotted lines are mean life in 10 year period
Maintain updated data products on the Web
Notify Argos of drifters that lost their drogue
to be noted in GTS message
Coordinate shipping and distribution, both
domestically and internationally
OGP Drifter Deployments in 2003
Send periodic database updates to MEDS for long
term archiving and distribution
Identify drifters that stopped transmitting or
those that ran aground, and determine last good
time and position
Dotted lines are mean life in 10 year period
Coordinate drifter deployments as per annual
plan, working with NOAA field personnel,
contractors, shipping companies participating in
VOS network, Naval Oceanographic Office and
international partners
Determine drogue lost date
Figures show improvement in mean life of drifters
in a 10 year period. Only drifters that did not
run aground or were retrieved were used.

• GDC/DAC 2004 goals
• Deployment of 712 drifters between October 2003
  and December 2004
• Concentration on southern oceans and enhancement
  of North Pacific on the
• order of 40 barometer drifters, upgraded by
  NODC
• Continue to work with co-operative agencies to
  upgrade buoys with barometers
• (118 SVP upgraded with barometers by
  NOAA/OGP)
• Continue to monitor hurricane array drifters
  performance status
• Develop standards for measuring drifter/sensor
  longevity, monitor their
• failures in real time
• Problem Areas
• Data voids
• GDC continues to seek deployment opportunities in
  those traditional
• data sparse regions (Gulf of Guinea, Indian
  ocean, South America Bight)

Compare SST with Reynolds climatology to
determine last good day for SST sensor
Remove bad position and SST values
Interpolate data to 6 hour intervals using
Kriging method
Evolution of Global Drifter Array as of December
2004