NOAA’s Global Drifter Program

1. 1 NOAA’s Global Drifter Program Surface Currents, Sea Surface Temperature, Winds, Atmospheric Pressure and Surface Salinity www.aoml.noaa.gov/phod/dac/gdp.html Rick Lumpkin (Rick.Lumpkin@noaa.gov) National Oceanic and Atmospheric Administration (NOAA) Atlantic Oceanographic and Meteorological Laboratory (AOML) Miami, Florida USA

2. 2 What is the Global Drifter Program? The Global Drifter Program is the principal component of the Global Surface Drifting Buoy Array, a branch of NOAA’s Global Ocean Observing System (GOOS) and Global Climate Observing System (GCOS) and a scientific project of the Data Buoy Cooperation Panel. Objectives: Maintain a global 5ºx5º array of ~1250 satellite-tracked Lagrangian surface drifting buoys to meet the need for an accurate and globally dense set of in-situ observations: mixed layer currents, SST, atmospheric pressure, winds, and salinity. Provide data processing system for scientific use of these data. These data support short-term (seasonal-to-interannual) climate predictions as well as climate research and monitoring.

3. The satellite-tracked drifter 3 Holey-sock drogue (sea anchor) Spherical surface float Polyurethane impregnated tether Holey Sock nylon drogue centered at 15-m depth D-cells batteries inside the float Sensors: Drogue: drogue detection by submergence or tether strain sensor Thermistor: measure SST Voltage: Indicates batteries’ life Cost: ~$1800 Other Sensors that can be added: Barometric pressure, wind, subsurface temperatures, salinity

4. 4 The Global Drifter Array Maintained by NOAA’s Global Drifter Program with numerous national and international partners

5. 5 Types of GDP drifters SVP: “Surface Velocity Program”. The “basic” drifter: SST and currents. SVPB: includes barometer on surface float. Data used to improve weather forecasts. SVPS: includes salinity at base of surface float. SVPW: includes barometer + wind vane and swivel (direction) + acoustic anemometer (wind speed)

6. 6 How are the drifter data helpful? • Sea surface temperature measurements: used to validate/calibrate satellite temperatures. Especially valuable after volcanic eruptions, when satellite measurements can have large biases • Barometric pressure measurements: put on the Global Telecommunications System to improve weather predictions worldwide. • Surface current measurements: applications include search and rescue, tracking marine debris, and understanding ocean transports at time scales from hourly to decadal.

7. Deploying a drifter 7 Designed to be easy for one person to deploy from a ship while underway at up to 20 knots. Average lifetime: 450 days.

8. 8 Tether and drogue secured with paper tape that dissolve in water Drogue starts sinking minutes after deployment Drogue stretches vertically, when tape dissolves. Data transmission starts.

9. 9 Deployment needs (short term) Image: forecast showing array coverage (% chance of having at least one drifter), assuming no further deployments. Gaps are being targeted by planned deployments, but more opportunities are always beneficial.

10. 10 Deployment needs (long term) Image: density of all drifter observations (drifter days per square degree) in Indian and western Pacific Oceans, 1979—2010. Any region that is not red (>200) has not been densely sampled over entire history of program.

11. 11 Research done with drifters Mapping ocean currents Examining climate-scale changes Understanding and predicting ocean transport

12. 12 Mapping ocean currents Mean speed of surface currents (cm/s) Root-mean-square variability of currents (cm/s)

13. 13 Mapping regional currents Image: Absolute sea level (area-mean subtracted) on 6 December 1993 computed from altimetry, drifters and wind (contours; interval is 10 cm), and trajectories of drogued drifters (solid black curves) from 16 November to 16 December 1993. From Niiler et al. (2002).

14. 14 Climate-scale changes in ocean circulation From Lumpkin and Garzoli (2011): drifter velocity combined with satellite observations to track long-term changes in Brazil/Malvinas Confluence. Time series (below) of Confluence location shows significant southward shift in last 15 years.

15. 15 Using drifter statistics to estimate the fate of floating marine debris • Strategy: • Divide world’s oceans into small boxes. • For each box, find all the drifters that were ever in the box. • Calculate where each of those drifters went five days later. • Assume that those statistics will also describe how marine debris will be carried by ocean currents and winds. • Use these statistics to simulate the spread of hundreds, thousands or millions of particles.

16. The evolution of marine debris Simulations by Nikolai Maximenko and Jan Hafner (Univ. Hawaii): drifter statistics used to estimate fate of debris from 11 March 2011 earthquake and tsunami. 16

17. 17 Exposure to marine debris Distribution of the concentration of floating marine debris in arbitrary units, 10 years after being released homogeneously at a concentration of 1. Vertical bars indicate the concentration of material that has washed ashore, with color corresponding to 10X the value in the color bar. Lumpkin et al. (2011)

18. 18 Our national and international partners NOAA’s Voluntary Observation Ships, Ships of Opportunity, and National Marine Fisheries Service programs Argo program International Ice Patrol Institut de Recherche pour le Développement; Météo-France (France) Leibniz-Institut für Meereswissenschaften an der Universität Kiel (Germany) New Zealand Met. Service Australian Bureau of Meteorology Fundação Universidade Federal do Rio Grande; Instituto Nacional de Metereologia; Centro de Hydrografia de Marinha; INPE (Nacional Space Institute); Brazilian Navy; Brazilian Naval Directorate of Hydrography and Navigation (Brazil) Fisheries Research Institute; Servicio de Hidrografía Naval (Argentina) Instituto Canario de Ciencias Marinas; Universidad de Las Palmas de Gran Canaria (Spain) Instituto Nazionale di Oceanografia e di Geofisica Sperimentale (Italy) National Institute of Oceanography; National Institute of Ocean Technology (India) Institute of Hydrological and Oceanic Services (Taiwan) Centro de Investigacion Cientifica y de Educacion Superior de Ensenada (Mexico) Korean Oceanographic Research and Dvelopment Institute, National Oceanographic Research Institute; Ministry of Maritime Affairs and Fisheries (Korea) Instituto del Mar del Peru Tristan da Cunha Administration, Tristan Island United Kingdom Met Office Fisheries Department of Falkland Islands Environment Canada University of Cape Town; South African Weather Service (South Africa) Scripps Institution of Oceanography, Woods Hole Oceanographic Institution, Oregon State University, Marine Resources Research Institute, NOAA/Pacific Marine Environmental Laboratory, NOAA/National Data Buoy Center (United States of America) United States Air Force US Naval Oceanographic Office United States Coast Guard Raytheon Polar Services

19. 19 NOAA’s Global Drifter Program Surface Currents, Sea Surface Temperature, Winds, Atmospheric Pressure and Surface Salinity www.aoml.noaa.gov/phod/dac/gdp.html Rick Lumpkin (Rick.Lumpkin@noaa.gov) National Oceanic and Atmospheric Administration (NOAA) Atlantic Oceanographic and Meteorological Laboratory (AOML) Miami, Florida USA