1 / 47

The Hawaii Ocean Time-series and Science at Station ALOHA

The Hawaii Ocean Time-series and Science at Station ALOHA. Roger Lukas GES 100 9/22/11. What is a time-series?. Exploration/discovery in time in a consistent way!. green and orange symbols show different methods. expeditions. trend analysis highly uncertain.

walker
Download Presentation

The Hawaii Ocean Time-series and Science at Station ALOHA

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The Hawaii Ocean Time-series and Science at Station ALOHA Roger Lukas GES 1009/22/11

  2. What is a time-series? Exploration/discovery in time in a consistent way! green and orange symbols show different methods expeditions trend analysis highly uncertain Understanding Signals versus “Noise”(and Instrument/Methods Errors)

  3. Why do we need time series? • Expeditionary measurements explore the ocean and map distributions of stuff • affected by time in unknown ways (aliasing) • difficult to study processes and trends (rates of change) Aliasing

  4. visual aliasing due to inadequate resolution of brick wall structure

  5. processes Observational platforms The Ocean Sampling Problem Tommy Dickey (UCSB)

  6. Objectives of HOT • Observe and understand ocean physics and climate variations • Observe and understand biogeochemistry and ecosystem variations and their relation to climate

  7. What is HOT? • ~ monthly cruises since 1988 • NSF, State of Hawaii, NOAA, etc funding

  8. Why Station ALOHA? North Pacific subtropical gyre Representative of the subtropical gyre Deep ocean (~4800 m) Far enough from direct island influences Close enough to Honolulu(one day roundtrip)

  9. What (and how) do we measure? Shipboard lowering, water collection, drifting arrays, moorings

  10. What (and how) do we measure? • Moorings – show WHOTS deployment/recovery video • ACO deployment and seafloor video • Real-time data • audio! • video … • Gliders give us spatial perspective Shipboard Acoustic Doppler Current Profiler

  11. What (and how) do we measure? • ACO deployment and seafloor video • Real-time data • audio! • video …

  12. ALOHA Kauai Deep Oahu Seamounts Kaena Pt. Maui Deep Kahe Pt. HAW-4 cable Makaha cable station

  13. ALOHA Kauai Deep Oahu Seamounts Kaena Pt. Maui Deep Kahe Pt. HAW-4 cable Makaha cable station

  14. ALOHA Kauai Deep Oahu Seamounts cold overflow events Kaena Pt. Maui Deep Kahe Pt.

  15. What have we learned? • Variations and change are the rule in the ocean • Ocean climate is changing • Ocean and atmospheric physics drive ecosystem • Ecosystem is much more complex than imagined 20 years ago • 1-dimensional (depth-time) models are not adequate; advection is important (hmmm, currents)

  16. What is changing in the ocean? • Sea level • Temperature • Salinity • Circulation • Mixing • Biogeochemistry (CO2, pH, O2, nutrients, primary production, …) Density; stratification complex coupling

  17. Physics and Climate • Distinct trends over 20+ years • ENSO –> decadal large-scale wind and rainfall variations result in complex ocean changes • Salinity effects on stability (resistance to mixing) • Eddies are frequent • Internal tides – ALOHA is hot spot • Abyssal circulation – cold events and turbulence

  18. surface salinity 1 psu 1988 2007 1950 2007 Station ALOHALukas and Santiago-Mandujano (2008) 1988 2007

  19. Thermohaline Trends @ ALOHA θ(z) S(z) • Warming over much of upper ocean (x 275-350 m!) • Peak warming 150-200 m (Smax), not at surface • Cooling below 700 m • Salinity increasing in upper 200 m • Freshening in the thermocline 0.16/decade 0.4 °C/decade

  20. Density and Stratification σθ(z) N(z) • 0-100 m density ↑ • 100-1000 density ↓ • Stratification ↓ in upper ocean • 200-350 m ↑ 0 m Less stable dark blue – annual meanslight blue – cruise means more stable 200 m

  21. Low N:P of entrained nutrients Mean Nitracline Depth Updated and adapted from Dore et al. 2008, Prog Oceanogr 76:2

  22. Biogeochemistry • ENSO – decadal productivity and other ecosystem • regime shifts – N2 to P limitation • importance of events (e.g. eddies) to long-term upper-ocean nutrients and productivity

  23. pCO2 of surface ocean and overlying atmosphere

  24. Acidification @ ALOHA Updated and adapted from Dore et al. (2009, Proc Natl Acad Sci USA 106:12235 ) DIC Maximum not in surface layer pH of surface ocean pH trendvsdepth Annual, interannual, decadal and longer term changes in surface forcing, mixing, and advection Local and remote physics are crucial, not just pCO2, temperature and biology pH This point was made in the paper

  25. Anomalies of pH and mixed layer depth Updated and adapted from Dore et al. 2009, Proc Natl Acad Sci USA 106:12235

  26. P-stimulation of N2-supported blooms Dave Karl NASA

  27. Sources and sinks of DIC – balancing budgets Keeling et al. 2004, Global Biogeochem Cycles 18, GB4006, doi:10.1029/2004GB002227

  28. Resources • http://aloha.manoa.hawaii.edu • http://www.soest.hawaii.edu/HOT_WOCE/ • http://hahana.soest.hawaii.edu/hot/hot_jgofs.html • http://www.soest.hawaii.edu/whots/ • http://aco-ssds.soest.hawaii.edu/ACO • http://www.whoi.edu/virtual/oceansites/index.html • Karl, D.M., J.E. Dore, R. Lukas, A.F. Michaels, N.R. Bates, and A. Knap, 2001: Building the Long-Term Picture: The U.S. JGOFS Time-Series Programs. Oceanography 14(4):6-17 • Karl, D.M. 2010. Oceanic ecosystem time-series programs: Ten lessons learned. Oceanography 23(3):104–125, doi:10.5670/oceanog.2010.27.

  29. ALOHA Kauai Deep Oahu Seamounts Kaena Pt. Maui Deep Kahe Pt.

  30. pH of surface ocean Updated and adapted from Dore et al. 2009, Proc Natl Acad Sci USA 106:12235

  31. Acidification by carbonic acid Adapted from Dore et al. 2009, Proc Natl Acad Sci USA 106:12235

  32. Dissolved Oxygen and Nutrients O29 μmol/kg/decade Phosphate0.06 μmol/kg/decade Remineralization of organic material along streamlines?

More Related