1. The WHOI – Hawaii Ocean Time-series Station (WHOTS) Roger Lukas, Robert Weller and Albert Plueddemann

2. WHOTS @ Station ALOHA is an element of NOAA’s Ocean Reference Stations part of the OceanSITES & JCOMM OPS international network leverages long record and context from HOT (e.g. carbon cycle and salinity/hydrological cycle) near-surface measurements in real-time facilitating research @ ALOHA

3. Mauna Loa ALOHA/HOT pH pCO 2 trends, ENSO and annual cycle resolved by HOT from PMEL ocean carbon website effects of eddies and storms are not resolved by HOT but are resolved by WHOTS (NOAA&NSF) pCO 2 air pCO 2 water NOAA/PMEL MAPCO 2 SIO & NOAA/ESRL UH & SIO & OSU & UW & UM & WHOI &… NSF & NOAA

4. WHOTS surface buoy (real-time) – wind, T, RH – Radiation (short, long, up/down) – Rainfall – Near-surface ocean T, S – pCO 2 air and water; pH (PMEL) – soon: fluorescence in water (Laney/WHOI) – future: wave spectrum Mooring (delayed mode) – u, T, C, S, P [0-155 m] – near-bottom microcat to be added(~4750 m) – dissolved oxygen is a goal

5. 4750 m T S focus on salinity and hydrological cycle

6. sea surface salinity @ Koko Head SSS @ ALOHA 2000 34.5 35.5 1950 z potential density (kg m -3 ) 25 26 27 Local and Remotely-Forced Salinity Trends and Variations HOT WHOTS 35.4 34 fully-resolved temporal sampling historical hydrographic profiles within 200 km of ALOHA (note gaps) 20001950 HOT cruises 1988 - present decadal variations long-term trend (disrupted 2009-2011) Gunter Seckel – Bureau of Commercial Fisheries Honolulu Laboratory

7. Salinity plays an important role in stability of upper ocean on interannual and decadal time scales, with effects on mixing and productivity (Corno et al., 2007; Bidigare et al., 2009) HOT mixed layer temperature, salinity and density (top) and anomalies (bottom). [Note inverted temperature scale] WHOTS (incl. air-sea fluxes) poor ocean forcing data

8. Can we understand and close the upper ocean salt budget?

9. Evaporation: Comparison of WHOTS with ECMWF-Interim important biases in mean and variance of ECMWF analyzed evaporation WHOTS decorrelation scale for evaporation large relative to reanalysis grid scale – not spatial mismatch daily averages r2r2

10. Precipitation: WHOTS net evaporative regime under core of Trade Winds Sean Whelan (WHOI) Rainfall – Has small space-time scales Not well-observed from space Poorly represented in NWP model-reanalyses

11. Trend removed from net cumulative P-E (the freshwater needed to balance must arrive from higher latitudes directly via surface currents, or be entrained into the mixed layer at ALOHA after transport in the upper pycnocline) WHOTS mixed layer salinity compared to WHOTS freshwater fluxes S(t) has some correspondence with local freshwater flux anomalies

12. comparison of MLD from WHOTS mooring (colored lines) with estimates from high-resolution CTD profiles during HOT and WHOTS cruises

13. Price-Weller-Pinkel mixed layer model forced with WHOTS air-sea fluxes WHOTS mooring mixed layer depth Need to bring in 3-D advective contributions

14. interannual variations of eddies enhanced shear  vertical mixing lateral eddy transports?? rotation of currents due to eddies

15. WHOTS Sustained, collaborative, interdisciplinary science Air-sea fluxes, ocean-truthing atmospheric reanalyses, forcing and benchmarking ocean models Creating a high-resolution surface and upper ocean climatology including atmospheric forcing and carbon variables Facilitating research on eddies and ecosystem dynamics Impacts as part of a global observational network Assessing ocean changes (incl. C) and enabling climate predictions Atmosphere and ocean modeling – Ocean Reference Stations Institutions & agencies needed to sustain infrastructure Sustained multi-institutional collaboration (WHOI, UH/SOEST, PMEL) Collaborative funding, NOAA, NSF and SOEST OceanSITES data management (setting metadata standards)  WHOTS met/fluxes and subsurface incl. V though mid-2011

16. Thank You! WHOTS data are available via http://uop.whoi.edu http://www.soest.hawaii.edu/WHOTS http://www.oceansites.org ftp://ftp.ifremer.fr/ifremer/oceansites/ ftp://data.ndbc.noaa.gov/data/oceansites/

17. Salinity Trends on Isopycnals Freshening 24.8-26.3 σ θ (180-350 m) Max S↓ @ 25.4 -0.11/decade large! The freshening signal is very robust on isopycnal surfaces, filtering out noise from internal waves Smaller signal, but correlated with O 2 and nutrients Large upper pycnocline decadal variation since 2007 has disrupted mid-pycnocline trend

18. 20-Year Long Thermohaline Trends @ ALOHA Warming over much of upper ocean (x 275-350 m!) Peak warming 150-200 m (S max ), not at surface Cooling below 700 m Salinity increasing in upper 200 m Freshening in the thermocline θ(z)S(z) 0.4 °C/decade 0.16/decade 0-100 m density ↑; 100-1000 density ↓ Stratification ↓ in upper ocean! deeper mixing  productivity

19. Salinity trends on Isopycnals water on heavier isopycnals comes from farther away (Δpsu/50 yrs) 24 σ θ 25 σ θ Durack and Wijffels (2010) 26.75 σ θ 27.5 σ θ

20. Salinity Trends on Neutral Surfaces Durack and Wijffels (2010) zonally averaged salinity trends (Δpsu/1950-2008 ) 70 S70 N

21. Subduction of ML salinity anomalies + anomalous subduction Analysis of Argo float data Sasaki et al. (2010, GRL); see also Ren and Riser (2010, (Deep-Sea Research II – Suginohara memorial issue) Evolution of a fresh/cold anomaly

22. Updated and adapted from Dore et al. (2009, Proc Natl Acad Sci USA 106:12235 ) pH of surface ocean Acidification @ ALOHA pH trend vs depth Annual, interannual, decadal and longer term changes in surface forcing, mixing, and advection Local and remote physics are crucial, not just pCO 2, temperature and biology pH DIC This point was made in the paper Maximum not in surface layer

24. Integrated net heat flux (ΔT*MLD) Clearly, cold and salty water must be transported into the surface layer at ALOHA by some combination of horizontal advection, upwelling, and vertical mixing to provide a mean balance – how much do they contribute to interannual – decadal variations?