Meteorology and Air-Sea Fluxes from Ocean Reference Stations Al Plueddemann and Bob Weller, WHOI, Woods Hole, MA ORS provide accurate surface meteorology and air-sea fluxes at key sites The goals are to: Quantify air-sea exchanges of heat, freshwater and momentum Describe the local oceanic response to atmospheric forcing Assess and motivate improvements to NWP and satellite products Provide anchor points for the development of new, basin scale flux fields

Geographic Distribution Three ORS are presently operational: STRATUS (initiated Oct 2000) NTAS (initiated March 2001) WHOTS (initiated August 2004) UOP is also operating ASIMET meteorological systems on three VOS lines (see Weller, Bahr and Hosom poster)

Stratus First long-term, high quality surface flux measurements beneath the Peru/Chile stratus deck Key issues: Cooling influence of stratus clouds on local and global heat balance Role of stratus clouds in maintaining the equatorial asymmetry of sea surface temperatures and winds

NTAS Long-term surface flux record in NE trade wind region of tropical Atlantic Key issues: Air-sea interaction processes controlling local SST variability and the cross-equatorial SST gradient Modulation of the annual cycle of ITCZ migration and its role in regional climate dynamics

WHOI-HOT Site (WHOTS) Deployment of HOT site ORS accelerated as a result of cooperation between NOAA/OCO and NSF First 9 months of meteorological data available on UOP web site, mooring turnaround scheduled for July 2005 Key addition to a long-standing, interdisciplinary ocean observatory

Partnerships/Collaborations WHOTS: Fluxes for HOT; Ocean sensors from R. Lukas, UH (NSF) Stratus: Chilean Universities; Chilean and Ecuadorian Naval Hydrographic Offices; DART buoy servicing; Focal point for CLIVAR VOCALS process study NTAS: Co-located with GAGE/ MOVE transport array; Dialog with NHC/TPC for data exchange ECMWF: Data Exchange ORS Concept: Expansion to be proposed to NSF/ORION NCEP: Routinely acquire and examine reanalysis products. ETL: Field intercomparisons Argo: Drifter and float deployments Participation in international planning and management activities through: CLIVAR, CCSP, OOCP, GOOS, GWEX, SOLAS, ORION, OceanSITES With links to: NRC, WCRP, JCOMM, POGO, SURFA, CPT-Clouds, CPT-EMILIE, … Radiometer data: Instruments on NDBC buoys, Chesapeak Light Tower (BSRN); Data to PCMDI; CERES- ARM Validation Exp; Establishment of GEWEX Radiation Panel - Ocean Subgroup

Sensor Calibration Pre- and post-calibration at WHOI and by sensor manufacturers Field intercomparisons: buoy vs. ship and buoy vs. buoy Adjustment of bias and drift prior to flux calculation by bulk formulas

Sensor Accuracy First-generation IMET systems evaluated by Hosom et al., 1995 Second-generation ASIMET presently being evaluated (Colbo, et al.)

The Seasonal Cycle of Surface Heating NTAS Stratus

Seasonal Cycle: NTAS Comparison with NWP products and climatology Qnet: NWP biased low, 2 yr means are <0 whereas buoy shows +40 W/m 2 Timing of zero-crossings differ by 1-2 months Climatology better than any of the model products  : NWP typically within 0.01 of buoy and clearly better than climatology

Seasonal Cycle: Stratus Comparison with NWP products and climatology Heat flux components: Qsw: NCEP1 biased low, NCEP2 seasonal high- bias Qlw: NCEP2 biased low Qlat: Both NCEP1 and 2 show low bias Qsen: NCEP1 low bias Qnet: NCEP1 low, NCEP2 high

Annual Mean Heat Flux Comparison with NWP and reanalysis products NTAS Stratus ECMWF Qnet disagrees with buoy by ~25 W/m 2 in both years Interannual variability at buoy not reflected in ECMWF ECMWF agrees well with climatology NWP products under-estimate buoy Qnet by W/m2 Latent and shortwave fluxes are the primary contributors to discrepancy NWP products do not agree well with climatology

Improved Regional Flux Fields Evaluation of in-situ data vs. NWP products (Sun, Yu and Weller, 2003) Improved fluxes using NWP and satellite data: Synthesis using objective analysis, Validation with in-situ data (North Atlantic: Yu, Weller and Sun, 2004) Diagnosis of climate trends in the synthesized fluxes (Yu, Weller, and Jin, in progress)

Heat Budget Estimates Annual mean heat budget estimated at the Stratus site (Colbo and Weller, in progress) Non-local cooling is required to balance the surface fluxes Upwelled coastal water has little impact at the mooring site Eddy flux divergence is important even though overall eddy KE is relatively low

Synergy with the global observing system Colbo and Weller heat budget estimate uses a combination of: ORS mooring fluxes and heat content Satellite SST (Reynolds, TRMM/TMI) Satellite winds (QuikSCAT SeaWinds scatterometer) Surface drifter trajectories (Pazan and Niiler, MEDS/AOML) Climatology (World Ocean Atlas) Satellite altimetry (TOPEX/Poseidon)

Recommendations Improvements to ORS Portable shipboard met standard High latitude sites Direct covariance fluxes and motion packages on buoys Near real-time heat content from moorings Improved regional and global flux fields Continued validation, assessment and synthesis studies