1. ASCOS ocean boundary layer measurements Anders Sirevaag Sara de la Rosa WWW.BJERKNES.UIB.NO

2. Instrument systems:  Turbulence mast  Microstructure profiling  CTD measurements  Ice thermistors  Spectral radiometers & Transmission sensor Objectives:  Provide background hydrographic conditions in the upper ocean.  Measure and estimate fluxes of heat and salt at the ice/ocean interface.  Estimate mixing and turbulent fluxes in the mixed layer and across the pycnocline.

3. Turbulence mast Measurements:  3-D velocity, temperature and salinity.  2 levels in the surface layer Provides:  Covariance fluxes of heat, salt and momentum.  TKE terms in the surface layer. Sampling:  Continuous, maintain and adjust every ~ 6 - 12 hours

4. Microstructure profiler Measurements:  Profile of velocity shear; profiles of small scale temperature and salinity variations.  Range: 200 – 300m Provides:  Direct estimate of dissipation in and below mixed layer.  Calculated fluxes of heat and salt. Sampling:  Manual  As continuous as working schedule permits.

5. CTD measurements: Measurements:  Pressure, temperature, salinity  Range 200-300 m Provide:  Background stratification of mixed layer and pycnocline Sampling:  Manual  Every ~6 hours would be optimal

6. Spectral radiation Measurements:  Albedo  Transmission into ice and ocean  Snow-pit observations (thickness, temperature, density and grain size) Under-ice sensor 1m below Provide:  Optical surface properties & energy balance  Reflected and absorbed radiation Sampling:  Continous & Manual (once a week) TriOS Ramses spectral radiometers (cosine receptor, 320-950 nm)

7. Optimal outcome:  Verification of existing automated measurements in high arctic.  Provide some of the background dataset for development of new mixing parametrizations.  Contribution to NorClim – Climate of Norway and the Arctic in the 21st Century  Test and validate parametrizations of mixed layer dynamics and thermodynamics - 1Dimensional sea-ice model (Björk,1989,1997)