November 28, 2006 Representation of Skin Layer and Diurnal Warming Effects Gary Wick 1 and Sandra Castro 2 1 NOAA Earth System Research Laboratory 2 CCAR, University of Colorado

MISST Project Review November 28, 2006 Motivation Referencing retrievals to common time and measurement depth Production of SST analyses at arbitrary depths from the foundation analysis

MISST Project Review November 28, 2006 SST Definition Interface Skin Subskin Depth Foundation Temperature at a depth uninfluenced by diurnal warming NightDay TT From Donlon et al., 2002

MISST Project Review November 28, 2006 Skin Layer Cooling Multiple models proposed, extending back to Saunders (1967). Formally, a function of wind stress and the net heat flux at the interface Simplified model as a function of wind speed only proposed by Donlon et al. (2002). From Donlon et al., 2002  T = – 0.3 EXP(-u/3.7)

MISST Project Review November 28, 2006 Skin Effect Evaluation Evaluation to assess accuracy of simple skin layer treatment with available satellite wind products –Existing models –New exponential fit Direct skin observations matched with SSM/I wind speed retrievals Initially considered matches within 12 hours –Tightened time constraints –Mean of surface observations matched with satellite retrievals

MISST Project Review November 28, 2006 Skin Effect Observations Infrared skin temperature measurements from the CIRIMS of A. Jessup Through-the-hull temperature measurements at 2-m depth NOAA Ronald H. Brown Courtesy A. Jessup

MISST Project Review November 28, 2006 Nighttime Evaluation

MISST Project Review November 28, 2006 Revised Model  T = EXP(-0.38 u) Uncertainty: ~0.1 K

MISST Project Review November 28, 2006 Additional Dependencies? Matched satellite-derived estimate of turbulent heat flux to  T observations –Near-surface air temperature and specific humidity from Jackson et al. (2006) –Flux calculation using the COARE 3.0 algorithm Dependency observed, but no predictive skill for independent observations  T Residual

MISST Project Review November 28, 2006 Daytime Approach Revised model directly applicable to nighttime observations, but what about daytime? Two options: –Skin layer directly incorportated in diurnal warming (preferred) –Apply derived skin model to estimated sub-skin temperature

MISST Project Review November 28, 2006 Impact of Solar Absorption Simple new model compared with detailed cool skin model of Fairall et al. (1996) Good agreement at nighttime More difference during the day due to absorbed insolation

MISST Project Review November 28, 2006 Diurnal Study Objectives Assess ability to model warming at arbitrary depths Develop detailed uncertainty estimates Assess turbulent mixing schemes Evaluated warming using: –CIRIMS observations –SkinDeEP profiles

MISST Project Review November 28, 2006 Numerical Models Kantha and Clayson 2 nd moment turbulence closure –Enhanced turbulent mixing schemes –Refined solar penetration model Cool skin/warm layer component of the COARE 3.0 bulk flux algorithm (Fairall et al., 1996) –Based on Price, Weller, and Pinkel –Used for flux calculations

MISST Project Review November 28, 2006 CIRIMS Warming Assessment

MISST Project Review November 28, 2006 SkinDeEP Skin Depth Experimental Profiler –Measures temperature and conductivity with sub-centimeter resolution in the upper 10 m of the ocean Simulated several deployments during the Marine Optical Characterization Experiment (MOCE-5) in 1999.

MISST Project Review November 28, 2006 SkinDeEP Evaluation

MISST Project Review November 28, 2006 Conclusions Skin effect can be estimated to ~0.1 K accuracy using satellite-derived wind speeds Estimates of skin layer cooling provided with microwave level 2 (orbital) products Can provide skin layer analysis in conjunction with derived foundation temperature analysis Enhanced turbulent mixing schemes required to improve modeled diurnal warming