Indirect air–sea interactions simulated with a coupled turbulence-resolving model

A turbulence-resolving parallelized atmospheric large-eddy simulation model (PALM) has been applied to study turbulent interactions between the humid atmospheric boundary layer (ABL) and the salt water oceanic mixed layer (OML). The most energetic three-dimensional turbulent eddies in the ABL–OML system (convective cells) were explicitly resolved in these simulations. This study considers a case of shear-free convection in the coupled ABL–OML system. The ABL–OML coupling scheme used the turbulent fluxes at the bottom of the ABL as upper boundary conditions for the OML and the sea surface temperature at the top of the OML as lower boundary conditions for the ABL. The analysis of the numerical experiment confirms that the ABL–OML interactions involve both the traditional direct coupling mechanism and much less studied indirect coupling mechanism (Garrett Dyn Atmos Ocean 23:19–34, 1996). The direct coupling refers to a common flux-gradient representation of the air–sea exchange, which is controlled by the temperature difference across the air–water interface. The indirect coupling refers to thermal instability of the Rayleigh–Benard convection, which is controlled by the temperature difference across the entire mixed layer through formation of the large convective eddies or cells. The indirect coupling mechanism in these simulations explained up to 45 % of the ABL–OML co-variability on the turbulent scales. Despite relatively small amplitude of the sea surface temperature fluctuations, persistence of the OML cells organizes the ABL convective cells. Water downdrafts in the OML cells tend to be collocated with air updrafts in the ABL cells. The study concludes that the convective structures in the ABL and the OML are co-organized. The OML convection controls the air–sea turbulent exchange in the quasi-equilibrium convective ABL–OML system.

[1]  Hanna Pawlowska,et al.  A new method for large-eddy simulations of clouds with Lagrangian droplets including the effects of turbulent collision , 2012 .

[2]  Ulrich Schumann,et al.  Coherent structure of the convective boundary layer derived from large-eddy simulations , 1989, Journal of Fluid Mechanics.

[3]  Louis J. Wicker,et al.  Time-Splitting Methods for Elastic Models Using Forward Time Schemes , 2002 .

[4]  Antti Hellsten,et al.  Role of Convective Structures and Background Turbulence in the Dry Convective Boundary Layer , 2013, Boundary-Layer Meteorology.

[5]  C. Kottmeier,et al.  Roll Vortices and Boundary-Layer Development during a Cold Air Outbreak , 1997 .

[6]  Valerio De Angelis,et al.  Direct numerical simulation of near-interface turbulence in coupled gas-liquid flow , 1996 .

[7]  M. Tomczak,et al.  Tropical ocean response to atmospheric forcing at kilometer scales with light precipitation , 2001 .

[8]  Siegfried Raasch,et al.  A new method for large-eddy simulations of clouds with Lagrangian droplets including the effects of turbulent collision , 2012 .

[9]  R. Rotunno,et al.  Vertical-Velocity Skewness in the Buoyancy-Driven Boundary Layer , 1990 .

[10]  C. Frankignoul.  Sea surface temperature anomalies, planetary waves, and air‐sea feedback in the middle latitudes , 1985 .

[11]  Sanjoy Banerjee,et al.  The effect of boundary conditions and shear rate on streak formation and breakdown in turbulent channel flows , 1990 .

[12]  Siegfried Raasch,et al.  Modeling deep ocean convection: Large eddy simulation in comparison with laboratory experiments , 1998 .

[13]  I. Esau.  Amplification of turbulent exchange over wide Arctic leads: Large‐eddy simulation study , 2007 .

[14]  Siegfried Raasch,et al.  Heterogeneity-Induced Heat-Flux Patterns in the Convective Boundary Layer: Can they be Detected from Observations and is There a Blending Height?—A Large-Eddy Simulation Study for the LITFASS-2003 Experiment , 2013, Boundary-Layer Meteorology.

[15]  Lian Shen,et al.  Investigation of coupled air-water turbulent boundary layers using direct numerical simulations , 2009 .

[16]  Tong Lee,et al.  Mechanisms controlling the seasonal mixed-layer temperature and salinity of the Indonesian seas , 2011 .

[17]  Bernd Weissmuller.  The Near Surface Layer Of The Ocean , 2016 .

[18]  C. Lévi-Strauss,et al.  Experimental investigation , 2013 .

[19]  J. Deardorff.  Cloud Top Entrainment Instability , 1980 .

[20]  Siegfried Raasch,et al.  PALM - A large-eddy simulation model performing on massively parallel computers , 2001 .

[21]  T. Delcroix,et al.  An assessment of the mixed layer salinity budget in the tropical Pacific Ocean. Observations and modelling (1990–2009) , 2012, Ocean Dynamics.

[22]  R. Lukas,et al.  The Near-Surface Layer of the Ocean: Structure, Dynamics and Applications , 2010 .

[23]  Lian Shen,et al.  The Coupled Boundary Layers and Air–Sea Transfer Experiment in Low Winds , 2007 .

[24]  M. Latif,et al.  North Atlantic Ocean control on surface heat flux on multidecadal timescales , 2013, Nature.

[25]  J. S. Godfrey,et al.  A diagnostic model of the diurnal cycle of sea surface temperature for use in coupled ocean‐atmosphere models , 2005 .

[26]  Djamel Lakehal,et al.  Turbulence and heat exchange in condensing vapor-liquid flow , 2008 .

[27]  Carol Anne Clayson,et al.  The Effect of Diurnal Sea Surface Temperature Warming on Climatological Air–Sea Fluxes , 2013 .

[28]  Prashant D. Sardeshmukh,et al.  A Global View of Non-Gaussian SST Variability , 2008 .

[29]  I. Esau,et al.  Links between observed micro-meteorological variability and land-use patterns in the highveld priority area of South Africa , 2012, Meteorology and Atmospheric Physics.

[30]  Belmonte,et al.  Thermal signature of plumes in turbulent convection: The skewness of the derivative. , 1996, Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics.

[31]  C. Garrett.  Processes in the surface mixed layer of the ocean , 1996 .

[32]  Carol Anne Clayson,et al.  Sensitivity of a Coupled Single-Column Model in the Tropics to Treatment of the Interfacial Parameterizations. , 2002 .

[33]  Y. Noh,et al.  Influence of the Coriolis force on the formation of a seasonal thermocline , 2013, Ocean Dynamics.

[34]  Guy N. Pearson,et al.  Vertical velocity variance and skewness in clear and cloud‐topped boundary layers as revealed by Doppler lidar , 2009 .

[35]  J. S. Godfrey,et al.  On the turbulent fluxes of buoyancy, heat and moisture at the air-sea interface at low wind speeds , 1991 .

[36]  I. Steinhorn.  On the concept of evaporation from fresh and saline water bodies , 1991 .

[37]  Christopher W. Fairall,et al.  The influence of large convective eddies on the surface‐layer turbulence , 2006 .

[38]  I. Esau.  The Coriolis effect on coherent structures in planetary boundary layers , 2003 .

[39]  Igor Esau,et al.  Simulation of Ekman Boundary Layers by Large Eddy Model with Dynamic Mixed Subfilter Closure , 2004 .

[40]  Siegfried Raasch,et al.  The role of preconditioning in the evolution of open-ocean deep convection , 2003 .

[41]  J. Wyngaard,et al.  Application of a subfilter-scale flux model over the ocean , 2009 .

[42]  P. Sardeshmukh,et al.  A global view of air–sea thermal coupling and related non-Gaussian SST variability , 2009 .

[43]  Alberto Scotti,et al.  Large eddy simulation in the ocean , 2010 .

[44]  J. Saylor,et al.  An experimental investigation of the surface temperature field during evaporative convection , 2001 .

[45]  Siegfried Raasch,et al.  Examination of the Mixed Layer Deepening Process during Convection Using LES , 2010 .

[46]  Godfrey L. Smith,et al.  The thermal structure of an air–water interface at low wind speeds , 2001 .

[47]  Observations of planview flux patterns within convective structures of the marine atmospheric surface layer , 1993 .

[48]  J. Deardorff,et al.  Further results from a laboratory model of the convective planetary boundary layer , 1985 .

[49]  J. Curry,et al.  Evaluation of turbulent fluxes at the ocean surface using surface renewal theory , 1996 .

[50]  I. Esau,et al.  Universal dependences between turbulent and mean flow parameters instably and neutrally stratified Planetary Boundary Layers , 2006 .

[51]  M. Gregg,et al.  Convectively-driven turbulent mixing in the upper ocean , 1986 .

[52]  Paul Manneville,et al.  Rayleigh-Bénard Convection: Thirty Years of Experimental, Theoretical, and Modeling Work , 2006 .

[53]  J. McWilliams,et al.  Surface gravity wave effects in the oceanic boundary layer: large-eddy simulation with vortex force and stochastic breakers , 2007, Journal of Fluid Mechanics.

[54]  Judith A. Curry,et al.  Which Bulk Aerodynamic Algorithms are Least Problematic in Computing Ocean Surface Turbulent Fluxes , 2003 .

[55]  E. F. Bradley,et al.  Bulk Parameterization of Air–Sea Fluxes: Updates and Verification for the COARE Algorithm , 2003 .

[56]  Yoshimi Kawai,et al.  Diurnal sea surface temperature variation and its impact on the atmosphere and ocean: A review , 2007 .

[57]  James C. McWilliams,et al.  Large-Eddy Simulations and Observations of Atmospheric Marine Boundary Layers above Nonequilibrium Surface Waves , 2008 .

[58]  Effects of mesoscale atmospheric convection cells on the waters of the East China Sea , 1982 .

[59]  Rainer Feistel,et al.  Algorithms for Density, Potential Temperature, Conservative Temperature, and the Freezing Temperature of Seawater , 2006 .