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1. Introduction Accurate estimation and identification of the mechanisms controlling air–sea heat fluxes in the mid- and subpolar latitudes are both critically important for diagnosing their role in ocean and atmospheric dynamics. In the North Atlantic, very high heat fluxes cause anomalous surface density fluxes, resulting in the surface transformation of water masses and associated deep convection of the Labrador and Greenland–Iceland–Norwegian (GIN) Seas ( Moore et al. 2014 ; Holdsworth and
1. Introduction Accurate estimation and identification of the mechanisms controlling air–sea heat fluxes in the mid- and subpolar latitudes are both critically important for diagnosing their role in ocean and atmospheric dynamics. In the North Atlantic, very high heat fluxes cause anomalous surface density fluxes, resulting in the surface transformation of water masses and associated deep convection of the Labrador and Greenland–Iceland–Norwegian (GIN) Seas ( Moore et al. 2014 ; Holdsworth and
1. Introduction Surface momentum, sensible heat, and latent heat fluxes are critical for atmospheric processes such as clouds and precipitation, and are often parameterized in a variety of models due to limited grid resolution in these models, such as the Weather Research and Forecasting (WRF) model ( Skamarock et al. 2008 ) and general circulation models (GCMs). In numerical models, these turbulent flux parameterizations are collectively referred to as the surface flux parameterization (SFP
1. Introduction Surface momentum, sensible heat, and latent heat fluxes are critical for atmospheric processes such as clouds and precipitation, and are often parameterized in a variety of models due to limited grid resolution in these models, such as the Weather Research and Forecasting (WRF) model ( Skamarock et al. 2008 ) and general circulation models (GCMs). In numerical models, these turbulent flux parameterizations are collectively referred to as the surface flux parameterization (SFP
while Gallimore and Johnson (1981) and Johnson (1980a) based their calculations on isentropic θ coordinates. The tropical Hadley circulation is the dominant feature in p coordinates. Transient meridional eddy fluxes are directed poleward. These findings led to the generally accepted qualitative picture that the AAM removed in the midlatitudes by surface friction is replenished by eddy fluxes out of the tropics (e.g., Holton 1992 , his Fig. 10.10). Thus, vertical fluxes in midlatitudes would
while Gallimore and Johnson (1981) and Johnson (1980a) based their calculations on isentropic θ coordinates. The tropical Hadley circulation is the dominant feature in p coordinates. Transient meridional eddy fluxes are directed poleward. These findings led to the generally accepted qualitative picture that the AAM removed in the midlatitudes by surface friction is replenished by eddy fluxes out of the tropics (e.g., Holton 1992 , his Fig. 10.10). Thus, vertical fluxes in midlatitudes would
conclusive, there is a general consensus that the C d ceases to increase with wind speed at high wind speeds. Therefore, the present parameterization of the C d in atmospheric models, where the C d linearly increases with wind speed, clearly overestimates the momentum flux at high wind speeds. The overestimated momentum flux likely contributes to the limited skill of numerical hurricane intensity prediction. Reduced C d at high winds will likely have a significant impact not only on hurricane
conclusive, there is a general consensus that the C d ceases to increase with wind speed at high wind speeds. Therefore, the present parameterization of the C d in atmospheric models, where the C d linearly increases with wind speed, clearly overestimates the momentum flux at high wind speeds. The overestimated momentum flux likely contributes to the limited skill of numerical hurricane intensity prediction. Reduced C d at high winds will likely have a significant impact not only on hurricane
1. Introduction The turbulent fluxes of momentum τ , sensible heat H S , and latent heat L E at the air–sea interface characterize the exchanges of mechanical energy, temperature, and humidity between the sea and the atmosphere. The calculation of these fluxes is a key issue in climatology, meteorology, and oceanography because air–sea fluxes are a boundary condition for models of the atmosphere and the ocean. In most applications, turbulent fluxes are derived from
1. Introduction The turbulent fluxes of momentum τ , sensible heat H S , and latent heat L E at the air–sea interface characterize the exchanges of mechanical energy, temperature, and humidity between the sea and the atmosphere. The calculation of these fluxes is a key issue in climatology, meteorology, and oceanography because air–sea fluxes are a boundary condition for models of the atmosphere and the ocean. In most applications, turbulent fluxes are derived from
of heat from warm North Atlantic surface waters to the atmosphere causes ocean water to sink as part of the MOC, an important component of the global heat budget ( Bacon et al. 2003 ; Pickart et al. 2003 ; Sproson et al. 2008 ; Petersen and Renfrew 2009 ; Våge et al. 2011 ). Strong winds affect the ocean surface by inducing large sensible and latent heat fluxes from the ocean to the atmosphere, which decreases ocean water buoyancy and, in the right conditions, can lead to oceanic convection
of heat from warm North Atlantic surface waters to the atmosphere causes ocean water to sink as part of the MOC, an important component of the global heat budget ( Bacon et al. 2003 ; Pickart et al. 2003 ; Sproson et al. 2008 ; Petersen and Renfrew 2009 ; Våge et al. 2011 ). Strong winds affect the ocean surface by inducing large sensible and latent heat fluxes from the ocean to the atmosphere, which decreases ocean water buoyancy and, in the right conditions, can lead to oceanic convection
1. Introduction The thermodynamic disequilibrium between the tropical atmosphere and ocean provides an energy source for tropical cyclones (e.g., Kleinschmidt 1951 ; Emanuel 1986 ), arising primarily from the undersaturation of near-surface air. The dependence of the air–sea energy transfer rate on wind has been hypothesized to be the principal feedback mechanism that allows hurricanes to develop (e.g., Emanuel 2003 ). Hence, accurate knowledge of the latent heat flux across the air
1. Introduction The thermodynamic disequilibrium between the tropical atmosphere and ocean provides an energy source for tropical cyclones (e.g., Kleinschmidt 1951 ; Emanuel 1986 ), arising primarily from the undersaturation of near-surface air. The dependence of the air–sea energy transfer rate on wind has been hypothesized to be the principal feedback mechanism that allows hurricanes to develop (e.g., Emanuel 2003 ). Hence, accurate knowledge of the latent heat flux across the air
microphysics species, and places the considerable research using MM5 and WRF regarding orographic precipitation in context. Finally, another source of model error will be reviewed: model deficiencies in initializing and simulating the moisture fluxes approaching the Northwest terrain. 2. Positive-definite moisture advection Some moisture quantities, such as cloud liquid water, tend to have sharp gradients. The proximity of these sharp gradients to zero values makes these variables particularly susceptible
microphysics species, and places the considerable research using MM5 and WRF regarding orographic precipitation in context. Finally, another source of model error will be reviewed: model deficiencies in initializing and simulating the moisture fluxes approaching the Northwest terrain. 2. Positive-definite moisture advection Some moisture quantities, such as cloud liquid water, tend to have sharp gradients. The proximity of these sharp gradients to zero values makes these variables particularly susceptible
. Atmospheric rivers do not represent true trajectories of the core region of water vapor transport. Rather, they depict the instantaneous position of corridors of enhanced water vapor flux, typically focused in the lower troposphere below ∼700 hPa and in the portion of the warm conveyor belt near the leading edge of the polar cold front. Similarly, jet streams/jet streaks are instantaneous snapshots of corridors of enhanced flow rather than a trajectory perspective of these flow features. The majority
. Atmospheric rivers do not represent true trajectories of the core region of water vapor transport. Rather, they depict the instantaneous position of corridors of enhanced water vapor flux, typically focused in the lower troposphere below ∼700 hPa and in the portion of the warm conveyor belt near the leading edge of the polar cold front. Similarly, jet streams/jet streaks are instantaneous snapshots of corridors of enhanced flow rather than a trajectory perspective of these flow features. The majority
flux of scalar quantities such as heat or moisture across the boundary as well. A brief overview of the method is presented in the following section. Section 3 describes the implementations of the method in both pressure–velocity and vorticity–streamfunction models and introduces a simple 2D test problem designed to demonstrate the accuracy of the implementations. The performance of the method for a series of 3D problems is considered in section 4 . Both a topographic wake problem and a thermal
flux of scalar quantities such as heat or moisture across the boundary as well. A brief overview of the method is presented in the following section. Section 3 describes the implementations of the method in both pressure–velocity and vorticity–streamfunction models and introduces a simple 2D test problem designed to demonstrate the accuracy of the implementations. The performance of the method for a series of 3D problems is considered in section 4 . Both a topographic wake problem and a thermal
