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Joseph Egger and Klaus-Peter Hoinka

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

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William B. Bennett, Jingfeng Wang, and Rafael L. Bras

1. Introduction Ground heat flux (GHF), one of the main components of the land surface energy budget, is the dominant source of energy near the surface soil layer and is of primary importance to the ecosystem of the earth. GHF is comparable in magnitude to sensible and latent heat flux over relative dry soil at a diurnal time scale. The widely used Penman approach (e.g., Arya 1988 ) for the estimation of evaporation in land surface schemes of regional and global climatic models requires GHF

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L. Mahrt and Tihomir Hristov

1. Introduction The literature has largely excluded measurements of small values of the air–sea temperature difference for prediction of the surface heat flux because of suspected important observational errors and perceived ill-defined behavior in the relationship between the surface heat flux and small values of the air–sea temperature difference. Exceptions include Smedman et al. (2007) , who were able to determine the air–sea temperature difference down to small values on the order of 0

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Erik Sahlée, Ann-Sofi Smedman, Anna Rutgersson, and Ulf Högström

1. Introduction The single most important source of atmospheric water vapor is evaporation from the global oceans ( Peixoto and Oort 1992 ). Thus, it is easy to realize the importance of understanding the processes governing the air–sea flux of water vapor for predicting and understanding climate and climate change. Compared to the latent heat flux, the air–sea flux of sensible heat per area unit is generally much smaller over the ocean. However, since the global oceans cover about 70% of the

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Kun Yang, Toshio Koike, Hirohiko Ishikawa, Joon Kim, Xin Li, Huizhi Liu, Shaomin Liu, Yaoming Ma, and Jieming Wang

1. Introduction Turbulent flux near the earth’s surface is the key quantity for hydrometeorological modeling of land–atmosphere interactions and remote sensing of water resources. Aerodynamic and thermal roughness lengths are the two crucial parameters for bulk transfer equations to calculate turbulent flux. They are defined so that a surface nonslip condition and surface skin temperature can be applied within the framework of Monin– Obukhov similarity theory. The aerodynamic roughness length

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Fabrice Veron, W. Kendall Melville, and Luc Lenain

1. Introduction The air–sea fluxes of heat and momentum play a pivotal role in weather, global climate, and the general circulation of the ocean and atmosphere. Exchanges between the atmosphere and the ocean occur across the surface layers, and the rate at which they do is greatly influenced by the kinematics and dynamics of the boundary layers. This is particularly true for the transfer of heat that relies on exchange processes through the thermal molecular layer, which is usually located

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Il-Ju Moon, Isaac Ginis, Tetsu Hara, and Biju Thomas

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

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Donald T. Resio, Charles E. Long, and William Perrie

the f −4 form has been theoretically linked to nonlinear energy fluxes from low- to high-frequency regions of the spectrum ( Zakharov and Filonenko 1966 ; Kitaigorodskii 1983 ). Because different portions of a spectrum can have different source term balances affecting them, it is possible that spectral shapes will change their form within different frequency ranges. In fact, Forristall (1981) and Long and Resio (2007) have presented observational evidence suggesting that spectra shift from

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Denis Bourras, Gilles Reverdin, Guy Caniaux, and Sophie Belamari

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

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S. W. Hoch, P. Calanca, R. Philipona, and A. Ohmura

1. Introduction The divergence of the longwave radiative fluxes is an important component of the thermodynamics of the atmospheric boundary layer ( Kondratyev 1969 ; Garratt and Brost 1981 ). The cooling associated with the divergence of longwave radiation is understood to be essential for the establishment and maintenance of persistent surface inversion layers close to the surface during the polar night ( Cerni and Parish 1984 ). Over large ice sheets, the strong radiative cooling has been

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