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Erik O. Nilsson, Anna Rutgersson, and Peter P. Sullivan

1. Introduction The eddy correlation method is a standard method to determine turbulent scalar fluxes. The method uses correlation of the high-frequency signal of the vertical velocity and the scalar of interest. If the two signals are measured by separate instruments (which is the case for many scalars), the sensors must be separated to avoid flow distortion. This displacement unfortunately attenuates the flux estimate. The loss of flux occurs because of an unavoidable decorrelation between

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G. Guo and J. A. Coakley Jr.

1. Introduction The National Aeronautics and Space Administration’s (NASA) Clouds and Earth Radiant Energy System (CERES) has, as one of its goals, estimating surface radiative fluxes ( Wielicki et al. 1996 ). Estimates from CERES rely on a mix of broadband radiances, which are obtained from the CERES radiometers on the Terra and Aqua satellites; high-spatial-resolution multispectral imagery, obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS); analyzed meteorological

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Yanwu Zhang, James G. Bellingham, and Yi Chao

1. Introduction Measurement of fluxes of water mass, heat, chemicals, and biological organisms is fundamental to the understanding of ocean circulation, marine ecology, and global climate ( Dickson et al. 2007 ; Münchow et al. 2006 ; Cuny et al. 2005 ; Ganachaud and Wunsch 2003 ; Tanhua and Olsson 2006 ; Holmes et al. 2000 ; Spurrier and Kjerfve 1988 ; Bryden et al. 2005 ). For example, measurement of mass and heat transports is key to the studies of the California Current System (CCS

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David A. Rutan, Seiji Kato, David R. Doelling, Fred G. Rose, Le Trang Nguyen, Thomas E. Caldwell, and Norman G. Loeb

more complex than at the TOA, as it requires a radiative transfer model and satellite-derived properties of clouds and aerosols and atmospheric state from either satellites or reanalysis. Underlying assumptions in the radiative transfer model calculations and ancillary input data error increases the uncertainty in the surface radiation budget estimates. Furthermore, it is known that the diurnal cycle of clouds and their contribution to the diurnal cycle of surface radiant flux must be taken into

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J. Mann, A. Peña, F. Bingöl, R. Wagner, and M. S. Courtney

1. Introduction Measurements of the vertical flux of horizontal momentum are important for understanding the atmosphere and for testing models of the atmospheric flow over terrain. Methods of extracting the momentum flux from conically scanning Doppler lidars have been described before, for example, by Eberhard et al. (1989) and Gal-Chen et al. (1992) . Techniques for analyzing lidar data are very similar to those applied to radars. Apart from the vertical flux of horizontal momentum, the

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Liguo Su, Richard L. Collins, David A. Krueger, and Chiao-Yao She

heat fluxes (i.e., u ′ w ′ , υ ′ w ′ , w ′ T  ′ ), and the resultant forcing of the mean flow due to the vertical gradients in these fluxes, places even greater demands on the accuracy and precision of the measurements. Measurements of the momentum flux have attracted the most attention because the formulation of the gravity wave forcing arises in the momentum equations of the general circulation, and radar systems capable of measuring winds have been operated since the 1980s ( Vincent and Reid

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Brian S. Chinn and Sarah T. Gille

1. Introduction Eddy heat fluxes are thought to be important contributors to the time-mean ocean heat transport ( Jayne and Marotzke 2002 ). However, existing observations provide only a limited view of total eddy heat fluxes. Estimates from satellite data are confined to the surface layer of the ocean and rely on a number of assumptions ( Keffer and Holloway 1988 ; Stammer 1998 ). Subsurface estimates from current meter data are restricted to the specific locations at which current meters

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H. Wang, R. T. Pinker, P. Minnis, and M. M. Khaiyer

1. Introduction Solar radiation incident at the earth’s surface determines the surface temperature and sensible and latent heat fluxes that govern most of the dynamical and hydrological processes ( Stephens and Greenwald 1991 ). It plays an essential role in controlling biological processes ( Running et al. 1999 ; Platt 1986 ) and is also needed for validating climate models ( Garratt et al. 1993 ; Wild et al. 1995 ; Wielicki et al. 2002 ). Clouds strongly interact with solar and terrestrial

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Ronald Dobosy, David Sayres, Claire Healy, Edward Dumas, Mark Heuer, John Kochendorfer, Bruce Baker, and James Anderson

1. Introduction Surface heterogeneity is a prime reason to make flux measurements from aircraft, but it is also a significant source of uncertainty. One approach is to sample above the blending height ( Wieringa 1986 ; Mahrt 2000 ) to obtain a measure of the bulk flux. If the intent is to develop and improve models relating surface flux to remotely sensible parameters, however, it is important to acquire the signal of the surface’s influence on air–surface exchange. Depending on the parameters

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Zuohao Cao and Jianmin Ma

1. Introduction Accurate representation of the surface sensible heat flux over the Arctic sea ice is important to characterize the energy transfer between the atmosphere and its underlying surface, and to better understand the interaction occurring in this coupled system ( Cao et al. 2002 ). Precisely modeling the sensible heat flux, however, is a very challenging issue because computation of the surface sensible heat flux in a numerical weather prediction (NWP) model and a general circulation

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