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Monica Górska, Jordi Vilà-Guerau de Arellano, Margaret A. LeMone, and Chiel C. van Heerwaarden

the grass vegetation became the dominant factor in the CO 2 diurnal variability. The majority of the ABL studies concerned with the vertical structure of the turbulent fluxes and entrainment assume a homogeneous surface. However, the land surface can be rather heterogeneous, resulting in horizontal variability in the surface fluxes. The entrainment of heat, moisture, and carbon dioxide could be influenced by the variability of the surface properties as well. Analysis of idealized large

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Margaret A. LeMone, Fei Chen, Mukul Tewari, Jimy Dudhia, Bart Geerts, Qun Miao, Richard L. Coulter, and Robert L. Grossman

1. Introduction This paper the first part of a two-part series that uses a combination of numerical simulations and observations of the fair-weather convective boundary layer (CBL) to explore the relationship of surface heterogeneity and associated fluxes (W m −2 ) of sensible heat H and latent heat LE, to CBL potential temperature Θ (K), mixing ratio Q (g kg −1 ), depth, and circulations on scales from 1 to 100 km. At the same time, we evaluate the numerical simulations and

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Margaret A. LeMone, Mukul Tewari, Fei Chen, Joseph G. Alfieri, and Dev Niyogi

1. Introduction This paper is the third of a series that addresses the horizontal variability of sensible and latent heat fluxes, H and LE, and their representation in land surface models, this time in the form of the Noah land surface model–based High-Resolution Land Data Assimilation System (HRLDAS; Chen et al. 2007 ). In the first two papers ( LeMone et al. 2003 , 2007b ), we examined horizontal variability along the amply watered and densely vegetated eastern track in Fig. 1 , using

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Diane Strassberg, Margaret A. LeMone, Thomas T. Warner, and Joseph G. Alfieri

mesoscale model by developing a method to downscale surface winds using local roughness lengths. We explore the daytime model–observation discrepancy associated with using point measurements by comparing surface winds observed at well-exposed locations to surface winds calculated by applying Monin–Obukhov (MO) similarity theory to aircraft data averaged along 50–60-km flight tracks, supplemented with thermodynamic data from nearby surface-flux towers ( Fig. 1 ). The data were collected in the convective

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F. Couvreux, F. Guichard, P. H. Austin, and F. Chen

moisture that are strongly modulated by precipitation ( Chen et al. 2001 ; Trier et al. 2004 ; Holt et al. 2006 ). It has been difficult to assess the impact of either fixed or transient surface heterogeneity because of the scarcity of measurements: local surface flux measurements can suffer from a lack of representativeness that limits their use at the mesoscale ( André et al. 1990 ). Although satellites may provide some estimates at the large scale, it has been more common to use idealized studies

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Edward I. Tollerud, Fernando Caracena, Steven E. Koch, Brian D. Jamison, R. Michael Hardesty, Brandi J. McCarty, Christoph Kiemle, Randall S. Collander, Diana L. Bartels, Steven Albers, Brent Shaw, Daniel L. Birkenheuer, and W. Alan Brewer

simultaneous lidar measurements of moisture and wind. We next focus attention on the bulk properties and effects of scales of motion in section 4 by computing layer-averaged fluxes through sections that bracket the LLJ. From these results, we are able to compute Reynolds averages within the layers, from which we estimate the bulk effect of so-called “prime–prime” terms, interpreted as integrated estimates of the contribution of small-scale (mesoscale to convective scale) circulations to the overall

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S. B. Trier, F. Chen, K. W. Manning, M. A. LeMone, and C. A. Davis

resulting soil moisture field used to initialize experiment HRLDAS1 ( Fig. 1 ) contains both localized finescale structure and a regional-scale gradient across the SGP. HRLDAS1 is compared to a simulation that uses the less sophisticated simple slab soil model (SLAB) LSM to calculate the surface fluxes; this simulation is termed SLAB1. Comparisons with simulations that use a relatively simple LSM such as SLAB can help determine the dominant physical processes in the more complete and complicated Noah

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Robert J. Conzemius and Evgeni Fedorovich

–south-oriented dryline that moved slowly eastward across the panhandles. a. Observational input data During IHOP_2002, intensive profiler, radiosonde, and lidar measurements were taken at a field station about 30 km southwest of Beaver, Oklahoma, which was designated, for operational coordination purposes, as the Homestead site. A 10-cm research radar [S-band dual-polarization Doppler radar (S-Pol); Weckwerth et al. 2004 ] was located approximately 17 km west of this site. Three integrated surface flux facility

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Margaret A. LeMone, Fei Chen, Mukul Tewari, Jimy Dudhia, Bart Geerts, Qun Miao, Richard L. Coulter, and Robert L. Grossman

1. Introduction This paper is the second of a two-part series that uses a combination of numerical simulations and observations to explore the relationship of surface heterogeneity and associated fluxes (W m −2 ) of sensible heat H and latent heat (LE), to potential temperature Θ (K), mixing ratio Q (g kg −1 ), depth, and convective structure on scales from 1 to 100 km in the fair-weather convective boundary layer (CBL), while evaluating the numerical simulations. The

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Lindsay J. Bennett, Tammy M. Weckwerth, Alan M. Blyth, Bart Geerts, Qun Miao, and Yvette P. Richardson

.g., Mahrt 1976 ; Crook 1996 ; Linne et al. 2007 ). It has been suggested that the vertical gradient is a result of entrainment of dry air at the top of the boundary layer outweighing the moistening by surface fluxes and the vertical transport of this moist air ( Mahrt 1976 ). Mahrt (1991) suggested that the diurnal evolution of the boundary layer could be characterized by two regimes. The moistening regime occurs during the early morning and is associated with large surface evaporation. The drying

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