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Robert S. Arthur, Katherine A. Lundquist, Jeffrey D. Mirocha, and Fotini K. Chow

mesoscale atmospheric model was done by Colette et al. (2003) in the Advanced Regional Prediction System (ARPS). Since then, other models have included topographic effects on radiation. These include the fifth-generation Pennsylvania State University–National Center for Atmospheric Research Mesoscale Model (MM5; Zängl 2005 ) and the Weather Research and Forecasting (WRF) Model ( Skamarock et al. 2008 ), which is used in this study. Although topographic shading improves the representation of surface

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Feimin Zhang and Zhaoxia Pu

with land-cover conditions such as snow on the ground. In light of the outstanding problems around fog prediction and their association with inaccurate near-surface atmospheric conditions as well as the previous results from the MATERHORN-Fog program, it is our purpose to examine the effects of land surface parameters, especially albedo and snow depth, on the prediction of near-surface atmospheric conditions. In this study, a series of numerical simulations are conducted to elaborate the

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Jeffrey D. Massey, W. James Steenburgh, Sebastian W. Hoch, and Derek D. Jensen

1. Introduction The variability of regional land surface characteristics in mesoscale numerical weather prediction (NWP) models has a potentially strong influence on near-surface forecasts. Some sources of land surface variability, such as coastlines and topographic features, are easily represented in NWP models, but other more subtle land surface characteristics (e.g., albedo, emissivity, roughness length, soil porosity, soil texture, and soil moisture) are more difficult to specify and

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Sean M. Wile, Joshua P. Hacker, and Kenneth H. Chilcoat

[e.g., Zach et al. (2011) and reports cited therein] at spatial scales similar to those here, finding some utility in sensitivities just upstream from a wind farm. Those studies did not evaluate the validity of the assumptions underlying the ESA nor did they quantify the effect of sampling error. Fog in the Salt Lake basin is expected to challenge ESA in two ways. First, the forcing is weak. Variability is on relatively small scales, and spatial covariances are weak. We can expect the effects

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Jeffrey D. Massey, W. James Steenburgh, Jason C. Knievel, and William Y. Y. Cheng

assimilation system (LDAS), but our own in-house comparison between the high-resolution LDAS (HRLDAS) soil moisture and GFS soil moisture yielded similar results. In this paper we examine how a regional overestimation of near-surface soil moisture in operational analyses over the Intermountain West during the fall (i.e., September and October) contributes to the underprediction of the DTR in a WRF-based forecasting system over Dugway Proving Ground (DPG) in the Great Salt Lake Desert of northwest Utah

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Hailing Zhang, Zhaoxia Pu, and Xuebo Zhang

spacing are generally incremental. With a regional climate simulation over complex terrain, Leung and Qian (2003) found that a higher-resolution simulation improves not only the spatial distribution and regional mean precipitation during summer but also snowpack during winter. However, they also commented that the accuracy of snow simulation is limited by factors such as deficiencies in the land surface model or biases in other model variables. The disagreement between these different studies

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H. J. S. Fernando, E. R. Pardyjak, S. Di Sabatino, F. K. Chow, S. F. J. De Wekker, S. W. Hoch, J. Hacker, J. C. Pace, T. Pratt, Z. Pu, W. J. Steenburgh, C. D. Whiteman, Y. Wang, D. Zajic, B. Balsley, R. Dimitrova, G. D. Emmitt, C. W. Higgins, J. C. R. Hunt, J. C. Knievel, D. Lawrence, Y. Liu, D. F. Nadeau, E. Kit, B. W. Blomquist, P. Conry, R. S. Coppersmith, E. Creegan, M. Felton, A. Grachev, N. Gunawardena, C. Hang, C. M. Hocut, G. Huynh, M. E. Jeglum, D. Jensen, V. Kulandaivelu, M. Lehner, L. S. Leo, D. Liberzon, J. D. Massey, K. McEnerney, S. Pal, T. Price, M. Sghiatti, Z. Silver, M. Thompson, H. Zhang, and T. Zsedrovits

state. This differs from very stable boundary layers over flat terrain, where turbulence is highly intermittent in space and time ( Mahrt 1999 ). F ig . 1. Physical processes in complex terrain, illustrated on a topographic map of the DPG domain. The spatial and the elevation (shading) scales are shown below. Blue arrows represent nocturnal flows; red arrows represent daytime flows. An arbitrary direction has been used for illustration of synoptic effects (which typically varies from northwest to

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Jeffrey D. Massey, W. James Steenburgh, Sebastian W. Hoch, and Jason C. Knievel

-start initial conditions ( Fig. 2 ). The initial 6 h of each simulation is excluded from the study to reduce the influence of model spinup of the atmosphere. The large 1.3-km domain allows us to cover the entire playa and to use a broader range of regional surface observations for model validation. We generate a nine-member ensemble for each of the three cases on the basis of three different parameterizations of soil thermal conductivity and three different top-layer (5 cm) soil-moisture initial analyses in

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Matthew E. Jeglum, Sebastian W. Hoch, Derek D. Jensen, Reneta Dimitrova, and Zachariah Silver

occurs 4–5 h after sunset and the cessation of the flow lags sunrise by a similar amount of time. Local horizontal thermal contrasts due to the playa surface remaining much warmer at night than the east basin ( Rife et al. 2002 ) would be expected to produce an easterly or northeasterly flow in the gap at night. The observed flow in the gap is directly opposed to this. The strong bias toward southwesterly flow under higher static stability may indicate that regional-scale boundary layer heterogeneity

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