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Hailing Zhang, Zhaoxia Pu, and Xuebo Zhang

complicated in complex terrain. Liu et al. (2008) conducted an interrange comparison of the model analyses and forecasts of five U.S. Army test and evaluation command ranges over a 5-yr period. They concluded that forecast errors vary from range to range and season to season. They also found that larger errors are typically associated with complex terrain. Zhong and Fast (2003) compared three mesoscale numerical models and evaluated the simulations over the Salt Lake Valley for cases influenced by

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

on the indicated day) to encompass the full nocturnal period. To investigate a possible connection between LTF occurrences and synoptic or mesoscale conditions, ERA-Interim reanalyses and additional observations at DPG were used. The ERA-Interim, a global reanalysis dataset operated by the European Centre for Medium-Range Weather Forecasts, is run with 60 vertical levels and a reduced Gaussian grid with 79-km spacing for surface and other gridpoint fields ( Dee et al. 2011 ). Using the ERA

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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

outset, the existing barriers to mountain weather forecasting were reviewed and critical science and modeling needs were identified, and based on which, a multifaceted research effort was developed. Commensurate with available resources, the focus was limited to arid/semiarid regions and scales at or smaller than the mesoscale, thus deemphasizing issues such as orographic precipitation and marine pushes. Two extensive field campaigns were conducted within the first 3 years, and their design drew

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Feimin Zhang and Zhaoxia Pu

general, ice fog forms through a complex interplay among surface radiative cooling, turbulent mixing in the surface layer, aerosol growth by deliquescence, activation of fog droplets related to the microphysical properties of crystals ( Gultepe et al. 2017a , b ), and mesoscale and microscale variations associated with changes in the landscape, etc. (e.g., snow cover). Because of the complexity of its formation, Gultepe et al. (2015) emphasized the difficulty of forecasting ice fog with numerical

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

of wind speed and temperature profiles in the unstable atmospheric surface layer . J. Appl. Meteor. , 9 , 857 – 861 , doi: 10.1175/1520-0450(1970)009<0857:TMROWS>2.0.CO;2 . Ryerson, W. R. , and Hacker J. P. , 2014 : The potential for mesoscale visibility predictions with a multimodel ensemble . Wea. Forecasting , 29 , 543 – 562 , doi: 10.1175/WAF-D-13-00067.1 . Skamarock, W. C. , and Coauthors , 2008 : A description of the Advanced Research WRF version 3. NCAR Tech. Note, NCAR

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

viewpoint of surface exchange coefficients . Geophys. Res. Lett. , 36 , L10404 , doi: 10.1029/2009GL037980 . Chen, F. , Janjić Z. , and Mitchell K. , 1997 : Impact of atmospheric surface-layer parameterization in the new land-surface scheme of the NCEP mesoscale Eta Model . Bound.-Layer Meteor. , 85 , 391 – 421 , doi: 10.1023/A:1000531001463 . Cheng, W. Y. Y. , and Steenburgh W. J. , 2005 : Evaluation of surface sensible weather forecasts by the WRF and the Eta Models over the western

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Joshua P. Hacker and Lili Lei

between the initial conditions and a forecast metric is spuriously large because of sampling error, and the analysis error statistics do not overestimate the covariance as severely, the sensitivity can be overestimated. Most results in the literature so far have used an approximation to the analysis error covariance, where it is assumed diagonal (e.g., Ancell and Hakim 2007 ; Torn and Hakim 2008 ). Across a broad range of problems, and in particular for mesoscale sensitivities lacking strong forcing

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

.1175/1520-0442(1995)008<1965:VIMLDA>2.0.CO;2 . Dudhia , J. , 1989 : Numerical study of convection observed during the winter monsoon experiment using a mesoscale two-dimensional model . J. Atmos. Sci. , 46 , 3077 – 3107 , doi: 10.1175/1520-0469(1989)046<3077:NSOCOD>2.0.CO;2 . Edwards , J. M. , J. R. McGregor , M. R. Bush , and F. J. Bornemann , 2011 : Assessment of numerical weather forecasts against observations from Cardington: Seasonal diurnal cycles of screen-level and surface temperatures and surface

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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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