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Daniel T. Dawson II, Brett Roberts, and Ming Xue

-scale balance is upset. This problem has historically made it difficult to control the environmental wind profile while simultaneously incorporating the effects of surface friction through, for example, a drag parameterization or other imposition of no-slip or semislip lower boundary conditions. At least partly for this reason, the vast majority of idealized modeling studies have elected to use free-slip lower boundary conditions, thereby ignoring the direct effects of surface friction entirely. However, it

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Torben Kunz and Richard J. Greatbatch

infinitely deep atmosphere, the upper and lower boundary conditions are given by as either z → −∞ or z → +∞, respectively, because the finite angular momentum input, associated with , can produce only a finite angular momentum response. Thus, the solution to the forced vertical structure equation (i.e., the Green’s function response to the mechanical forcing in a single Hough mode, concentrated at one particular level at z = 0) consists of an upward-decaying component above (at z > 0) and a

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A. McDonald

. Because of the iterative nature of 4DVAR the influence of the boundary conditions spreads farther into the limited area domain with each iteration. When the adjoint model is integrated backward in time, what were formerly boundary points with incoming characteristic velocities may become points describing error gradient fields with outgoing characteristic velocities. These must now pass out of the limited area without reflection. If our boundary treatment is only partially successful in doing this

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June 1971537UDC SSl.465.755:661.48B.4:632.6THE USE OF OPEN BOUNDARY CONDITIONS WITH THE STORM-SURGE EQUATIONSM. G. WURTELE and JAN PAEGLEUniversity of California, Los Angeles, Calif. ANITA SlELECKlHebrew University, Jerusalem, IsraelABSTRACTOpen boundaries are desirable when the region of interest of a computation is a localized area of a much largerdomain. Boundary conditions are developed for the linear storm-surge equations (without Coriolis effects) that per-mit disturbances to pass out

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Claire Louise Vincent and Andrea N. Hahmann

. There is an alternative option in the WRF Model to apply nudging only above the time-varying top of the boundary layer. However, because of concerns about nudging being applied close to the surface when the boundary layer height is small during stable conditions, this option was avoided. The nudging coefficient for all nudged fields was: 0 for levels 1–10, 3 × 10 −5 s −1 at level 11, and 3 × 10 −4 s −1 for level 12 to the top of the model at 50 hPa. The third configuration of the WRF Model

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Christopher A. Jeffery

Across Scales (MPAS) modeling system ( Ringler et al. 2011 ). This extension of Williamson et al. (1992) 's classic SW test cases is complicated by the implementation of domain boundary conditions (BCs) that play a crucial role in forcing the SW simulations, yet contain an element of arbitrariness in both specification (e.g., radiation, perfectly matched) and implementation (e.g., cell edge or center quantities). In this study, we specify straightforward, albeit ill-posed, BCs in which prognostic

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Hajime Nishigaki

the alongpath momentum balance is made and proves to be applicable because the path cannot be determined by the balance of the potential vorticity alone. A no-slip boundary condition is applied to the coast because it seems to make conditions similar to Nishigaki’s (1995) model, in which a stagnant region is assumed inshore of the boundary current. Cases with a free-slip coastal boundary condition are also examined. In no-slip and weakly viscous cases of this study, the supply of momentum and

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Martin W. Jury, Andreas F. Prein, Heimo Truhetz, and Andreas Gobiet

2010 ). Thereby, the quality of the lateral boundary conditions (LBCs) from the GCM has a direct effect on the quality of the RCM simulation, which is often referred to as the “garbage in garbage out” problem ( Giorgi and Mearns 1991 ; Wang et al. 2004 ; Diaconescu et al. 2007 ). Frequently, GCM performance is analyzed by evaluating near-surface parameters within the RCM domain ( van Ulden and van Oldenborgh 2006 ; Maxino et al. 2008 ; Pierce et al. 2009 ; Errasti et al. 2011 ). However, since

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P. Alpert, S. O. Krichak, T. N. Krishnamurti, U. Stein, and M. Tsidulko

JULY 1996 ALPERT ET AL. 1091The Relative Roles of Lateral Boundaries, Initial Conditions, and Topography in Mesoscale Simulations of Lee Cyclogenesis P. ALPERT * AND S. O. KRICHAKDepartment of Geophysics and Planetary Sciences, Tel Aviv University, Tel Aviv, Israel T. N. KRISHNAMURTIDepartment of Meteorology, The Florida State University

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S. G. Gopalakrishnan, Maithili Sharan, R. T. McNider, and M. P. Singh

(1974) and Estournel and Guedalia, (1985 , 1987) ] have been more or less restricted to strong or moderate wind situation. Further, the geostrophic wind as reported by Garratt (1982) for various nocturnal boundary layer experiments such as the Wangara, Minnesota, Cabauw, and Koorin indicates that the winds were strong or moderate in almost all the cases. However, weak wind conditions occur frequently over the Tropics and it is a situation that is not well understood. Sharan et al. (1995) have

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