Numerical Simulation of Katabatic Flow with Changing Slope Angle

Smith, Craig M.; Skyllingstad, Eric D.
November 2005
Monthly Weather Review;Nov2005, Vol. 133 Issue 11, p3065
Academic Journal
A large eddy simulation (LES) model and the Advanced Regional Prediction System (ARPS) model, which does not resolve turbulent eddies, are used to study the effect of a slope angle decrease on the structure of katabatic slope flows. For a simple, uniform angle slope, simulations from both models produce turbulence kinetic energy and momentum budgets that are in good overall agreement. Simulations of a compound angle slope are compared to a uniform angle slope to demonstrate how a changing slope angle can strongly affect the strength of katabatic flows. Both ARPS and the LES model show that slopes with a steep upper slope followed by a shallower lower slope (concave shape) generate a rapid acceleration on the upper slope followed by a transition to a slower evolving structure characterized by an elevated jet over the lower slope. In contrast, the case with uniform slope (having the same total height change) yields a more uniform flow profile with stronger winds at the slope bottom. Higher average slope in the uniform slope angle case generates greater gravitational potential energy, which is converted to kinetic energy at the bottom of the slope. Analysis of the total energy budget of slope flows indicates a consistent structure where potential energy generated at the top of the slope is transported downslope and converted into kinetic energy near the slope base.


Related Articles

  • The Interaction of Katabatic Flow and Mountain Waves. Part II: Case Study Analysis and Conceptual Model. Poulos, Gregory S.; Bossert, James E.; McKee, Thomas B.; Pielke Sr., Roger A. // Journal of the Atmospheric Sciences;Jun2007, Vol. 64 Issue 6, p1857 

    Via numerical analysis of detailed simulations of an early September 1993 case night, the authors develop a conceptual model of the interaction of katabatic flow in the nocturnal boundary layer with mountain waves (MKI). A companion paper (Part I) describes the synoptic and mesoscale...

  • Theoretical considerations of meandering winds in simplified conditions. Goulart, Antônio G. O.; Degrazia, Gervásio A.; Acevedo, Otávio C.; Anfossi, Domenico // Boundary-Layer Meteorology;Nov2007, Vol. 125 Issue 2, p279 

    The influence of turbulence on the meandering phenomenon is investigated. The study, based on the three-dimensional Navier–Stokes equations, shows that when the turbulent fluxes can be neglected an asymptotic solution results. This solution reproduces a horizontal wind oscillation with an...

  • Atmospheric Boundary-Layer Evening Transitions: A Comparison Between Two Different Experimental Sites. Sastre, Mariano; Yagüe, Carlos; Román-Cascón, Carlos; Maqueda, Gregorio // Boundary-Layer Meteorology;Dec2015, Vol. 157 Issue 3, p375 

    The planetary boundary-layer (PBL) afternoon and evening transition is investigated with measurements from two-month datasets, gathered at two experimental sites significantly different regarding heterogeneity, the degree of terrain wetness, and proximity to mountains. The period of 4 h prior to...

  • The Role of Katabatic Winds on the Antarctic Surface Wind Regime. Parish, Thomas R.; Cassano, John J. // Monthly Weather Review;Feb2003, Vol. 131 Issue 2, p317 

    Antarctica is known for its strong and persistent surface winds that are directed along topographic pathways. Surface winds are especially strong during the winter period. The high directional constancy of the wind and the close relationship of the wind direction to the underlying terrain can be...

  • Diagnosis of the Katabatic Wind Influence on the Wintertime Antarctic Surface Wind Field from Numerical Simulations. Parish, Thomas R.; Cassano, John J. // Monthly Weather Review;Jun2003, Vol. 131 Issue 6, p1128 

    Katabatic winds have long been recognized as one of the key climatic variables of the low-level Antarctic environment. Antarctic surface winds display a high degree of persistence with mean directions related to the local topographic configuration of the ice sheet, consistent with katabatic...

  • A study of turbulent fluxes and their measurement errors for different wind regimes over the tropical Zongo Glacier (16° S) during the dry season. Litt, M.; Sicart, J.-E.; Helgason, W. // Atmospheric Measurement Techniques;2015, Vol. 8 Issue 8, p3229 

    Over glaciers in the outer tropics, during the dry winter season, turbulent fluxes are an important sink of melt energy due to high sublimation rates, but measurements in stable surface layers in remote and complex terrains remain challenging. Eddy-covariance (EC) and bulk-aerodynamic (BA)...

  • A Case Study of Antarctic Katabatic Wind Interaction with Large-Scale Forcing*. Parish, Thomas R.; Bromwich, David H. // Monthly Weather Review;Jan1998, Vol. 126 Issue 1, p199 

    Surface pressure decreases of up to 20 hPa occurred over much of the Antarctic continent during a 4-day midwinter period of 1988. The widespread change in the pressure field accompanied intense cyclonic activity to the north of the ice sheet. The equatorward mass transport across the Antarctic...

  • Analysis of Hawaiian diurnal rainfall patterns. Roy, S. Sen; Balling Jr., R. C. // Theoretical & Applied Climatology;2004, Vol. 79 Issue 3/4, p209 

    We analyzed hourly precipitation data over the period 1965-1998 for 133 stations located throughout the Hawaiian Islands and found distinctive diurnal cycles in the amount and frequency of the rainfall. The diurnal signals were generally strongest on the island of Hawaii and more pronounced in...

  • Foehn Winds in the McMurdo Dry Valleys, Antarctica: The Origin of Extreme Warming Events*. Speirs, Johanna C.; Steinhoff, Daniel F.; McGowan, Hamish A.; Bromwich, David H.; Monaghan, Andrew J. // Journal of Climate;Jul2010, Vol. 23 Issue 13, p3577 

    Foehn winds resulting from topographic modification of airflow in the lee of mountain barriers are frequently experienced in the McMurdo Dry Valleys (MDVs) of Antarctica. Strong foehn winds in the MDVs cause dramatic warming at onset and have significant effects on landscape forming processes;...


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics