Search Results

You are looking at 1 - 10 of 7,311 items for :

  • Orographic effects x
  • Refine by Access: All Content x
Clear All
Lukas Umek and Alexander Gohm

generated by a combination of lake effects (e.g., latent and sensible heat input to the planetary boundary layer) and orographic effects, such as flow deflection and forced lifting by the surrounding terrain. For the formation of lake-effect snowstorms in the Great Lakes area, the difference between the LST and the temperature at 850 hPa has to be greater than the dry adiabatic temperature decrease ( Holroyd 1971 ). This threshold often appears in literature and is also used for other lakes (e.g., the

Full access
Lulin Xue, Amit Teller, Roy Rasmussen, Istvan Geresdi, and Zaitao Pan

the relatively weak and organized dynamics, the sensitivity to aerosol characteristics due to the constrained time available to form precipitation in rising air parcels, and the inconclusive estimates of the aerosol effects on orographic clouds and precipitation from observations. Many recent numerical simulations of orographic precipitation showed that the amount of orographic precipitation is sensitive to the available CCN (e.g., Thompson et al. 2004 ; Lynn et al. 2008 ; Khain et al. 2008

Full access
Lulin Xue, Amit Teller, Roy Rasmussen, Istvan Geresdi, Zaitao Pan, and Xiaodong Liu

. More recently, Saleeby and Cotton (2008) and Lin and Colle (2011) applied different size-dependent riming approaches to orographic cloud simulations. Their results showed that significant improvements of snowfall prediction over mountainous areas have been achieved compared to size-independent riming approach. Muhlbauer et al. (2010) investigated the anthropogenic aerosol effects on mixed-phase orographic clouds by simulating an ideal two-dimensional bell-shaped case with three dynamic

Full access
Jinqiang Chen and Simona Bordoni

in (a) shows where orography intersects the 800-hPa level. The EASM is different from the Indian monsoon and other monsoon systems in that it is characterized by mixed tropical and midlatitude influences with frontal systems and jet stream effects ( Ding and Chan 2005 ; Molnar et al. 2010 ). One of its notable features is its seasonal northward and northeastward migration remarked by three stationary periods, two abrupt northward jumps, and rapid southward retreat: heavy rainfall starts in the

Full access
Gregor Gläser, Peter Knippertz, and Bernd Heinold

depth improves the model performance significantly, suggesting that the model underestimates the dust emission in the Sahara ( Mangold et al. 2011 ). This study has shown that an accurate treatment of orographic and diabatic effects in models has the potential to improve simulations of synoptic-scale dust outbreaks. Acknowledgments The authors would like to acknowledge funding through the German Science Foundation (DFG) Emmy Noether program (Grant KN 581/2–3) to PK. We thank the anonymous reviewers

Full access
R. M. Samelson and P. L. Barbour

the West Coast (e.g., Perlin et al. 2004 ). As with Samelson et al. (2006) , it is presumed here that the Nares Strait regional implementation of the Polar MM5 will reproduce similar orographic effects in this region with similar accuracy. Previous successful MM5 simulations of flow through a narrow channel with steep sides include those of Colle and Mass (2000) . For this analysis, hourly model fields from daily simulations during August 2003–July 2005 were concatenated into a single

Full access
Guihua Wang, Dake Chen, and Jilan Su

of orographic effects. Several previous studies have associated some of the mesoscale eddies observed in the eastern SCS with wind forcing. For example, Wang and Chern (1987) suggest that an anticyclonic eddy observed southwest of Taiwan in their 1974 hydrographic survey may result from the joint effect of winter monsoon and the Kuroshio. Both Qu (2000) and Metzger (2003) note the existence of a cyclonic eddy offshore of northwest Luzon during the winter and point out its likely connection

Full access
Mark R. Hjelmfelt

rates and mesoscale updrafts and strengthens the land breeze. The mild orographic changes east of LakeMichigan as modeled with an 8-kin horizontal grid are not sufficient to overcome the dominance of the lakeland temperature difference for any of the cases simulated. However, significant local effects are observed inareas of more prominent topographic features. These local effects are strongly affected by wind direction.1. Introduction Orography has long been noted to have an impacton lake

Full access
Feng Hsiao, Yi-Leng Chen, Hiep Van Nguyen, David Eugene Hitzl, and Robert Ballard

August 2013 are used for model verification. The first 12 h of model run are considered as the model spinup because the initial conditions interpolated from the CFSv2 analyses to the high-resolution model domains may not contain adequate information concerning local and orographic effects on airflow, clouds, and precipitation. Smolarkiewicz et al. (1988) showed that for the island of Hawaii, the model spinup time is about 3 h. Thus, the 12-h spinup window used is more than sufficient for the model

Restricted access
Heather Dawn Reeves and Richard Rotunno

1. Introduction From a theoretical perspective, orographic blocking of dry air is well understood. Moist flow has received less attention, but latent-heat release is known to alter wind patterns over a mountain with saturated flow tending to suffer less upstream-flow deceleration than dry flow. Attempts to quantify moist effects using moist nondimensional control parameters that are simple extensions of known dry ones have so far been unsuccessful. In this paper, the flow dependence on moisture

Full access