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Topic: Orography

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	Simulations paper
		The heaviest rainfall is simulated along the important barrier of the Alps, and the sharp topographic gradient of the topography of the eastern slopes toward the Po Valley is associated with a comparable gradient in the precipitation, both observed (Fig.
		For the "Algeria" and "Piedmont" cases, we consider the impact of the orography and of the flux of water vapor from the Mediterranean Sea.
		Orography is very important in the simulation of the windflow at low levels over the eastern Spanish coast.
	www.cimms.ou.edu /~doswell/mallorca_papers/simulations.html (7795 words)

	Met Office: Orography
		The standard deviation of the sub-grid orography (actually 2.5 times the standard deviation) defines the depth of the layer of air that intersects the sub-grid orography.
		These fields ensure that when the sub-grid orography is anisotropic (non-circular), the drag is proportional to the component of the wind perpendicular to the major axis of the sub-grid orography.
		The A/S field is the frontal area of the sub-grid orography per unit area, whilst the peak to trough height is calculated as the standard deviation of the high resolution data set within the grid-box.
	www.metoffice.gov.uk /research/nwp/numerical/surface/orography.html (351 words)

	The model orography
		The resulting mean orography gives quite a realistic description over most of the land areas, but is insufficient in high mountain areas where the sub-grid orographic variability becomes important.
		To represent these mountain effects the mean orography is supplemented by four additional sub-grid fields: the standard deviation, anisotropy (aspect ratio of the obstacle), slope and geographical orientation of the sub-grid orography.
		They are added to the mean orography to provide flow dependent blocking of the air flow and to generate gravity waves.
	www.ecmwf.int /products/forecasts/guide/The_model_orography.html (254 words)

	Met Office: Orography
		Orography is the term used to describe undulations on the surface of the Earth of any size and shape, from small hills to major mountain ranges that span continents.
		Understanding and representing the effects of orography (such as drag) in numerical weather prediction models is of crucial importance for weather forecasting and climate prediction since the phenomena usually occur on scales too small to be resolved by the models.
		The role of the Orography Group is to improve our understanding of flow over hills and mountains and their parametrization in numerical weather prediction models.
	www.metoffice.gov.uk /research/apr/orography.html (309 words)

	GANDIA / TOUS paper
		That is, the north African orography is removed prior to the initialization of the model, and latent heating terms (both absorption and release by the water phases) appearing in the temperature tendency equation are explicitly set to zero.
		This result is obtained through (a) the action of the Atlas orography irrespectively of latent heat-induced processes, or (b) by the action of latent heat exchanges irrespectively of the presence of the Atlas Mountains, or (c) by the interaction between the two factors.
		The effects of Atlas orography on the sea level pressure and low-levels wind field for a representative time (21 UTC), and on the total precipitation, are shown in Fig.
	www.cimms.ou.edu /~doswell/valencia/valencia_paper.html (9611 words)

	Orographic mask fields (Site not responding. Last check: 2007-11-02)
		It is sometimes useful to indicate the height of orography on plots.
		One of the integer switches in each non-orographic field, IMSK, is used to indicate whether the orography should be added to the plot.
		IMSK is 1 if the field is a cross-section of some kind (plot types 11-12) and the orography is to be added to the plot.
	www.atm.ch.cam.ac.uk /acmsu/utf/orographic.html (576 words)

	[No title]
		The subgrid scale variance of orography, used in parameterizations in model, is different as well as the mean orography on the model grid.
		Difference in orography new minus old Contour interval 100 m; higher heights in new solid and in greenish hues, lower heights dashed and in reddish hues; zero omitted.
		The vertical profile in sigma of the vertical diffusion of zonal momentum averaged over 30-60N over 33 days of 6 hour forecasts for the old and new orography The fl curve is for the run with old orography; the green the run with new.
	www.emc.ncep.noaa.gov /gmb/noor/uzmar99/text.html (2160 words)

	[No title] (Site not responding. Last check: 2007-11-02)
		A new sub-grid scale orographic drag parametrization: its formulation and testing Frangois Lott and Martin Miller A scheme for the representation of Sub-grid Scale Orography (SSO) in NWP and climate models is presented.It arose in part from a desire to represent nonlinear low level mountain drag effects not currently parametrized.
		An important feature of the scheme is that it deals explicitly with low-level flow which is "blocked", when the effective height of the sub-grid scale orography is high enoughi In this new scheme, it is assumed dust for this 'blocked" flow, separation occurs at the mountain flanks rwwting in a form drag.
		With this new scheme and a mean, orography, the ECMWF model outperforms a version of the model which has an envelope orography and the old gravity wave drag scheme in temis of forecast skill, while no longer suffering any disadvantages of envelope orography.
	www.lmd.jussieu.fr /~mclanc/abstracts/97/JOB16.TXT (289 words)

	Sensitivity experiments (Site not responding. Last check: 2007-11-02)
		Three sets are considered: a "Standard" orography consisting of an envelope orography produced originally for the ECMWF model, a"Navy" orography directly from the US Navy data and a "Scripps" orography based on the data set originally compiled several years ago at Scripps.
		The sensitivity experiments show that orography is still an important factor in controlling the model performance even in this class of models that use a semi-lagrangian formulation for water vapour, that in principle should be less sensitive to Gibbs oscillations than the Eulerian formulation.
		The largest impact can be seen in the stationary waves (asymmetric part of the geopotential at 500 mb) where the differences in total height and spatial pattern generate up to 60 m differences, and in the surface fields where the Gibbs removal procedure is successful in alleviating the appearance of unrealistic oscillations over the ocean.
	www.ingv.it /~wwwannali/navarra433.htm (243 words)

	Heavy Rainfall due to Orography
		Local orography governs the spatial distribution of precipitation over complex terrain both for annual sums as well as for single events.
		Intense, lengthy precipitation events are typically found on the upwind side of the mountains, while shorter events with less intensity are characteristic for the lee side.
		Besides the orography the rain enhancement is governed also by several atmospheric parameters like horizontal wind velocity and stability of the stratification.
	www.gknk.uni-karlsruhe.de /miku/Project.shtml (961 words)

	Dependence of the annular mode in the troposphere and stratosphere on orography and land-sea heating contrasts
		Only the combined forcing of orography and land-sea heating contrast leads to a localization of the AM similar to the North Atlantic Oscillation, and additionally, to a stratospheric AM and its downward propagation.
		A tropospheric feedback mechanism between the anomalies of zonal-mean wind and stationary waves applies in the simulation with the combined forcing only, where the coupling of orographically and thermally forced waves reproduces the observed stationary waves, and where the simulated diabatic heating supports the feedback mechanism.
		Citation: Körnich, H. Schmitz, and E. Becker (2003), Dependence of the annular mode in the troposphere and stratosphere on orography and land-sea heating contrasts, Geophys.
	www.agu.org /pubs/crossref/2003/2002GL016327.shtml (243 words)

	GFDL Experimental Prediction Group - documentation of GFDL/DERF spectral model as configured for AMIP II
		Orography obtained from a 1 x 1-degree Scripps dataset (Gates and Nelson 1975 [26]) is interpolated to the model's Gaussian grid (see Horizontal Resolution).
		In contrast to the procedure of the AMIP I model, the orography is first smoothed by application of the two-dimensional isotropic filter of Navarra et al.
		Other changes include: smoothed orography and some different surface characteristics, a new soil hydrology scheme, and modified formulations of cloud formation and surface fluxes.
	www.gfdl.noaa.gov /~wfs/DocGFDLSM_v197_AMIP2.html (2124 words)

	Klaus Grosfeld of Geosystem Modeling Group, Department of Physics, University of Bremen (Site not responding. Last check: 2007-11-02)
		By using an atmospheric genaral circulation model of intermediate complexity we investigate the sensitivity of the atmospheric temperature and circulation during glacial climate, focussing on the impact of the orography and different oceanic heat conditions.
		The blocking effect of the elevated orography due to the Laurentide Ice Sheet over the North American continent forces a deflection of westerlies, their enhancement and a southward displacement over the Atlantic.
		Finally, we find that the altered orography in the Northern Hemisphere and different oceanic heat transports result in a changed hydrology, a reduction of the Hadley circulation, and a southward shift of the Intertropical Convergence Zone in the boreal winter during glacial times.
	www.palmod.uni-bremen.de /~grosfeld/RLGB04.html (215 words)

	The GFS Atmospheric Model description
		The treatment of the gravity-wave drag parameterization in the lower troposphere is improved by the use of the Kim and Arakawa (1995) enhancement.
		New orography data sets are constructed based on a United States Geological Survey (USGS) global digital elevation model (DEM) with a horizontal grid spacing of 30 arc seconds (approximately 1 km).
		Orography statistics including average height, mountain variance, maximum orography, land-sea-lake masks are directly derived from a 30-arc second DEM for a given resolution.
	wwwt.emc.ncep.noaa.gov /gmb/moorthi/gam.html (4190 words)

	Modulation of the Great Plains low-level jet and moisture transports by orography and large-scale circulations
		Month-long simulations with monthly averaged conditions suggest that the Great Plains LLJ is a component of the large-scale circulation associated with the topography of the western United States.
		Orography thus provides a scale transfer mechanism that focuses global-scale features into the regional-scale responses.
		A theoretical interpretation of the large-scale, mechanical influence of orography on surrounding low-level circulations is proposed.
	www.agu.org /pubs/crossref/2003/2002JD003005.shtml (375 words)

	MM5 Experiments
		By examining the differences between the experiments with and without orography (0407 and 0407o respectively) we can determine whether the presence of orography acts to enhance the off-coastal convective diurnal signal amplitude.
		Therefore, in the absence of orography it appears there is some association between the land and ocean diurnal cycle which leads to the off-coastal enhancement of the diurnal cycle.
		Namely that the convection associated with the sea-breeze is stronger and has more coherent propagation in the absence of orography, and the coastal oceanic convective diurnal cycle is greater with orography.
	ugamp.nerc.ac.uk /hot/rbn_mm5/mm5.htm (2332 words)

	CP - Abstract - Effect of land albedo, CO<sub>2</sub>, orography, and oceanic heat transport on extreme ...
		Using an atmospheric general circulation model of intermediate complexity coupled to a sea ice – slab ocean model, we perform a number of sensitivity experiments under present-day orbital conditions and geographical distribution to assess the possibility that land albedo, atmospheric CO, orography and oceanic heat transport may cause an ice-covered Earth.
		We find that the most significant factor leading to an ice-covered Earth is the high land albedo in combination with initial temperatures set equal to the freezing point.
		Extremely low concentrations of CO also appear to be insufficient to provoke a runaway ice-albedo feedback, but the strong deviations in surface air temperatures in the Northern Hemisphere point to the existence of a strong nonlinearity in the system.
	www.clim-past.net /2/31/2006/cp-2-31-2006.html (273 words)

	Table 2-5
		The table lists the instances of application of time filtering, spatial filtering/smoothing of model atmosphere and orography, or filling of spurious negative values of atmospheric moisture.
		(For orography, only smoothing procedures more complex than the area-averaging of orographic heights over model grid boxes and/or the truncation of spectral representations of orography at grid resolution are tracked here.
		The use of enhanced orography is also noted as appropriate.) Hyperlinks connect to the summary report for each AMIP model version.
	www-pcmdi.llnl.gov /projects/modeldoc/amip/10Tbl2.5.html (78 words)

	Roughness and Wind Shear
		In the lower layers of the atmosphere, however, wind speeds are affected by the friction against the surface of the earth.
		In the wind industry one distinguishes between the roughness of the terrain, the influence from obstacles, and the influence from the terrain contours, which is also called the orography of the area.
		We shall be dealing with orography, when we investigate so called speed up effects, i.e.
	www.windpower.org /en/tour/wres/shear.htm (635 words)

	ALADINthèquei: index
		The study deals with the use of a new envelope orography formulation, previously introduced in the ALADIN model by Vladimir Ivanovici, and the comparison with the former representation of orography.
		Furthermore, the effect of the variability of the sub-grid orography is taken into account by adding the root mean square of the high-resolution orography to the mean height.
		Secondly, the orography is introduced and the horizontal diffusion is progressively reduced, until the same ratio is obtained.
	www.cnrm.meteo.fr /aladin/publications/theque.html (11443 words)

	Orography (Site not responding. Last check: 2007-11-02)
		For TM5 we only store the 2D orography (=surface geopotential), full 3D geopotential could be computed online.
		The orography is not supposed to change very much, and therefore defined for date 00-00-0000.
		NOTE: the orography is also part of the surface files...
	www.knmi.nl /~segers/TMPP/DOC/html/node36.html (76 words)

	1
		The reference experiment and two sensitivity studies are carried out to study the orography and diabatic effects on the cyclone development and maintenance.
		is visible in a high-low couplet over the orography and strong winds behind the cyclone and along the coast.
		The absence of latent heat release leads to the weaker cyclonic circulation.
	geofizika-journal.gfz.hr /abs14.htm (917 words)

	DUO - Digital utgivelse ved Universitetet i Oslo - Orografiske effekter og diabatiske prosesser i kraftige lavtrykk ... (Site not responding. Last check: 2007-11-02)
		In addition, the role of SST gradients are investigated in the September case and the role of surface albedo in the August case.
		In the August case the precipitation is strongly enhanced by orography due to the northely onshore winds.
		Removing the orography of Scandinavia leads to greatly reduced precipitation and a deformation of the cyclone.
	wo.uio.no /as/WebObjects/theses.woa/wa/these?WORKID=28204 (538 words)

	Research Interests - Silvio Davolio
		Together with Maurizio Fantini, a semigeostrophic model of frontal passage over isolated orography was developed in order to examine an orographic perturbation which grows in the presence of a finite amplitude primary wave, in a dry atmosphere.
		The model initial state is constituted of a uniform vertical shear (baroclinic condition) and a 2-Dimensional Eady wave of desired amplitude.
		In particular, IOP 2 and IOP 15 have been widely studied with respect to mesoscale phenomena, and the effects of orography have been evaluated, especially concerning the formation of the orographic cyclone during IOP 15.
	www.isac.cnr.it /~dinamica/old/silvio/res.html (1684 words)

	Fundamental Science Directorate at PNNL - Steven Ghan (Site not responding. Last check: 2007-11-02)
		He has focused on parameterizations that represent cloud-aerosol interactions and the subgrid influence of orography on atmospheric and land surface processes.
		He has worked closely with atmospheric chemists to produce self-consistent treatments of not only the influence of aerosols on clouds, but also the influence of clouds on aerosols.
		For the last fifteen years, Dr. Ghan's second research passion has been the representation of the subgrid influence of orography on atmospheric and land surface processes.
	www.pnl.gov /fsd/staff/staff_info.asp?staff_num=5663 (1376 words)

	Mesh-maker and Roll-Your-Own-Hill (Site not responding. Last check: 2007-11-02)
		is a program for generating three-dimensional unstructured tetrahedral mesh for use in studies of flow over orography.
		The mesh is generated from an initial non-uniform three-dimensional grid of nodes.
		Nodes on this grid which lie below the lower surface are removed and the survivors displaced vertically to follow the orography.
	www.env.leeds.ac.uk /~jason/Mesh-Maker/doc (158 words)

	XSUMO - panel help
		This is the full pathname of the ancillary data file containing the model orography - this must be specified if you wish to include orography in your analysis.
		This should currently be set to the full pathname of the directory (not file) containing the model orography file.
		If SUMO will not be using an orography file, then it can point to the work directory.
	ugamp.nerc.ac.uk /xsumo/xsumohelp.html (5771 words)

	Wind Energy Training Course 1.4.2
		As hills are seldom symmetrical, some hills can have good flow characteristics for a sector of wind directions, but very poor characteristics for a different sector.
		The air flow at the hill is also influenced by the orography upwind.
		There are many numerical models which try to model the effect of orography, but the complexity of most hilly or mountainous areas makes this difficult.
	www.iesd.dmu.ac.uk /wind_energy/wetc142.html (642 words)

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