Slope Winds

2019 ◽  
pp. 1-9
Author(s):  
Benjamin J. Hatchett ◽  
Michael L. Kaplan ◽  
Nicholas J. Nauslar ◽  
Craig M. Smith ◽  
Kellen Nelson
Keyword(s):  
Slope Winds

Slope Winds

2020 ◽  
pp. 922-930
Author(s):  
Benjamin J. Hatchett ◽  
Michael L. Kaplan ◽  
Nicholas J. Nauslar ◽  
Craig M. Smith ◽  
Kellen Nelson
Keyword(s):  
Slope Winds

scholarly journals Evolution of Late Wintertime Thermally Driven Local Flows and Temperature Fields over Far-Western Nepal

2016 ◽  
Vol 21 (1) ◽  
pp. 35-47
Author(s):  
Ram P. Regmi ◽  
Sangeeta Maharjan
Keyword(s):  
Thermal Environment ◽  
Flow Characteristics ◽  
Temperature Fields ◽  
Valley Wind ◽  
Plain Area ◽  
Slope Winds ◽  
Thermally Driven ◽  
Slope Wind ◽  
Wrf Modeling ◽  
Southern Plain

Atmospheric processes over the Himalayan complex terrain are yet to be studied extensively. Only a few significant researches are reported from this region and the Far-Western Region (FWR) of Nepal still remains untouched. Thus, the present study was conceived to understand the meteorological flow characteristics and thermal environment over the region and associated areas during the late wintertime with the application of the state-of-the-art-of Weather Research and Forecasting (WRF) Modeling System. The study revealed that the northern mountainous region developed strong down slope wind during the night and morning times, which sweeps out the southern plain area of Nepal and may reach just beyond the border. The wind over the plain was very shallow whose depth was just about 100 m. The down slope winds over the southern slope of the Daijee and Nandhaur mountain ranges were significantly enhanced by the subsidence of the southerly wind that prevails above 1 km height above the mean sea level. Close to the noon time a very gentle southerly valley wind from the southern plain replaced the nighttime down slope. Very shallow but strong surface inversion builds up over the plain that breaks up in the late morning. The depth of the mixed layer and the valley wind may reach up to 1km in the afternoon. The thermal environment over the FWR of Nepal was fairly hot that may remain around 35°C in the afternoon around the Mahendranagar area whereas the temperature during the nighttime may go as low as 23°C. The study revealed that, contrary to the general perception, temperature over plain areas of Nepal was significantly higher than further southern areas belonging to India. The meteorological flow fields over the FWR of Nepal executed diurnal periodicity with little day-to-day variation during the late wintertime.Journal of Institute of Science and TechnologyVolume 21, Issue 1, August 2016, page: 35-47

Valley winds and slope winds ? Observations and elementary thoughts

1987 ◽  
Vol 36 (1-4) ◽  
pp. 264-286 ◽  
Author(s):  
I. Vergeiner ◽  
E. Dreiseitl
Keyword(s):  
Slope Winds

Slope and Valley Winds in the Columbia River Valley *

1950 ◽  
Vol 31 (3) ◽  
pp. 79-84 ◽  
Author(s):  
C. M. Cross
Keyword(s):  
Columbia River ◽  
River Valley ◽  
Wind Pattern ◽  
Slope Winds ◽  
Wind Velocities ◽  
The Alps ◽  
Diurnal Wind ◽  
The Town ◽  
Made In ◽  
The Ideal

The behavior of slope and valley winds near the town of Trail in the Columbia River valley system in southern British Columbia was studied, and the results compared with those obtained from similar studies made in the Alps. The hourly wind velocities for two stations—one in the main valley, the other in a side valley—were resolved into components parallel to and at right angles to the valley. This procedure gives the valley and slope winds respectively. The usual diurnal wind pattern was found to prevail in most instances, with up-slope and up-valley winds during the day, and down-slope and down-valley winds at night. These systems were much better developed during the summer than in winter, and approximated the ideal pattern more closely on sunny days when the overall pressure gradient was weak.

Relation of slope winds to the ambient flow over gentle terrain

1990 ◽  
Vol 53 (1-2) ◽  
pp. 93-102 ◽  
Author(s):  
L. Mahrt ◽  
S�ren Larsen
Keyword(s):  
Ambient Flow ◽  
Slope Winds

scholarly journals Daytime Heat Transfer Processes Related to Slope Flows and Turbulent Convection in an Idealized Mountain Valley

2010 ◽  
Vol 67 (11) ◽  
pp. 3739-3756 ◽  
Author(s):  
Stefano Serafin ◽  
Dino Zardi
Keyword(s):  
Heat Transfer ◽  
Ground Surface ◽  
Turbulent Convection ◽  
Mountain Valley ◽  
Transfer Processes ◽  
Slope Winds ◽  
Large Eddy ◽  
Thermally Driven ◽  
Slope Wind ◽  
The Impact

Abstract The mechanisms governing the daytime development of thermally driven circulations along the transverse axis of idealized two-dimensional valleys are investigated by means of large-eddy simulations. In particular, the impact of slope winds and turbulent convection on the heat transfer from the vicinity of the ground surface to the core of the valley atmosphere is examined. The interaction between top-down heating produced by compensating subsidence in the valley core and bottom-up heating due to turbulent convection is described. Finally, an evaluation of the depth of the atmospheric layer affected by the slope wind system is provided.

scholarly journals A theory for surface-layer scaling of thermally-driven slope flows

2021 ◽  
Author(s):  
Dino Zardi
Keyword(s):  
Boundary Layer ◽  
Surface Layer ◽  
Sensible Heat Flux ◽  
Viscous Sublayer ◽  
Transport Processes ◽  
Heat Fluxes ◽  
Night Time ◽  
Slope Winds ◽  
Thermally Driven ◽  
Momentum And Heat Fluxes

<p>Sloping terrains of any inclination favour the development, under the daily cycle of day time surface heating and night time cooling, of thermally-driven organised flows, displaying peculiar boundary layer structures, and eventually triggering the development of atmospheric convection.</p><p>The ubiquitous occurrence over the Earth of variously tilted surfaces - from gently sloping plains to steep cliffs, or valley and basin sidewalls – makes the understanding of such flows of utmost importance in view of the appropriate forecasting of the associated boundary layer transport processes. Also, they display a highly conceptual relevance, as they represent a prototypal situations for many other thermally driven-flows over complex terrain.   </p><p>An appropriate surface-layer scaling for slope wind is derived extending the classical analysis for flat horizontal terrain situations to the cover inclines. In the former, momentum and heat fluxes at the surface are two independent quantities, and vertical profiles of velocity and temperature can only be connected to them by means  of similiarity relationships, as fluxes are nearly invariant with height.</p><p>Instead, equations governing slope winds show that the mean wind and temperature profiles are closely connected to the flux structure normal to the slope, as this is not constant. Also, surface values of momentum flux and sensible heat flux are shown to be proportional to each other.</p><p>Based on the above relationships, suitable expressions are derived for the slope-normal profiles of velocity and temperature, both in the viscous sublayer and in the fully turbulent surface layer, as well as for the appropriate scaling factors in the two regions.</p>

scholarly journals Temperature and humidity monitoring to identify ideal periods for liquefaction on Earth and Mars – data from the High Andes

2020 ◽  
Vol 64 (4) ◽  
Author(s):  
Akos KERESZTURI ◽  
Bernadett PAL ◽  
Akos GYENIS
Keyword(s):  
Atmospheric Pressure ◽  
Atacama Desert ◽  
High Elevation ◽  
Strong Impact ◽  
Night Time ◽  
Slope Winds ◽  
The Future ◽  
Low Humidity ◽  
Time Fluctuation ◽  
Humidity Monitoring

During an almost two week-long field campaign in the Atacama Desert high altitude region of Ojos del Salado volcano, temperature (T) and relative humidity (RH) values were monitored on the surface and <1–5 cm sized rocks, focusing on the night-time values. The aim was to identify and evaluate potential temporal characteristics of daily T and RH changes, searching for ideal periods for deliquescence that has recently been proposed for Mars. Although the atmospheric pressure on Mars is much lower than on Earth, and the atmosphere is drier in general, the huge daily temperature fluctuation there could produce elevated humidity values at night-time; this aspect has thus been analysed on Earth at a desert location, where because of the high elevation night-time cooling is very strong, just like on Mars. Different nearby surface locations showed the same temporal T/RH characteristics, but evident variations were observed between different days. Strong fluctuations could be observed on 10–20 minute long temporal scales, that might influence the deliquescence process, and should be accounted for in future missions aiming to analyse this process on Mars. Night-time periods were favourable for deliquescence. Among the modelled Mars-relevant salts [CaCl2, Ca(ClO4)2, Mg(ClO4)2, NaCl] the longest durations of possible deliquescence were for CaCl2, Ca(ClO4)2 and Mg(ClO4)2, ~7–12 hours for one day. The duration for deliquescence showed some increase along with the rising elevation, due to the decreasing night-time temperature. Thus despite the low humidity on Mars, the cold nights may cause elevated RH towards deliquescence. The Atacama Desert locations analysed are a useful analogue of the deliquescence process on Mars. Fluctuation in RH was observed in night-time, suggesting that similar variability might be present on Mars, and that should be considered in the future, including in evaluating how fast the microscopic liquid formation progresses. Night-time slope winds expected on Mars might have a strong impact on the local T/RH conditions. A more detailed analysis in the future should focus on identifying and separating regions with and without much of the expected night-time fluctuation

Investigating the dynamics of thermally driven up-slope flows: analysis of data from measurements in the Inn Valley (Austria) and comparison with a simple model

2021 ◽  
Author(s):  
Mattia Marchio ◽  
Sofia Farina ◽  
Dino Zardi
Keyword(s):  
Surface Temperature ◽  
Prediction Models ◽  
Weather Prediction ◽  
Slope Angle ◽  
Turbulent Fluxes ◽  
Surface Energy Budget ◽  
Valley Wind ◽  
Slope Winds ◽  
Slope Wind ◽  
Slope Flow

&lt;p&gt;&lt;span&gt;Diurnal wind systems typically develop in mountainous areas following the daytime heating and nighttime cooling of sloping surfaces. While down-slope winds have been extensively treated in the literature, up-slope winds have received much less attention. In particular, the physical mechanisms associated with the development of these winds, as well as the search for appropriate parameterization of turbulent fluxes of mass, momentum, and heat over slopes in numerical weather prediction models are still open research topics.&lt;/span&gt;&lt;/p&gt;&lt;p&gt;&lt;span&gt;Here we present some preliminary results from the analysis of turbulence data (sonic wind speed, temperature, humidity, and turbulent fluxes) collected at two slope stations which are part of the i-Box initiative. The i-Box project (Rotach et al. 2017) aims at studying turbulent exchange processes in complex terrain areas. The experimental setup is composed of six stations disseminated in the surroundings of the alpine city of Innsbruck, in the Inn Valley. The two stations adopted for the present study are located at different points on the valley sidewalls, one with a slope angle of 27&amp;#176; (labelled NF27) and one with a slope angle of 10&amp;#176; (NF10). Both stations are located over slopes covered by alpine meadow and at an altitude of about 1000 m MSL (400 m above the valley floor). The station NF27 has two measurement points, 1.5 and 6.8 m AGL, while the station NF10 has one measurement point, at 6.2 m AGL.&lt;/span&gt;&lt;/p&gt;&lt;p&gt;&lt;span&gt;The analysis shows that criteria proposed in the literature for the selection of valley-wind days may not apply for the identification of slope-wind days. Furthermore, from the analysis of second order moments, scaling relationships are derived for up-slope flow conditions. In addition, measurements representing the evolution of the up-slope flow structure from the early morning to the mid-afternoon are compared with an existing, simplified, analytical model, which provides the evolution of the vertical profiles of temperature and along-slope wind velocity as generated by a sinusoidal forcing representing the daily cycle of surface temperature. An improvement of the existing model, where the surface energy budget is considered as the boundary condition for the surface temperature, is also tested.&lt;/span&gt;&lt;/p&gt;

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