scholarly journals The impact of a foehn wind on PM10 concentrations and the urban boundary layer in complex terrain: a case study from Kraków, Poland

Tellus B ◽  
2021 ◽  
Vol 73 (1) ◽  
pp. 1-26
Author(s):  
Piotr Sekuła ◽  
Anita Bokwa ◽  
Zbigniew Ustrnul ◽  
Mirosław Zimnoch ◽  
Bogdan Bochenek
Keyword(s):  
Boundary Layer ◽  
Complex Terrain ◽  
Urban Boundary Layer ◽  
The Impact

scholarly journals Plume Dispersion Anomalies in a Nocturnal Urban Boundary Layer in Complex Terrain

2008 ◽  
Vol 47 (11) ◽  
pp. 2857-2878 ◽  
Author(s):  
Dennis Finn ◽  
Kirk L. Clawson ◽  
Roger G. Carter ◽  
Jason D. Rich ◽  
K. Jerry Allwine
Keyword(s):  
Boundary Layer ◽  
Complex Terrain ◽  
Salt Lake ◽  
Salt Lake City ◽  
Urban Canopy ◽  
Monitoring Network ◽  
Urban Boundary Layer ◽  
Small Scale ◽  
Plume Dispersion ◽  
Lake City

Abstract The URBAN 2000 experiments were conducted in the complex urban and topographical terrain in Salt Lake City, Utah, in stable nighttime conditions. Unexpected plume dispersion often arose because of the interaction of complex terrain and mountain–valley flow dynamics, drainage flows, synoptic influences, and urban canopy effects, all within a nocturnal boundary layer. It was found that plume dispersion was strongly influenced by topography, that dispersion can be significantly different than what might be expected based upon the available wind data, and that it is problematic to rely on any one urban-area wind measurement to predict or anticipate dispersion. Small-scale flows can be very important in dispersion, and their interaction with the larger-scale flow field needs to be carefully considered. Some of the anomalies observed include extremely slow dispersion, complicated recirculation dispersion patterns in which plume transport was in directions opposed to the measured winds, and flow decoupling. Some of the plume dispersion anomalies could only be attributed to small-scale winds that were not resolved by the existing meteorological monitoring network. The results shown will make clear the difficulties in modeling or planning for emergency response to toxic releases in a nocturnal urban boundary layer within complex terrain.

scholarly journals The impact of embedded valleys on daytime pollution transport over a mountain range

2015 ◽  
Vol 15 (20) ◽  
pp. 11981-11998 ◽  
Author(s):  
M. N. Lang ◽  
A. Gohm ◽  
J. S. Wagner
Keyword(s):  
Boundary Layer ◽  
Complex Terrain ◽  
Mountain Range ◽  
Topographic Effects ◽  
Pollution Transport ◽  
Convective Boundary ◽  
Vertical Exchange ◽  
Boundary Layer Height ◽  
Thermally Driven ◽  
The Impact

Abstract. Idealized large-eddy simulations were performed to investigate the impact of different mountain geometries on daytime pollution transport by thermally driven winds. The main objective was to determine interactions between plain-to-mountain and slope wind systems, and their influence on the pollution distribution over complex terrain. For this purpose, tracer analyses were conducted over a quasi-two-dimensional mountain range with embedded valleys bordered by ridges with different crest heights and a flat foreland in cross-mountain direction. The valley depth was varied systematically. It was found that different flow regimes develop dependent on the valley floor height. In the case of elevated valley floors, the plain-to-mountain wind descends into the potentially warmer valley and replaces the opposing upslope wind. This superimposed plain-to-mountain wind increases the pollution transport towards the main ridge by an additional 20 % compared to the regime with a deep valley. Due to mountain and advective venting, the vertical exchange is 3.6 times higher over complex terrain than over a flat plain. However, the calculated vertical exchange is strongly sensitive to the definition of the convective boundary layer height. In summary, the impact of the terrain geometry on the mechanisms of pollution transport confirms the necessity to account for topographic effects in future boundary layer parameterization schemes.

Can the Deforestation Breeze Change the Rainfall in Amazonia? A Case Study for the BR-163 Highway Region

2010 ◽  
Vol 14 (18) ◽  
pp. 1-25 ◽  
Author(s):  
Sandra I. Saad ◽  
Humberto R. da Rocha ◽  
Maria A. F. Silva Dias ◽  
Rafael Rosolem
Keyword(s):  
Boundary Layer ◽  
Large Scale ◽  
Three Dimensional ◽  
Atmospheric Modeling ◽  
Thermal Cell ◽  
Soil Wetness ◽  
Soil Dryness ◽  
Regional Atmospheric Modeling ◽  
The Impact

Abstract The authors simulated the effects of Amazonian mesoscale deforestation in the boundary layer and in rainfall with the Brazilian Regional Atmospheric Modeling System (BRAMS) model. They found that both the area and shape (with respect to wind incidence) of deforestation and the soil moisture status contributed to the state of the atmosphere during the time scale of several weeks, with distinguishable patterns of temperature, humidity, and rainfall. Deforestation resulted in the development of a three-dimensional thermal cell, the so-called deforestation breeze, slightly shifted downwind to large-scale circulation. The boundary layer was warmer and drier above 1000-m height and was slightly wetter up to 2000-m height. Soil wetness affected the circulation energetics proportionally to the soil dryness (for soil wetness below ∼0.6). The shape of the deforestation controlled the impact on rainfall. The horizontal strips lined up with the prevailing wind showed a dominant increase in rainfall, significant up to about 60 000 km2. On the other hand, in the patches aligned in the opposite direction (north–south), there was both increase and decrease in precipitation in two distinct regions, as a result of clearly separated upward and downward branches, which caused the precipitation to increase for patches up to 15 000 km2. The authors’ estimates for the size of deforestation impacting the rainfall contributed to fill up the low spatial resolution in other previous studies.

scholarly journals The Impact of Mount Washington on the Height of the Boundary Layer and the Vertical Structure of Temperature and Moisture

Atmosphere ◽  
2018 ◽  
Vol 9 (8) ◽  
pp. 293 ◽  
Author(s):  
Eric Kelsey ◽  
Adriana Bailey ◽  
Georgia Murray
Keyword(s):  
Boundary Layer ◽  
Air Quality ◽  
Complex Terrain ◽  
Free Atmosphere ◽  
Air Mass ◽  
Meteorological Observations ◽  
Measurement Strategies ◽  
The Impact ◽  
Mass Type ◽  
Mount Washington

Discrimination of the type of air mass along mountain slopes can be a challenge and is not commonly performed, but is critical for identifying factors responsible for influencing montane weather, climate, and air quality. A field campaign to measure air mass type and transitions on the summit of Mount Washington, New Hampshire, USA was performed on 19 August 2016. Meteorological observations were taken at the summit and at several sites along the east and west slopes. Ozone concentrations were measured at the summit and on the valley floor. Additionally, water vapor stable isotopes were measured from a truck that drove up and down the Mount Washington Auto Road concurrent with radiosonde launches that profiled the free atmosphere. This multivariate perspective revealed thermal, moisture, and air mass height differences among the free atmosphere, leeward, and windward mountain slopes. Both thermally and mechanically forced upslope flows helped shape these differences by altering the height of the boundary layer with respect to the mountain surface. Recommendations for measurement strategies hoping to develop accurate observational climatologies of air mass exposure in complex terrain are discussed and will be important for evaluating elevation-dependent warming and improving forecasting for weather and air quality.

A case study of the impact of boundary layer aerosol size distribution on the surface UV irradiance

2001 ◽  
Vol 35 (30) ◽  
pp. 5041-5051 ◽  
Author(s):  
Ülle Kikas ◽  
Aivo Reinart ◽  
Mai Vaht ◽  
Uno Veismann
Keyword(s):  
Boundary Layer ◽  
Size Distribution ◽  
Aerosol Size Distribution ◽  
Uv Irradiance ◽  
The Impact

Investigations of high-density urban boundary layer under summer prevailing wind conditions with Doppler LiDAR: A case study in Hong Kong

Urban Climate ◽  
2021 ◽  
Vol 38 ◽  
pp. 100884
Author(s):  
Yueyang He ◽  
Chao Ren ◽  
Hugo Wai Leung Mak ◽  
Changqing Lin ◽  
Zixuan Wang ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Hong Kong ◽  
Urban Boundary Layer ◽  
High Density ◽  
Prevailing Wind ◽  
Doppler Lidar

scholarly journals Interactions Between the Nocturnal Low-Level Jets and the Urban Boundary Layer: A Case Study over London

2022 ◽  
Author(s):  
Aristofanis Tsiringakis ◽  
Natalie E. Theeuwes ◽  
Janet F. Barlow ◽  
Gert-Jan Steeneveld
Keyword(s):  
Boundary Layer ◽  
Wind Speed ◽  
Urban Areas ◽  
Prediction Models ◽  
Weather Prediction ◽  
Urban Boundary Layer ◽  
Limited Area ◽  
Low Level ◽  
Low Level Jets

AbstractUnderstanding the physical processes that affect the turbulent structure of the nocturnal urban boundary layer (UBL) is essential for improving forecasts of air quality and the air temperature in urban areas. Low-level jets (LLJs) have been shown to affect turbulence in the nocturnal UBL. We investigate the interaction of a mesoscale LLJ with the UBL during a 60-h case study. We use observations from two Doppler lidars and results from two high-resolution numerical-weather-prediction models (Weather Research and Forecasting model, and the Met Office Unified Model for limited-area forecasts for the U.K.) to study differences in the occurrence frequency, height, wind speed, and fall-off of LLJs between an urban (London, U.K.) and a rural (Chilbolton, U.K.) site. The LLJs are elevated ($$\approx $$ ≈ 70 m) over London, due to the deeper UBL, while the wind speed and fall-off are slightly reduced with respect to the rural LLJ. Utilizing two idealized experiments in the WRF model, we find that topography strongly affects LLJ characteristics, but there is still a substantial urban influence. Finally, we find that the increase in wind shear under the LLJ enhances the shear production of turbulent kinetic energy and helps to maintain the vertical mixing in the nocturnal UBL.

Model representation of boundary-layer convergence triggering deep convection over complex terrain: A case study from COPS

2010 ◽  
Vol 95 (2-3) ◽  
pp. 172-185 ◽  
Author(s):  
Christian Barthlott ◽  
Janus Willem Schipper ◽  
Norbert Kalthoff ◽  
Bianca Adler ◽  
Christoph Kottmeier ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Complex Terrain ◽  
Deep Convection ◽  
Model Representation
Sign in / Sign up

Export Citation Format

Share Document