scholarly journals A Numerical Study of Mountain-Plain Breeze Circulation in Eastern Chengdu, China

2019 ◽  
Vol 11 (10) ◽  
pp. 2821 ◽  
Author(s):  
Yue Tian ◽  
Junfeng Miao
Keyword(s):  
Cross Sections ◽  
Numerical Study ◽  
Turbulent Transport ◽  
Temperature Inversion ◽  
Turbulent Heat ◽  
Breeze Circulation ◽  
Local Circulation ◽  
Mountain Areas ◽  
Mountain Area ◽  
The North

The spatiotemporal structure and evolution of the thermally-induced mountain-plain breeze circulation in the Longquan Mountain, eastern Chengdu, are studied by the WRF-ARW model based on a two-day case. Turbulence characteristics are also examined to better understand the local circulation of the area. Simulation results show that the 2 m temperature distribution of the plain and mountain areas is peculiar due to the occurrence of the temperature inversion. The plain and mountain breezes can be predicted explicitly by the model, and the consequent circulations are coupled with other factors such as turbulent movement and vertically propagating mountain waves. Owing to this unique terrain feature, the north portion of the mountain demonstrates more evident mountain and plain breezes compared to the south and middle portions. Stronger turbulences are formed over the mountain area compared to the plain area. Vertical cross-sections of turbulent heat, moisture and momentum fluxes show that turbulent transport plays an important role in the development and elimination of mountain-plain breeze circulation.

scholarly journals A numerical study of the transport and diffusion of coastal pollutants during the breeze cycle in the Island of Mallorca

1996 ◽  
Vol 14 (3) ◽  
pp. 351-363 ◽  
Author(s):  
R. Romero ◽  
C. Ramis
Keyword(s):  
Numerical Study ◽  
Ground Level ◽  
North Coast ◽  
Land Breeze ◽  
Local Circulation ◽  
Physical Mechanisms ◽  
The North ◽  
Ground Level Concentration ◽  
Transport And Diffusion ◽  
Reactive Pollutant

Abstract. An Eulerian study of the distribution over the Island of Mallorca of a non-reactive pollutant (SO2) emitted from an electric power plant operating at present on the north coast is performed using a meso-β numerical model, paying particular attention to the diffusive physical mechanisms. The study is applied to the conditions of sea-land breeze development. This is a local circulation that dominates the flow during the summer and favours transporting pollutants from the coast toward the centre of the island. Results indicate that values of the ground-level concentration higher than 5 μ g/m3 are restricted over a limited and mountainous region during the whole diurnal cycle. However, when the simulation is carried out with the inclusion of a twin electric plant which may be built on the south coast, the affected area becomes larger, especially early in the morning, when air over the island is sinking as a consequence of the land breeze development. The inclusion of dry deposition in the simulations does not produce important changes in the spatial and temporal evolution of the ground-level concentration.

scholarly journals The Secondary Low and Heavy Rainfall Associated with Typhoon Mindulle (2004)

2008 ◽  
Vol 136 (4) ◽  
pp. 1260-1283 ◽  
Author(s):  
Cheng-Shang Lee ◽  
Yi-Chin Liu ◽  
Fang-Ching Chien
Keyword(s):  
Heavy Rainfall ◽  
Numerical Study ◽  
North Coast ◽  
Mountain Range ◽  
Mountain Area ◽  
The North ◽  
Main Circulation ◽  
Upper Level ◽  
The Taiwan Strait ◽  
Strong Vorticity

Abstract This paper presents an observational and numerical study of Typhoon Mindulle (2004) as it affected Taiwan. Mindulle made landfall on the east coast of Taiwan at 1500 UTC 1 July 2004, and after 13 h, it exited Taiwan from the north coast. Severe rainfall (with a maximum amount of 787 mm) occurred over central-southwestern Taiwan on 2 July 2004. During the landfall of Mindulle’s main circulation, a secondary low formed over the Taiwan Strait. However, the secondary low, after it developed significantly (vorticity exceeded 5 × 10−4 s−1 over a 30-km radius), did not replace the original center as was observed in many other storms. Instead, it moved inland and dissipated after the original center redeveloped near the north coast of Taiwan. In this study, the evolution of the secondary low, the redevelopment of the primary center, and the processes leading to the severe rainfall were examined. Results showed that the processes leading to the formation and the development of the secondary low were similar to those described in previous studies. These processes include the leeside subsidence warming, the horizontal transport of vorticity around the northern tip of the Central Mountain Range (CMR), and the overmountain upper-level vorticity remnant. However, because of the northward track, Mindulle preserved some strong vorticity on the eastern slope of the CMR. This strong vorticity remnant was steered northward over the ocean offshore from the north coast where the redevelopment of the primary center occurred. This “quasi-continuous track” of Mindulle has not been documented in previous studies. The vortex interaction between the redeveloped primary center and the secondary low resulted in the northeastward movement of the secondary low, which then dissipated after making landfall. Analyses also showed that even though heavy rainfall would occur over the mountain area when only the southwesterly flow prevailed, as on 3 July 2004, Typhoon Mindulle and the secondary low provided extra convergence that resulted in the west–east-oriented convective bands. These convective bands and the orographic lifting of the circulation associated with the secondary low resulted in the heavy rainfall over the central-western plains area.

scholarly journals Field relations, age, and tectonic setting of metamorphic and plutonic rocks in the Creignish Hills – North Mountain area, southwestern Cape Breton Island, Nova Scotia, Canada

2016 ◽  
Vol 52 ◽  
pp. 037 ◽  
Author(s):  
Chris E. White ◽  
Sandra M. Barr ◽  
Donald W. Davis ◽  
David S. Swanton ◽  
John W.F. Ketchum ◽  
...  
Keyword(s):  
Tectonic Setting ◽  
Passive Margin ◽  
Mountain Areas ◽  
Mountain Area ◽  
Cape Breton Island ◽  
Metasedimentary Rocks ◽  
The North ◽  
Rock Types ◽  
Cape Breton ◽  
Depositional Age

 The Creignish Hills and North Mountain areas of southwestern Cape Breton Island consist mostly of Neoproterozoic rocks typical of the Ganderian Bras d’Or terrane. U-Pb ages presented here for detrital zircon in the Blues Brook Formation of the Creignish Hills confirm a depositional age no greater than about 600 Ma. Although it is possible that some components of the formation are much older, similarities in rock types and field relations suggest that this is not the case. It is likely that the equivalent Malagawatch Formation of the North Mountain area, as well as high-grade metasedimentary rocks of the Melford Formation and Chuggin Road complex in the Creignish Hills and Lime Hill gneiss complex in the North Mountain area, represent the same or stratigraphically equivalent units as the Blues Brook Formation. The minimum ages of all of these units are constrained by cross-cutting syn- and post-tectonic plutons with ages mostly between 565 and 550 Ma, indicating that sediments were deposited, regionally metamorphosed, deformed, and intruded by plutons in less than 40–50 million years. The assemblage of pelitic, psammitic, and carbonate rocks indicates that a passive margin in a tropical climate was quickly changed to an active Andean-type continental margin in which voluminous calcalkaline dioritic to granitic plutons were emplaced. This sedimentary and tectonic history is characteristic of the Bras d’Or terrane and is shared by its likely correlative, the Brookville terrane in southern New Brunswick. 

EVALUATION OF MOUNTAIN AREA AS NON-POINT SOURCE OF NITROGEN FOR SETO INLAND SEA: THE NORTHERN SHIKOKU REGION, JAPAN

2017 ◽  
Author(s):  
Shohei Morisawa ◽  
Shohei Morisawa ◽  
Yukio Komai ◽  
Yukio Komai ◽  
Takao Kunimatsu ◽  
...  
Keyword(s):  
Average Concentration ◽  
Point Sources ◽  
Seto Inland Sea ◽  
Mountain Streams ◽  
Unit Load ◽  
Mountain Areas ◽  
Mountain Area ◽  
The Seto Inland Sea ◽  
Unit Load Method ◽  
Important Position

The northern Shikoku region is located in the Western part of Japan and faces towards the Seto Inland Sea. The forest area, which is one of the non-point sources in the Seto Inland Sea watershed, occupies 75% of the land use in the watershed of the northern Shikoku region. The amount of loadings of nutrients and COD in the Seto Inland Sea has been estimated by the unit load method but actually the data has not been investigated. It is however, necessary to know the real concentration of nitrogen in mountain streams to evaluate the role which is the mountain area plays as non-point sources. Therefore, more water samples of mountain streams in the watershed need to be taken and the concentrations of nitrogen analyzed. The mountain streams in the northern Shikoku area were investigated from April, 2015 to November, 2015. The number of sampling sites was 283, in addition to the past data by Kunimatsu et al. The average concentration of nitrate nitrogen in Ehime, Kagawa, and Tokushima was 0.61mg/L, 0.78mg/L and 0.34mg/L, respectively. The environmental standard range for nitrogen in the Seto Inland Sea is from between less than 0.2mg/L and less than 1mg/L. Therefore, the average concentration of nitrogen in these regions was over category II, and those of mountain streams in Kagawa Prefecture exceeded category III. About 20% of mountain streams were more than 1mg/L. It has become clear that mountain areas occupy an important position as non-point sources for the Seto Inland Sea.

scholarly journals Aluminium alloy cross-sections under uniaxial bending and compression: A numerical study

2021 ◽  
Vol 1058 (1) ◽  
pp. 012011
Author(s):  
Evangelia Georgantzia ◽  
Michaela Gkantou ◽  
George S. Kamaris ◽  
Kunal Kansara ◽  
Khalid Hashim
Keyword(s):  
Aluminium Alloy ◽  
Cross Sections ◽  
Numerical Study

scholarly journals Seasonal Variability of the Acoustic Climate of Ski Resorts in the Aosta Valley Territory

Environments ◽  
2020 ◽  
Vol 7 (3) ◽  
pp. 18 ◽  
Author(s):  
Christian Tibone ◽  
Marco Masoero ◽  
Filippo Berlier ◽  
Giovanni Tabozzi ◽  
Daniele Crea ◽  
...  
Keyword(s):  
Environmental Protection Agency ◽  
Winter Season ◽  
Noise Pollution ◽  
Sound Sources ◽  
Mountain Areas ◽  
Mountain Area ◽  
North West ◽  
Ski Resorts ◽  
Acoustic Quality ◽  
High Level

The Aosta Valley is an alpine region in north-west Italy that is characterized by a high level of naturalness, with extensive uninhabited areas that are distant from artificial sound sources. The Aosta Valley Regional Environmental Protection Agency (ARPA-VdA) has been particularly sensitive to the preservation of the soundscape, which is considered an integral part of the landscape, since the laws on noise pollution were first introduced. The nature of the ski areas in the Aosta mountains, which undergoes changes throughout the year, is surely of great importance, especially during the winter season, when the number of visitors is particularly high. In fact, during the winter, the sounds of nature are replaced by those produced by recreation and sports activities. Mountain and snow tourism, which are developed in sensitive environmental contexts in the Aosta Valley, are sectors of immense social and economic importance. Much of this tourism takes place in ski resorts. Three mountain areas with different characteristics, in terms of attendance and recreational/sport activities, have been examined in this paper, as part of a collaboration between ARPA-VdA and the Politecnico di Torino. Acoustic measurements were performed in order to identify the seasonal variations of sound emissions from both natural and anthropic sound sources. In addition to the standard environmental acoustic descriptors foreseen by European legislation (LAeq, Ln, Lden, etc.), the harmonica (IH) index, which provides a quantitative evaluation of the acoustic quality on a zero to ten numerical scale, was used to qualify the acoustic climate of the three areas. The results presented in the paper provide useful information on a relevant subject—the preservation of the acoustic quality of a mountain area of touristic importance—which has been scarcely investigated so far.

scholarly journals Mechanisms for a remote response to Asian anthropogenic aerosol in boreal winter

2019 ◽  
Vol 19 (14) ◽  
pp. 9081-9095 ◽  
Author(s):  
Laura J. Wilcox ◽  
Nick Dunstone ◽  
Anna Lewinschal ◽  
Massimo Bollasina ◽  
Annica M. L. Ekman ◽  
...  
Keyword(s):  
North Pacific ◽  
Western Europe ◽  
Large Temperature ◽  
Boreal Winter ◽  
Far Field ◽  
Anthropogenic Aerosols ◽  
Local Circulation ◽  
The North ◽  
The North Pacific ◽  
Circulation Changes

Abstract. Asian emissions of anthropogenic aerosols and their precursors have increased rapidly since 1980, with half of the increase since the pre-industrial era occurring in this period. Transient experiments with the HadGEM3-GC2 coupled model were designed to isolate the impact of Asian anthropogenic aerosols on global climate in boreal winter. It is found that this increase has resulted in local circulation changes, which in turn have driven decreases in precipitation over China, alongside an intensification of the offshore monsoon flow. No large temperature changes are seen over China. Over India, the opposite response is found, with decreasing temperatures and increasing precipitation. The dominant feature of the local circulation changes is an increase in low-level convergence, ascent, and precipitation over the Maritime Continent, which forms part of a tropical Pacific-wide La Niña-like response. HadGEM3-GC2 also simulates pronounced far-field responses. A decreased meridional temperature gradient in the North Pacific leads to a positive Pacific–North American circulation pattern, with associated temperature anomalies over the North Pacific and North America. Anomalous northeasterly flow over northeast Europe drives advection of cold air into central and western Europe, causing cooling in this region. An anomalous anticyclonic circulation over the North Atlantic causes drying over western Europe. Using a steady-state primitive equation model, LUMA, we demonstrate that these far-field midlatitude responses arise primarily as a result of Rossby waves generated over China, rather than in the equatorial Pacific.

A Numerical and Experimental Investigation of Turbulent Heat Transport Downstream From an Abrupt Pipe Expansion

1983 ◽  
Vol 105 (4) ◽  
pp. 862-869 ◽  
Author(s):  
R. S. Amano ◽  
M. K. Jensen ◽  
P. Goel
Keyword(s):  
Heat Transfer ◽  
Numerical Solutions ◽  
Numerical Study ◽  
Separated Flow ◽  
Flow Region ◽  
Reynolds Numbers ◽  
Turbulent Heat ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Pipe Expansion

An experimental and numerical study is reported on heat transfer in the separated flow region created by an abrupt circular pipe expansion. Heat transfer coefficients were measured along the pipe wall downstream from an expansion for three different expansion ratios of d/D = 0.195, 0.391, and 0.586 for Reynolds numbers ranging from 104 to 1.5 × 105. The results are compared with the numerical solutions obtained with the k ∼ ε turbulence model. In this computation a new finite difference scheme is developed which shows several advantages over the ordinary hybrid scheme. The study also covers the derivation of a new wall function model. Generally good agreement between the measured and the computed results is shown.

scholarly journals Empirical Mode Reduction in a Model of Extratropical Low-Frequency Variability

2006 ◽  
Vol 63 (7) ◽  
pp. 1859-1877 ◽  
Author(s):  
D. Kondrashov ◽  
S. Kravtsov ◽  
M. Ghil
Keyword(s):  
Numerical Study ◽  
Singular Spectrum Analysis ◽  
Low Frequency ◽  
The Arctic ◽  
Reduced Model ◽  
The North ◽  
Low Frequency Variability ◽  
Intraseasonal Oscillations ◽  
The Arctic Oscillation ◽  
The North Atlantic Oscillation

Abstract This paper constructs and analyzes a reduced nonlinear stochastic model of extratropical low-frequency variability. To do so, it applies multilevel quadratic regression to the output of a long simulation of a global baroclinic, quasigeostrophic, three-level (QG3) model with topography; the model's phase space has a dimension of O(104). The reduced model has 45 variables and captures well the non-Gaussian features of the QG3 model's probability density function (PDF). In particular, the reduced model's PDF shares with the QG3 model its four anomalously persistent flow patterns, which correspond to opposite phases of the Arctic Oscillation and the North Atlantic Oscillation, as well as the Markov chain of transitions between these regimes. In addition, multichannel singular spectrum analysis identifies intraseasonal oscillations with a period of 35–37 days and of 20 days in the data generated by both the QG3 model and its low-dimensional analog. An analytical and numerical study of the reduced model starts with the fixed points and oscillatory eigenmodes of the model's deterministic part and uses systematically an increasing noise parameter to connect these with the behavior of the full, stochastically forced model version. The results of this study point to the origin of the QG3 model's multiple regimes and intraseasonal oscillations and identify the connections between the two types of behavior.

EXPERIENCE OF USING THE CLUSTER APPROACH IN ASSESSING THE SUSTAINABLE DEVELOPMENT OF THE MOUNTAINOUS TERRITORIES OF THE NORTH CAUCASUS

2021 ◽  
Vol 1 (11) ◽  
pp. 37-46
Author(s):  
Rita I. Batyaeva ◽  
◽  
Tat’yana G. Shelkunova ◽  
Irina Yu. Khetagurova ◽  
Tamara G. Khetagurova ◽  
...  
Keyword(s):  
Sustainable Development ◽  
Economic Development ◽  
Social Indicators ◽  
Federal District ◽  
North Caucasus ◽  
Mountain Areas ◽  
The Sustainable Development ◽  
The North ◽  
Technological Level ◽  
National Environmental

The article provides an overview of the effects of the resonant impact of clusters on the ability of mountain areas to adapt to the modern realities of the technological level, as well as the ability to apply innovations, attract investment in the agro-industrial and tourist cluster. A panel of indicators is presented that provides correct comparability of achievements and reflects information for aggregation by various parameters of the economic and geographical indicators of the region: the national environmental rating of the subjects of the North Caucasus Federal District; indicators of sustainable development of the Russian Federation and the North Caucasus Federal District; investment risk of the republics of the North Caucasus Federal District; the main economic and social indicators of the RSO-Alania. It is established that the geoinformation study of the use of a multicomponent indicator of the state of mountain territories is the basis for determining the vector of their further socio-economic development and justifying appropriate management decisions to stabilize economic development. The peculiarity of the approach is the selection of criteria that will be used in the development of mechanisms for the sustainable development of mountain territories according to the target indicators, in accordance with the UN resolution "Transforming our world in the field of sustainable develop-ment for the period up to 2030".

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