scholarly journals Sensitivity studies on the air flow characteristics In Kharagpur using a meso-scale model

MAUSAM ◽  
2022 ◽  
Vol 44 (4) ◽  
pp. 329-336
Author(s):  
D LOHAR ◽  
B CHAKRAVARTY ◽  
B. Pal
Keyword(s):  
West Bengal ◽  
Surface Wind ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Sea Breeze ◽  
Scale Model ◽  
Monsoon Period ◽  
Sea Breezes ◽  
Differential Heating ◽  
South West

  A three-dimensional hydrostatic model has been employed for the study of sea breeze circulations over south West Bengal with special reference to an inland station Kharagpur (22°.21' N, 87° 19'E). A series of sensitivity experiments have been performed to stress the Importance of differential heating on circulation over south West Bengal during pre-monsoon period. It is found that due to differential heating rate between land and sea surfaces, sea breezes can penetrate to the inland station Kharagpur and beyond even in case of moderate gradient wind. Surface observations at Kharagpur and pilot balloon observation at nearby station Kalaikunda are used to compare the model results. The onset of sea breezes, variation of the air temperature and humidity are In fairly good agreement whereas It over estimates the depth of the circulation and cannot predict the variation  of the late morning hours surface wind.

scholarly journals The effect of coastal upwelling on the sea-breeze circulation at Cabo Frio, Brazil: a numerical experiment

1998 ◽  
Vol 16 (7) ◽  
pp. 866-871 ◽  
Author(s):  
S. H. Franchito ◽  
V. B. Rao ◽  
J. L. Stech ◽  
J. A. Lorenzzetti
Keyword(s):  
Coastal Upwelling ◽  
Surface Wind ◽  
Three Dimensional ◽  
Sea Breeze ◽  
Atmospheric Model ◽  
Ocean Model ◽  
Breeze Circulation ◽  
Mesoscale Meteorology ◽  
Forcing Function ◽  
Cabo Frio

Abstract. The effect of coastal upwelling on sea-breeze circulation in Cabo Frio (Brazil) and the feedback of sea-breeze on the upwelling signal in this region are investigated. In order to study the effect of coastal upwelling on sea-breeze a non-linear, three-dimensional, primitive equation atmospheric model is employed. The model considers only dry air and employs boundary layer formulation. The surface temperature is determined by a forcing function applied to the Earth's surface. In order to investigate the seasonal variations of the circulation, numerical experiments considering three-month means are conducted: January-February-March (JFM), April-May-June (AMJ), July-August-September (JAS) and October-November-December (OND). The model results show that the sea-breeze is most intense near the coast at all the seasons. The sea-breeze is stronger in OND and JFM, when the upwelling occurs, and weaker in AMJ and JAS, when there is no upwelling. Numerical simulations also show that when the upwelling occurs the sea-breeze develops and attains maximum intensity earlier than when it does not occur. Observations show a similar behavior. In order to verify the effect of the sea-breeze surface wind on the upwelling, a two-layer finite element ocean model is also implemented. The results of simulations using this model, forced by the wind generated in the sea-breeze model, show that the sea-breeze effectively enhances the upwelling signal.Key words. Meteorology and atmospheric dynamics (mesoscale meteorology; ocean-atmosphere interactions) · Oceanography (numerical modeling)

scholarly journals A Linear Theory of Three-Dimensional Land–Sea Breezes

2012 ◽  
Vol 69 (6) ◽  
pp. 1890-1909 ◽  
Author(s):  
Qingfang Jiang
Keyword(s):  
Gravity Waves ◽  
Three Dimensional ◽  
Vertical Motion ◽  
Early Morning ◽  
Earth’S Rotation ◽  
Earth's Rotation ◽  
Motion Patterns ◽  
Sea Breezes ◽  
Differential Heating ◽  
Downwind Side

Abstract Land–sea breezes (LSBs) induced by diurnal differential heating are examined using a three-dimensional linear model employing fast Fourier transform with emphasis on the complex coastline shape and geometry, the earth’s rotation, and background wind effects. It has been demonstrated that the low-level vertical motion associated with LSB can be significantly enhanced over a bay (peninsula) because of convergence of perturbations induced by differential heating along a seaward concave (convex) coastline. The dependence of surface winds and vertical motion patterns and their evolutions on the coastline geometries such as the width and the aspect ratio of the bay, the earth’s rotation, and the background winds are investigated. The LSB induced by an isolated tropical island is characterized by onshore flow and ascent over the island in the afternoon to early evening, with a reversal of direction from midnight to early morning. The diurnal heating–induced vertical motion is greatly enhanced over the island and weakened offshore because of the convergence and divergence of perturbations. In the presence of background flow, stronger diurnal perturbations are found at the downwind side of the island, which can extend far downstream associated with inertia–gravity waves.

scholarly journals Influence of winds on temporally varying short and long period gravity waves in the near shore regions of Eastern Arabian Sea

2012 ◽  
Vol 9 (5) ◽  
pp. 3021-3047
Author(s):  
J. Glejin ◽  
V. Sanil Kumar ◽  
T. N. Balakrishnan Nair ◽  
J. Singh
Keyword(s):  
West Coast ◽  
Sea Breeze ◽  
Monsoon Period ◽  
West Coast Of India ◽  
Intermediate Period ◽  
Long Period ◽  
Post Monsoon ◽  
South West ◽  
South West Monsoon ◽  
West Monsoon

Abstract. Wave data collected off Ratnagiri, west coast of India during 1 May 2010 to 30 April 2012 is used in the study. Seasonal and annual variation in wave data controlled by the local wind system such as sea breeze and land breeze, and remote wind generated long period waves observed along the west coast of India, is studied. Sea breeze plays an important role in determining the sea state during pre and post monsoon seasons and the maximum wave height is observed during peak hours of sea breeze at 15:00 UTC. Long period waves (peak period over 13 s) are observed mainly during the pre and the post monsoon season. Maximum peak period observed during the study is 22 s and is in the month of October. Long period waves observed during the south west monsoon period of 2011 are identified as swell propagated from the Southern Ocean with an estimated travelling time of 5–6 days. The swells reaching the Arabian Sea from the South Indian Ocean and Southern Ocean, due to storms during the pre and post monsoon periods will modify the near surface winds, due to the dominant wave induced wind regime. Energy spectrum of observed waves indicates onset and decline of strong south west monsoon winds. Convergence of energy-containing frequency bands corresponding to short period waves (Tp < 8 s) and long period waves (Tp > 13 s) to intermediate period waves (8 < Tp < 13 s) are observed at the end of the pre monsoon season; divergence is observed during the start of the post monsoon period from intermediate period waves to short period waves and long period waves. South west monsoon period is characterized by the energy corresponding to the frequency band of intermediate period waves along the west coast of India.

scholarly journals Performance of the WRF Model for Surface Wind Prediction around Qatar

2018 ◽  
Vol 35 (3) ◽  
pp. 575-592 ◽  
Author(s):  
B. S. Sandeepan ◽  
V. G. Panchang ◽  
S. Nayak ◽  
K. Krishna Kumar ◽  
J. M. Kaihatu
Keyword(s):  
Boundary Layer ◽  
Large Scale ◽  
Surface Wind ◽  
Wrf Model ◽  
Wave Model ◽  
Sea Breeze ◽  
Surface Winds ◽  
Model Errors ◽  
Sea Breezes ◽  
Practical Applications

AbstractThe performance of the Weather Research and Forecasting (WRF) Model is examined for the region around Qatar in the context of surface winds. The wind fields around this peninsula can be complicated owing to its small size, to a complex pattern of land and sea breezes influenced by the prevailing shamal winds, and to its dry and arid nature. Modeled winds are verified with data from 19 land stations and two offshore buoys. A comparison with these data shows that nonlocal planetary boundary layer (PBL) schemes generally perform better than local schemes over land stations during the daytime, when convective conditions prevail; at nighttime, over land and over water, both schemes yield similar results. Among other parameters, modifications to standard USGS land-use descriptors were necessary to reduce model errors. The RMSE values are comparable to those reported elsewhere. Simulated winds, when used with a wave model, result in wave heights comparable to buoy measurements. Furthermore, WRF results, confirmed by data, show that at times sea breezes develop from both coasts, leading to convergence in the middle of the country; at other times, the large-scale wind impedes the formation of sea breezes on one or both coasts. Simulations also indicate greater land/sea-breeze activity in the summer than in the winter. Differences in the diurnal evolution of surface winds over land and water are found to be related to differences in the boundary layer stability. Overall, the results indicate that the WRF Model as configured here yields reliable simulations and can be used for various practical applications.

scholarly journals Diurnal Cycle of Surface Winds in the Maritime Continent Observed through Satellite Scatterometry

2019 ◽  
Vol 147 (6) ◽  
pp. 2023-2044 ◽  
Author(s):  
Ewan Short ◽  
Claire L. Vincent ◽  
Todd P. Lane
Keyword(s):  
Diurnal Cycle ◽  
Surface Wind ◽  
Sea Breeze ◽  
Surface Winds ◽  
Time Data ◽  
Maritime Continent ◽  
Sea Breezes ◽  
Diurnal Cycles ◽  
Using Data ◽  
Precipitation Cycles

Abstract The diurnal cycle of surface winds throughout the Maritime Continent plays a significant role in the formation of precipitation over the islands of the region and over the surrounding seas. This study investigates the connection between the diurnal cycles of surface wind and offshore precipitation using data from four satellite scatterometer instruments and two satellite precipitation radar instruments. For the first time, data from three scatterometer instruments are combined to yield a more temporally complete picture of the surface wind diurnal cycles over the Maritime Continent’s surrounding seas. The results indicate that land–sea breezes typically propagate over 400 km offshore, produce mean wind perturbations of between 1 and 5 m s−1, and propagate as gravity waves at 25–30 m s−1. Diurnal precipitation cycles are affected through gravity wave propagation processes associated with the land–sea breezes, and through the convergence of land breezes from nearby islands. These observational results are then compared with previous mesoscale modeling results. It is shown that land–sea breezes occur too early, and are too intense in these modeling results, and this may partly explain why these modeling results also exhibit an early, overly intense diurnal precipitation cycle. This study also investigates variations in the diurnal cycle of surface winds at seasonal and intraseasonal time scales. Previous work has suggested that seasonal and intraseasonal variations in surface heating affect the land–sea breeze circulation and diurnal precipitation cycles; we argue that variations in background winds also play a defining role in modulating coastally influenced local winds.

scholarly journals Numerical simulation of sea breeze in south Andamans

MAUSAM ◽  
2021 ◽  
Vol 42 (4) ◽  
pp. 339-346
Author(s):  
S.C. Kar ◽  
N. Ramanathan
Keyword(s):  
Three Dimensional ◽  
Sea Breeze ◽  
Heat Fluxes ◽  
Scale Model ◽  
Land Breeze ◽  
Turbulent Heat ◽  
Vegetative Cover ◽  
Turbulent Heat Fluxes ◽  
South Andaman ◽  
Meso Scale

The air flow over the south Andaman island is simulated using a three dimensional numerical meso-scale model. Port Blair observations are used as initial data. The surface orography, soil moisture soil albedo variations and vegetations effects are included in the model. The combined effect of these factors on the development of sea/land breeze circulations is obtained quantitatively. The model simulated results are compared with the available observations. The principal results obtained are : (1) The meso-scale circulations induced by the differential heating of the island were intensified by topography. (2) The ground vegetative cover trans- port higher amount of turbulent heat fluxes: to the atmosphere and the meso-circulations appeared with higher intensities. (3) If we Include the lateral variations of flux with topographic and coastal asymmetries the induced meso-scale circulations appeared with different intensities along meridional direction and the inland penetration distances varied in y direction. The maximum Inland penetration of sea breeze was seen, where the inland was widest and terrain height was maximum. Stronger sea breeze was simulated over the central/northern parts of the island.

scholarly journals Numerical modelling of pollutant dispersion in sea breeze conditions

1996 ◽  
Vol 14 (6) ◽  
pp. 665-677 ◽  
Author(s):  
J. Camps ◽  
J. Massons ◽  
M. R. Soler
Keyword(s):  
Mesoscale Model ◽  
Numerical Study ◽  
Surface Wind ◽  
Three Dimensional ◽  
Coastal Region ◽  
Pollutant Dispersion ◽  
Sea Breeze ◽  
Wind Fields ◽  
Wind Measurements ◽  
Reactive Pollutant

Abstract. The characteristics of air pollution in Tarragona (Spain) were investigated. Tarragona has an important petrochemical industry in a coastal region with a complex terrain. The numerical study was made in sea breeze conditions with a three-dimensional mesoscale model. Temporal and spatial variations of the wind fields have been used in the Eulerian equation for a non-reactive pollutant. The results of this study reveal the complexity of the dispersion patterns due to the combined effects of the sea breeze circulation and the orography. This work presents a comparison between the model output and the observed wind data by sodar and surface wind measurements. The evaluation shows that the model is capable of providing very realistic wind fields within this domain.

Forecasting of Summer Monsoon Rainfall over Gangetic West Bengal, India Utilising Intrinsic Mode Functions, Linear and Neural Regression

2020 ◽  
Vol 12 (1) ◽  
pp. 60-69 ◽  
Author(s):  
Pijush Basak
Keyword(s):  
Neural Network ◽  
West Bengal ◽  
Monsoon Rainfall ◽  
Linear Part ◽  
Intrinsic Mode Functions ◽  
Quasi Biennial Oscillation ◽  
Nonlinear Part ◽  
South West ◽  
South West Monsoon ◽  
West Monsoon

The South West Monsoon rainfall data of the meteorological subdivision number 6 of India enclosing Gangetic West Bengal is shown to be decomposable into eight empirical time series, namely Intrinsic Mode Functions. This leads one to identify the first empirical mode as a nonlinear part and the remaining modes as the linear part of the data. The nonlinear part is modeled with the technique Neural Network based Generalized Regression Neural Network model technique whereas the linear part is sensibly modeled through simple regression method. The different Intrinsic modes as verified are well connected with relevant atmospheric features, namely, El Nino, Quasi-biennial Oscillation, Sunspot cycle and others. It is observed that the proposed model explains around 75% of inter annual variability (IAV) of the rainfall series of Gangetic West Bengal. The model is efficient in statistical forecasting of South West Monsoon rainfall in the region as verified from independent part of the real data. The statistical forecasts of SWM rainfall for GWB for the years 2012 and 2013 are108.71 cm and 126.21 cm respectively, where as corresponding to the actual rainfall of 93.19 cm 115.20 cm respectively which are within one standard deviation of mean rainfall.

Three-dimensional Reconstruction of Microscopic Image Based on Multi-ST Algorithm

2020 ◽  
Vol 64 (2) ◽  
pp. 20506-1-20506-7
Author(s):  
Min Zhu ◽  
Rongfu Zhang ◽  
Pei Ma ◽  
Xuedian Zhang ◽  
Qi Guo
Keyword(s):  
3D Reconstruction ◽  
Three Dimensional ◽  
Scale Model ◽  
Microscopic Image ◽  
Multi Scale ◽  
Gaussian Pyramid ◽  
Cost Aggregation ◽  
Dimensional Reconstruction ◽  
Image Pairs ◽  
Accurate Matching

Abstract Three-dimensional (3D) reconstruction is extensively used in microscopic applications. Reducing excessive error points and achieving accurate matching of weak texture regions have been the classical challenges for 3D microscopic vision. A Multi-ST algorithm was proposed to improve matching accuracy. The process is performed in two main stages: scaled microscopic images and regularized cost aggregation. First, microscopic image pairs with different scales were extracted according to the Gaussian pyramid criterion. Second, a novel cost aggregation approach based on the regularized multi-scale model was implemented into all scales to obtain the final cost. To evaluate the performances of the proposed Multi-ST algorithm and compare different algorithms, seven groups of images from the Middlebury dataset and four groups of experimental images obtained by a binocular microscopic system were analyzed. Disparity maps and reconstruction maps generated by the proposed approach contained more information and fewer outliers or artifacts. Furthermore, 3D reconstruction of the plug gauges using the Multi-ST algorithm showed that the error was less than 0.025 mm.

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