scholarly journals Numerical Simulation of Sea Breeze Convergence over Antarctic Peninsula

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Alcimoni Nelci Comin ◽  
Otávio Costa Acevedo
Keyword(s):  
Antarctic Peninsula ◽  
Large Scale ◽  
Potential Temperature ◽  
Sensible Heat Flux ◽  
Wrf Model ◽  
Sea Breeze ◽  
Circulation System ◽  
Breeze Circulation ◽  
Synoptic Wind ◽  
Cold Anomaly

The convergence zone induced by sea breeze systems over Antarctic Peninsula is analyzed for the summer season of 2013–2015. 59 days, selected by satellite images for the absence of major synoptic forcing, are simulated using the WRF model. Sea breeze convergence has been detected in 21 of these days, mostly during evening hours and under large-scale winds. Breeze events are associated with a cold anomaly at the peninsula with respect to the climatology. This condition favors the onset of the necessary horizontal thermal gradients to trigger the breeze circulation. At the same time, no anomaly of the average pressure at sea level is found, indicating that events are favored when the average synoptic flow is present. Case studies indicate that the convergence location over the peninsula is controlled by the synoptic wind. An average convergence over the peninsula happens from 14:00 to 22:30 UTC, with a maximum at 18:00 UTC. There is a strong potential temperature gradient between the surface of the peninsula and the sea, with the sea breeze circulation system extending up to 1.2 km or higher. The sensible heat flux reaches 80 W/m2at the top of mountains and 10 W/m2near the coast.

Analyzing the atmospheric scales involved in sea-breeze formation and frontal characteristics

2020 ◽  
Author(s):  
Jon Ander Arrillaga ◽  
Pedro Jiménez ◽  
Jordi Vilà-Guerau de Arellano ◽  
Maria Antonia Jiménez ◽  
Carlos Román-Cascón ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Large Scale ◽  
Surface Wind ◽  
Sensible Heat Flux ◽  
Wrf Model ◽  
Sea Breeze ◽  
Stable Stratification ◽  
Horizontal Resolution ◽  
Sea Temperature ◽  
The Moment

<p>We investigate sea-breeze (SB) frontal passages troughout a 10-year period. Spanning the whole period, numerical simulations from the Weather Research and Forecasting (WRF) model are compared with a comprehensive observational database from the Cabauw Experimental Site (Ruisdael Project). On the one hand, a fine horizontal resolution of 2 km is employed in the numerical simulations, and the observational vertical levels within the first 200 m above the surface are replicated. On the other hand, an algorithm based on objective and strict filters is applied to both observations and simulations to select the SB events. This methodology allows to investigate the atmospheric scales influencing the SB formation and their interaction with local turbulence in a robust and objective way.</p><p>By carrying out a filter-by-filter comparison, we find that the simulated large-scale conditions show a good rate of coincidence with the observations (69%). Small biases in the large scale wind direction, however, induce important deviations in the surface-wind evolution. Regarding the mesoscale forcings, the land-sea temperature gradient is overestimated in average up to 4 K, producing stronger SB fronts in WRF. The analysis of the SB frontal characteristics and impacts is carried out by classifying the events into three boundary-layer regimes (convective, transition and stable) based on the value of the sensible-heat flux at the moment of the SB onset. The stronger SB in the model leads to enhanced turbulence particularly in the convective and transition regimes: the friction velocity, for instance, is overstated by around 50% at the SB onset. In addition, the arrival of the SB front enhances the stable stratification and gives rise to faster afternoon and evening transitions compared with situations solely driven by local atmospheric turbulence.</p><p>The obtained results can be considered a benchmark of the aspects to be improved in order to produce finer SB forecasts and more adequate representations of the associated physical processes, particularly during the afternoon and evening transition of the ABL.</p>

scholarly journals Numerical Study of the Effects of Topography and Urbanization on the Local Atmospheric Circulations over the Beijing-Tianjin-Hebei, China

2015 ◽  
Vol 2015 ◽  
pp. 1-16 ◽  
Author(s):  
Yucong Miao ◽  
Shuhua Liu ◽  
Yijia Zheng ◽  
Shu Wang ◽  
Bicheng Chen
Keyword(s):  
Numerical Study ◽  
Wrf Model ◽  
Sea Breeze ◽  
Land Breeze ◽  
Bohai Bay ◽  
Breeze Circulation ◽  
Thermally Induced ◽  
Atmospheric Circulations ◽  
Mountain Valley ◽  
Bth Region

The effects of the topography and urbanization on the local atmospheric circulations over the Beijing-Tianjin-Hebei (BTH) region were studied by the weather research and forecasting (WRF) model, as well as the interactions among these local atmospheric circulations. It was found that, in the summer day time, the multiscale thermally induced local atmospheric circulations may exist and interact in the same time over the BTH region; the topography played a role in the strengthening of the sea breeze circulations; after sunset, the inland progress of sea breeze was slowed down by the opposite mountain breeze; when the land breeze circulation dominated the Bohai bay, the mountain breeze circulation can couple with the land breeze circulation to form a large circulation ranging from the coastline to the mountains. And the presence of cities cannot change the general state of the sea-land breeze (SLB) circulation and mountain-valley breeze (MVB) circulation but acted to modify these local circulations slightly. Meanwhile, the development of the urban heat island (UHI) circulation was also strongly influenced by the nearby SLB circulation and MVB circulation.

scholarly journals Coastal Wind and Turbulence Observations during the Morning and Evening Transitions over Tropical Terrain

2017 ◽  
Vol 56 (12) ◽  
pp. 3167-3185 ◽  
Author(s):  
Derek D. Jensen ◽  
Timothy A. Price ◽  
Daniel F. Nadeau ◽  
Jacob Kingston ◽  
Eric R. Pardyjak
Keyword(s):  
Heat Flux ◽  
Large Scale ◽  
Sensible Heat Flux ◽  
Sea Breeze ◽  
Flow Regimes ◽  
Resource Assessment ◽  
Sensible Heat ◽  
Coastal Site ◽  
Synoptic Forcing ◽  
Mean Wind Speed

AbstractData collected during a multiyear, wind-resource assessment over a multi-land-use coastal environment in Belize are used to study the development and decay of wind and turbulence through the morning and evening transitions. Observations were made on three tall masts, forming an inland transect of approximately 5 km. The wind distribution is found to be bimodal and governed by synoptic scales, with onshore and offshore flow regimes. The behavior between the coastal and inland sites is found to be very similar when the flow is directed offshore; for onshore flow, stark differences occur. The mean wind speed at the coastal site is approximately 20% greater than the most inland site and is nearly constant throughout the diurnal cycle. For both flow regimes, the influence of the land–sea breeze circulation is inconsequential relative to the large-scale synoptic forcing. Composite time series are used to study the evolution of sensible heat flux and turbulence kinetic energy (TKE) throughout the morning and evening transitions. The TKE budget reveals that at the coastal site mechanical production of TKE is much more important than buoyant production. This allows for the unexpected case in which TKE increases through the ET despite the decrease of buoyant TKE production. Multiresolution flux decomposition is used to further study this phenomenon as well as the evolution of the sensible heat flux at differing time scales. An idealized schematic is presented to illustrate the timing and structure of the morning and evening transitions for an inland site and a coastal site that are subjected to similar synoptic forcing.

Anatomy of the sea-breeze circulation in Athens area under weak large-scale ambient winds

1998 ◽  
Vol 32 (12) ◽  
pp. 2223-2237 ◽  
Author(s):  
D. Melas ◽  
I. Ziomas ◽  
O. Klemm ◽  
C.S. Zerefos
Keyword(s):  
Large Scale ◽  
Sea Breeze ◽  
Breeze Circulation ◽  
Athens Area

scholarly journals A modified lightning potential index for numerical models with parameterized deep convection

2021 ◽  
Author(s):  
Guido Schröder
Keyword(s):  
Central Europe ◽  
Vertical Velocity ◽  
Large Scale ◽  
Numerical Models ◽  
Deep Convection ◽  
Potential Temperature ◽  
Wrf Model ◽  
Lightning Flash ◽  
Potential Index ◽  
Forecasting System

<p>A modified lightning potential index (MLPI) for numerical models with parameterized deep convection is presented. It is based on the LPI formula of Lynn and Yair (2010). Following the idea of Lopez (2016), the quantities (e.g. vertical velocity) needed in the LPI formula are derived from the updraft of the Bechtold-Tiedtke parameterization scheme (Bechtold et al., 2014). The formula is further improved by taking into account the vertical equivalent potential temperature gradient.</p><p>The LPI and MLPI are tested in ICON with 20km resolution (ICON-20) over central Europe. A key component in the LPI is the vertical velocity. To assess its quality, the vertical velocity of the updraft in the convection scheme in ICON-20 is compared to updrafts in the convection-resolving COSMO model with 2.2 km resolution (COSMO-D2). It is shown that in ICON-20 the extension of the vertical velocity is generally broader with the maximum located in higher altitudes. In the charge separation area where the vertical velocity is relevant, the ICON-20 vertical velocity is less than in COSMO-D2. Consequently, the LPI values in ICON-20 are lower by a factor of 2 compared to COSMO-D2.</p><p>The MLPI is verified against LINET lightning data (Betz et al. 2009) over central Europe for summer 2020 and compared to LPI in COSMO-D2. The MLPI is also compared to the LPI and the lightning flash density (LFD,  Lopez, 2016), all computed in ICON-20. For the test period the MLPI outperforms the LPI and LFD. However, the quality of the LPI in COSMO-D2 cannot quite be reached.</p><p> </p><p>Bechtold et al. 2014: Representing Equilibrium and Nonequilibrium Convection in Large-Scale Models. J. Atmos. Sci. 71, 734-753.</p><p>Betz et al., 2009:  LINET - An international lightning detection network in Europe. Atmos.  Res. 91 564–573.</p><p>Lopez, 2016: A Lightning Parameterization for the ECMWF Integrated Forecasting System. Mon. Wea. Rev., 144, 3057-2075.</p><p>Lynn and Yair, 2010: Prediction of lightning flash density with the WRF model  Adv. Geosci., 23, 11–16.</p>

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 Evaluating transport in the WRF model along the California coast

2012 ◽  
Vol 12 (7) ◽  
pp. 16851-16884
Author(s):  
C. Yver ◽  
H. Graven ◽  
D. D. Lucas ◽  
P. Cameron-Smith ◽  
R. Keeling ◽  
...  
Keyword(s):  
High Frequency ◽  
Large Scale ◽  
Transport Model ◽  
Wrf Model ◽  
Sea Breeze ◽  
California Coast ◽  
The North ◽  
European Database ◽  
Hfc 134A ◽  
Simulated Concentration

Abstract. This paper presents a step in the development of a top-down method to complement the bottom-up inventories of halocarbon emissions in California using high frequency observations, forward simulations and inverse methods. The Scripps Institution of Oceanography high-frequency atmospheric halocarbon measurement sites are located along the California coast and therefore the evaluation of transport in the chosen Weather Research Forecast (WRF) model at these sites is crucial for inverse modeling. The performance of the transport model has been investigated by comparing the wind direction and speed at four locations along the coast using aircraft weather reports. Different planetary boundary layer (PBL) schemes, nesting options and two meteorological datasets have been tested. Finally, simulated concentration of an inert tracer has been briefly investigated. All the PBL schemes present similar results that generally agree with observations, except in summer when the model sea breeze is too strong. At the coarse 12 km resolution, using ERA-interim (ECMWF Re-Analysis) as initial and boundary conditions leads to improvements compared to using the North American Model (NAM) dataset. Adding higher resolution nests also improves the match with the observations. However, no further improvement is observed from increasing the nest resolution from 4 km to 0.8 km. Once optimized, the model is able to reproduce tracer measurements during typical winter California large-scale events (Santa Ana). Furthermore, with the WRF/CHEM chemistry module and the European Database for Global Atmospheric Research (EDGAR) version 4.1 emissions for HFC-134a, we find that using a simple emission scaling factor is not sufficient to infer emissions, which highlights the need for more complex inversions.

scholarly journals Boundary layer characteristics associated with sea breeze circulation over Cochin

MAUSAM ◽  
2021 ◽  
Vol 58 (1) ◽  
pp. 75-86
Author(s):  
HAMZA V ◽  
C. A. BABU
Keyword(s):  
Boundary Layer ◽  
Heat Flux ◽  
Drag Coefficient ◽  
Momentum Flux ◽  
Sensible Heat Flux ◽  
Sea Breeze ◽  
Surface Fluxes ◽  
Land Breeze ◽  
Sensible Heat ◽  
Breeze Circulation

Features of sea and land breezes, surface fluxes and drag coefficient over Cochin are studied using more than 300 daily observations of air temperature, wind speed and direction data. The duration and intensity of sea breeze circulation vary with the rain or cloud as it reduces the differential heating. Onset of sea breeze is early in summer season for the near equatorial station compared to winter season. Cessation is almost same for all seasons and is around 1900 hours. The sea breeze circulation is almost westerly and land breeze circulation is almost easterly in all the seasons. It is found that in most of the cases, the temperature and wind speed decreases at the time of onset of sea breeze and turning of wind direction with height becomes counter clockwise (backing) during the transition period from land breeze to sea breeze. In all seasons, the momentum flux is directed downward. High values of momentum flux were found during the presence of sea breeze in pre-monsoon season. Average sensible heat flux is directed upward during the entire period and during nighttime it is almost zero in the winter and monsoon seasons. The intensity of momentum flux decreases during onset and cessation of sea breeze for all the cases. The cold air advection associated with the sea breeze results in the decrease of sensible heat flux at the time of onset of sea breeze. Averaged surface momentum and sensible flux patterns resemble closely to the instantaneous pattern for all the seasons. Generally, sea breeze is stronger than land breeze in all the seasons. Accordingly, the drag coefficient power relationship with wind is different for sea breeze and land breeze circulations.Key words – Sea breeze circulation, Monsoon boundary layer, Surface fluxes, Drag coefficient, Diurnal variation.

Sign in / Sign up

Export Citation Format

Share Document