Development Of Sea Breeze Research Articles

Effect of Sea Breeze on Air Pollution in the Greater Athens Area. Part I: Numerical Simulations and Field Observations

Numerical simulations compared with field measurements are used to explain the effect of sea breezes on photochemical smog episodes in Athens during the Mediterranean Campaign of Photochemical Tracers on 12–14 September 1994. The numerical simulations, performed using a nonhydrostatic vorticity mesoscale model coupled to the Lurmann–Carter–Coyner photochemical module, are compared with ground-based lidar and aircraft measurements. The current analysis shows that the three selected days include the two main summertime flow patterns characteristic of the Athens peninsula, each of which lead to significantly different pollution amounts. On 12 and 13 September, a strong, northerly synoptic wind reduces the inland penetration of the sea breeze so that ozone concentrations within the greater Athens area remained low. In contrast, the weaker synoptic forcing on 14 September allowed the development of sea breezes over the whole peninsula and high ozone concentrations were found north and east of the city. An analysis based on pollution amounts and wind patterns is carried out to divide the peninsula into regions, each of which corresponds to a specific pollutant behavior.

Numerical Simulation of a Sea Breeze Under Dominant Synoptic Conditions at Perth

The development and movement of sea breezes under the influence of a thermally induced synoptic coastal trough and coastal terrain are simulated. These simulations are analyzed in the context of an extensive observational data set. The synoptic trough acts to determine the presence and intensity of the sea breeze through the advection of warm air in the surface layer whereas local topography acts to enhance the breeze and turn the low-level flow. Interaction between the sea breeze circulation and the trough assists trough movement across the coastline.

Wind climatology, atmospheric turbulence and internal boundary-layer development in Athens during the MEDCAPHOT-TRACE experiment

This paper presents an analysis of wind field and atmospheric turbulence in Athens, Greece covering a typical late-summer period with prevailing northerly wind. The wind climatology study shows a distinct difference between the northern and southern parts of the urban area. In the northern part of Athens the northerly flows (315°–45°) occur more than 60% of the time and the winds from all other directions are equally frequent (about 5% per 30° sector). In the southern part of Athens the northerly flows are more than 50%, but southerly flows (165°–225°) occur about 25% of the time indicating sea breeze development. The variability of the flow characteristics in the whole area was classified into three categories: northerly winds in the whole Athens basin; sea breeze throughout the whole Athens basin; and changing sea breeze (comprising partial penetration of the sea breeze over the city and/or changing wind direction throughout the day). This classification was used as basis for the investigation of the atmospheric turbulence and vertical profiles of meteorological parameters over the area. A model of the internal boundary layer height over an area with irregular coastline ( Gryning and Batchvarova (1996) Boundary Layer Meteorology 78, 405–413) is applied for an Athens site and the results are in good agreement with the measurements.

Meteorological Pre-processing over Highly Complex Terrains

A reliable method for meteorological pre-processing over complex topographies has been developed and implemented into the DETRACT code system, which is integrated into the RODOS decision support system. Shortcomings with respect to topography aspects, limited number of available stations and existing methods which depend on pure mathematics, have been tackled. The method relies on the efficient coupling of meteorology and topography. The main characteristic is the ground-attached cell classification according to land type, topography slopes and station range of influence. The interpolation scheme, for the wind field construction, is affected by the cell classification. The present method has been applied with reasonable success to two characteristic cases. First is the simulation of the MEDCAPHOT experiment in Attiki, Greece, where the regional meteorological conditions are determined by sea breeze development. Second is the simulation of the TRANSALP experiment over the Alps, where local valley winds play a key role in the meteorological situation. The simulated wind fields show that the main features are well reproduced.

The Effects of Width of Landmasses on the Development of Sea Breezes

Abstract A two-dimensional hydrostatic model has been employed to simulate sea-breeze circulations introduced by different-sized landmasses. The following influences on the sea breeze are examined. 1) environmental thermal stratification, 2) synoptic flow, and 3) latitude. In the simulation of a strip of land with a width of 150 km, the maximum sea-breeze convergence is much better developed than for other widths. This maximum computed upward velocity occurred when two sea-breeze cells from the two sides of the land merge together in the late afternoon. For the experiments presented here, the sea breeze reached the strongest vertical velocity (1.7 m s−1) when the environmental vertical gradient of potential temperature is 2.5°C km−1 with a land width of 150 km. With a very stable static stability, the sea breeze is not well developed. When the sea breeze occurs at 20°N, its intensity is the strongest, presumably because the solar insulation is greatest at this latitude for the separate simulations. At 60°...

いわゆる「大規模海風」を生成する海風と谷風の相互作用の数値実験

A two-dimensional numerical experiment with sea, plain, slope and plateau and a three-dimensional numerical experiment with sea, plain, slope, valley and plateau were executed to investigate the interaction between the sea breeze and the thermally and topographically induced flow. Generation of the so-called "extended sea breeze (ESB)" was also investigated. In the two-dimensional experiment with sea, plain, slope and plateau, a weak wind towards inland appeared between the sea breeze front and inland slope over the plain whose length was 113.3km. The topography was changed to a valley in the three-dimensional model. The mouth and end of the valley were located 20km and 106.7km from the coastline, respectively. The addition of this valley caused the surface wind in the area between the sea breeze front and the end of the valley to become stronger, and showed the long-range penetration of the ESB. The depth of the wind system in the valley was equal to or greater than the depth of the mixing layer in the valley. The additional experiments in which the width of the valley was changed showed that the wind in the valley was strongest in the narrowest valley. The mechanism was basically consistent with the discussion by Defant (1951). In the case that the distance between the coastline and inland topography was short, the sea breeze was enhanced in the morning; however, the same topography worked to stop the advance of the sea breeze in the late afternoon. The non-linear effect was important to the development of the combined sea breeze and valley wind and the generation of a unified circulation (i. e. the ESB).

Evaluation of Cloud Shading Effects on the Generation and Modification of Mesoscale Circulations

This study presents scale analysis and numerical model evaluations of the impact of cloud shading on (1) the development of sea breeze and thermally induced upslope flows and (2) the generation of mesoscale circulations between cloudy areas adjacent to clear areas. Based on the assumption of modifications of solar and longwave radiation which are typical for some overcast conditions, it was found that the reduction in the first type of circulation is significant and most noticeable in the vertical velocities. In the second case, thermally induced circulations in favorable conditions appear to approach the typical intensity of the sea breeze.

A numerical study of the effects of a large Sandbar upon Sea Breeze development

Two-dimensional numerical simulations of sea breeze development over a large sandbar on the North Sea coast of Germany are reported. The numerical model used in these experiments contains a detailed treatment of soil moisture, which allows evaluation of the effects of differential surface characteristics on the airflow pattern. Results of the simulations indicate that the contrast between the moist sandbar and adjacent dry land, the tidal inundation of the sandbar, and the westward penetration of the Baltic sea breeze play important roles in the development of mesoscale airflow patterns in the sandbar region.

Characteristics of Local Winds in Northwest Hawaii

During the period 22–29 June 1978, meteorological data were collected at six stations arranged in nearly linear transection extending from the coast at Anaehoomalu, Hawaii to Waimea Airport, 25 km inland and 800 m higher. Sea breeze response to synoptic-scale weather patterns was documented. Within the six days of 24 h measurements, two disturbances embedded in the prevailing trade winds passed over the island. Three different types of sea breeze development ensued. Sea breeze variability appears to be related to both synoptic-scale cloud and wind distributions and to the thermal properties of lava surfaces situated within the transection. Days of maximum insolation corresponded to minimum sea breeze advance through the network. It is suggested that numerical models be employed with this data set to test the sensitivity of sea breezes to soil and cloud conditions.

The Sea Breeze at Visakhapatnam

The development of sea breeze and its vertical structure at Visakhapatnam are studied during the premonsoon period. A number of observed characteristics of the sea breeze are described and discussed. The winds at an inland station 10 km distant from the coast are also examined to study the variations, as the sea breeze spreads inland.