Showing papers on "Sea breeze published in 1974"

A Three-Dimensional Numerical Model of the Sea Breezes Over South Florida

Abstract: An eight-level three-dimensional primitive equation model which includes a detailed boundary layer parameterization scheme has been used to describe the initiation and evolution of sea-breeze convergence patterns over south Florida as a function of the surface heat and momentum fluxes and of the large-scale synoptic forcing. A minimum grid spacing of 11 km was used. Model results are presented for several different initial conditions and the results, when compared against cumulus cloud and shower patterns, demonstrate that the dry sea-breeze circulations are the dominant control on the locations of thunderstorm complexes over south Florida on undisturbed days. It is also shown that, in contrast to the differential roughness, the differential heating between land and water over south Florida is the primary determinant of the magnitudes of convergence. The values of surface roughness, however, indirectly influence convergence patterns by affecting the intensity of the vertical turbulent transport o...

Sea Breeze Theory and Applications

Abstract: The linearized Boussinesq equations with rotation, viscosity, conduction, and a mean stratification are used to model the sea breeze in two dimensions. The motion is forced by a prescribed surface temperature function. The linear model produces a sea breeze with realistic velocities and spatial dimensions. Hydrostatic solutions are found to differ very little from nonhydrostatic solutions. The only distinguishing feature of the solution at the inertial latitude is an amplitude maximum far from the coastline. Both the phase and the amplitude depend on the mean atmospheric stability. The computed vertical heat fluxes, when summed along the coastlines of the principal land masses, indicate that the sea breeze effect can account for several percent of the globally averaged vertical flux of sensible heat at a height of several hundred meters. The land-sea temperature difference required by the model to create a net onshore flow in opposition to a basic current agrees well with the empirical criterion ...

The wind regime in the north-west section of the Dead-Sea

Abstract: During the period April 1969 to March 1970 a topo-climatological research was carried out in the Kallia region in the north-western section of the Dead-Sea. This article deals only with the wind regime in this area. The unusual location of the Dead-Sea in the Jordan Rift Valley combined with the developing of pressure systems in summer over the eastern Mediterranean are and passing over Israel in winter, the influence of the Mediterranean-sea breeze and lastly the sea breeze which the Dead-Sea develops because of being itself a large body of water, couse a complicated daily and seasonal wind system. In summer the regional pressure systems are of a great steadiness, a fact which is of great importance in the developing of the daily wind regime in this area. On the other hand, in winter, because three out of the four main factors influencing the wind system weaken, the degree of steadiness of the dominent winds reduce and the wind regime changes.

Mesoscale Transport and Dispersion of Airborne Pollens

Abstract: Pollen transport and dispersion from generalized area sources was studied by 29 flights to distances of 100 km and heights of 3 km using an aircraft-mounted isokinetic sampler. Tree pollens and ragweed pollen served as tracers. Four types of flights were made to study various aspects of pollen transport: 1) ascents over a fixed location to investigate vertical distribution; 2) flights over a source-free area to document change of concentration with distance, 3) east-west flights along Long Island to study the influx of pollen from the mainland with westerly winds; and 4) vertical ascents and horizontal flights during sea breeze flows to determine their effect on pollen concentrations. It was found that large quantities of pollen are transported in orderly fashion from their source regions but pollen often travels in large, discrete clouds. Pollen is transported to Long Island from the mainland in some quantity. Sea breeze flows greatly decrease low-level concentrations but pollen is carried aloft...

A Theoretical Study of the Sea and Land Breezes of Circular Islands

Abstract: The axisymmetric sea and land breezes of circular islands are studied. First we show, from the equation of turbulent energy, that the marked horizontal convergence of the sea breeze intensifies the turbulence in the flow and that this conclusion affects the equations that model the turbulence. Next, the equations of motion are integrated numerically for two circular islands: a “large” island of radius 51.25 km and a “small” island of radius 26.25 km. The horizontal grid is 2.5 km and the vertical 100 m beginning from the top of a postulated constant-flux layer 25 m thick. Large island. The sea-breeze front (SBF) is much better developed than in the case of a straight coast. In the first hours of the afternoon the low-level winds ahead of the front are nearly opposite in direction to those of the sea breeze behind the front. There is a strong horizontal convergence in advance of, and divergence behind, the front up to an altitude of 400–500 m; the reverse distribution is the case aloft, where the ...

Nearshore Circulations under Sea Breeze Conditions and Wave-current Interactions in the Surf Zone

Abstract: : Numerical models for nearshore circulation patterns in the surf zone were developed and applied to an observed condition subjected to a sea breeze environment Bottom topography and input waves were derived from observed data to predict surf zone circulation as a function of time of day It was found that many features observed in the surf zone were modeled but wave-current interactions are known to be important Wave-current interactions were modeled for shallow water assuming a two-dimensional motion which included rip current and lonshore current components The refraction effects caused by even small currents produce major changes in the wave induced driving forces in the surf zone which leads to the prediction of entirely different rip-current patterns when wave-current interactions are considered Numerical results are presented and a discussion of the numerical techniques is included A review of water wave theories to include mass transport, vorticity and current was made for a vertical section in shallow water of constant depth

A Comparison of Three-Dimensional and Two-Dimensional Numerical Predictions of Sea Breezes

Abstract: Two-dimensional and three-dimensional sea breeze model results are compared for the same set of initial conditions and values of prescribed parameters. It is shown that with two-dimensional forcing, the two models produce identical results, but only when the explicit horizontal diffusion in the two-dimensional model is increased so as to account for resolvable scale fluxes which cannot be properly handled without including the third dimension. It is additionally demonstrated that a two-dimensional sea breeze model cannot produce accurate simulations of the sea breeze over south Florida even with added vertical resolution. The conclusion is made that for most practical simulations of the sea breeze, a full three-dimensional model is required.

A Numerical Model of Trade Wind Weather on Oahu

Abstract: A single-layer mesoscale model, originally developed for the study of wintertime take-effect storms, is applied to the airflow over the Island of Oahu, Hawaii. Terrain effects, land roughness, island heating, and surface evaporation are all included. Convective precipitation and latent heating are parameterized in terms of larger-scale motions resolved on the 3-km × 3-km grid. Experiments were conducted with an atmospheric structure consistent with typical trade conditions as well as with variations from normal wind speed and inversion height. Satisfactory agreement was achieved with observed patterns of inversion height, cloud base height, temperature, relative humidity, wind flow, and precipitation under typical conditions. Mixing of dry air through the inversion from above was deduced to be very important. In most experiments the model generated a hydraulic jump to the lee of the mountains. Sea breeze effects were only partially simulated. Under some conditions the blocking effect of the Islan...

Summertime surface diurnal period winds measured over an upwelling region near the Oregon coast

Abstract: Wind measurements were made during July and August 1973 from surface floats installed 13 and 120 km from the Oregon coast. The striking feature of the kinetic energy spectra was the large peak at the diurnal frequency at the inshore site; at the offshore station the 24-hour peak was one fifth as large. At both sites the amplitude of the meridional or longshore component of the tidal wind was stronger than the zonal component by a factor of about 2, the shape of the hodograph was elliptical, and the velocity vector rotated in the clockwise direction. The horizontal coherence between the diurnal period winds was low, most likely because of the sharpness of the spectral peak. Mean daily variations of the eastward velocity component were consistent with local sea breeze circulation, and the sea breezelike pattern was superimposed upon the fairly steady northerly winds. With wind data obtained at five coastal stations, strong correspondence was found between the orientation and proximity of the coastal mountains and the ratio of the meridional to zonal components of the tidal wind. The diurnal period onshore winds may have been turned southward by the mountain barrier, causing the early morning increase in the northerly winds.

a Theoretical Study of the Sea Breeze.

Abstract: Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Meteorology, February 1974.

Land Breezes and Mountain-Plain Winds Over the Natal Coast

Abstract: In fine weather the nocturnal low-level offshore circulation along the Natal coast is found to be compounded of a land breeze and mountain-plain wind. Initially, the land breeze is an independent system and in the early evening the growth of the circulation is marked by the progressive inland extension of a shear line separating offshore from onshore wind components. Concomitantly, mountain winds in inland valleys deepen above ridge levels and combine into a mountain-plain wind which blows towards the coast. In the Durban area integration of the two wind systems takes place over the Hillcrest-Kloof plateau.

A High Resolution Numerical Study of the Sea‐Breeze Front

Abstract: The primitive equations are integrated numerically using a high resolution grid to investigate the sea‐breeze front. Two cases of the sea‐breeze front are presented; the first produced in an atmosphere with a prevailing offshore flow, and the second produced in an atmosphere initially at rest.

Wind-Induced Currents and Sea Surface Slopes in the Eastern Gulf of Mexico.

Abstract: : Meteorological and tidal records at three Florida Gulf coast stations have been examined for the period 1965-67. Cross spectral analysis of daily winds and sea levels showed a high coherence at periods of 4 to 20 days. Daily sea levels have been correlated with winds of varying directions and speeds with good results. Sea level was found to be most responsive to winds that were within about 10 degrees of parallel to the direction of the coastline. A longshore wind of 4.5 m/sec caused a sea level fluctuation of 20 cm. Onshore-offshore winds did not produce sea level fluctuations that were discernible above the noise level. Wind components at weather stations separated by up to 300 km were found to have coherence above 0.6 for the periods of 4 to 100 days. (Modified author abstract)

Atmospheric diffusion from an off-shore site

Abstract: From symposium on the physical behavior of radioactive containment in the atmosphere; Vienna, Austria (12 Nov 1973). Analysis of the fate of airborne effluerts from a nuclear reactor at an off-shore site requires a better understanding of overwater atmospheric dispersion than currently exists. For this reason, a diffus1on study was undertaken off the south shore of Long Island, New York, about 100 km from New York City. This study is using tracer material (oil fog smoke) released from an anchored boat. Measurements of mean wind, turbulence, and temperature are made on portable towers on the beach, from an aircraft, and aboard the source boat. Plume geometry 1s documented by photography and from quantitative concentration measurements. Experiments under a variety of meteorolog1cal conditions indicate that over-water dispers1on is very sensitive to meteorological conditions. From measured is significantly less than over land, particularly when the onshore flow is due to the sea breeze. This is because of the low aerodynamic roughness of the water, and because low level stable conditions are established because the water is at lower temperature than the air. Crosswind standard deviations of the plume a factor two less than the prediction of Pasquill category F have been observedmore » at the shore with the source 6 km off shore. (auth)« less

Case Studies of Coastal Convective Storms as Observed by Doppler Radar.

Abstract: : The life cycles of coastal convective storms are studied utilizing a Doppler weather radar. The cases presented involve storms triggered by the sea breeze front. Horizontal and vertical scanning as well as fixed vertical pointing were utilized to observe the storms. Analyses of the observations suggest that convective storms move with the source of the updraft rather than the environmental wind and that the interaction between the vertically moving air and the environmental flow determines the time history of the storm structure. (Author)

Distribution of summer wind in the kushiro district hokkaido

Abstract: The summer climate of Kushiro, locating on the coast of eastern Hokkaido, is charac-terized by sea fog, which results in relatively low temperature, high humidity, and insufi-cient sunshine. The sea fog in this district is explained as follows. The prevailing south-erly air flows, which have travelled over the cold sea surface of the NW-Pacific, are cooled from its lower level to form sea fog. The sea fog invades as an advection fog in the Kushlro District. At eight stations in the Kushiro District (Fig. 1), wind observations with recording windvanes were carried out for three years from 1970 to 1972, for the purpose of air pollution resarches. In the present study, the author analysed the data from May to August for the three years. Some field observations and analyses of winds were made in June and August, 1972. In addition, the observations on wind-shaped trees were made in order to make clear the detailed distribution of the prevailing wind in summer. The results obtained are summerized as follows. (1) The wind roses for every three hours in a given period at each observation station (Fig. 2-Fig. 6), show that there is a marked diurnal change. Calm and weak northerly winds prevail from mid-night to early morning. In the forenoon, the wind direction changes clockwise from the north to the south (i.e., the beginning of sea breeze). At noon, winds reach its maximum speed. After about 15h, winds become gradually weak or calm, and then are replaced by weak northerly winds. This wind system seems to be a character of land sea breezes. (2) The sea breeze sets in on the coast first, and then gradually invades inland (Fig. 7 and Fig. 8). From the daily records of wind direction and speed at each station from May to August in 1972, frequencies of the onset time of sea breeze are shown in Fig. 9. Fig ure 10 illustrates the relationship between the mean onset time of sea breeze (Ts in hour) and the distance from the coast to the station (D in km). The relation is represented by the following equation Ts=0.11 D+8.00. (3) The diurnal change of wind speed at each station is shown in Fig. 11. This figure was made by averages of 26 days in June, 1972. Each station shows a remarkable regularity with maximum in the daytime and minimum early in the morning. The wind speed increases for 4-5 hours after the sea breeze invasion and reaches its maximum nearly at noon. (4) An observation of wind shaped trees enables the author to draw detailed stream lines in the district (Fig. 12). The stronger wind regions appear in the eastern part of the district, on the north-western slope of the Lake Harutori, west of the Nishi Port and the inland marshy ground (Kushiro Shitsugen). Topographical features, land uses, vegetations and geographical distribution of urbanized areas influence slightly on the wind directions. (5) Fig. 13 clarifies the relation between the mean wind speed of the prevailing winds in summer at the eight stations and the degree of deformation of wind-shaped trees of larch (Larix leptolepis) near each station. The result is represented by the following equation Ws=0.51 G1+2.57 where, Ws means mean wind speed (m/sec) of prevailing wind direction at each observation station, GL the degree of deformation of wind-shaped trees of larix.