Showing papers on "Sea breeze published in 1980"

A Numerical Investigation of Several Factors Contributing to the Observed Variable Intensity of Deep Convection over South Florida

Abstract: This study employs a revised version of the Colorado State University three-dimensional numerical cloud scale model to investigate the observed behavior of deep convection over South Florida on 17 July 1973. A brief description of recent model improvements is made. A combined balance and dynamics initialization procedure designed to introduce variable magnitudes and distributions of low-level wind convergence to the initial fields is described. Using radiosonde and PIBAL data collected by the NOAA/ERL Florida Area Cumulus Experiment (FACE) and the National Weather Service at Miami on 17 July 1973, composite wind, temperature, pressure and moisture profiles were constructed to depict the state of the atmosphere at the time of deep convection. Mesoscale convergence was estimated from results of a mesoscale model simulation of low-level sea breeze convergence made by Pielke (personal communication) for the same case study day. Several numerical simulations were performed using the sounding data as a...

Diurnal Rainfall Variation in Northeast Brazil

Abstract: The diurnal rainfall variation in northeast Brazil is investigated for the period 1961–70. Most coastal areas are found to experience a nocturnal maximum in rainfall activity. probably due to convergence between the mean onshore flow and the offshore land breeze. Areas 100–300 km inland experience a daytime maximum, associated with the development and inland advance of the sea breeze. The diurnal rainfall variability, at most interior locations, seems to be, due to mountain-valley breezes. Seasonal variations am noted for areas of the north coast of Brazil. Soure, located near the mouth of the Amazon River, experiences a nocturnal maximum between January and May, and an afternoon maximum between June and September. Evidence is presented which shows that this seasonal variation is linked to the seasonal variation in the low-level mean now. Seasonal variations in the mew monthly rainfall for eastern coastal areas am shown to correlate well with the intensity of the land breeze, which is represented...

Numerical experiments on the inland penetration of the sea breeze

Abstract: A two-dimensional primitive-equation model is used to investigate various aspects of the sea-breeze phenomenon. The influence of soil moisture content is examined by varying the Bowen ratio of the underlying land surface. This is equivalent to controlling the magnitude of the sensible heat flux at the ground since the diurnal variation of net radiation minus ground heat flux is approximately the same in all cases. It is found that the inland penetration rate of the sea breeze varies significantly with the degree of soil moisture. The model predicts a significant slowing of the frontal advance around midday for the case of ‘relatively weak’ sensible heating over the land, as well as reproducing the frontal acceleration observed in late afternoon for all cases. The sea-breeze circulation detaches itself from the coastline around sunset and moves rapidly inland with diminishing magnitude and this aspect is discussed in relation to observations in the south of England. An attempt is made to model the southern England sea breeze of 14 June 1973. Various experiments are discussed, including one in which different values of Bowen ratio are specified ahead of and behind the front. Fairly good agreement is found, although it is not possible to reproduce all features of the inland penetration curve for that day. Some implications of these experiments for the production of daily forecasts by mesoscale models are briefly discussed.

On mesoscale characteristics of bora conditions in Yugoslavia

Abstract: The local wind bora is a well-known phenomenon on the eastern coast of the Adriatic Sea, where steep mountains, the Dinaric Alps, closely follow the coast. In a relatively undisturbed atmosphere the coastal thermal effect and the dynamic effect of orography give rise to a cool downslope land breeze, the borino, which develops at night-time, and particularly in the winter season, when the land—sea temperature contrast is large. The causes of cold bora, with strong and gusty winds, are then attributed to the synoptic scale effects upon the local flow intensification and inland cold air supply. Since the interaction processes on various scale motions are involved in a sequence of bora spells, it is shown how the large scale anomalies may subsequently change the mesoscale characteristics of the bora environment and eventually make the bora appear as a relatively warm wind.

Mountain barrier baroclinity effects on surface winds along the Alaskan Arctic Coast

Abstract: The deployment of offshore pressure and position relaying buoys in February 1979 within the arctic ice pack has allowed for a more complete investigation of a wintertime mesoscale meteorological effect known as mountain barrier baroclinity (MBB). Total atmospheric boundary layer turning with height was estimated by comparing computed three hourly geostrophic winds (above the boundary layer) to simultaneous surface winds at Barter Island, Alaska. This total turning compared closely with wind velocity versus height data obtained through rawinsonde launches at Barter Island. Results indicate that the average turning of the wind from above the boundary layer to the surface was 140° during periods of MBB influence. In addition the average difference between simultaneously measured surface winds at Barter Island and Pt. Barrow, Alaska (during MBB periods) was 140°, which cannot be explained by existing synoptic (large-scale) weather charts. The evidence explains the wintertime abundance of west to southwest winds seen on historical monthly wind direction histograms from Barter Island (64 km north of the Brooks Range) while Pt. Barrow (300 km north of the Brooks Range) histograms for similar months show an east to northeast bias. Finally, the occurrences of the MBB effect and a summertime sea breeze effect have been related to arctic tundra surface albedo.

A study of atmospheric structures using sodar in relation to land and sea breezes

Abstract: Simultaneous observations were made by an acoustic sounder and on a meteorological tower during the month of May 1978 at the Atomic Power Station Tarapur. The probing range of the acoustic sounder was 700 m. The meteorological tower could sense wind and temperature at various levels up to a height of 120 m.

On the correction of land-based wind measurements for oceanographic applications

Abstract: Simultaneous offshore and onshore wind measurements were made at stations ranging from Somalia, near the equator, to the Gulf of Alaska. Offshore data obtained from standard U.S. NOAA buoys, research platforms, and merchant ships were compared with data from coastal stations. The results indicated that, under the commonly observed speed of 5-6 m/s, land measurements of mean wind speed are only 63% of the offshore mean speed. Furthermore, it was found that only those stations located in the beach area that measure wind speed above both the internal boundary layer and the nocturnal inversion height represent offshore conditions. In order to correct land-measured wind data, a formula is developed and verified by all 2/3 existing data sets. A simplified equation, i.e., U = 3 U1 s is proposed for offshore applications. Criteria for in situ wind measurements near the coast are outlined. Data reduction procedures for inland stations are also provided.

Transport of sulfur oxides within the Los Angeles sea breeze/land breeze circulation system

Abstract: The sea breeze/land breeze circulation system in the Los Angeles area results in transport of pollutants seaward at night followed by return of aged material inland the next day. This characteristic wind reversal pattern both increases the retention time available for the oxidation of SO_2 to form sulfates and causes individual air parcels to make multiple passes over large coastal emissions sources. As a result, the Los Angeles atmosphere exhibits high peak day and high annual mean sulfate concentrations in spite of the fact that sulfate concentrations in marine background or desert air are low.

Association of non-marine sulfate aerosol with sea breeze circulation in Tampa bay

Abstract: Peak concentrations of aerosol sulfur in Tampa, Florida may be the result of either regional-scale transformation and transport processes or local-scale transport from nearby air pollution sources. The existence of the latter has been demonstrated in Tampa through correspondence of sulfur with sea breeze circulation patterns and the resulting chloride concentration maxima (which serve as indicators of the marine aerosol), vanadium concentration maxima (which indicate times of high concentrations of certain plume constituents), and the locations of sources favorable for high concentrations of air pollution-derived sulfate during occurrences of the sea breeze. The analysis indicates that locally derived sulfate in the Tampa atmosphere, which may be less abundant than sulfate due to regional-scale processes, can be identified by the use of combined meteorological and chemical tracer interpretation.

The Role of Convective Instability in an Oklahoma Squall Line

Abstract: Previous investigations of the 8 June 1966 National Severe Storms Laboratory case show that mesoscale lift from an “inland sea breeze” due to a newly formed temperature gradient preceded convection. Using additional surface data, this case was reanalyzed over all of Oklahoma. Cloud work functions were calculated from real and interpolated data to measure convective instability. The results indicated that the above temperature gradient was the eastern one of two gradients located on either side of a warm tongue. The cells formed over the eastern gradient where the convective instability was highest.

A physical approach to air pollution climatological modelling in a complex site

Abstract: A Gaussian climatological model which takes into account physical factors affecting air pollutant dispersion, such as nocturnal radiative inversion and mixing height evolution, associated with land breeze and sea breeze regimes, respectively, has been applied to the topographically complex area of La Spezia (a basin surrounded by hilly terrain, located on the Italian coast). Results from the measurements of the dynamic and thermodynamic structure of the lower atmosphere, obtained by a series of field experiments, are utilized in the model to calculate SO2 seasonal average concentrations. The model has been tested on eight three-monthly periods by comparing the simulated values with the ones measured at the SO2 stations of the local air pollution monitoring network. Comparison of simulated and measured values was very satisfactory and proved the applicability of the implemented model for urban planning and establishment of air quality strategies also at a topoghraphically complex site.

Low-Level Atmospheric Changes over Oregon's Coastal Upweliing Region

Abstract: Temporal and spatial variations in the structure of the lower atmosphere off Oregon's central coast are studied. The response of the wind and thermal fields to a synoptic-scale realignment aloft that causes a rapid shift from surface southerly to northerly winds is detailed. The effects and importance of the infrequent southerlies on the marine inversion, sea breezes and upwelling is also investigated. A vast array of meteorological and oceanographic observations were measured by aircraft, land stations, buoys and ships during the first Coastal Upwelling Experiment I (CUE-I). The winds, air and water temperature, and currents from the surface ocean layer to 1.5 km are compared during 16–29 August 1972. The period of southerly surface winds created a warm moist lower atmosphere, weak sea breezes, and brought about a cessation to previous upwelling. In contrast, northerlies and ridging aloft produced a distinct marine inversion, strong sea breezes, and an upwelling event. The marked changes reveal ...

Pilot Balloon Techniques

Abstract: Within the planetary boundary layer, the difference between the actual wind and the geostrophic wind is called the ageostrophic wind. This is the result of an imbalance of forces, which generates the momentum (wind stress) that is transferred from the atmosphere to the ocean. The actual wind profile within the planetary boundary layer can be obtained from the tracking of pilot balloons (pibals). Of the various methods of tracking, the use of a theodolite is the least demanding on instrumentation and trained observers. Determination of the wind stress from such pilot balloon observations was one of the first methods to give reasonable stress estimates. The analysis of the data, however, depends very much on the assumptions used. The best examples of determining stress from pilot balloon observations at sea are the Scilly and Heligoland wind profiles (Lettau, 1957; Lettau and Hoeber, 1964). Pilot balloon observations may be used for other applications, e.g. in studies of flow over coastal bluffs or land/sea breeze flows.