Sea breeze

About: Sea breeze is a research topic. Over the lifetime, 2544 publications have been published within this topic receiving 55651 citations.

Determining the power-law wind-profile exponent under near-neutral stability conditions at sea

Abstract: On the basis of 30 samples from near-simultaneous overwater measurements by pairs of anemometers located at different heights in the Gulf of Mexico and off the Chesapeake Bay, Virginia, the mean and standard deviation for the exponent of the power-law wind profile over the ocean under near-neutral atmospheric stability conditions were determined to be 0.11 ± 0.03. Because this mean value is obtained from both deep and shallow water environments, it is recommended for use at sea to adjust the wind speed measurements at different heights to the standard height of 10 m above the mean sea surface. An example to apply this P value to estimate the momentum flux or wind stress is provided.

Photooxidant dynamics in the Mediterranean basin in summer: Results from European research projects

Abstract: Most of the Mediterranean Sea is surrounded by mountains 1500 m or higher. Their east and south facing slopes favor the early formation of upslope winds, reinforcing the sea breezes. These slopes also act as orographic chimneys which link the surface winds directly with their return flows aloft, creating recirculations. To characterize the dynamics of pollutants in the Mediterranean basin and to compose a mosaic of the atmospheric circulations involved, the European Commission (EC) supported the following projects: (1) meso-meteorological cycles of air pollution in the Iberian Peninsula (MECAPIP), 1988–1991, intended to document the atmospheric circulations over the Iberian Peninsula; (2) regional cycles of air pollution in the west central Mediterranean area (RECAPMA), 1990–1991, which extended the characterization from the Atlantic coast of Portugal to Italy; and (3) south European cycles of air pollution (SECAP), 1992–1995, for the whole of the basin. The level of interpretation of the data and the elaboration and validation of working hypotheses across the basin have followed, in turn, with the corresponding lags in space and time. The purpose of this paper is to present a summary (to 1995) of the documented, as well as the postulated, processes involved. The MECAPIP and RECAPMA projects have shown that stacked layer systems form along the Spanish Mediterranean coasts, 2–3 km deep and more than 300 km wide, with the most recent layers at the top and the older ones near the sea. These act as a reservoir for aged pollutants to reenter land the next day, and tracer experiments have shown that turnover times are from 2 to 3 days. During the night, part of this system drifts along the coast. Under strong insolation these circulations become “large natural photochemical reactors,” where most of the NOx emissions and other precursors are transformed into oxidants, acidic compounds, aerosols, and O3 (exceeding some EC directives for several months). Finally, the preliminary analysis of the data obtained in the SECAP project supports the hypothesis that pollutants emitted in the Mediterranean basin could be transported toward the Intertropical Convergence Zone, located along northern Africa in summer, and pumped directly into the upper troposphere. If this is verified, the Mediterranean basin could be one place where all the links from the local to the global scales could be identified and documented.

The influence of urban design on outdoor thermal comfort in the hot, humid city of Colombo, Sri Lanka

Abstract: The outdoor environment is deteriorating in many tropical cities due to rapid urbanization. This leads to a number of problems related to health and well-being of humans and also negatively affects social and commercial outdoor activities. The creation of thermally comfortable microclimates in urban environments is therefore very important. This paper discusses the influence of street-canyon geometry on outdoor thermal comfort in Colombo, Sri Lanka. Five sites with different urban geometry, ground cover, and distance from the sea were studied during the warmest season. The environmental parameters affecting thermal comfort, viz. air temperature, humidity, wind speed, and solar radiation, were measured, and the thermal comfort was estimated by calculating the physiologically equivalent temperature (PET). The thermal comfort is far above the assumed comfort zone due to the combination of intense solar radiation, high temperatures, and low wind speeds, especially on clear days. The worst conditions were found in wide streets with low-rise buildings and no shade trees. The most comfortable conditions were found in narrow streets with tall buildings, especially if shade trees were present, as well as in areas near the coast where the sea breeze had a positive effect. In order to improve the outdoor comfort in Colombo, it is suggested to allow a more compact urban form with deeper street canyons and to provide additional shade through the use of trees, covered walkways, pedestrian arcades, etc. The opening up of the city's coastal strip would allow the sea breeze to penetrate further into the city.