Sea breeze

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

Evaluation of regional air quality models over Sydney and Australia: Part 1-Meteorological model comparison

Abstract: The ability of meteorological models to accurately characterise regional meteorology plays a crucial role in the performance of photochemical simulations of air pollution. As part of the research funded by the Australian government’s Department of the Environment Clean Air and Urban Landscape hub, this study set out to complete an intercomparison of air quality models over the Sydney region. This intercomparison would test existing modelling capabilities, identify any problems and provide the necessary validation of models in the region. The first component of the intercomparison study was to assess the ability of the models to reproduce meteorological observations, since it is a significant driver of air quality. To evaluate the meteorological component of these air quality modelling systems, seven different simulations based on varying configurations of inputs, integrations and physical parameterizations of two meteorological models (the Weather Research and Forecasting (WRF) and Conformal Cubic Atmospheric Model (CCAM)) were examined. The modelling was conducted for three periods coinciding with comprehensive air quality measurement campaigns (the Sydney Particle Studies (SPS) 1 and 2 and the Measurement of Urban, Marine and Biogenic Air (MUMBA)). The analysis focuses on meteorological variables (temperature, mixing ratio of water, wind (via wind speed and zonal wind components), precipitation and planetary boundary layer height), that are relevant to air quality. The surface meteorology simulations were evaluated against observations from seven Bureau of Meteorology (BoM) Automatic Weather Stations through composite diurnal plots, Taylor plots and paired mean bias plots. Simulated vertical profiles of temperature, mixing ratio of water and wind (via wind speed and zonal wind components) were assessed through comparison with radiosonde data from the Sydney Airport BoM site. The statistical comparisons with observations identified systematic overestimations of wind speeds that were more pronounced overnight. The temperature was well simulated, with biases generally between ±2 °C and the largest biases seen overnight (up to 4 °C). The models tend to have a drier lower atmosphere than observed, implying that better representations of soil moisture and surface moisture fluxes would improve the subsequent air quality simulations. On average the models captured local-scale meteorological features, like the sea breeze, which is a critical feature driving ozone formation in the Sydney Basin. The overall performance and model biases were generally within the recommended benchmark values (e.g., ±1 °C mean bias in temperature, ±1 g/kg mean bias of water vapour mixing ratio and ±1.5 m s−1 mean bias of wind speed) except at either end of the scale, where the bias tends to be larger. The model biases reported here are similar to those seen in other model intercomparisons.

Short-term wind power prediction for offshore wind farms Evaluation of Fuzzy-Neural network based models

Abstract: Future major developments of wind power capacities are likely to take place offshore. As for onshore wind parks, short-term wind power prediction up to 48 hours ahead is expected to be of major importance for the management of offshore farms and their secure integration to the grid. Modeling the behavior of large wind farms of several tens or hundreds of MWs installed capacity and covering areas of several square kilometers is going to be a challenge. The adaptation of wind power forecasting methods to reach the specificities of the offshore case is not straightforward and very few results are available in the literature. The paper presents the new considerations that have to be made when dealing with large offshore wind farms and therefore the necessary evolutions of prediction models. Then, a state-of-the-art fuzzy-neural network based wind power forecasting model is described. Its performance is assessed for offshore conditions and compared to its level of performance for typical onshore parks. A general methodology dedicated to large offshore wind farms is developed. In order to deal with the spread of the turbines in such cases, methods based on the division of large wind farms into clusters are proposed. Furthermore, the use of satellite images for mapping the wind flow behavior inside offshore parks is investigated.

A Numerical Study of Mesoscale Eddy Development over the Santa Barbara Channel

Abstract: The development of the “midchannel eddy” over the Santa Barbara Channel represents a mesoscale response of the large-scale airflow to the combination of the diurnal heating cycle over land surfaces, the curvature of the coastline, and the orientation of major ridges with respect to the coastline. In this paper we analyze and discuss the results of a numerical simulation of mesoscale airflow over the Santa Barbara Channel and adjacent land areas on 23–24 September 1985, with emphasis upon nocturnal mesoscale eddy development. Simulated winds are compared with SCCCAMP 1985 wind observations. Both simulation and observations indicate inception of a midchannel eddy in the vicinity of Santa Barbara during the late evening of 23 September, followed by westward and southward expansion of the eddy. Our analyses indicate that simulated midchannel eddy development is associated with the following sequence of events: 1) offshore-directed flow develops over coastal ridges in the early evening, associated wit...

Breezes along the Tanzanian east coast

Abstract: At the Tanzanian east coast the prevailing winds of the general circulation exhibit seasonal changes in direction in a kind of monsoonal system. The sea and land breezes, which are limited here to diurnal modifications of the general winds, therefore also vary with the seasons. During the northeast monsoon a sea breeze trend prevails most of the time, while in the southeast monsoon season the main trend is from the land. Only during the intermediate periods between the monsoons a diurnal reversal of sea and land breezes develops regularly. The effects of these winds, especially the sea breeze, on the physiological temperature conditions near the coast are of considerable importance. A decrease of the physiological temperature is produced by the advection of cool air, and a further reduction of thermal stress is provided by the improved air ventilation related to the higher wind velocities of the breezes. Since all impressions of physiological temperature are subjective, it is difficult to express these influences quantitatively. However, estimates indicate that the old adage that “the winter in the tropics occurs at night” is no longer valid at the Tanzanian coast when the physiological temperature is considered, because the seasonal differences are larger than the diurnal variations.