Thesis (M.S. in Meteorology and Physical Oceanography)--Naval Postgraduate School, March 2004. / Thesis advisor(s): Wendell A. Nuss. Includes bibliographical references (p. 59-60). Also available online.

The main aim of this research is to improve our knowledge of the sea breeze circulation in the complex coastal environments, where more than one mesoscale circulations occur. Interaction of these circulations with each other and with external factors such as topographical features and large scale winds leads to pronounced changes in the thermodynamic structure of the boundary layer. The variations in sea breeze circulation also have distinct effect on the pollutant transport and dispersion mechanisms in the coastal urban areas. In this research, dynamic and thermodynamic characteristics of the sea breeze circulation and their associated air pollution potential have been investigated by utilizing observational data for two summer periods and numerical modelling techniques. Effect of some external factors such as gradient flow and terrain elevation has also been examined. Observed meteorological and air quality data was obtained from a number of monitoring sites within and around Auckland while Advanced Weather Research & Forecasting (WRF) and ‘The Air Pollution Model’ (TAPM) were employed to simulate meteorology and pollutant dispersion in Auckland. WRF is used to investigate the thermally induced mesoscale circulation while TAPM has been employed to examine the pollutant dispersion in the region. Both models were validated against observed data from six different sites within Auckland. Validation results of WRF and TAPM are also compared with surface meteorology. Validation and inter-comparison of the two models show that WRF performed better than TAPM for all the surface meteorology variables. WRF showed a positive bias in predicted winds speed and relative humidity and a cold bias in the near surface Temperature. TAPM on the other hand under-predicted surface winds, while near surface temperature and relative humidity are similar to WRF. Results show that the sea breeze occurred around 20% of the two summer periods of 2006 and 2007. Both observed data analysis and the numerical modelling results confirmed the existence of two thermally induced systems in the Auckland region. Bay breezes are initiated in the morning hours (0800 – 1000 hours) from small bodies of water (Manukau, Waitemata, and Kaipara Harbour, and along the Hauraki Gulf coastline), followed by mature sea breezes from the main bodies of water (Tasman Sea and larger Hauraki Gulf area) in the late morning. The cessation of sea breezes started after 1600 hours. Frequency of sea breeze days was the highest under coast-parallel gradient winds (southeast and northwest), with speeds < 6 m s-1. The predicted depth of the sea breeze inflow ranged between 200 and 600 m, while the depth of the return flow was in the range of 200 – 500 m. Sensible heat flux is an important control in the development of sea breeze over the region. Coastal mountain ranges helped early onset of the sea breeze, but also inhibited inland propagation. Strong jet-like westerly winds along the coastline near the Manukau Harbour are due partly to the narrow opening at the Manukau Head, reduced friction over the harbour water, and divergence of wind due to coastline shape. Gradient winds significantly affect the evolution of the sea breeze and modify many of its dynamics, such as the sea breeze inflow layer, return flow, inland penetration, sea breeze head, etc. Under northerly gradient flow northeast sea breeze lasts longer while under southerly gradient flow cessation of the westerly sea breeze was delayed. Over both east and west coasts, WRF predicted anticlockwise rotation, especially under easterly gradient wind conditions. However, inland stations near Manukau Harbour show partial and complete clockwise rotation, which is primarily due to orographic features of the region. The diurnal rotation of the sea breeze system may contribute to recirculation of pollutants in the morning hours under coast-parallel gradient wind conditions. Pollutants that are emitted during morning peak traffic hours and advected towards Manukau Harbour by the remnants of the land breeze may be returned by bay breezes in the mid morning hours. Mixed layer height over land before arrival of the sea breeze also varied a lot and ranged between 600 to 1400 m. A convective internal boundary layer (CIBL) forms in the surface layer after arrival of the sea breeze. The CIBL under coast parallel gradient winds was relatively shallow (200 – 400 m), while under coasts-normal gradient winds (southwest and northeast), the predicted depth was in the range of 400 to 500 m. However, the inland extent of the CIBL was greater under coast-normal winds, especially under south-westerly gradient winds. The ground level concentration of air pollutants thus can be increased during sea breeze inflow over the region. Both bay breeze and mature sea breeze contribute towards development, extent and strength of the sea breeze convergence zones (SBCZs). Gradient winds and terrain play an important role in the position and strength of SBCZs. Under strong south-westerly gradient flow, a SBCZ is formed along the eastern coastline, while under north-easterly gradient winds a SBCZ is formed along the west coastline. During coast-parallel gradient winds the SBCZ is formed in the middle of landmass, and is then gradually displaced eastward or westward depending on the balance between large scale PGF and surface friction effect. In addition to SBCZs, terrain and coastline-induced convergences were also evident. Higher ground level concentrations of pollutants are expected under coast-normal gradient winds, when SBCZs are formed in the middle of the land mass and the wind speed of the sea breeze inflow and the sea breeze front is relatively low. This may increase pollution concentration, especially in the evening hours, to unacceptable levels. Results of this research suggest that given the size, synoptic meteorology and specific geography of the region, significant recirculation of pollutants is not likely to happen to contribute to next day’s pollution. The pollutant concentration may increase in the SBCZs, but their ability to recirculate the pollutants requires more extensive research. A closed sea breeze circulation cell is unlikely to form in this region due to topographical influences and a strong gradient wind effect. The pollutant plume is expected to be advected in the return flow over the peaks of higher terrain and via the top of the convergence zones, but its remixing in the onshore flow is subject to many factors such as gradient wind speed and direction, direction of the return flow and nature (size and state) of the pollutant. In appropriate conditions, pollution levels may reach to unhealthy levels under coast-parallel gradient wind condition.

Approved for public release, distribution is unlimited / The Monterey Bay sea breeze varies because of the influence of features such as inversions, clouds, synopticscale flow, and topography. The sea breeze is important because it impacts fire weather, air pollution, agriculture, and aviation operations, among other things. Analyses are conducted using a multi-quadric based program, which incorporates aircraft data, surface observations, and profiler data, to investigate the Monterey Bay sea breeze during 01-31 August 2003. Factors including inversions, cloud cover, amount of heating, distribution of heating, synoptic-scale flow, and topography are studied to determine their influence on the sea breeze. Six days are selected that best illustrate the factors that influence the structure of the Monterey Bay sea breeze. Results show that offs hore flow weakened the strength of the sea breeze and decreased the depth. A cooling trend in surface temperatures at the end of August also weakened the strength of the sea breezes and decreased the depth. Clouds are present during this period, which influenced the amount of heating, and consequently, the sea breeze response. The presence of a marine layer weakened the thermal gradient that in turn, weakened the sea breeze circulation. / Lieutenant Junior Grade, United States Naval Reserve

O presente trabalho teve por objetivo caracterizar as circulações locais que se formam na região central do Chile (RCC). Uma análise sinótica para o ano 2004 mostrou que durante o verão a condição de tempo dominante foi de céus claros associados à presença do Anticiclone Subtropical do Pacífico Sul com o deslocamento de baixas pressões litoral que mudam o regime de ventos. Dados da Armada do Chile mostraram que, no litoral da Região de Valparaíso, a amplitude anual de temperatura é de aproximadamente de 8 ºC. Os extremos de temperatura ocorrem entre as 09 e 12 UTC para as mínimas e 18 e 21 UTC para as máximas. O vento apresenta um ciclo anual com domínio da componente oeste no verão e componente leste no inverno. Maiores intensidades estão associadas à passagem de sistemas frontais no inverno. A brisa marítima é melhor caracterizada nos valores médios horários do vento no período de verão, sendo observada a partir das 12 UTC, com ventos de maior intensidade entre 18 e 21 UTC. A brisa terrestre é observada a partir das 00 UTC com ventos de menor intensidade que na brisa marítima. Dados da CONAMA-RM mostraram um ciclo diurno de temperatura bem definido na Região Metropolitana de Santiago com as temperaturas mínimas ocorrendo entre 06 e 09 HL e valores máximos entre 14 e 16 HL. Ao agrupar as estações localizadas dentro e fora dos limites urbanos foi possível identificar o efeito da ilha de calor (IC). Para o período de verão a IC apresentou intensidades positivas e no inverno uma maior freqüência de valores negativos. A intensidade do vento sofre também os efeitos da cidade, observando-se uma redução desta nas estações que se localizam no centro da Grande Santiago. Valores mínimos de intensidade do vento por períodos prolongados levaram a um incremento nas concentrações de material particulado. A diminuição nas concentrações está associada à passagem de frentes e ao incremento na intensidade do vento. Os efeitos da cidade na atmosfera foram estudados com mais detalhamento mediante a utilização do BRAMS. A análise sinótica mostrou uma região de vento fraco e baixo gradiente barométrico na região de estudo para a maior parte do período. Foi possível identificar a brisa marítima com maior intensidade do vento entre 18 e 19 UTC. A brisa terrestre foi identificada na maior parte das noites, com intensidade de vento maior próximo das 04 UTC. As cidades localizadas na RCC apresentam a tendência de resfriar o ar próximo da superfície e modificam a intensidade do vento e os padrões de umidade relativa. Embora os efeitos das cidades tenham sido encontrados, os efeitos da topografia no escoamento são ainda mais importantes, gerando circulações sobre a região central do Chile que não são completamente modificadas pela presença das cidades. / The objective of this work was to characterize the local circulations that are generated in the Central Chile (CC) region. A synoptic analyze for 2004 show that clear sky weather conditions associated to the Subtropical Anticyclone of South Pacific (SASP) was dominant during the summer. Coastal lows moving from north to CC interacts with SASP changing the wind regime. Meteorological data from Armada do Chile showed that on the coast of Valparaíso, the annual temperature amplitude was approximately 8 ºC. Temperature extremes occur between 09 and 12 UTC for minimum and 18 and 21 UTC for maximum values. The wind showed an annual cycle, with dominant direction to west during summer, while in wintertime, wind dominant direction is to the east. Higher values of wind speed are associated with frontal passages during winter. The sea breeze was better seen in the wind mean hourly values between 12 UTC and 21 UTC with higher wind speeds at 18 UTC. Land breeze was observed around 00 UTC, with lower wind speeds than in the sea breeze case. Meteorological data form CONAMA-RM showed a well defined diurnal cycle of temperature in the Metropolitan Region of Santiago with minimum temperatures occurring between 06 and 09 LT and maximum values between 14 and 16 LT. The urban heat island effect was seen grouping urban and non urban meteorological stations. The urban heat island is, in general, positive during the summer but, during the winter, negative values of intensity are frequent. The wind speed also shows the urban effects, with a wind speed decrease in the meteorological station inside the city. Long periods of low wind speed are associated with an increase in the particulate matter concentrations. The decrease in these concentrations is associated with the passage of frontal systems, as well as wind speed increase. The city effects on the atmosphere were studied in more details through the use of BRAMS. The synoptic analysis showed a weak wind region and low pressure gradient in the study region for most part of the period. The sea breeze was identified with higher wind speeds between 18 and 19 UTC. The land breeze was identified in the most part of the nights, with higher wind speeds near 04 UTC. The cities situated in CC have a tendency to cool down the air near to the surface and modify the wind speed and relative humidity patterns. Although the effects of the cities have been found, the topography effects on the wind flow are even more important, generating circulations over Central Chile that are not completely modified by the presence of the cities.

Os efeitos causados pela presença de áreas urbanizadas da Região Metropolitana de São Paulo (RMSP), conhecidos por ilha de calor urbana, são estudados através da modelagem numérica e da análise de alguns dados observacionais, coletados no período de inverno de 1999 durante a 1ª Fase intensiva de medidas de campo do Projeto Temático FAPESP “Meteorologia e Poluição do Ar em São Paulo" e da rede automática da CETESB. Através da utilização de imagens do satélite LANDSAT-5, foi obtido um arquivo de ocupação do solo na RMSP numa resolução de aproximadamente 424 m. Foram definidos dois tipos de ocupação urbana que diferem principalmente na verticalização e espaçamento entre as construções. Simulações realizadas com uma parametrização adequada ao tratamento das propriedades da superfície em áreas urbanas, o modelo RAMS-TEB, mostraram que as fontes antropogênicas de calor de origem veicular são de grande importância no ciclo diurno de temperatura e umidade na RMSP. Uma comparação entre os dados simulados pelo modelo e dados observacionais de superfície apresentou coeficientes de correlações superiores a 0,9 para a temperatura e superiores a 0,8 para a umidade relativa. A interação entre a brisa marítima e a ilha de calor intensifica as zonas de convergência no centro da cidade, podendo ocasionar a re-circulação de poluentes nessa região. Simulações sobre o efeito da urbanização mostram que a ilha de calor urbana faz com que haja uma propagação mais rápida da frente de brisa até o centro da RMSP, que permanece estacionária por algum tempo nessa região. Os efeitos da topografia mostraram-se fundamentais na intensidade da brisa marítima e sua propagação sobre o continente. A presença de grandes corpos d’água, tais como a represa de Guarapiranga e Billings, contribui para a diminuição das amplitudes do ciclo diurno de temperatura na RMSP através das circulações do tipo brisa lacustre geradas pelos mesmos. O uso de um modelo de dispersão mostrou que, com a propagação da frente de brisa para o interior (na direção SE-NW), poluentes emitidos na RMSP são transportados para áreas remotas, diminuindo a concentração dos mesmos nas regiões emissoras. / The effects caused by urbanization in the Metropolitan Area of São Paulo (MASP), known as urban heat island, are studied through the use of numerical modeling and some observed data, collected in the 1999’s winter time during the first phase of intensive field measurements from the Thematic Project FAPESP “Meteorology and Air Pollution in São Paulo" and also from CETESB automatic network. A 424 m resolution land use file was created using LANDSAT-5 satellite pictures where two different kinds of urban regions were identified. The main differences between these regions are the vertical structure and spacing between buildings. Simulations performed with an appropriate parameterization for the treatment of surface properties in urban areas showed that anthropogenic sources due to traffic are of great importance to the temperature and humidity diurnal cycle in MASP. Comparisons between simulated and observed surface data had a correlation coefficient greater than 0.9 for temperature and greater than 0.8 for relative humidity. The interaction between the see breeze and the urban heat island intensify the convergence zones in the center of the city, eventually causing the re-circulation of pollutants in this region. Simulations of the urbanization effects showed that the urban heat island is responsible for a faster propagation of the sea breeze front up to the center of the MASP, remaining stationary in this region for some time. The topographic effects are fundamental in the intensity of the sea breeze and its inland propagation. The presence of large water bodies, as the Guarapiranga and Billings Dams, contribute to a decrease in the temperature diurnal cycle amplitudes because of the lake breeze circulations generated by them. The use of a simple dispersion model showed that with the propagation of the sea breeze front to the countryside (in the direction SE-NW), pollutants emitted in MASP are transported to remote areas, causing a decrease in the concentration of these pollutants in the source region.

This research consists of two related yet distinct studies: an observational study of the surface character of the penetration of marine air into the southern Willamette Valley and a climatological study of the summertime air masses of northwestern Oregon. For the observational study, temperature and estimated wind data were gathered by automobile. Mesoscale analysis of several cases indicate that the Marine Air Penetration (MAP) occurs regularly in approximately the same area and is strongly controlled by the topography. Qualitative observation and reasoning strongly suggests that the strong winds and increased stability at the top of the marine layer have an adverse effect upon agricultural field fires. Results of the climatological study indicated that the application of the partial collective method of analysis to July maximum temperature data from the U.S. Climatological Network yielded a meaningful air mass climatology for northwestern Oregon. To our knowledge, this is the first time that the partial collective method has been applied to a region with mountainous areas west of the Rocky Mountains or to the mesoscale. / Graduation date: 1981

The spatial structure and temporal evolution of sea breeze and the latitudinal distribution of propagation and mixing of sea breeze driven near-inertial ocean response in the Gulf of Mexico are investigated using comprehensive data sets and a non-linear numerical model. Near 30�N, inertial oceanic response is significantly enhanced by a near-resonant condition between inertial and diurnal forcing frequencies. Observational results indicate that sea breeze variability peaks in summer and extends at least 300 km offshore with continuous seaward phase propagation. The maximum near-inertial oceanic response occurs in June when there is a shallow mixed layer, strong stratification, and an approximately 10-day period of continuous sea breeze forcing. Near-inertial current variance decreases in July and August due to the deepening of the mixed layer and a more variable phase relationship between the wind and current. River discharge varies interannually and can significantly alter the oceanic response during summer. During 1993, the ?great flood? of the Mississippi River deepens the summer mixed layer and reduces the sea breeze response. The near-inertial currents can provide considerable vertical mixing on the shelf in summer, as seen by the suppression of bulk Richardson number during strong near-inertial events. Three-dimensional idealized simulations show that the coastal oceanic response to sea breeze is trapped poleward of 30� latitude, however, it can propagate offshore as Poincare waves equatorward of 30� latitude. Near 30� latitude, the maximum oceanic response to sea breeze moves offshore slowly because of the near-zero group speed of Poincare waves at this latitude. The lateral energy flux convergence plus the energy input from the wind is maximum near the critical latitude, leading to increased vertical mixing. This local dissipation is greatly reduced at other latitudes. Simulations with realistic bathymetry of the Gulf of Mexico confirm that a basin-wide ocean response to coastal sea breeze forcing is established in the form of Poincare waves. This enhanced vertical mixing is consistent with observations on the Texas-Louisiana Shelf. Comparison of the three-dimensional and one-dimensional models shows some significant limitations of one-dimensional simplified models for sea breeze simulations near the critical latitude.

Thesis (M.S.)--Naval Postgraduate School, 1993. / Includes bibliographical references (p. 95-98).

Thesis (M.Sc.)(Meteorology)--University of Pretoria, 2007. / Includes summary. Includes bibliographical references. Available on the Internet via the World Wide Web.

O presente trabalho teve por objetivo caracterizar as circulações locais que se formam na região central do Chile (RCC). Uma análise sinótica para o ano 2004 mostrou que durante o verão a condição de tempo dominante foi de céus claros associados à presença do Anticiclone Subtropical do Pacífico Sul com o deslocamento de baixas pressões litoral que mudam o regime de ventos. Dados da Armada do Chile mostraram que, no litoral da Região de Valparaíso, a amplitude anual de temperatura é de aproximadamente de 8 ºC. Os extremos de temperatura ocorrem entre as 09 e 12 UTC para as mínimas e 18 e 21 UTC para as máximas. O vento apresenta um ciclo anual com domínio da componente oeste no verão e componente leste no inverno. Maiores intensidades estão associadas à passagem de sistemas frontais no inverno. A brisa marítima é melhor caracterizada nos valores médios horários do vento no período de verão, sendo observada a partir das 12 UTC, com ventos de maior intensidade entre 18 e 21 UTC. A brisa terrestre é observada a partir das 00 UTC com ventos de menor intensidade que na brisa marítima. Dados da CONAMA-RM mostraram um ciclo diurno de temperatura bem definido na Região Metropolitana de Santiago com as temperaturas mínimas ocorrendo entre 06 e 09 HL e valores máximos entre 14 e 16 HL. Ao agrupar as estações localizadas dentro e fora dos limites urbanos foi possível identificar o efeito da ilha de calor (IC). Para o período de verão a IC apresentou intensidades positivas e no inverno uma maior freqüência de valores negativos. A intensidade do vento sofre também os efeitos da cidade, observando-se uma redução desta nas estações que se localizam no centro da Grande Santiago. Valores mínimos de intensidade do vento por períodos prolongados levaram a um incremento nas concentrações de material particulado. A diminuição nas concentrações está associada à passagem de frentes e ao incremento na intensidade do vento. Os efeitos da cidade na atmosfera foram estudados com mais detalhamento mediante a utilização do BRAMS. A análise sinótica mostrou uma região de vento fraco e baixo gradiente barométrico na região de estudo para a maior parte do período. Foi possível identificar a brisa marítima com maior intensidade do vento entre 18 e 19 UTC. A brisa terrestre foi identificada na maior parte das noites, com intensidade de vento maior próximo das 04 UTC. As cidades localizadas na RCC apresentam a tendência de resfriar o ar próximo da superfície e modificam a intensidade do vento e os padrões de umidade relativa. Embora os efeitos das cidades tenham sido encontrados, os efeitos da topografia no escoamento são ainda mais importantes, gerando circulações sobre a região central do Chile que não são completamente modificadas pela presença das cidades. / The objective of this work was to characterize the local circulations that are generated in the Central Chile (CC) region. A synoptic analyze for 2004 show that clear sky weather conditions associated to the Subtropical Anticyclone of South Pacific (SASP) was dominant during the summer. Coastal lows moving from north to CC interacts with SASP changing the wind regime. Meteorological data from Armada do Chile showed that on the coast of Valparaíso, the annual temperature amplitude was approximately 8 ºC. Temperature extremes occur between 09 and 12 UTC for minimum and 18 and 21 UTC for maximum values. The wind showed an annual cycle, with dominant direction to west during summer, while in wintertime, wind dominant direction is to the east. Higher values of wind speed are associated with frontal passages during winter. The sea breeze was better seen in the wind mean hourly values between 12 UTC and 21 UTC with higher wind speeds at 18 UTC. Land breeze was observed around 00 UTC, with lower wind speeds than in the sea breeze case. Meteorological data form CONAMA-RM showed a well defined diurnal cycle of temperature in the Metropolitan Region of Santiago with minimum temperatures occurring between 06 and 09 LT and maximum values between 14 and 16 LT. The urban heat island effect was seen grouping urban and non urban meteorological stations. The urban heat island is, in general, positive during the summer but, during the winter, negative values of intensity are frequent. The wind speed also shows the urban effects, with a wind speed decrease in the meteorological station inside the city. Long periods of low wind speed are associated with an increase in the particulate matter concentrations. The decrease in these concentrations is associated with the passage of frontal systems, as well as wind speed increase. The city effects on the atmosphere were studied in more details through the use of BRAMS. The synoptic analysis showed a weak wind region and low pressure gradient in the study region for most part of the period. The sea breeze was identified with higher wind speeds between 18 and 19 UTC. The land breeze was identified in the most part of the nights, with higher wind speeds near 04 UTC. The cities situated in CC have a tendency to cool down the air near to the surface and modify the wind speed and relative humidity patterns. Although the effects of the cities have been found, the topography effects on the wind flow are even more important, generating circulations over Central Chile that are not completely modified by the presence of the cities.