The influence of chemical mechanisms and meteorological parameterizations on pollutant concentrations calculated with an air quality model is studied. The influence of the differences between two gas-phase chemical mechanisms on the formation of ozone and aerosols in Europe is low on average. For ozone, the large local differences are mainly due to the uncertainty associated with the kinetics of nitrogen monoxide (NO) oxidation reactions on the one hand and the representation of different pathways for the oxidation of aromatic compounds on the other hand. The aerosol concentrations are mainly influenced by the selection of all major precursors of secondary aerosols and the explicit treatment of chemical regimes corresponding to the nitrogen oxides (NOx) levels. The influence of the meteorological parameterizations on the concentrations of aerosols and their vertical distribution is evaluated over the Paris region in France by comparison to lidar data. The influence of the parameterization of the dynamics in the atmospheric boundary layer is important ; however, it is the use of an urban canopy model that improves significantly the modeling of the pollutant vertical distribution

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Este trabalho investiga a evolução espacial da Camada Limite Planetária (CLP) na região do Canal de São Sebastião (CSS) - SP, uma das áreas mais impactadas por derramamentos acidentais de óleo das regiões sul e sudeste do Brasil. Para tanto, foi feito levantamento da topografia e cobertura do solo para uma região de 12 km x 12 km no CSS com o intuito de levantar parâmetros essenciais para a estimativa do balanço de energia sobre o continente. Foram utilizados dados médios horários de vento, temperatura e umidade específica do ar coletados pelo Centro de Biologia Marinha (CEBIMar), e temperatura do oceano obtida de um fundeio ancorado próximo ao centro do canal. Os dados médios foram utilizados para estimar o balanço de energia sobre o continente, utilizando o método proposto por Deardorff (1978), e sobre o oceano através de parametrização do tipo bulk para as condições de verão e inverno. Com os resultados obtidos foi determinada a altura da CLP para ambas as superfícies e, em seguida, aplicada uma média móvel com advecção destas alturas no sentido do vento zonal - a componente mais intensa do vento ao longo do dia segundo análise de dados para ambas estações estudadas - para investigar sua evolução espacial ao longo de duas linhas de latitude: uma interceptando o CEBIMar e outra, mais ao sul, numa região composta por água e continente em igual proporção. / This work investigates the spatial evolution of the Planetary Boundary Layer in the region of São Sebastião Channel (SSC) - SP, one of the most impacted area by accidental oil spilling in the South and Southeast regions of Brazil. It was performed a topographic and soil cover survey for a region of 12 km x 12 km in the SSC region in order to obtain the essential parameters to estimate the energy balance over the continent. Hourly averaged data of wind, air temperature and specific humidity collected by the Marine Biologic Center (CEBIMar) and ocean temperature obtained by a mooring near the center of the channel were used in this work to estimate the energy balance over the continent using the routine proposed by Deardorff (1978) and over the ocean using bulk parameterizations for winter and summer conditions. The obtained results were used to determine the PBL height for both surfaces. To investigate the PBL spatial evolution in the transition continent-water-continent it was applied a movable average with advection of the PBL height in the zonal wind direction the wind component more intense during winter and summer, according to the data analysis- to investigate the PBL spatial evolution through two latitude lines: one intercepting the CEBIMar and another in an region southward with equal water and continent proportion.

Este trabalho investiga a evolução espacial da Camada Limite Planetária (CLP) na região do Canal de São Sebastião (CSS) - SP, uma das áreas mais impactadas por derramamentos acidentais de óleo das regiões sul e sudeste do Brasil. Para tanto, foi feito levantamento da topografia e cobertura do solo para uma região de 12 km x 12 km no CSS com o intuito de levantar parâmetros essenciais para a estimativa do balanço de energia sobre o continente. Foram utilizados dados médios horários de vento, temperatura e umidade específica do ar coletados pelo Centro de Biologia Marinha (CEBIMar), e temperatura do oceano obtida de um fundeio ancorado próximo ao centro do canal. Os dados médios foram utilizados para estimar o balanço de energia sobre o continente, utilizando o método proposto por Deardorff (1978), e sobre o oceano através de parametrização do tipo bulk para as condições de verão e inverno. Com os resultados obtidos foi determinada a altura da CLP para ambas as superfícies e, em seguida, aplicada uma média móvel com advecção destas alturas no sentido do vento zonal - a componente mais intensa do vento ao longo do dia segundo análise de dados para ambas estações estudadas - para investigar sua evolução espacial ao longo de duas linhas de latitude: uma interceptando o CEBIMar e outra, mais ao sul, numa região composta por água e continente em igual proporção. / This work investigates the spatial evolution of the Planetary Boundary Layer in the region of São Sebastião Channel (SSC) - SP, one of the most impacted area by accidental oil spilling in the South and Southeast regions of Brazil. It was performed a topographic and soil cover survey for a region of 12 km x 12 km in the SSC region in order to obtain the essential parameters to estimate the energy balance over the continent. Hourly averaged data of wind, air temperature and specific humidity collected by the Marine Biologic Center (CEBIMar) and ocean temperature obtained by a mooring near the center of the channel were used in this work to estimate the energy balance over the continent using the routine proposed by Deardorff (1978) and over the ocean using bulk parameterizations for winter and summer conditions. The obtained results were used to determine the PBL height for both surfaces. To investigate the PBL spatial evolution in the transition continent-water-continent it was applied a movable average with advection of the PBL height in the zonal wind direction the wind component more intense during winter and summer, according to the data analysis- to investigate the PBL spatial evolution through two latitude lines: one intercepting the CEBIMar and another in an region southward with equal water and continent proportion.

The atmospheric boundary layer (ABL) is the lowest layer of the atmosphere where surface effects are felt on time scales of about an hour. While its properties are determined by the surface characteristics, season and synoptic conditions, they in turn determine convective cloud properties and are required for the representation of cloud processes in atmospheric models. Further, interaction of the ABL with the surface layer of the ocean is a key component of ocean-atmosphere coupling. ABL characteristics over ocean surrounding the sub-continent become very important for understanding the monsoon processes during the monsoon season because the roots of many monsoon systems, that give rain to India, are over there. In this thesis data used are from three major field experiments namely the Bay of Bengal Monsoon Experiment (BOBMEX, 1999), Arabian Sea Monsoon Experiment (ARMEX, in two phases, ARMEX-I during 2002 and ARMEX-II in 2003), and Continental Tropical Convergence Zone (CTCZ) experiment (Pilot in 2009) which were carried out under the Indian Climate Research Programme (ICRP). While there have been few studies on ABL characteristics for individual cruises, a comprehensive study considering all available radiosonde data from the above cruises has been missing. This study fills this gap and focuses on the vertical structure of ABL using more than 400 high resolution Vaisala GPS radiosonde data collected over Bay of Bengal and Arabian Sea. The study attempts at first to look at the ABL characteristics of individual cruises and then compare and contrast them over the Bay of Bengal and Arabian Sea. ABL height Hm, estimated by using virtual potential temperature (θv) profile, shows diurnal variation during weak phase of convection while maximum in early morning during active phase of convection. Different variables i.e. moist static energy (h), specific humidity (q), convective available potential energy (CAPE), virtual potential temperature (θv) and equivalent potential temperature (θe) also differ during weak and active convection periods. Conserved variables mixing line approach gives the height up to which ground thermals penetrate in the vertical. This height, denoted by MH that represents the actual ABL height, is 2-3 times larger than Hm when shallow convective clouds are present. In general both Hm and MH are 20-30% larger over Arabian Sea compares to that over Bay of Bengal. Comparison of surface convective available potential energy (CAPE) and equivalent potential temperature (θe) between normal and deficit monsoon years shows that convective instability was as large in deficit years. This means that dynamic and not thermodynamics, controlled the occurrence of convection.