Durante a estação seca, é comum se observar um grande número de queimadas ocorrendo no Brasil. A fumaça proveniente da queima intensa é facilmente vista em imagens de satélite, principalmente na região de Cerrado e na Bacia Amazônica, e é responsável pela injeção de uma grande quantidade de partículas na atmosfera. Essas partículas de aerossol irão interagir diretamente com a radiação solar incidente, pelos processos de absorção e espalhamento, o que afetará a irradiância solar global incidente em superfície, a fração entre componente direto e difuso e a distribuição espectral. A modelagem precisa dessa interação ainda requer investigação científica. Nesse contexto, os resultados apresentados neste trabalho buscaram avaliar o desempenho de modelos ópticos para o aerossol de queimadas propostos por Rosário (2011) para a região da Reserva Biológica do Jaru (ou Rebio Jaru), Rondônia, durante a estação seca de 2007. Os modelos ópticos foram separados em intervalos de albedo simples, resultando em três grupos ou regimes: um mais absorvedor, um moderadamente absorvedor e um mais espalhador. Os dados simulados utilizando o código de transferência radiativa SBDART foram comparados com medidas feitas in situ na Rebio Jaru. Os dados foram obtidos entre os dias 24 de agosto e 31 de outubro de 2007. Foram analisados dados medidos por um Multifilter Rotating Shadowband Radiometer (MFRSR - canais de 670, 870 e 1036 nm e da irradiância solar total), por um sensor PAR (irradiância fotossinteticamente ativa) e dados de um pirânometro (irradiância solar total). A irradiância fotossinteticamente ativa compreende o intervalo entre 400 e 700 nm e corresponde à energia solar utilizada na fotossíntese realizada pelas plantas. Ela foi utilizada para avaliar o desempenho dos modelos propostos por Rosário (2011). Para esse intervalo espectral, o modelo óptico mais espalhador é o que melhor representou o período analisado. Estudos de caso foram feitos para avaliar o comportamento dos demais dados para dias com valores distintos da profundidade óptica do aerossol em 550nm. Os resultados obtidos pela análise das medidas feitas pelo MFRSR divergiram com relação ao do sensor PAR e do Piranômetro. As divergências observadas podem estar associadas à degradação instrumental. Sugere-se que sejam realizados estudos mais detalhados levando em consideração o conteúdo integrado de vapor dágua, entre outras variáveis meteorológicas, com a finalidade de definir um método eficiente para determinar o melhor modelo óptico para o aerossol de queimadas e para diferentes regiões da Bacia Amazônica, como efetuado por Rosário (2011) na região de Alta Floresta. / During the dry season biomass burning activities are frequent in Brazil. The smoke from these intense fires can easily be seen with satellite imaging, mostly in the centermost region of Brazil and the Amazon, and it is responsible for the input of large amounts of particles to the atmosphere. These aerosol particles interact directly with the incoming solar radiation, through absorption and scattering processes, which will affect the incoming global solar irradiation reaching the surface, the fraction between the direct and diffuse components and the spectral distribution. The accurate modeling of these interactions requires further scientific investigation. In this context, the present work evaluated the performance of biomass burning aerosol optical models proposed by Rosario (2011) for the southern Amazon, in the Jaru Biological Reserve, Rondônia, during the dry season of 2007. The proposed models were classified according to single scattering albedo intervals, and three distinct groups or regimes were identified: one for more absorbing particles, one for moderately absorbing particles and one for more scattering particles. Simulated data using the Radiative Transfer code SBDART were compared with in situ measurements performed at Rebio Jaru. The data were collected between August 24th and October 31st 2007. Data measured by a Multifilter Shadowband Rotating Radiometer (MFRSR - channels 670, 870 and 1036 nm and the total solar irradiance) from a PAR sensor (photosynthetically active radiation) and from a pyranometer (total solar irradiance) were included in the analysis. Photosynthetically active irradiance spectral interval spans between 400 and 700 nm, and corresponds to the solar energy used on the vegetation photosynthesis. This spectral region was chosen to evaluate the performance of the optical models. For this spectral interval, the more scattering optical model better represented the measured values. Case studies were conducted to evaluate the performance of the radiative transfer code and the optical models on days with distinct values of the aerosol optical depth at 550nm. The results showed that simulations for MFRSR channels diverged from the PAR sensor and the pyranometer. These divergences could be associated to instrumental degradation. It is suggested that further studies be conducted taking into account water vapor content variability, and other meteorological variables, in order to define an efficient method to determine the best optical model for the smoke aerosol and for different regions in the Amazon Basin, as performed by Rosario (2011) for Alta Floresta.

Com o objetivo de estabelecer as possíveis correlações entre os ácidos orgânicos na precipitação e as alterações no uso do solo, amostras de água da chuva e aerossol foram coletadas nos Parques Estaduais de Intervales (PEI) e Morro do Diabo (PEMD), no Estado de São Paulo, cuja vegetação é formada por florestas pertencentes ao domínio Mata Atlântica. Entre julho de 2002 a julho de 2004 foram coletadas 232 amostras de água de chuva em PEI e 96 amostras em PEMD, determinando-se os teores de formato, acetato, metanosulfonato, piruvato, oxalato, maleato, valerato, citrato, butirato, tartarato, cloreto, nitrato, sulfato, sódio, amônio, potássio, cálcio e magnésio por cromatografia iônica (CI). Também foram determinadas as concentrações de carbono orgânico dissolvido (COD), carbono inorgânico dissolvido (CID) e o pH das amostras. Entre julho de 2002 a maio de 2003, amostras de aerossol inalável (PM10), subdividido nas frações fina (dp < 2,5 µm) e grossa (2,5 < dp < 10 µm), foram coletadas separadamente, totalizando 60 amostras para cada fração no PEMD e 90 amostras para cada fração no PEI, determinando-se as concentrações em massa por gravimetria e a composição química do material solúvel em água por CI. Eventos de chuva ácida ocorreram nos dois locais ao longo do período de amostragem. Os ácidos orgânicos contribuíram com até 16% da somatória iônica (µeq.L-1) no PEI e até 12% no PEMD, com predominância do ácido acético no PEI e com predominância de ácido fórmico no PEMD. A emissão direta da vegetação foi a principal fonte de ácidos orgânicos no PEI, uma vez que a razão entre o ácido fórmico e ácido acético < 1,0. No PEMD, a razão entre ácido fórmico e acético > 1,0 indicou como as principais fontes as reações secundárias de oxidação fotoquímicas no local e a emissão direta biogênica da vegetação. A contribuição dos ácidos orgânicos para a acidez da água da chuva foi de até 40% no PEI e até 30% no PEMD. Adicionalmente, as correlações significantes entre H+ e COD (p < 0,05) sugerem contribuições de compostos orgânicos para acidez da água da chuva. A influência de fontes regionais de queima de biomassa e das condições meteorológicas na composição química da atmosfera no PEMD é evidenciada pela concentração média de PM10 (22 ug.m-3); pela concentração de \"black carbon\" (40 ?g.m-3), superiores às verificadas no PEI, pela maior contribuição da fração fina do aerossol para a concentração de COD da fração solúvel em água. Por outro lado, no PEI, a fração grossa relacionada à compostos biogênicos, aerossol marinho e partículas de solo foi a maior contribuinte para o COD. Dos ácidos orgânicos detectados no aerossol solúvel em água, o ácido oxálico foi o mais abundante. / In order to establish the possible correlations among organic acids in the precipitation and land use changes, rain water and aerosol samples were collected in the State Parks of Intervales (PEI) and Morro do Diabo (PEMD), in the State of São Paulo. The vegetation there is formed by Mata Atlântica forests (Atlantic forest). Between July, 2002 and July, 2004, 232 samples of rainwater were collected in PEI and 96 samples in PEMD, for the analysis of formate, acetate, methanesulfonate, pyruvate, oxalate, malate, valerate, citrate, butyrate, tartarate, chloride, nitrate, sulfate, sodium, ammonium, potassium, calcium, magnesium for ionic chromatography (CI). The concentrations of dissolved organic carbon (COD), dissolved inorganic carbon (CID) and pH of the samples were also determined. Between July, 2002 and May, 2003, samples of inhalable aerosol (PM10), subdivided in fine fraction (dp <2.5 µm) and coarse fraction (2.5 <dp <10 µm), were collected separately, in a total of 60 samples for each fraction in PEMD and 90 samples for each fraction in PEI, submitted to the analyses of concentration in mass through gravimeter and the chemical composition of the water soluble aerosol for CI. Events of acid rain were verified along the sampling period in both places and the organic acids contributed up to 16% of the ionic sum (µeq.L-1) in PEI and up to 12% in PEMD, with predominance of acetic acid in PEI and with predominance of formic acid in PEMD. The direct emission from vegetation was the main source of organic acids in PEI, once the ratio between the formic acid and acetic acid was <1.0 and that the effects of biomass burns are not verified. In PEMD, the ratio among formic and acetic acid >1.0 indicated the secondary reactions of photo-chemical oxidation ?in situ? and biogenic direct emission from the vegetation as the main source. The contribution of the organic acids for the acidity of the rainwater was up to 40% in PEI and up to 30% in PEMD. In addition to the strong correlations between H+ and COD (p <0.05) they suggest contributions of organic compositions for the acidity of the rainwater. The influence of regional sources of biomass burning and of the meteorological conditions in the chemical composition of the atmosphere in PEMD is also observed by the medium concentration of PM10 (22 µg.m-3) and concentration of \"black carbon\" (40 ?g.m-3), both higher than the ones observed in PEI, and for the highest contribution of fine fraction of aerosol for the concentration of COD analyzed from the water soluble fraction. In PEI, the coarse fraction related to biogenic compounds, marine aerosol and soil particles were the greatest responsible agents for COD. Oxalic acid was the most abundant organic acid detected.

Com o objetivo de estabelecer as possíveis correlações entre os ácidos orgânicos na precipitação e as alterações no uso do solo, amostras de água da chuva e aerossol foram coletadas nos Parques Estaduais de Intervales (PEI) e Morro do Diabo (PEMD), no Estado de São Paulo, cuja vegetação é formada por florestas pertencentes ao domínio Mata Atlântica. Entre julho de 2002 a julho de 2004 foram coletadas 232 amostras de água de chuva em PEI e 96 amostras em PEMD, determinando-se os teores de formato, acetato, metanosulfonato, piruvato, oxalato, maleato, valerato, citrato, butirato, tartarato, cloreto, nitrato, sulfato, sódio, amônio, potássio, cálcio e magnésio por cromatografia iônica (CI). Também foram determinadas as concentrações de carbono orgânico dissolvido (COD), carbono inorgânico dissolvido (CID) e o pH das amostras. Entre julho de 2002 a maio de 2003, amostras de aerossol inalável (PM10), subdividido nas frações fina (dp < 2,5 µm) e grossa (2,5 < dp < 10 µm), foram coletadas separadamente, totalizando 60 amostras para cada fração no PEMD e 90 amostras para cada fração no PEI, determinando-se as concentrações em massa por gravimetria e a composição química do material solúvel em água por CI. Eventos de chuva ácida ocorreram nos dois locais ao longo do período de amostragem. Os ácidos orgânicos contribuíram com até 16% da somatória iônica (µeq.L-1) no PEI e até 12% no PEMD, com predominância do ácido acético no PEI e com predominância de ácido fórmico no PEMD. A emissão direta da vegetação foi a principal fonte de ácidos orgânicos no PEI, uma vez que a razão entre o ácido fórmico e ácido acético < 1,0. No PEMD, a razão entre ácido fórmico e acético > 1,0 indicou como as principais fontes as reações secundárias de oxidação fotoquímicas no local e a emissão direta biogênica da vegetação. A contribuição dos ácidos orgânicos para a acidez da água da chuva foi de até 40% no PEI e até 30% no PEMD. Adicionalmente, as correlações significantes entre H+ e COD (p < 0,05) sugerem contribuições de compostos orgânicos para acidez da água da chuva. A influência de fontes regionais de queima de biomassa e das condições meteorológicas na composição química da atmosfera no PEMD é evidenciada pela concentração média de PM10 (22 ug.m-3); pela concentração de \"black carbon\" (40 ?g.m-3), superiores às verificadas no PEI, pela maior contribuição da fração fina do aerossol para a concentração de COD da fração solúvel em água. Por outro lado, no PEI, a fração grossa relacionada à compostos biogênicos, aerossol marinho e partículas de solo foi a maior contribuinte para o COD. Dos ácidos orgânicos detectados no aerossol solúvel em água, o ácido oxálico foi o mais abundante. / In order to establish the possible correlations among organic acids in the precipitation and land use changes, rain water and aerosol samples were collected in the State Parks of Intervales (PEI) and Morro do Diabo (PEMD), in the State of São Paulo. The vegetation there is formed by Mata Atlântica forests (Atlantic forest). Between July, 2002 and July, 2004, 232 samples of rainwater were collected in PEI and 96 samples in PEMD, for the analysis of formate, acetate, methanesulfonate, pyruvate, oxalate, malate, valerate, citrate, butyrate, tartarate, chloride, nitrate, sulfate, sodium, ammonium, potassium, calcium, magnesium for ionic chromatography (CI). The concentrations of dissolved organic carbon (COD), dissolved inorganic carbon (CID) and pH of the samples were also determined. Between July, 2002 and May, 2003, samples of inhalable aerosol (PM10), subdivided in fine fraction (dp <2.5 µm) and coarse fraction (2.5 <dp <10 µm), were collected separately, in a total of 60 samples for each fraction in PEMD and 90 samples for each fraction in PEI, submitted to the analyses of concentration in mass through gravimeter and the chemical composition of the water soluble aerosol for CI. Events of acid rain were verified along the sampling period in both places and the organic acids contributed up to 16% of the ionic sum (µeq.L-1) in PEI and up to 12% in PEMD, with predominance of acetic acid in PEI and with predominance of formic acid in PEMD. The direct emission from vegetation was the main source of organic acids in PEI, once the ratio between the formic acid and acetic acid was <1.0 and that the effects of biomass burns are not verified. In PEMD, the ratio among formic and acetic acid >1.0 indicated the secondary reactions of photo-chemical oxidation ?in situ? and biogenic direct emission from the vegetation as the main source. The contribution of the organic acids for the acidity of the rainwater was up to 40% in PEI and up to 30% in PEMD. In addition to the strong correlations between H+ and COD (p <0.05) they suggest contributions of organic compositions for the acidity of the rainwater. The influence of regional sources of biomass burning and of the meteorological conditions in the chemical composition of the atmosphere in PEMD is also observed by the medium concentration of PM10 (22 µg.m-3) and concentration of \"black carbon\" (40 ?g.m-3), both higher than the ones observed in PEI, and for the highest contribution of fine fraction of aerosol for the concentration of COD analyzed from the water soluble fraction. In PEI, the coarse fraction related to biogenic compounds, marine aerosol and soil particles were the greatest responsible agents for COD. Oxalic acid was the most abundant organic acid detected.

The determination of the atmospheric aerosol size distribution is an inverse illposed problem. The shape and the material composition of the air-carried particles are two substantial model parameters. Present evaluation algorithms only used an approximation with spherical homogeneous particles. In this paper we propose a new numerically efficient recursive algorithm for inhomogeneous multilayered coated and absorbing particles. Numerical results of real existing particles show that the influence of the two parameters on the model is very important and therefore cannot be ignored.

Diese Dissertation ist innerhalb eines Teilprojekts des Schwerpunktprogramms SPP1233 ”Megacities Megachallenge - Informal Dynamics of Global Change“ entstanden. Thema der vorliegenden Arbeit ist die Untersuchung der heterogenen Reflexion der Sonnenstrahlung an urbanen Bodenoberflächen, sowie deren Einfluss auf die Bestimmung der optischen Dicke von Aerosolpartikeln aus Satellitendaten. Zu diesem Zweck wurden flugzeuggetragene Messungen der spektral aufgelösten, reflektierten solaren Strahlung durchgeführt. In dieser Arbeit werden Messungen mit dem SMART-Albedometer (Spectral Modular Airborne Radiation measurement sysTem) präsentiert, die im Rahmen zweier Messkampagnen in Leipzig im September 2007 und in Zhongshan, China im Dezember 2009 erfasst wurden. Die spektrale Bodenreflektivität und Bodenalbedo wurden aus den spektralen Messungen der aufwärtsgerichteten Stahldichte (Radianz) und Strahlungsflussdichte (Irradianz) bestimmt. Dazu wurden eindimensionale Strahlungsübertragungsrechnungen durchgeführt. Der Einfluss der Flughöhe auf die Bodenreflektivität und Bodenalbedo wird anhand eines Messbeispiels, sowie einer Modellstudie mit ein- und dreidimensionalen Strahlungsübertragungsrechnungen diskutiert. Für beide Untersuchungsgebiete, Leipzig und Zhongshan, wird die Heterogenität der Reflexion solarer Strahlung an urbanen Oberflächen gezeigt. Der Einfluss der im operationellen Aerosolalgorithmus des satellitengetragenen Instrumentes MODIS (MODerate resolution Imaging Spectroradiometer) getroffenen Annahmen zur Bodenreflektivität auf die optische Dicke von Aerosolpartikeln, wurde mittels der gemessenen spektralen Bodenreflektivität und einer auf Strahlungsübertragungsrechnungen basierenden Modellstudie quantifiziert. Ein linearer Zusammenhang zwischen Bodenreflektivität und optischer Dicke von Aerosolpartikeln wird für beide Fallbeispiele gezeigt. Mittels der Messungen in Zhongshan kann bestätigt werden, dass die Bodenreflektivität für urbane Oberflächen im Aerosolalgorithmus unterschätzt wird. Im Rahmen der Modellstudie wird die Sensitivität des Aerosolalgorithmus auf die programminternen Annahmen zur Bodenreflektivität quantifiziert.

Im Rahmen der vorliegenden Arbeit wurden die Eigenschaften von atmosphärischen Aerosolpartikeln im tropischen Regenwald des Amazonasgebietes bestimmt. Dazu wurden die Daten einer fast einjährigen Lidarmesskampagne ausgewertet und diskutiert. Die Messungen wurden mit einem automatischen Mehrwellenlängen-Polarisations-Raman-Lidar im zentralen Amazonasbecken nahe Manaus, Brasilien, im Zeitraum von Januar bis November 2008 durchgeführt. Somit konnten erstmalig optische und mikrophysikalische Aerosoleigenschaften im Amazonasgebiet während der Regenzeit (ca. Dezember-Mai) und Trockenzeit (ca. Juni-November) höhenaufgelöst charakterisiert werden. Einleitend werden die meteorologischen Bedingungen im Amazonasgebiet erläutert und eine Literaturübersicht über Aerosolforschung in dieser Region gegeben. Das Messgerät sowie verschiedene Kalibrier- und Korrekturschemen, die zur Datenauswertung notwendig sind, werden vorgestellt. Auch Vergleiche mit anderen Messgeräten werden diskutiert. Diese zeigen, dass die aus den Lidarmessungen abgeleiteten Parameter von hoher Qualität sind. Anhand von Fallstudien werden mit Hilfe von Rückwärtstrajektorien und Satellitenmessungen typische Aerosolbedingungen am Messstandort diskutiert. Um die generellen Unterschiede zwischen Regen- und Trockenzeit zu quantifizieren, wird eine statistische Auswertung aller analysierten Lidarmessungen präsentiert. Die Analyse der Lidardaten zeigt, dass während der Regenzeit im Amazonasgebiet in ca. der Hälfte aller Fälle sehr saubere Bedingungen mit einer Aerosol Optischen Dicke (AOD) von weniger als 0.05 (bei 532 nm) vorherrschen können. Allerdings wurde in ca. 30% aller analysierten Fälle im Zeitraum von Januar bis Mai auch afrikanisches Aerosol, vornehmlich Saharastaub und Biomasseverbrennungsaerosol (BBA), am Messstandort detektiert. Dabei dominierte meist BBA die Aerosolpopulation, wie die Depolarisationsmessungen zeigten. In der Trockenzeit ist die Atmosphäre im Amazonasbecken hauptsächlich mit BBA aus Südamerika belastet. Daher ist die AOD im Durchschnitt um einen Faktor drei größ er als in der Regenzeit. BBA wurde zu dieser Jahreszeit regelmäßig bis zu einer Höhe von 4-6 km detektiert. Basierend auf den vorgestellten Langzeitmessungen werden erstmalig die optischen Eigenschaften von südamerikanischem BBA statistisch analysiert und diskutiert. / Continuous lidar measurements were performed in the Amazon rain forest for almost one year in 2008. The results of the automated multiwavelength-Raman-polarization lidar observations were presented in this dissertation. These measurements are the first long-term observations of the vertical aerosol structure ever made in the Amazon Basin. The advanced lidar observations were conducted 60 km north of Manaus in the central northern part of Amazonia. The area is widely covered with pristine rain forest. A HYSPLIT backward-trajectory analysis showed that the observations were representative on a regional scale for the central northern part of the Amazon rain forest. The general weather conditions in this region are characterized by a wet (December-June) and a dry season (July-November). During the dry season, a high fire activity occurs in Amazonia, which heavily influences the atmospheric conditions. With the lidar instrument, vertical profiles of the particle backscatter coefficient at 355, 532, and 1064 nm, of the particle extinction coefficient at 355 and 532 nm, and of the particle linear depolarization ratio at 355 nm can be determined. The results from the long-term lidar observations performed in Brazil contain a lot of new information about the aerosol conditions in the central northern Amazon Basin and corroborate certain findings from former aerosol measurements in Amazonia. It was shown for the first time that advection of Saharan dust together with biomass burning aerosol (BBA) from Africa occurred regularly throughout the wet season. In about one third (32%) of all lidar observations during the wet season, African aerosol was dominating the optical aerosol properties in Amazonia. The analysis of the vertical aerosol structure during such events revealed that the African aerosol arriving in the central northern Amazon Basin was usually trapped in the lowermost 3-3.5 km of the troposphere. To quantify the amount of Saharan dust and African smoke transported towards the lidar site, the dust contribution to the measured optical aerosol properties was separated by means of the measured particle depolarization ratio. This study led to the result that in about one half of the cases with African aerosol advection, smoke particles contributed to more than 50% to the total Aerosol Optical Depth (AOD). The smoke transport from Africa towards Amazonia occurred predominantly between January and April when the fire activity in Central Africa was highest. BBA is thus a major constituent of the aerosol plumes that are regularly transported from Africa towards Amazonia. This is a key finding of the presented study. During clean conditions, an AOD (532 nm) of less than 0.05 was observed and the aerosol was trapped in the lowermost 2 km of the troposphere. However, the analysis of the long-term data set revealed that these clean atmospheric conditions occurred in only 48% of all wet-season cases. One example for such background conditions was intensively discussed and it was shown that a major meso-scale rain event occurred in the Amazon region at the same time. This precipitation event was possibly partly responsible for the very low aerosol load. Two case studies from the dry season were presented for which BBA dominated the optical properties. In the first case, a comparable high aerosol load (AOD of 0.41) prevailed while in the second one, a medium aerosol load (AOD of 0.15) was observed. Aged BBA advected from regions south of the lidar site were identified to be the dominant aerosol species for both cases. However, very different geometrical, optical and microphysical properties of BBA (e.g., vertical layering, lidar ratio, Ångström exponent, effective radius, SSA) were observed on both days. In the first case, aerosol was present up to about 4.5 km. Extinction-related Ångström exponent s of about 1 and lidar ratios between 70 and 90 sr were found at different heights for the smoke aerosol. The BBA was highly absorbing (SSA of 0.81) at heights of the highest RH (85%), whereas above under dry conditions (RH=50%) only moderate absorption (SSA of 0.93) was detected. In the second case, smoke was detected up to 4.5 km, and Ångström exponent of about 2 and lidar ratios of 45-55 sr were measured in the aerosol layers. The BBA was only moderately absorbing indicated by SSA values between 0.92 and 0.94. The reason for the differences in the smoke properties could be the shorter travel time to the lidar site (<24 h), different aging processes (e.g., cloud/rain processing), or different burning conditions. In both cases, no depolarizing effects of the BBA could be observed. The strong contrast between the aerosol conditions in the dry season and the wet season were confirmed by the statistical analysis of all lidar observations in 2008. Due to the high BBA concentration in the atmosphere, the mean AOD of the dry season was found to be a factor of 3 higher than the mean AOD of the wet season (0.26 compared to 0.08 at 532 nm). Maximum AOD values were less than 0.55 (at 532 nm) and hence show that the lidar location was not in the direct vicinity of fire events. In only 7% of all cases in the dry season 2008, an AOD below 0.1 was observed. Also the maximum extinction and backscatter coefficient values in the dry season 2008 were 2-3 times higher than during the wet season of this year. The vertical aerosol distributions differ also significantly between the two seasons. In the wet season, the aerosol was mostly trapped in the lowermost 2.5 km, while in the dry season aerosol typically reached up to 4.5 km. Aerosol was occasionally detected up to 6.14 km in the dry season. The majority of the aerosol (95% of the AOD), however, was found to be on average below 2.3 km in the wet season and below 3 km in the dry season. During the wet season, lofted aerosol layers and multiple aerosol stratification was less frequent than in the dry season. The extent of BBA plumes during the dry season showed no correlation to the ML top height. Virtually uniform smoke haze layers were observed up to the AL top. Thus, pyro-convection and/or cloud-related mixing seem to be the major processes for the vertical distribution of BBA.

Earth's radiation budget is directly influenced by aerosols through the absorption of solar radiation and subsequent heating of the atmosphere. Aerosols modulate the hydrological cycle indirectly by modifying cloud properties, precipitation and ocean heat storage. In addition, polluting aerosols impose health risks in local, regional and global scales. In spite of recent advances in the study of aerosols variability, uncertainty in their spatial and temporal distributions still presents a challenge in the understanding of climate variability. For example, aerosol loading varies not only from year to year but also on higher frequency intraseasonal time scales producing strong variability on local and regional scales. An assessment of the impact of aerosol variability requires long period measurements of aerosols at both regional and global scales. The present dissertation compiles a large database of remotely sensed aerosol loading in order to analyze its spatio-temporal variability, and how this load interacts with different variables that characterize the dynamic and thermodynamic states of the environment. Aerosol Index (AI) and Aerosol Optical Depth (AOD) were used as measures of the atmospheric aerosol load. In addition, atmospheric and oceanic satellite observations, and reanalysis datasets is used in the analysis to investigate aerosol-environment interactions. A diagnostic study is conducted to produce global and regional aerosol satellite climatologies, and to analyze and compare the validity of aerosol retrievals. We find similarities and differences between the aerosol distributions over various regions of the globe when comparing the different satellite retrievals. A nonparametric approach is also used to examine the spatial distribution of the recent trends in aerosol concentration. A significant positive trend was found over the Middle East, Arabian Sea and South Asian regions strongly influenced by increases in dust events. Spectral and composite analyses of surface temperature, atmospheric wind, geopotential height, outgoing longwave radiation, water vapor and precipitation together with the climatology of aerosols provide insight on how the variables interact. Different modes of variability, especially in intraseasonal time scales appear as strong modulators of the aerosol distribution. In particular, we investigate how two modes of variability related to the westward propagating synoptic African Easterly Waves of the Tropical Atlantic Ocean affect the horizontal and vertical structure of the environment. The statistical significance of these two modes is tested with the use of two different spectral techniques. The pattern of propagation of aerosol load shows good correspondence with the progression of the atmospheric and oceanic synoptic conditions suitable for dust mobilization over the Atlantic Ocean. We present extensions to previous studies related with dust variability over the Atlantic region by evaluating the performance of the long period satellite aerosol retrievals in determining modes of aerosol variability. Results of the covariability between aerosols-environment motivate the use of statistical regression models to test the significance of the forecasting skill of daily AOD time series. The regression models are calibrated using atmospheric variables as predictors from the reanalysis variables. The results show poor forecasting skill with significant error growing after the 3rd day of the prediction. It is hypothesized that the simplicity of linear models results in an inability to provide a useful forecast.

Recent research has shown that secondary organic aerosols (SOA) are major contributors to ultrafine particle growth to climatically relevant sizes, increasing global cloud condensation nuclei (CCN) concentrations within the continental boundary layer (BL). This thesis contains two separate studies investigating SOA characteristics and the implications of SOA on global climate. The first study investigates two critical, but uncertain, characteristics of SOA: (1) the amount of SOA available to condense and (2) the volatility or condensational behavior of SOA. The second study investigates the effect of biological volatile organic compound (BVOC) emission changes on SOA formation from preindustrial to present day, and the effect on CCN concentrations using BVOC emission estimates over the last millennium.

Disertacija skirta smulkiosios aerozolio dalelių frakcijos šaltinių, fizikinių ir cheminių savybių įvertinimui kompleksiškai apjungiant įvairius tyrimo metodus. Darbe susieti elementinės ir organinės anglies koncentracijų pokyčiai su tolimąja oro masių pernaša, įvertinta regiono bei vietinių šaltinių įtaka bendrai aerozolio dalelių taršai. Aprašyti anglies turinčių aerozolio dalelių pasiskirstymai pagal dydį foninėse vietovėse ir miesto aplinkoje. Naudojant aerozolio masių spektrometrą Preilos atmosferos užterštumo tyrimų stotyje buvo identifikuotas biogeninis organinių medžiagų šaltinis, kuris vidutiniškai sudaro 15 % nuo organinių medžiagų masės, tačiau Šiaurės Atlanto oro masėje biogeninių medžiagų indėlis siekia net 50 %. Atlikus kompleksinę aerozolio ir stabiliųjų anglies izotopų masių spektrometrinę analizę buvo nustatyta, kad pirminis anglies turinčio aerozolio dalelių šaltinis mieste yra autotransportas, o Rūgšteliškio foninėje vietovėje – biomasės deginimas. Taip pat buvo nustatyta, kad Vilniuje dominavo antropogeninės antrinės organinės medžiagos (76 %), o Rūgšteliškyje vyravo biogeninės antrinės organinės medžiagos (apie 50%). Vertinant tolimosios oro masių pernašos įtaką vietinės kilmės aerozolio dalelių formavimuisi ir kaitai, buvo nustatyta, kad vulkaninės kilmės aerozolio dalelės turi įtakos submikroninės aerozolio dalelių frakcijos koncentracijai, cheminei sudėčiai ir pasiskirstymui pagal dydį. / The objective of the work was to investigate physical and chemical properties and sources of the atmospheric aerosol particles in the submicron fraction by combining different analytical techniques. The dependence of concentrations of organic and elemental carbon in different air masses was determined and the contribution of regional and local sources to the net aerosol particle pollution was estimated. Analysis of the size distribution of carbonaceous aerosol particles in background and urban areas was performed. Biogenic organic aerosol made up 15 % of the organic aerosol mass at the Preila atmospheric pollution research station, but in the North Atlantic air masses this factor was up to 50 %. Aerosol and stable isotope ratio mass spectrometry has revealed that traffic is the primary source of aerosol particles in the city, while biomass burning is the primary source at the Rūgšteliškis background station. It was determined that secondary anthropogenic organic compounds were dominating (76 %) in Vilnius, while in Rūgšteliškis secondary biogenic organic compounds made up 50 % of the total organic aerosol mass. The influence of the long-range air mass transport on the local origin aerosol particle formation and transformation has been evaluated and it has been shown that volcanic aerosol particles can significantly change the concentration, chemical composition and size distribution of local aerosol particles in the submicron range.

The objective of the work was to investigate physical and chemical properties and sources of the atmospheric aerosol particles in the submicron fraction by combining different analytical techniques. The dependence of concentrations of organic and elemental carbon in different air masses was determined and the contribution of regional and local sources to the net aerosol particle pollution was estimated. Analysis of the size distribution of carbonaceous aerosol particles in background and urban areas was performed. Biogenic organic aerosol made up 15 % of the organic aerosol mass at the Preila atmospheric pollution research station, but in the North Atlantic air masses this factor was up to 50 %. Aerosol and stable isotope ratio mass spectrometry has revealed that traffic is the primary source of aerosol particles in the city, while biomass burning is the primary source at the Rūgšteliškis background station. It was determined that secondary anthropogenic organic compounds were dominating (76 %) in Vilnius, while in Rūgšteliškis secondary biogenic organic compounds made up 50 % of the total organic aerosol mass. The influence of the long-range air mass transport on the local origin aerosol particle formation and transformation has been evaluated and it has been shown that volcanic aerosol particles can significantly change the concentration, chemical composition and size distribution of local aerosol particles in the submicron range. / Disertacija skirta smulkiosios aerozolio dalelių frakcijos šaltinių, fizikinių ir cheminių savybių įvertinimui kompleksiškai apjungiant įvairius tyrimo metodus. Darbe susieti elementinės ir organinės anglies koncentracijų pokyčiai su tolimąja oro masių pernaša, įvertinta regiono bei vietinių šaltinių įtaka bendrai aerozolio dalelių taršai. Aprašyti anglies turinčių aerozolio dalelių pasiskirstymai pagal dydį foninėse vietovėse ir miesto aplinkoje. Naudojant aerozolio masių spektrometrą Preilos atmosferos užterštumo tyrimų stotyje buvo identifikuotas biogeninis organinių medžiagų šaltinis, kuris vidutiniškai sudaro 15 % nuo organinių medžiagų masės, tačiau Šiaurės Atlanto oro masėje biogeninių medžiagų indėlis siekia net 50 %. Atlikus kompleksinę aerozolio ir stabiliųjų anglies izotopų masių spektrometrinę analizę buvo nustatyta, kad pirminis anglies turinčio aerozolio dalelių šaltinis mieste yra autotransportas, o Rūgšteliškio foninėje vietovėje – biomasės deginimas. Taip pat buvo nustatyta, kad Vilniuje dominavo antropogeninės antrinės organinės medžiagos (76 %), o Rūgšteliškyje vyravo biogeninės antrinės organinės medžiagos (apie 50%). Vertinant tolimosios oro masių pernašos įtaką vietinės kilmės aerozolio dalelių formavimuisi ir kaitai, buvo nustatyta, kad vulkaninės kilmės aerozolio dalelės turi įtakos submikroninės aerozolio dalelių frakcijos koncentracijai, cheminei sudėčiai ir pasiskirstymui pagal dydį.