Optical and geometrical properties of cirrus clouds in Amazonia derived from 1 year of ground-based lidar measurements

Cirrus clouds cover a large fraction of tropical latitudes and play an important role in Earth's radiation budget. Their optical properties, altitude, vertical and horizontal coverage control their radiative forcing, and hence detailed cirrus measurements at different geographical locations are of utmost importance. Studies reporting cirrus properties over tropical rain forests like the Amazon, however, are scarce. Studies with satellite profilers do not give information on the diurnal cycle, and the satellite imagers do not report on the cloud vertical structure. At the same time, ground-based lidar studies are restricted to a few case studies. In this paper, we derive the first comprehensive statistics of optical and geometrical properties of upper-tropospheric cirrus clouds in Amazonia. We used 1 year (July 2011 to June 2012) of ground-based lidar atmospheric observations north of Manaus, Brazil. This dataset was processed by an automatic cloud detection and optical properties retrieval algorithm. Uppertropospheric cirrus clouds were observed more frequently than reported previously for tropical regions. The frequency of occurrence was found to be as high as 88% during the wet season and not lower than 50% during the dry season. The diurnal cycle shows a minimum around local noon and maximum during late afternoon, associated with the diurnal cycle of precipitation. The mean values of cirrus cloud top and base heights, cloud thickness, and cloud optical depth were 14.3 +/- 1.9 (SD) km, 12.9 +/- 2.2 km, 1.4 +/- 1.1 km, and 0.25 +/- 0.46, respectively. Cirrus clouds were found at tem-peratures down to 90 degrees C. Frequently cirrus were observed within the tropical tropopause layer (TTL), which are likely associated to slow mesoscale uplifting or to the remnants of overshooting convection. The vertical distribution was not uniform, and thin and subvisible cirrus occurred more frequently closer to the tropopause. The mean lidar ratio was 23.3 +/- 8.0 sr. However, for subvisible cirrus clouds a bimodal distribution with a secondary peak at about 44 sr was found suggesting a mixed composition. A dependence of the lidar ratio with cloud temperature (altitude) was not found, indicating that the clouds are vertically well mixed. The frequency of occurrence of cirrus clouds classified as subvisible (tau 0 : 3). Hence, in central Amazonia not only a high frequency of cirrus clouds occurs, but also a large fraction of subvisible cirrus clouds. This high frequency of subvisible cirrus clouds may contaminate aerosol optical depth measured by sun photometers and satellite sensors to an unknown extent.CNPq fellowship programCAPES project on the program Science without FrontiersSAVERNET projectFAPESP Research Program on Global Climate ChangeUniv Sao Paulo, Inst Phys, Dept Appl Phys, Sao Paulo, SP, BrazilMeteorol Inst Cuba, Atmospher Opt Grp Camaguey, Camaguey, CubaUniv Magallanes, Atmospher Res Lab, Punta Arenas, ChileLeibniz Inst Tropospher Res TROPOS, Leipzig, GermanyUniv Fed Sao Paulo, Dept Environm Sci, Diadema, SP, BrazilUniv Fed Sao Paulo, Dept Environm Sci, Diadema, SP, BrazilCAPES: A016_2013FAPESP Research Program on Global Climate Change: 2008/58100-1FAPESP Research Program on Global Climate Change: 2009/15235-8FAPESP Research Program on Global Climate Change: 2012/16100-1FAPESP Research Program on Global Climate Change: 2013/50510-5FAPESP Research Program on Global Climate Change: 2013/05014-0Web of Scienc

A permanent Raman lidar station in the Amazon: description, characterization, and first results

A permanent UV Raman lidar station, designed to perform continuous measurements of aerosols and water vapor and aiming to study and monitor the atmosphere from weather to climatic time scales, became operational in the central Amazon in July 2011. the automated data acquisition and internet monitoring enabled extended hours of daily measurements when compared to a manually operated instrument. This paper gives a technical description of the system, presents its experimental characterization and the algorithms used for obtaining the aerosol optical properties and identifying the cloud layers. Data from one week of measurements during the dry season of 2011 were analyzed as a mean to assess the overall system capability and performance. Both Klett and Raman inversions were successfully applied. A comparison of the aerosol optical depth from the lidar and from a co-located Aerosol Robotic Network (AERONET) sun photometer showed a correlation coefficient of 0.86. By combining nighttime measurements of the aerosol lidar ratio (50-65 sr), back-trajectory calculations and fire spots observed from satellites, we showed that observed particles originated from biomass burning. Cirrus clouds were observed in 60% of our measurements. Most of the time they were distributed into three layers between 11.5 and 13.4 km a. g. l. the systematic and long-term measurements being made by this new scientific facility have the potential to significantly improve our understanding of the climatic implications of the anthropogenic changes in aerosol concentrations over the pristine Amazonia.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Instituto Nacional de Ciencia e Tecnologia (INCT) - Mudancas ClimaticasConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Univ São Paulo, Inst Fis, BR-05508090 São Paulo, BrazilInst Meteorol Cuba, Ctr Meteorol Camaguey, Matanzas, CubaUNIFESP, Dept Ciencias Exatas & Terra, Diadema, SP, BrazilInst Nacl de Pesquisas da Amazonia, Manaus, AM, BrazilUniv Estado Amazonas, Manaus, AM, BrazilInst Fed Educ Ciencia & Tecnol São Paulo, São Paulo, BrazilUNIFESP, Dept Ciencias Exatas & Terra, Diadema, SP, BrazilFAPESP: 2008/58100-1FAPESP: 2009/15235-8FAPESP: 2011/50170-4FAPESP: 2012/14437-9FAPESP: 2012/16100-1CNPq: 477575/2008-0CNPq: 475735/2012-9CNPq: 457843/2013-6Web of Scienc

The influence that different urban development models has on PM2.5 elemental and bioaccessible profiles

Limited studies have reported on in-vitro analysis of PM2.5 but as far as the authors are aware, bioaccessibility of PM2.5 in artificial lysosomal fluid (ALF) has not been linked to urban development models before. The Brazilian cities Manaus (Amazon) and Curitiba (South region) have different geographical locations, climates, and urban development strategies. Manaus drives its industrialization using the free trade zone policy and Curitiba adopted a services centered economy driven by sustainability. Therefore, these two cities were used to illustrate the influence that these different models have on PM2.5 in vitro profile. We compared PM2.5 mass concentrations and the average total elemental and bioaccessible profiles for Cu, Cr, Mn, and Pb. The total average elemental concentrations followed Mn > Pb > Cu > Cr in Manaus and Pb > Mn > Cu > Cr in Curitiba. Mn had the lowest solubility while Cu showed the highest bioaccessibility (100%) and was significantly higher in Curitiba than Manaus. Cr and Pb had higher bioaccessibility in Manaus than Curitiba. Despite similar mass concentrations, the public health risk in Manaus was higher than in Curitiba indicating that the free trade zone had a profound effect on the emission levels and sources of airborne PM. These findings illustrate the importance of adopting sustainable air quality strategies in urban planning

An overview of the first decade of PollyNET: An emerging network of automated Raman-polarization lidars for continuous aerosol profiling

A global vertically resolved aerosol data set covering more than 10 years of observations at more than 20 measurement sites distributed from 63° N to 52° S and 72° W to 124° E has been achieved within the Raman and polarization lidar network PollyNET. This network consists of portable, remote-controlled multiwavelength-polarization-Raman lidars (Polly) for automated and continuous 24/7 observations of clouds and aerosols. PollyNET is an independent, voluntary, and scientific network. All Polly lidars feature a standardized instrument design with different capabilities ranging from single wavelength to multiwavelength systems, and now apply unified calibration, quality control, and data analysis. The observations are processed in near-real time without manual intervention, and are presented online at http://polly.tropos.de/. The paper gives an overview of the observations on four continents and two research vessels obtained with eight Polly systems. The specific aerosol types at these locations (mineral dust, smoke, dust-smoke and other dusty mixtures, urban haze, and volcanic ash) are identified by their Ångström exponent, lidar ratio, and depolarization ratio. The vertical aerosol distribution at the PollyNET locations is discussed on the basis of more than 55 000 automatically retrieved 30 min particle backscatter coefficient profiles at 532 nm as this operating wavelength is available for all Polly lidar systems. A seasonal analysis of measurements at selected sites revealed typical and extraordinary aerosol conditions as well as seasonal differences. These studies show the potential of PollyNET to support the establishment of a global aerosol climatology that covers the entire troposphere

Soluble iron nutrients in Saharan dust over the central Amazon rainforest

The intercontinental transport of aerosols from the Sahara desert plays a significant role in nutrient cycles in the Amazon rainforest, since it carries many types of minerals to these otherwise low-fertility lands. Iron is one of the micronutrients essential for plant growth, and its long-range transport might be an important source for the iron-limited Amazon rainforest. This study assesses the bioavailability of iron Fe(II) and Fe(III) in the particulate matter over the Amazon forest, which was transported from the Sahara desert (for the sake of our discussion, this term also includes the Sahel region). The sampling campaign was carried out above and below the forest canopy at the ATTO site (Amazon Tall Tower Observatory), a near-pristine area in the central Amazon Basin, from March to April 2015. Measurements reached peak concentrations for soluble Fe(III) (48 ng m−3), Fe(II) (16 ng m−3), Na (470 ng m−3), Ca (194 ng m−3), K (65 ng m−3), and Mg (89 ng m−3) during a time period of dust transport from the Sahara, as confirmed by ground-based and satellite remote sensing data and air mass backward trajectories. Dust sampled above the Amazon canopy included primary biological aerosols and other coarse particles up to 12 µm in diameter. Atmospheric transport of weathered Saharan dust, followed by surface deposition, resulted in substantial iron bioavailability across the rainforest canopy. The seasonal deposition of dust, rich in soluble iron, and other minerals is likely to assist both bacteria and fungi within the topsoil and on canopy surfaces, and especially benefit highly bioabsorbent species. In this scenario, Saharan dust can provide essential macronutrients and micronutrients to plant roots, and also directly to plant leaves. The influence of this input on the ecology of the forest canopy and topsoil is discussed, and we argue that this influence would likely be different from that of nutrients from the weathered Amazon bedrock, which otherwise provides the main source of soluble mineral nutrients

Auto calibration and determination of matrices covariance measurements of energy in gamma spectroscopy.

Foram medidas as energias de 21 transições gama dos nuclídeos 57Co,60Co, 133Ba, 137Cs e 192Ir, utilizando um detetor HPGe de 75cm3. Na análise dos dados foi aplicado o procedimento de auto calibração,baseado no Método dos Mínimos Quadrados, no qual as informações experimentais e dos dados de entrada são incluídas em um único passo. Como conseqüência do procedimento estatístico adotado, foi possível atualizar os valores de 309 outras transições gama não medidas, mas covariantes com aquelas que foram medidas, bem como de sua matriz de covariância. Assim, certas transições tiveram redução de variâncias superiores a 80% em relação aos dados então disponíveis na bibliografia e 50% em relação aos dados reanalisados considerando toda a matriz de covariância.We measured 21 gamma-ray energies from 57Co, 60Co, 133Ba, 137Cs and 192Ir decay, with a 75 cm3 HPGe detector. The data analysis was performed usin a self calibration procedure, based on the Least Square Method, where experimental and input data are included in a single step. As result of this statistical procedure, 309 other gamma-ray energies not measured, but covariant with the measured ones, as well the covariance matrix were updated. Some transitions got a variance reduction over than 80% when compared with the bibliography, and of 50% when compared with the reanalyzed data that consider all the covariance matrix

Effect of biomass-burning emitted aerosols on cloud droplets formation and rainwater chemistry in the Amazon Basin

Este trabalho teve como objetivo investigar a relação entre produtos de atividades antropogênicas na Amazônia e sua influência no efeito indireto dos aerossóis no clima. Para isso, foi feita uma caracterização físico-química detalhada dos aerossóis naturais e de queimadas na Amazônia e procurou-se compreender como estes diferentes tipos de aerossóis se comportam como Núcleos de Condensação de Nuvens. Foi estudado também a influência dos aerossóis de queimadas na composição química da precipitação e no transporte de nutrientes. Visando atingir estes objetivos, foram feitas medidas em regiões distintas da Amazônia com relação ao impacto por atividades antropogênicas, principalmente queimadas. Foi possível observar em várias circunstâncias uma relação entre a composição do material particulado e da precipitação, o que nos permitiu concluir que as emissões antropogênicas influenciam significativamente a composição da precipitação. Foram identificadas as principais componentes que afetam a composição do material particulado em suspensão na Amazônia, e concluimos que o material particulado originado de emissões biogênicas é predominante em regiões preservadas, com pequena contribuição também de poeira de solo e transporte de aerossóis marinhos. Em regiões sob influência de atividades antropogênicas, observou-se que a composição dos aerossóis e da precipitação é afetada mesmo na estação úmida. No estudo das propriedades físicas e químicas das partículas de aerossol que são relevantes para o seu papel como Núcleos de Condensação de Nuvens, concluiu-se que a distribuição de tamanho é mais importante do que a composição química das partículas, devido ao fato das emissões de novas partículas por queimadas ocorrer predominantemente acima do diâmetro seco de ativação. A composição química só foi importante em valores de supersaturação baixos (< 0.2%), o que significa que esse efeito pode ser importante para nuvens estratiformes, onde o valor máximo de supersaturação é baixo, devido a baixa velocidade de ascensão das parcelas. A exportação de nutrientes devido ao transporte em larga escala de aerossóis de emissões de queimadas se mostrou particularmente crítica com relação às quantidades de fósforo que estão sendo perdidas irreversivelmente pela floresta amazônica, que foi cerca de 7 vezes maior do que a quantidade reposta por deposição úmida. Essa perda de fósforo pode ser crítica para o ecossistema em longo prazo.The main objective of this study was to investigate the relationship between anthropogenic emissions in the Amazon basin and the indirect aerosol effect on climate. A detailed study of physical and chemical properties of natural and biomass burning aerosols was conducted, in order to understand how these completely different aerosols behave as Cloud Condensation Nuclei (CCN). It was also investigated the influence of biomass burning aerosols in chemical composition of precipitation, and transport of nutrients. The measurements were carried out in completely different regions respect to the impact of anthropogenic activities, especially biomass burning emissions. The analysis of aerosols and rainwater chemistry showed that anthropogenic emissions have a significant influence in the composition of precipitation. Factor analysis was applied to perform source identification, and the conclusion is that at remote and free of anthropogenic emission areas, the most important contribution was from biogenic emissions, with a small contribution of soil dust and marine aerosols advection. It was quite different at regions under influence of anthropogenic activities, where measurements showed a clear anthropogenic influence even during wet season both in aerosols and precipitation chemistry. In the study of hygroscopic properties of aerosol particles, the main conclusion was that size distribution of particles is the most important parameter to determine the ability of aerosols to act as CCN, because most of biomass burning emission are particles bigger than the activation diameter. Chemical composition was an important factor only if supersaturation is below 0.2%, because in this supersaturation range the activation diameter is extremely sensible to small changes in supersaturation. Transport of nutrients due to largescale transport of biomass burning aerosols was specially critical concerning phosphorus exportation, estimated as 7 times the apportionment through wet deposition. Continuous exportation of phosphorus can be a long term limitation to the forest ecosystem, if biomass burning activity maintain its present levels

Auto calibration and determination of matrices covariance measurements of energy in gamma spectroscopy.

Foram medidas as energias de 21 transições gama dos nuclídeos 57Co,60Co, 133Ba, 137Cs e 192Ir, utilizando um detetor HPGe de 75cm3. Na análise dos dados foi aplicado o procedimento de auto calibração,baseado no Método dos Mínimos Quadrados, no qual as informações experimentais e dos dados de entrada são incluídas em um único passo. Como conseqüência do procedimento estatístico adotado, foi possível atualizar os valores de 309 outras transições gama não medidas, mas covariantes com aquelas que foram medidas, bem como de sua matriz de covariância. Assim, certas transições tiveram redução de variâncias superiores a 80% em relação aos dados então disponíveis na bibliografia e 50% em relação aos dados reanalisados considerando toda a matriz de covariância.We measured 21 gamma-ray energies from 57Co, 60Co, 133Ba, 137Cs and 192Ir decay, with a 75 cm3 HPGe detector. The data analysis was performed usin a self calibration procedure, based on the Least Square Method, where experimental and input data are included in a single step. As result of this statistical procedure, 309 other gamma-ray energies not measured, but covariant with the measured ones, as well the covariance matrix were updated. Some transitions got a variance reduction over than 80% when compared with the bibliography, and of 50% when compared with the reanalyzed data that consider all the covariance matrix