Measurement report: An exploratory study of fluorescence and cloud condensation nuclei activity of urban aerosols in San Juan, Puerto Rico

Many atmospheric aerosols are cloud condensation nuclei (CCN), capable of activating as cloud droplets when the relative humidity exceeds 100 %. Some primary biological aerosol particles (PBAPs), such as plant spores, pollen, or bacteria, have been identified as such CCN. Urban environments are a source of these bioaerosols, some of which are naturally produced by the local flora or are transported from surrounding regions and others of which are a result of human activities. In the latter case, open sewage, uncovered garbage, mold or other products of such activities can be a source of PBAPs. There have been relatively few studies, especially in the tropics, where PBAPs and CCN have been simultaneously studied to establish a causal link between the two. The metropolis of San Juan, Puerto Rico, is one such urban area with a population of 2 448 000 people (as of 2020). To better understand the fluorescent characteristics and cloud-forming efficiency of aerosols in this region, measurements with a wideband integrated bioaerosol spectrometer (WIBS), a condensation nuclei (CN) counter and a CCN spectrometer were made at the University of Puerto Rico – Río Piedras Campus. Results show that the CCN / CN activation ratio and the fraction of fluorescing aerosol particles (FAPs) have repetitive daily trends when the FAP fraction is positively correlated with relative humidity and negatively correlated with wind speed, consistent with previous studies of fungi spores collected on substrates. The results from this pilot study highlight the capabilities of ultraviolet-induced fluorescence (UV-IF) measurements for characterizing the properties of FAPs as they relate to the daily evolution of PBAPs. The use of multiple excitation and emission wavelengths, along with shape detection, allows the differentiation of different PBAP types. These measurements, evaluated with respect to previous, substrate-based analysis of the local fungal and pollen spores, have established a preliminary database of measurements that future, longer-term studies will build upon.</p

Optical and physical properties of aerosols in the boundary layer and free troposphere over the Amazon Basin during the biomass burning season

As part of the Large Scale Biosphere-Atmosphere Experiment in Amazonia &ndash; Smoke, Aerosols, Clouds, Rainfall and Climate (LBA-SMOCC) campaign, detailed surface and airborne aerosol measurements were performed over the Amazon Basin during the dry to wet season from 16 September to 14 November 2002. Optical and physical properties of aerosols at the surface, and in the boundary layer (BL) and free troposphere (FT) during the dry season are discussed in this article. Carbon monoxide (CO) is used as a tracer for biomass burning emissions. At the surface, good correlation among the light scattering coefficient (&sigma;_<i>s</i> at 545 nm), PM2.5, and CO indicates that biomass burning is the main source of aerosols. Accumulation of haze during some of the large-scale biomass burning events led to high PM2.5 (225 &mu;g m^&minus;3), &sigma;_<i>s</i> (1435 Mm^&minus;1), aerosol optical depth at 500 nm (3.0), and CO (3000 ppb). A few rainy episodes reduced the PM2.5, number concentration (CN) and CO concentration by two orders of magnitude. The correlation analysis between &sigma;_<i>s</i> and aerosol optical thickness shows that most of the optically active aerosols are confined to a layer with a scale height of 1617 m during the burning season. This is confirmed by aircraft profiles. The average mass scattering and absorption efficiencies (545 nm) for small particles (diameter D_<i>p</i><1.5 &mu;m) at surface level are found to be 5.0 and 0.33 m² g^&minus;1, respectively, when relating the aerosol optical properties to PM2.5 aerosols. The observed mean single scattering albedo (&omega;_<i>o</i> at 545 nm) for submicron aerosols at the surface is 0.92&plusmn;0.02. The light scattering by particles (&Delta;&sigma;_<i>s</i>/&Delta; CN) increase 2&ndash;10 times from the surface to the FT, most probably due to the combined affects of coagulation and condensation

A qualidade da informação financeira previsional como instrumento de avaliação do pressuposto da continuidade: o caso das empresas municipais

Mestrado em AuditoriaCom a crise e com os escândalos financeiros nos últimos anos, tem-se assistido à falência de várias empresas em todo o mundo, o que tem gerado grande insegurança nos mercados, afetando a tomada de decisões por parte dos diversos stakeholders, que têm por base as informações financeiras divulgadas pelas empresas. Consequentemente, o papel do auditor foi também bastante afetado com os escândalos que surgiram, o que gerou grande desconfiança por parte dos stakeholders, tendo as grandes organizações mundiais tomado medidas e criado mecanismos e controlos mais incisivos para colmatar esta desconfiança, por forma a aumentar a importância de um dos principais pressupostos da contabilidade: o princípio da continuidade. Neste contexto, “A qualidade da informação financeira previsional como instrumento de avaliação do pressuposto da continuidade: o caso das empresas municipais” vem mostrar a importância da divulgação da informação financeira previsional (IFP), como esta pode ser útil para a tomada de decisão e para o trabalho do auditor. O estudo centra-se em bibliografia emitida pelas grandes organizações internacionais e nacionais na área da auditoria e contabilidade, quer em sítios da Internet, como em publicações de artigos académicos e de outros autores especialistas na área, e num estudo baseado na informação financeira divulgada pelas empresas municipais, do qual deriva o fundamento empírico da dissertação. A metodologia baseia-se na análise documental, mais concretamente na comparação entre a informação financeira previsional e a informação financeira histórica recolhida dos vários sítios das empresas municipais. Embora não se consiga extrapolar uma conclusão que cubra todo o universo do estudo, concluiu-se, que na sua maioria, as previsões efetuadas não diferem muito da realidade, o que denota que esta é uma informação que pode ser bastante útil, permitindo assim antecipar cenários com maior precisão e dar um maior apoio à tomada de decisão dos diversos stakeholders.Due to crisis and financial scandals in recent years, several companies in the world have bankrupted. This situation has generated high uncertainty in the markets, affecting decision-making by the different stakeholders, which are based on the financial information disclosed by the companies. Consequently the auditor's role was also quite affected with those emerged scandals, which generated great distrust from stakeholders. Thus, major world organizations took action and created mechanisms and more incisive controls to overcome this distrust in order to increase importance of the key assumptions of accounting: Going Concern. In this context, "Prospective financial information quality as a basic tool for the evaluation of going concern: the case of municipal companies" is going to show the importance of disclosure of prospective financial information, as this can be useful for decision-making and for auditor. The study focuses on literature issued by major international and national organizations in the field of auditing and accounting, websites, academic articles and publications from other expert authors in this field, and in a study based on the financial information disclosed by municipal companies, which the empirical basis of the dissertation is from. The methodology is based on document analysis, specifically in real-provided comparison of financial information collected from different sites of the municipal companies. Although we can not extrapolate a conclusion that cover all universe of the study, it was concluded that the majority of the forecasts made do not differ much from reality, which indicates that this information can be very useful, allowing to anticipate scenarios with greater accuracy and increased support to the different decision-making stakeholders

Clouds and aerosols in Puerto Rico ─ a new evaluation

The influence of aerosols, both natural and anthropogenic, remains a major area of uncertainty when predicting the properties and behaviour of clouds and their influence on climate. In an attempt to better understand warm cloud formation in a tropical marine environment, a period of intensive measurements took place in December 2004 in Puerto Rico, using some of the latest developments in online instrumentation such as aerosol mass spectrometers, cloud condensation nuclei counters and a hygroscopicity tandem differential mobility analyser. Simultaneous online measurements of aerosol size distributions, composition, hygroscopicity and optical properties were made near the lighthouse of Cape San Juan in the north-eastern corner of the island and at the top of East Peak mountain (1040 m a.s.l.), the two sites separated by 17 km. Additional measurements of the cloud droplet residual and interstitial aerosol properties were made at the mountain site, accompanied by measurements of cloud droplet size distributions, liquid water content and the chemical composition of cloud and rain water samples. <br><br> Both aerosol composition and cloud properties were found to be sensitive to wind sector. Air from the east-northeast (ENE) was mostly free of anthropogenic influences, the submicron fraction being mainly composed of non-sea salt sulphate, while that from the east-southeast (ESE) was found to be moderately influenced by populated islands upwind, adding smaller (&lt;100 nm), externally mixed, carbonaceous particles to the aerosol that increased the number concentrations by over a factor of 3. This change in composition was also accompanied with a reduction in the measured hygroscopicity and fractional cloud activation potential of the aerosol. At the mountain site, the average cloud droplet concentrations increased from 193 to 519 cm^&minus;3, median volume diameter decreased from 20 to 14 μm and the liquid water content increased from 0.24 to 0.31 g m^&minus;3 when the winds shifted from the ENE to ESE. Larger numbers of interstitial particles were recorded, most notably at sizes greater than 100 nm, which were absent during clean conditions. The average size of the residual particles and concentrations of cloudwater nitrate, sulphate and insoluble material increased during polluted conditions. <br><br> Previous studies in Puerto Rico had reported the presence of a significant non-anthropogenic organic fraction in the aerosols measured and concluded that this was a factor controlling the in situ cloud properties. However, this was not observed in our case. In contrast to the 1.00&plusmn;0.14 μg m^&minus;3 of organic carbon measured in 1992 and 1995, the organic matter measured in the current study of 0.17&plusmn;0.35 μg m^&minus;3 is many times lower, most of which can be attributed to anthropogenic sources. During clean conditions, the submicron aerosol was observed to be almost entirely inorganic, an observation supported by the hygroscopicity measurements. This suggests that organic aerosols from marine sources may not be completely ubiquitous (either spatially or temporally) in this environment and requires further investigation to quantify their true extent and implications, with more extensive, longer-term sampling in conjunction with wind field analyses

Observation and modeling of the historic “Godzilla” African dust intrusion into the Caribbean Basin and the southern US in June 2020

This study characterizes a massive African dust intrusion into the Caribbean Basin and southern US in June 2020, which is nicknamed the “Godzilla” dust plume, using a comprehensive set of satellite and ground-based observations (including MODIS, CALIOP, SEVIRI, AERONET, and EPA Air Quality network) and the NASA GEOS global aerosol transport model. The MODIS data record registered this massive dust intrusion event as the most intense episode over the past 2 decades. During this event, the aerosol optical depth (AOD) observed by AERONET and MODIS peaked at 3.5 off the coast of West Africa and 1.8 in the Caribbean Basin. CALIOP observations show that the top of the dust plume reached altitudes of 6–8 km in West Africa and descended to about 4 km altitude over the Caribbean Basin and 2 km over the US Gulf of Mexico coast. The dust intrusion event degraded the air quality in Puerto Rico to a hazardous level, with maximum daily PM10 concentration of 453 µg m−3 recorded on 23 June. The dust intrusion into the US raised the PM2.5 concentration on 27 June to a level exceeding the EPA air quality standard in about 40 % of the stations in the southern US. Satellite observations reveal that dust emissions from convection-generated haboobs and other sources in West Africa were large albeit not extreme on a daily basis. However, the anomalous strength and northern shift of the North Atlantic Subtropical High (NASH) together with the Azores low formed a closed circulation pattern that allowed for accumulation of the dust near the African coast for about 4 d. When the NASH was weakened and wandered back to the south, the dust outflow region was dominated by a strong African easterly jet that rapidly transported the accumulated dust from the coastal region toward the Caribbean Basin, resulting in the record-breaking African dust intrusion. In comparison to satellite observations, the GEOS model reproduced the MODIS observed tracks of the meandering dust plume well as it was carried by the wind systems. However, the model substantially underestimated dust emissions from haboobs and did not lift up enough dust to the middle troposphere for ensuing long-range transport. Consequently, the model largely missed the satellite-observed elevated dust plume along the cross-ocean track and underestimated the dust intrusion into the Caribbean Basin by a factor of more than 4. Modeling improvements need to focus on developing more realistic representations of moist convection, haboobs, and the vertical transport of dust

Biogeography in the air: fungal diversity over land and oceans

Biogenic aerosols are relevant for the Earth system, climate, and public health on local, regional, and global scales. Up to now, however, little is known about the diversity and biogeography of airborne microorganisms. We present the first DNA-based analysis of airborne fungi on global scales, showing pronounced geographic patterns and boundaries. In particular we find that the ratio of species richness between Basidiomycota and Ascomycota is much higher in continental air than in marine air. This may be an important difference between the 'blue ocean' and 'green ocean' regimes in the formation of clouds and precipitation, for which fungal spores can act as nuclei. Our findings also suggest that air flow patterns and the global atmospheric circulation are important for the understanding of global changes in biodiversity.Max Planck Society (MPG)Max Planck Society (MPG)LEC Geocycles in MainzLEC Geocycles in Mainzstate Rheinland-Pfalz [596]state RheinlandPfalzGerman Research Foundation [DE1161/2-1, PO1013/5-1, FOR 1525 INUIT]German Research Foundatio