Atmósfera (Journal)
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Incremental excess of PM components and sources between two adjacent sites of Bogotá, Colombia
Get PDFAir pollution in towns adjacent to and downwind of large cities can be similar or even higher than in the city itself. In the case of towns constituting the greater Bogotá area, with more than half a million inhabitants and strong industrial activity, little is known about the factors that affect their poor air quality. This work investigated the incremental excess of the composition and source contribution to PM2.5 in two sites near Bogotá (Soacha: 4º35’4.59” N, 74º13’11.62” W; and Mosquera: 4º42’9.75” N, 74º13’54.94” W), using the Chemical Mass Balance receptor model with organic molecular markers, and back trajectory analysis. Simultaneous sample collection was carried out for two-months. Organic matter was the major component of the PM2.5 mass (66 ± 14% and 61 ± 12%), while secondary inorganic ions (sulfate, nitrate, and ammonium) constituted 13 ± 8 % and 10 ± 2 %. The main anthropogenic sources contributing to PM2.5 at Soacha were wood combustion (23%), diesel vehicles (19%), and coal combustion at small facilities (11%). At Mosquera, they were gasoline vehicles (26%), diesel vehicles (19%), and coal combustion at small inefficient facilities (15%). The contribution of regional secondary organic aerosol to PM2.5 was significant (19% and 15%), arriving mostly from the Orinoco basin but higher in air masses arriving from the Amazon rainforest. The regional contribution to secondary inorganic aerosols was higher with winds from the Magdalena Valley. The methods presented in this manuscript will be useful in other megacities and large cities to better manage impacts of local and regional air pollution sources
Atmospheric thermodynamics and dynamics during convective, stratiform and nonprecipitating clouds over the metropolitan area of Rio de Janeiro – Brazil
Get PDFPhysical mechanisms involved in the development and forecast of clouds and precipitation are both quite complex and dependent on the local atmospheric environment, especially when severe weather conditions are imminent. Research aimed at understanding the environmental mechanisms favorable to the different atmospheric scenarios can help operational weather forecasters to issue warnings. This paper provides qualitative and quantitative contributions from radiosondes, radar, and numerical simulations to evaluate the formation of convective, stratiform, and nonprecipitating clouds over the metropolitan area of Rio de Janeiro, Brazil. The convective available potential energy (CAPE) and lifted index (LI), showed higher values on convective days (CAPE = 2600 J.Kg–1 and LI = –4 ºC), followed by nonprecipitating (CAPE = 1500 J.Kg–1 and LI = –2 ºC) and stratiform cloud days (CAPE = 1400 J.Kg–1 and LI = –1.5 ºC). High wind convergence was observed at low- (1000–850 hPa) and mid- (850–700 hPa) levels on convective days (–16.5 s–1 and –9.6 s–1, respectively). In contrast, wind divergence at the same levels was observed on stratiform (6.4 s–1 and 6.9 s–1) and nonprecipitating (9.7 s–1 and 7.3 s–1) days. Higher wind divergence (8.3 s–1) was observed on convective days at upper levels (300–200 hPa) compared with stratiform (3.2 s–1) and nonprecipitating (2.8 s–1) days. Results show a coupling of wind convergence, moisture and energy in the lower troposphere and divergence at upper levels on convective days. Despite moisture availability on stratiform days and thermodynamic energy on nonprecipitating days, the respective coupling between these conditions and dynamic triggers was not observed
Vorticity and Thermodynamics in a Gulf of Mexico Atmospheric River
Get PDFThis paper examines the interaction of tropical moisture with an atmospheric river. The analysis of this paper is focused mainly on dropsonde data collected during the fifth day of the Convective Processes Experiment (CPEX). An area of interest is chosen over the central Gulf of Mexico, where the remnant moisture of the tropical system Beatriz penetrated from the Eastern Pacific after making landfall in the western coast of Mexi-co. Results in this study show an eastward-tilting pattern of enhanced mid-level vorticity, coupled with high saturation fraction and low instability index in the predominantly stratiform regime present in the region. An inverse relation between saturation fraction and instability index, as indicated by moisture quasi-equilibrium (MQE), is found in a previously-dominant convective regime. Strong vertical shear signals that the vorticity pattern within this stratiform system is being advected poleward into mid-latitudes. Poleward-moving moisture plumes in narrow channels called atmospheric rivers (ARs) are observed during the mission. We provide insights into vorticity and MQE as conceptual tools to characterize the moisture mechanism of atmospheric rivers near the tropics, where the physical processes behind these river-like structures are less well-understood
Evaluating the rate of atmospheric dust deposition in Isfahan city
Get PDFDust deposition occurs extensively in arid and semi-arid areas. Dust particles have a high adsorption capacity and therefore high pollution potential. The present study investigates seasonal and spatial variations in atmospheric dust deposition rate (DDR) and the concentration of dust-borne heavy metals in the eastern part of Isfahan as well as Segzi plain located in the central part of Iran. Dust samples were collected from nine different sites on a monthly basis from December 2016 to September 2017 using glass trays. The total concentrations of Pb and Zn were measured. The lowest concentrations of Pb with 16.95 ± 25.21 mg kg–1 and Zn with 2.34 ± 0.80 mg kg–1 were recorded. The lowest value of seasonal DDR (0.7 ± 0.1 ton km–2 season–1) was observed in the winter due to low amount of precipitation, and the highest value (40.8 ± 0.1 ton km–2 season–1) was recorded in the summer. Spatial distribution of dust-borne Pb and Zn followed almost the same trend and the highest concentrations were observed in the western parts of the study area. It seems that fossil fuel, traffic, and industrial activities are the most important anthropogenic factors contributing to dust-borne heavy metals in the study area
Synoptic patterns of South Atlantic Convergence Zone episodes associated with heavy rainfall events in the city of Rio de Janeiro, Brazil
Get PDFThe present study provides a synoptic characterization of South Atlantic Convergence Zone (SACZ) episodes that caused heavy rainfall events (HRE) in the city of Rio de Janeiro (CRJ) between 2006 and 2016. A total of 77 SACZ episodes were identified in the CRJ (SCRJ), which represented 81% of the total SACZ events in Brazil. At least one day of HRE during the SACZ period (SHRE) was found in 37 SCRJ episodes, representing almost half (48%) of the SACZ events in the CRJ. In 68.6% of these cases, the heavy rainfall occurred on the first two days of the SHRE period. The mean synoptic pattern of SHRE showed a cold front in the Atlantic Ocean connected with a low-pressure system located near the coast of Rio de Janeiro state (RJ). The 850 hPa specific humidity showed a dipole pattern with positive anomalies in southeastern Brazil and negative anomalies in southern Brazil since the day before the occurrence of SHRE. An anomalous upper-level ridge in southeastern Brazil was relevant to intensifying the heavy rainfall in the CRJ. The synoptic classification showed four main surface synoptic patterns associated with SHRE. The two most frequent patterns were associated with a cold front close to the coast of RJ, and the other two were related to the presence of an anticyclone with blocking characteristics and to the presence of a weak extratropical cyclone near the coast of RJ
Wavelet coherence between ENSO indices and two precipitation database for the Andes region of Colombia.
Get PDFThe influence of El Niño Southern Oscillation (ENSO) on Colombia's hydrological variables has been shown in different studies. Most of the methodologies implemented have identified linear relationships and have associated the warm (cold) phase called El Niño (La Niña) with negative (positive) rainfall and streamflow anomalies. One of the most adverse impacts founded is the reduction in water supply during the warm phase. Therefore, it is necessary to study the linkage between ENSO and precipitation variability for efficient management of water resources. Consequently, the present paper has two purposes. The first one is to explore nonlinear correlations of the ENSO-precipitation relationship, particularly for specific regions where the freshwater resources have been significantly reduced during El Niño events. The second one is to identify which indices will enable in improving the predictability of hydro-climatological variables. The research was based on the wavelet coherence analysis of monthly precipitation time series from 1981-2016 and the ENSO indices for the same period. The results show that ENSO events influence the precipitation as periods of rainfall deficit or excess. Also, precipitation is organized in bands and that the 2–8-year scales explain most of their variance. The most significant sectors are those that cover El Niño events. In contrast, sectors are smaller when La Niña episodes. Then impacts on precipitation tend to be greater for warm events. Results also allowed to identify that El Niño 3, Niño 3,4, ONI, and BEST indices can be good indicators for forecasting work in these specific places. The use of two kinds of data, one in situ and the other from CHIRPS program, allows to establish the feasibility of using data from satellite origin in regions without enough information; the results showed that CHIRPS data tend to report fewer anomalies than data in situ. However, the coherence structure is similar, but in periods between 36 and 48 months, there were discrepancies of pi/4 in the phase difference, that is, between 3 and 6 months of difference in lags calculated with each database
Thermodynamic analysis of convective events that occurred in Belém-PA city
Get PDFThe Amazon Basin is dominated by convective rainfall with significant spatial and diurnal variability. Diurnal and seasonal distributions of convective events were determined from rainfall and Cloud Top Temperature (CTT) between January 2008 and December 2010 in city Belém-PA. The decis technique was used to select the most intense events (rainfall rate ≥ 15 mm h–1), which were subsequently, subclassified into deep convection events (DCE) and shallow convection events (SCE). Ninety four cases were found, mostly occurring between 12 and 19 LT, and 55% in the rainy season. Another set of DCE and SCE with rainfall rate ≥ 1 mm h–1 was selected to analyze the effect of seasonality. Of these, 42 cases were found also between 12 and 19 LT, with a maximum at 16 LT. Temperature profiles differed between the rainy and less rainy seasons, in the intensification of shallow and deep convection. Moisture profiles showed greater variability between 850 and 500 hPa, indicative of their role in convective activity; during the rainy season the atmosphere was more humid (less humid) before (at the time) of the occurrence of DCE. Wind components showed significant shear between surface and ~850 hPa, with stronger zonal component in the cases of DCE. The highest values of CAPE were observed about 2 to 3 hours before DCE and SCE, with maximum values before DCE in the rainy season. Results presented here are relevant to improve short-term forecasts and convective event simulations with numerical weather and climate models
Prediction of atmospheric corrosion from meteorological parameters: Case of the atmospheric basin of the Costa Rican Western Central Valley
Get PDFThe assessment of atmospheric corrosion is currently based on the study of atmospheric basins (AB). Modeling atmospheric corrosion in many cases involves the measurement of several meteorological and atmospheric pollution parameters, specifically temperature, relative humidity, chloride, and sulfur dioxide, making the estimation process more complex. However, for the Western Central Valley (WCV) in Costa Rica, a low-pollution AB, it is possible to develop simplified atmospheric corrosion models based on a small number of atmospheric parameters. In this paper, the meteorological variables of the study region were analyzed in terms of their dependency on altitude and their applicability in the development of a simplified model to predict the corrosion rate (Vcorr). The output of the predictive model was compared with the standard model of ISO 9223:2012, showing a higher skill and giving reliable results for a wide interval of altitudes.
The negative impact of biomass burning and the Orinoco low-level jet on the air quality of the Orinoco River basin (edited by Dr. M. Grutter)
Get PDFBiomass burning (BB) is a common activity in developing countries and has been identified as a serious air pollution threat. The present work for the first time evaluates the air quality of the largest town in the extensive Colombian savannas (250,000 km2), from measurements over three consecutive years (2017-2020). Although the air quality in Villavicencio is good in terms of PM10 and O3 for most of the year, pollution levels for both pollutants exceed the World Health Organization recommended limits during the dry season (February to April). The combination of the Orinoco low-level jet (OLLJ) and BB emissions from the Venezuelan and the Colombian savannas was identified as the main cause of poor air quality episodes during the dry season in this city. Organic carbon derived from reanalysis was identified as the main component of the high PM10 concentrations during the dry season. However, mineral dust and sea salt particles were also found to play an important role in the poor air quality observed in Villavicencio and likely along the Orinoco river basin region. Finally, between November and March, the OLLJ was found to be an efficient mechanism for the transport of air pollutants from the Atlantic Ocean and the savanna regions in the Orinoco River Basin in Venezuela and Colombia towards southern regions of Colombia, and in some cases even reaching Ecuador
Quantification of greenhouse gas emissions of a steel factory in Brazil
Get PDFThis work aimed to identify and quantify greenhouse gases (GHG) emissions of a steel factory, considering the importance of these data in the context of large global GHG emissions. As a result, Scope 1 emissions were identified as the highest in the industry, representing more than 89% of total emissions in CO2eq. This scenario is mainly identified a result of the Brazilian energy matrix configuration, which contributes to reduce Scope 2 emissions. The used methodology (GHG Protocol v. 2018.1.4) proved to be appropriate for calculating emissions within a broader report (annual amount). However, in order to develop an indicator for the organization, with monthly detailed data, it was necessary to adapt the tool, which is the differential of this work