Distribution Of Carbon Monoxide Research Articles

Dual-agent intelligent fire detection method for large commercial spaces based on numerical databases and artificial intelligence

Fires in commercial buildings can lead to significant casualties and property damage. Thus, rapidly and accurately identifying the source of a fire and its intensity is crucial for guiding rescue operations. This study aims to explore the use of distributed fiber optic temperature sensing systems, combined with deep learning algorithms, to predict key information about fires in commercial buildings, including the location of the fire source, the intensity of fire development, and the critical planar distribution of carbon monoxide. Based on the Fire Dynamic Simulation (FDS) data, a dual-agent model was developed, and with a sensor sampling interval of 3 s, 30 s of historical data achieved prediction accuracies of 94.23 % for fire intensity and 99.28 % for fire location. Upon reducing the intervals for fire location, the accuracy reached 93.56 %. Additionally, the Random Forest algorithm for mapping carbon monoxide distribution demonstrated an overall Mean Absolute Percentage Error (MAPE) of 5.87 %. Within the 0–150 ppm range, the MAPE was 2.46 %, far below the error levels of existing CO sensors. The database configurations and the sensors' spatiotemporal arrangement were also optimized to rapid and reliable fire prediction. This research demonstrates the feasibility of using artificial intelligence for critical fire scene information detection.

Evidence of a dual African and Australian biomass burning influence on the vertical distribution of aerosol and carbon monoxide over the southwest Indian Ocean basin in early 2020

Abstract. During the 2020 austral summer, the pristine atmosphere of the southwest Indian Ocean (SWIO) basin experienced significant perturbations. This study examines the variability of aerosols and carbon monoxide (CO) over this remote oceanic region and investigates the underlying processes in the upper troposphere–lower stratosphere (UT-LS). Aerosol profiles in January and February 2020 revealed a multi-layer structure in the tropical UT-LS. Numerical models – the FLEXible PARTicle dispersion model (FLEXPART) and the Modèle Isentropique de transport Mésoéchelle de l'Ozone Stratosphérique par Advection (MIMOSA) – indicated that the lower-stratospheric aerosol content was influenced by the intense and persistent stratospheric aerosol layer generated during the 2019–2020 extreme Australian bushfire events. A portion of this layer was transported eastward by prevailing easterly winds, leading to increased aerosol extinction profiles over Réunion on 27 and 28 January. Analysis of advected potential vorticity revealed isentropic transport of air masses containing Australian biomass burning aerosols from extratropical latitudes to Réunion at the 400 K isentropic level on 28 January. Interestingly, we found that biomass burning (BB) activity in eastern Africa, though weak during this season, significantly influenced (contributed up to 90 % of) the vertical distribution of CO and aerosols in the upper troposphere over the SWIO basin. Ground-based observations at Réunion confirmed the simultaneous presence of African and Australian aerosol layers. This study provides the first evidence of African BB emissions impacting the CO and aerosol distribution in the upper troposphere over the SWIO basin during the convective season.

Probabilistic model for predicting fire casualties in an urban traffic tunnel

Fire accidents could result in severe casualties in an urban traffic tunnel due to the concentration of users and narrow space. However, fire casualties could not be easily predicted due to the complicated evacuation environment and uncertainty in personnel distribution. This paper proposes a probabilistic model to predict the fire casualties in an urban traffic tunnel with only natural ventilation, considering the effects of the thermal and carbon monoxide distribution, in addition to the arrangement of various vehicles. First, the general framework of the probabilistic model was put forward and the methods to analyze the fire scenario, evacuation process, casualty criteria, and probability curve were introduced in details. Then, a case study based on a three-lane traffic tunnel was conducted, and the effects of maximum heat release rate on probabilistic curve of fire casualties were discussed. The results showed that the fire casualty increased with the maximum heat release rate. Besides this, when the distance between fire source and evacuation exit was reduced to 150 m, the impact of maximum heat release rate would decrease significantly. This study made notable contributions toward evaluating the personnel loss in tunnel fire and laid a foundation for assessing and improving the resilience of tunnel.

Distribution of ozone, carbon monoxide and oxides of nitrogen over an urban location in the foothills of the North-Western Himalayas

Increasing anthropogenic activities and biomass burning events over the Northern Indian region severely affect the pristine environment of North-Western Himalayas. To investigate their influence in this data sparse region, continuous monitoring of O3, CO and NOx are made during January 2018 to December 2019 over Dehradun, an urban location in the foothills of North-western Himalayas. Ozone shows daytime broad peak and CO and NOx show two peaks during morning and evening hours. The maximum daytime ozone is observed during spring with 58.2 ± 2.0 ppbv (56.2 ± 2.7 ppbv) during 2018 (2019). CO and NOx show maximum value during winter and minimum during summer-monsoon. Their concentrations are found to be influenced from stubble burning and forest fire emissions during late spring. WRF-Chem simulations are made with and without biomass burning emissions to quantify the contribution of these emissions on the variability of these gases over Dehradun. Sensitivity simulations reveal that biomass burning over northern Indian region contributed 43 ppbv, 79 ppbv and 1.2 ppbv increase in O3, CO and NOx mixing ratios over Dehradun. In addition, dust storm event in June 2018 contributed for lower ozone levels in 2018 (16.1 ± 9.3 ppbv) and stratosphere troposphere exchange process enhanced surface ozone in June 2019 (53.6 ± 22.3 ppbv).

Tropical tropospheric ozone and carbon monoxide distributions: characteristics, origins, and control factors, as seen by IAGOS and IASI

Abstract. The characteristics and seasonal variability in the tropical tropospheric distributions of ozone (O3) and carbon monoxide (CO) were analysed based on in situ measurements provided by the In-service Aircraft for a Global Observing System (IAGOS) programme since 1994 and 2002, respectively, combined with observations from the Infrared Atmospheric Sounding (IASI) instrument on board the MetOp-A satellite since 2008. The SOFT-IO (SOft attribution using FlexparT and carbon monoxide emission inventories for In-situ Observation database) model, which couples back trajectories with CO emission inventories, was used to explore the origins and sources of the tropical CO observed by IAGOS. The highest O3 and CO mixing ratios occur over western Africa in the lower troposphere (LT: surface to 750 hPa) during the fire season (75 ppb of O3 at 2.5 km and 850 ppb of CO at 0.3 km over Lagos in January), mainly due to anthropogenic (AN) emissions and a major contribution from fires. The secondary maxima are observed in Asia in the mid-troposphere (MT: 750–300 hPa) and upper troposphere (UT: 300–200 hPa) in April for O3 and in the LT in January for CO, with larger contributions from AN emissions. The lowest O3 and CO mixing ratios occur over Caracas. In the tropical LT, the majority of the location clusters are affected by local and regional AN emissions. The highest AN impact is found over Asia, Arabia and eastern Africa, and South America (>75 % of CO). Biomass burning (BB) emissions also originate from local or regional sources but with stronger seasonal dependence. The highest BB impact is found over southern tropical Africa (57 %–90 %), except in April, mostly due to local fires, but also from Northern Hemisphere Africa in January (45 %–73 %) and Southern Hemisphere South America in October (29 % over Windhoek). In the MT and UT, AN emissions are more important and dominate in the eastern part of the tropics (from the Middle East to Asia). BB contributions are more important than in the LT, especially from the African fires in January and July and from South East and equatorial Asia in April and October. The overall highest amount of CO is exported from Africa, with the main transport pathway from the dry-season African regions towards the wet-season ones. In contrast, the impact of the Asian emissions in the LT and MT is limited on a local or regional scale. The transport of polluted Asian air masses is important in the UT during the Asian summer monsoon and post-monsoon seasons, when convection is active.

Inferring the vertical distribution of CO and CO2 from TCCON total column values using the TARDISS algorithm

Abstract. We describe an approach for determining limited information about the vertical distribution of carbon monoxide (CO) and carbon dioxide (CO2) from total column ground-based Total Carbon Column Observation Network (TCCON) observations. For CO and CO2, it has been difficult to retrieve information about their vertical distribution from spectral line shapes because of the errors in the spectroscopy and the atmospheric temperature profile that mask the effects of variations in their mixing ratio with altitude. For CO2 the challenge is especially difficult given that these variations are typically 2 % or less. Nevertheless, if sufficient accuracy can be obtained, such information would be highly valuable for evaluation of retrievals from satellites and more generally for improving the estimate of surface sources and sinks of these trace gases. We present here the Temporal Atmospheric Retrieval Determining Information from Secondary Scaling (TARDISS) retrieval algorithm. TARDISS uses several simultaneously obtained total column observations of the same gas from different absorption bands with distinctly different vertical averaging kernels. The different total column retrievals are combined in TARDISS using a Bayesian approach where the weights and temporal covariance applied to the different retrievals include additional constraints on the diurnal variation in the vertical distribution for these gases. We assume that the near-surface part of the column varies rapidly over the course of a day (from surface sources and sinks, for example) and that the upper part of the column has a larger temporal covariance over the course of a day. Using measurements from the five North American TCCON sites, we find that the retrieved lower partial column (between the surface and ∼ 800 hPa) of the CO and CO2 dry mole fractions (DMFs) have slopes of 0.999 ± 0.002 and 1.001 ± 0.003 with respect to lower column DMF from integrated in situ data measured directly from aircraft and in AirCores. The average error for our lower column CO retrieval is 1.51 ppb (∼ 2 %) while the average error for our CO2 retrieval is 5.09 ppm (∼ 1.25 %). Compared with classical line-shape-derived vertical profile retrievals, our algorithm reduces the influence of forward model errors such as imprecision in spectroscopy (line shapes and intensities) and in the instrument line shape. In addition, because TARDISS uses the existing retrieved column abundances from TCCON (which themselves are computationally much less intensive than profile retrieval algorithms), it is very fast and processes years of data in minutes. We anticipate that this approach will find broad application for use in carbon cycle science.

CO Excitation in High-z Main-sequence Analogues: Resolved CO(4−3)/CO(3−2) Line Ratios in DYNAMO Galaxies

The spectral line energy distribution of carbon monoxide contains information about the physical conditions of the star-forming molecular hydrogen gas; however, the relation to local radiation field properties is poorly constrained. Using ∼1–2 kpc scale Atacama Large Millimeter Array observations of CO(3−2) and CO(4−3), we characterize the CO(4−3)/CO(3−2) line ratios of local analogues of main-sequence galaxies at z ∼ 1–2, drawn from the DYnamics of Newly Assembled Massive Objects (DYNAMO) sample. We measure CO(4−3)/CO(3−2) across the disk of each galaxy and find a median line ratio of R 43 = 0.54 for the sample. This is higher than literature estimates of local star-forming galaxies and is consistent with multiple lines of evidence that indicate DYNAMO galaxies, despite residing in the local universe, resemble main-sequence galaxies at z ∼ 1–2. Comparing with existing lower-resolution CO(1−0) observations, we find R 41 and R 31 values in the range ∼0.2–0.3 and ∼0.4–0.8, respectively. We combine our kiloparsec-scale resolved line ratio measurements with Hubble Space Telescope observations of Hα to investigate the relation to the star formation rate surface density and compare this relation to expectations from models. We find increasing CO(4−3)/CO(3−2) with increasing star formation rate surface density; however, models overpredict the line ratios across the range of star formation rate surface densities we probe, in particular at the lower range. Finally, Stratospheric Observatory for Infrared Astronomy observations with the High-resolution Airborne Wideband Camera Plus and Field-Imaging Far-Infrared Line Spectrometer reveal low dust temperatures and no deficit of [Cii] emission with respect to the total infrared luminosity.

Ignition characteristics of methane-air mixture at low initial temperature

In this paper, FLUENT software coupled with the chemical reaction mechanism is used to study the ignition characteristics of methane-air mixtures at low temperature. Variations of the main free radical concentrations, the critical conditions for a successful ignition and the chemical reaction rate of each elementary reaction for a failure ignition are obtained, respectively. Results indicate that the consumption of methane immediately affects the concentration distribution of carbon monoxide, which presents the opposite relationship with that of methane. Mass fractions of the intermediate products and H, O free radicals are low in the burnt zone and unburnt zone, whereas reach the maximum on the flame front. OH is not only the intermediate free radical, but also the combustion product remained by the intermediate reactions. At a low temperature of 150 K, the critical radius and temperature of methane ignition are 4.6 mm and 1180 K, respectively. When ignition radius is smaller than the critical value, the failed ignition of methane is caused by the termination of the elementary reactions: R8: H + O2 = OH + O, R9: OH + O = O2 + H, R12: O + H2O = 2OH and R13: 2OH = O + H2O. However, when ignition temperature is lower than the critical value, because of the failed initiation of elementary reaction R1: CH4 = CH3 + H, the combustion of methane is not occurred.

Effect of Mass Transport by Convective Flow on the Distribution of Dissolved Carbon Monoxide in a Stirred Tank

The dissolved gas concentration in a stirred tank has significant importance in the chemical and biological processing industries as mass transfer from the injected gas to an aqueous solution must occur for the gas to be usable. As the solubility of the gas in the solution is low and there are no probes for measuring dissolved gas concentration, a volumetric mass transfer coefficient is selected as a criterion of design for the scale-up of stirred reactors. However, it is difficult to accurately predict the non-equilibrium state dissolved gas distribution using only the volumetric mass transfer coefficient. In this study, computational fluid dynamics (CFD)-based numerical analysis was conducted to systematically evaluated the effects of mass transport by convective flow on the distribution of dissolved carbon monoxide in a stirred tank. The dissolved carbon monoxide distribution and the volumetric mass transfer coefficient were compared at various rotational speeds of the impellers. At a rotational speed of 900 RPM, the Pearson correlation coefficient was about 0.52, which denotes a moderate correlation. In contrast, Pearson correlation coefficients less than 0.20 were obtained for speeds less than 700 RPM, indicating a weak correlation. By considering the dissolved carbon monoxide transport that occurs during convective flow in stirred tanks, we can provide more accurate information about the dissolved carbon monoxide distribution.

Spatial Patterns of Carbon Monoxide Distribution to Traffic Jam in East Jakarta

The rapid growth of cities will certainly also increase traffic jams and emissions in the air. This study aims to analyze the increase in car volume and the CO distribution pattern in East Jakarta. Data for traffic jam patterns were recorded based on Google Maps on weekdays in the morning and evening. The spatial analysis method used to find the CO distribution pattern is the IDW interpolation, and the mathematical model calculates the moving emission based on the distance travelled (VKT). The spatial pattern of CO distribution in 2020 was scattered with high concentrations in Pasar Rebo, Ciracas, Cipayung, Kramat Jati, and Makasar Districts, with CO levels above 4,500 ppm. The spatial pattern of CO distribution from the mobile emission model differs from the air station IDW interpolation. The CO distribution pattern from the mobile emission model is very concentrated in Makassar, and Kramat Jati District was 6,740.91 tons/year. The result concluded that the increase in vehicle volume is not related to the distribution of the CO model from air station IDW interpolation, and the other hand, the congestion pattern was related to the distribution pattern of the CO model from vehicles from the level of congestion.

Analysis of carbon monoxide (CO) distribution in Pekanbaru City and its surroundings due to forest fires

One of the pollutants produced from forest fire is carbon monoxide (CO). The resulting CO pollutants can interfere with human health and even lead to death. In Riau Province, high forest fire was occurred in 2015, while low forest fire was occurred in 2017. An indicator that can be seen as a determinant of high or low forest fires is hotspots. The research was conducted with the aim of comparing the distribution of CO pollutants in 2015 and 2017, as well as find out the correlation between the number of hotspots and the CO concentration. The data used was obtained from the Giovanni website and FIRMS MODAPS NASA. The results showed there was a significant difference in the distribution of CO concentration in 2015 and 2017. In 2015, CO concentrations were higher than 2017. The highest value of CO concentration in 2015 was 226.949 g/m3 while the highest CO concentration value in 2017 was 109.966 g/m3. The relationship between the number of hotspots and the CO concentration values in 2015 and 2017 in Pekanbaru City and its surroundings are -0.585 and -0.602, respectively. The CO concentration in Pekanbaru is affected by surrounding area and the number of vehicles.

Spatial and diurnal distribution of carbon monoxide (CO) and its health and environmental implications in selected locations in the Niger Delta Area of Nigeria

Emission of carbon monoxide (CO) poses unprecedented risks in urban environments. Moreover, there has been a growing concern about the incidences of deaths arising from suffocation by CO fumes in Nigeria. Hence, this study attempts to evaluate the spatial and diurnal distribution of CO and its health and environmental implications in selected Niger Delta areas of Port Harcourt (Rivers State), Yenagoa (Bayelsa State) and Effurun-Warri (Delta State). MultiRAE PLUS and PCMM05 Pyle® Carbon Monoxide Meter were used for in situ measurement. Spatial distribution amongst all the sampling locations shows that Rumuola Junction in Port Harcourt (Rivers State) ranked the highest in CO concentration with a mean value of 120.6 ppm while DSC Roundabout in Effurun/Warri (Delta State) ranked the lowest with a mean value of 6.1 ppm. Diurnal variations in CO distribution were statistically significant (P < 0.05) only in Airport Road and PTI Junction (Effurun-Warri, Delta State), Berger Junction and Swali Market (Yenagoa, Bayelsa State) sampling locations. The observed concentrations were largely higher than the 10 ppm Federal Ministry of Environment limit for ambient air. The high emissions, accumulation and dispersion of CO were attributed to frequent traffic congestion and high vehicular traffic density, among others. It is recommended that road design and maintenance should be greatly improved across the Niger Delta to mitigate traffic emissions. In addition, the public transport system should be improved so as to encourage more patronage and reduce the number of private vehicles on roadways.

Transport and Variability of Tropospheric Ozone over Oceania and Southern Pacific during the 2019–20 Australian Bushfires

The present study contributes to the scientific effort for a better understanding of the potential of the Australian biomass burning events to influence tropospheric trace gas abundances at the regional scale. In order to exclude the influence of the long-range transport of ozone precursors from biomass burning plumes originating from Southern America and Africa, the analysis of the Australian smoke plume has been driven over the period December 2019 to January 2020. This study uses satellite (IASI, MLS, MODIS, CALIOP) and ground-based (sun-photometer, FTIR, ozone radiosondes) observations. The highest values of aerosol optical depth (AOD) and carbon monoxide total columns are observed over Southern and Central Australia. Transport is responsible for the spatial and temporal distributions of aerosols and carbon monoxide over Australia, and also the transport of the smoke plume outside the continent. The dispersion of the tropospheric smoke plume over Oceania and Southern Pacific extends from tropical to extratropical latitudes. Ozone radiosonde measurements performed at Samoa (14.4°S, 170.6°W) and Lauder (45.0°S, 169.4°E) indicate an increase in mid-tropospheric ozone (6–9 km) (from 10% to 43%) linked to the Australian biomass burning plume. This increase in mid-tropospheric ozone induced by the transport of the smoke plume was found to be consistent with MLS observations over the tropical and extratropical latitudes. The smoke plume over the Southern Pacific was organized as a stretchable anticyclonic rolling which impacted the ozone variability in the tropical and subtropical upper-troposphere over Oceania. This is corroborated by the ozone profile measurements at Samoa which exhibit an enhanced ozone layer (29%) in the upper-troposphere. Our results suggest that the transport of Australian biomass burning plumes have significantly impacted the vertical distribution of ozone in the mid-troposphere southern tropical to extratropical latitudes during the 2019–20 extreme Australian bushfires.

Variability in the UTLS chemical composition during different modes of the Asian Summer Monsoon Anti-cyclone

The Asian Summer Monsoon Anticyclone (ASMA) is an important circulation in the upper troposphere and lower stratosphere (UTLS) region during the boreal summer. The center of the ASMA is not a stationary feature but oscillates between longitudes 50°-92.5°E showing different modes. The ASMA center oscillating over 50°-67.5°E, 80°-92.5°E and 67.5°-80°E are termed as IP (Iranian Plateau), TP (Tibetan Plateau) and Elongated mode, respectively. This work explores the spatial variability and the influence of the background dynamical conditions on the vertical chemical distribution of carbonmonoxide (CO), water vapor (WV) and ozone (O3) in the UTLS region during the different ASMA modes using MLS satellite and NCEP/NCAR reanalysis observations. MLS observations for the period 2010–2018 showed maximum CO, WV and minimum O3 concentrations at 100 hPa in the ASMA center over the respective IP, TP and elongated modes. Enhancement in the tropospheric tracers (CO and WV) throughout the upper troposphere during TP and Elongated mode is observed indicating the transport of boundary layer air to the UTLS region from across these regions. In contrast, the enhancement in the tropopause region during the IP mode is mainly due to the convective lifting over the Tibtean plateau longitudes and strong horizontal advection towards the IP longitudes. Our study also revealed that the vertical transport of the tropospheric tracers to the stratosphere is effective over Tibetan Plateau irrespective of the ASMA mode. The warmer tropopause temperature due to an increase in O3 concentrations over the TP supported the vertical transport of WV to lower stratosphere over this region irrespective of the ASMA mode.

Observations of Mars with ALMA: potential for future constraints of global circulation models

Validation of global climate models (GCMs) for planets in our solar system requires observational data, but observations from the orbit of Mars and its surface are limited in number and are constrained by their orbit or landing site. Ground-based observations of Mars can help by providing data across the entire Martian hemisphere, yet historically, ground-based observations at submillimeter wavelengths have been limited to disk-average, or at best, a few resolution elements across Mars. We used Atacama Large Millimeter/submillimeter Array (ALMA) observations of Mars to determine the spatial distribution of carbon monoxide in the Martian atmosphere, which can be related to the atmospheric temperature. ALMA’s comparably high spatial and spectral resolutions in the submillimeter wavelengths could allow the mapping of abundances and temperature profiles, and the comparison of these data to simulations generated by the Laboratoire de Météorologie Dynamique (LMD) Mars GCM. However, the long baselines associated with the high spatial resolution of ALMA introduced systematic errors that resulted in radiative transfer modeling degeneracies. We serve to provide insight to facilitate proposed ALMA observations of Mars in the future so that the systematic errors encountered within these observations might be avoided.

Comparison of Ensemble Kalman Filter, Unscented Kalman Filter, and Fractional Kalman Filter for estimating the concentration of CO and NO 2

Estimation distribution of air pollution is necessary to determine the level of pollution in a location so it can be used to recommend emission minimization. This research use some modification of Kalman Filter method for estimation distribution of air pollution. Three estimation methods namely Fractional Kalman Filter (FKF), Ensemble Kalman Filter (EnKF), Unscented Kalman Filter (UKF). The simulation result of three methods will be compared. Distribution of carbon monoxide and nitrogen dioxide in Surabaya was estimated using three methods. This reserach showed that Fractional Kalman Filter method is the best estimator among the others because error value is the smallest.

Experimental and simulation studies on hybrid ventilation in interlayer of underground depot with superstructure

With the modernization of urban development, land resources are becoming increasingly scarce. A new type of building model comprising an underground depot and a superstructure has been constructed. To study the hybrid ventilation (HV) in interlayer of the underground depot with a superstructure under monorail line section fire, full-scale numerical simulation and reduced-scale (1:50) experiment were performed. Five ventilation velocities were used under a certain heat release rate. The temperature distribution and stratification in the interlayer were examined, and the movement of the fire smoke was analyzed. The smoke layer was visualized using a laser sheet and the smoke layer thickness determined by N-percentage rule (N = 10, 20, 30) was compared with the results of visual observation. At the same time, CFD simulations were conducted to measure the height of smoke layer and the smoke front propagation. Besides, the distribution of carbon monoxide (CO) in the interlayer was also simulated. The results show that N value of 30 could properly determine the smoke layer thickness in relatively stable stage of combustion. HV had a better effect on smoke control than natural ventilation (NV) did. At a ventilation velocity of 1.4 m/s, the smoke layer in the interlayer remained in a steady state until its exclusion from the building. CO could be effectively controlled and did not spread all over the interlayer in HV systems. The structure of HV system can be adjusted according to the actual conditions of the various sizes and types of buildings. Thus, the HV system shows good adaptability and can be directly applied to the design and installation of new buildings such as underground garages and depots. The results of the fire dynamic simulations and experimental tests exhibited considerable agreement.

Observations of Emissions and the Influence of Meteorological Conditions during Wildfires: A Case Study in the USA, Brazil, and Australia during the 2018/19 Period

Wildfires can have rapid and long-term effects on air quality, human health, climate change, and the environment. Smoke from large wildfires can travel long distances and have a harmful effect on human health, the environment, and climate in other areas. More recently, in 2018–2019 there have been many large fires. This study focused on the wildfires that occurred in the United States of America (USA), Brazil, and Australia using Cloud-Aerosol Lidar with Orthogonal Polarisation (CALIOP) and a TROPOspheric Monitoring Instrument (TROPOMI). Specifically, we analyzed the spatial-temporal distribution of black carbon (BC) and carbon monoxide (CO) and the vertical distribution of smoke. Based on the results, the highest detection of smoke (~14 km) was observed in Brazil; meanwhile, Australia showed the largest BC column burden of ~1.5 mg/m2. The meteorological conditions were similar for all sites during the fires. Moderate temperatures (between 32 and 42 °C) and relative humidity (30–50%) were observed, which resulted in drier conditions favorable for the burning of fires. However, the number of active fires was different for each site, with Brazil having 13 times more active fires than the USA and five times more than the number of active fires in Australia. However, the high number of active fires did not translate to higher atmospheric constituent emissions. Overall, this work provides a better understanding of wildfire behavior and the role of meteorological conditions in emissions at various sites.

Investigating the Long-Range Transport of Aerosol Plumes Following the Amazon Fires (August 2019): A Multi-Instrumental Approach from Ground-Based and Satellite Observations

Despite a number of studies on biomass burning (BB) emissions in the atmosphere, observation of the associated aerosols and pollutants requires continuous efforts. Brazil, and more broadly Latin America, is one of the most important seasonal sources of BB, particularly in the Amazon region. Uncertainty about aerosol loading in the source regions is a limiting factor in terms of understanding the role of aerosols in climate modelling. In the present work, we investigated the Amazon BB episode that occurred during August 2019 and made the international headlines, especially when the smoke plumes plunged distant cities such as São Paulo into darkness. Here, we used satellite and ground-based observations at different locations to investigate the long-range transport of aerosol plumes generated by the Amazon fires during the study period. The monitoring of BB activity was carried out using fire related pixel count from the moderate resolution imaging spectroradiometer (MODIS) onboard the Aqua and Terra platforms, while the distribution of carbon monoxide (CO) concentrations and total columns were obtained from the infrared atmospheric sounding interferometer (IASI) onboard the METOP-A and METOP-B satellites. In addition, AERONET sun-photometers as well as the MODIS instrument made aerosol optical depth (AOD) measurements over the study region. Our datasets are consistent with each other and highlight AOD and CO variations and long-range transport of the fire plume from the source regions in the Amazon basin. We used the Lagrangian transport model FLEXPART (FLEXible PARTicle) to simulate backward dispersion, which showed good agreement with satellite and ground measurements observed over the study area. The increase in Rossby wave activity during the 2019 austral winter the Southern Hemisphere may have contributed to increasing the efficiency of large-scale transport of aerosol plumes generated by the Amazon fires during the study period.

Spatiotemporal distribution of traffic emission based on wind tunnel experiment and computational fluid dynamics (CFD) simulation

With the increasing urbanization and motorization, transportation has become one of the primary sources of carbon emission and air pollution, causing serious diseases to city residents. This study focuses on assessing pollutant dispersion patterns under multi-scenario situations and verifying the effectiveness of computational fluid dynamics (CFD) numerical simulation model using wind tunnel experiments and field measurements. A single-vehicle model was built to obtain the spatiotemporal distribution of Carbon Monoxide (CO) concentrations around the vehicle. Pressure coefficients of monitoring points were measured to compare with the values from the wind tunnel test. Then, numerical simulations were extended to car-following platoon and empirical street canyon scenarios. On-site measurements were carried out to ensure that the CFD model reflects the actual flow field around a vehicle in a certain precision range for given experimental design. The results indicated that the traffic-related pollutants were concentrated in the semicircle with the exhaust pipe as the center, with a radius of 1.5 m behind the vehicle. The podium building structure in the street perpendicular to the prevailing wind direction tends to induce the deposition of pollutants at the corner and bottom of the podium. Exhaust concentration at the right-angle area of a podium building on the leeward side of the wind direction is 221.1% higher than that in the windward side. Findings of this study may shed light on the street architecture design and the future applications of CFD model to estimate pollutant concentration along urban street canyons, thus to eventually improve urban environmental sustainability.