Effect of vertical parameterization of a missing daytime source of HONO on concentrations of HONO, O3 and secondary organic aerosols in eastern China

2020 ◽  
Author(s):  
Yitian Guo ◽  
Junling An ◽  
Jingwei Zhang ◽  
Yu Qu
Keyword(s):  
Secondary Organic Aerosols ◽  
Theoretical Calculations ◽  
Eastern China ◽  
Organic Aerosols ◽  
Field Measurements ◽  
Field Studies ◽  
Weather Research And Forecasting ◽  
Photolysis Frequency ◽  
Almost All ◽  
New Formula

<p>Unexpectedly high daytime concentrations of nitrous acid (HONO) measured by field observations cannot be explained by theoretical calculations, implying that there may be a missing source of HONO in the daytime (P<sub>missing</sub>). The value of P<sub>missing</sub> near the ground (P<sub>Gmissing</sub>) is different from that measured higher in the atmosphere (P<sub>Hmissing</sub>) according to previous field studies, but the contribution of the vertical P<sub>missing</sub> profile in the atmospheric boundary layer (ABL) to air quality remains unknown. We derived a new formula P<sub>Gmissing</sub> = 0.180 × J(NO<sub>2</sub>) [ppb s<sup>-1</sup>] based on field measurements near the ground, where J(NO<sub>2</sub>) is the photolysis frequency of NO<sub>2</sub>, and used the value of P<sub>Hmissing</sub> inferred from Zeppelin measurements in the troposphere to parameterize P<sub>missing</sub> in the ABL. This parameterization was incorporated into the Weather Research and Forecasting model with Chemistry (WRF-Chem) to quantify the vertical effects of P<sub>missing</sub> on the concentrations of HONO, O<sub>3</sub> and secondary organic aerosols (SOAs) in eastern China. Our results showed that P<sub>Gmissing</sub> and P<sub>Hmissing</sub> together further narrowed the gap between the simulations and observations, leading to a daytime increase in HONO concentrations of about 160 ppt near the ground compared with P<sub>Gmissing</sub> only, an increase in the daytime concentrations of O<sub>3</sub> of 8–37 ppb within the ABL in almost all of the studied domain in summer (1–19 ppb in winter and 4–21 ppb in autumn) and the largest hourly increase in the concentration of SOAs of 22.5 (18.6) μg m<sup>-3</sup> in winter (summer). The results indicated that HONO sources near the ground have a limited effect on the HONO concentrations in the upper ABL even in summer in the presence of strong convective activities, while the HONO increase in the upper ABL can affect the concentration of HONO near the ground. When P<sub>Gmissing</sub> was inserted into each model layer in the ABL, the concentrations of HONO higher in the atmosphere were substantially overestimated, suggesting that observations of the vertical distribution of HONO in the ABL are required in polluted areas.</p>

CLT construction without weather protection requires extensive moisture control

2021 ◽  
pp. 174425912199638
Author(s):  
Lars Olsson
Keyword(s):  
Moisture Content ◽  
Field Measurements ◽  
Scientific Work ◽  
Field Studies ◽  
Microbiological Analysis ◽  
Mould Growth ◽  
Extensive Growth ◽  
Almost All ◽  
Dry Out ◽  
Moisture Conditions

This study examines how cross-laminated timber (CLT) constructions, including joints, connections and attachment points, are affected by precipitation during construction. The case studies are based on moisture content measurements and material sampling as well as microbiological analysis during the structure’s construction stage. The study does not include remediation control. The field measurements show microbiological growth in all buildings and almost all floor structures that were investigated. Of a total of 200 measuring points analysed, half had mould growth and around a third had moderate or extensive growth. The moisture content measurements for one of the locations with the largest percentage of elevated or high moisture content was at the top of the floor structure in the bottom gap between timbers in the CLT top layer. This is one example of several materials or construction components where there is limited possibility of dry out. Based on the outcome, it would appear difficult, or impossible, to avoid the appearance of microbial growth during construction with CLT without weather protection. Previous studies indicate that microbiological analysis of CLT is extremely rare in both laboratory and field studies, which implies that there are obvious shortcomings in the scientific work. The fact that mould growth is often invisible needs to be disseminated, especially in practical studies. However, there seems to be a good level of awareness in the literature that theoretical studies often conduct mould growth risk evaluations. There do not appear to be any moisture safety assembly methods or solutions for CLT construction that do not have weather protection or a declaration of the critical moisture conditions for CLT products.

scholarly journals Large Discrepancy in the Formation of Secondary Organic Aerosols from Structurally Similar Monoterpenes

2021 ◽  
Vol 5 (3) ◽  
pp. 632-644
Author(s):  
Ditte Thomsen ◽  
Jonas Elm ◽  
Bernadette Rosati ◽  
Jane Tygesen Skønager ◽  
Merete Bilde ◽  
...  
Keyword(s):  
Secondary Organic Aerosols ◽  
Organic Aerosols

A Comparative Study on the Noise between Floors of Apartment and Multiplex Housing

2015 ◽  
Vol 752-753 ◽  
pp. 1232-1235
Author(s):  
Ji Hun Kim ◽  
Yoon Seok Shin
Keyword(s):  
Comparative Analysis ◽  
Comparative Study ◽  
Field Measurements ◽  
Apartment Building ◽  
Noise And Vibration ◽  
Korean Government ◽  
Current State ◽  
The Future ◽  
House Type ◽  
Almost All

Since recently almost all housing built in Korean have shared walls and floor, diverse problems are unavoidable including noise between floor arising from noise and vibration. Many efforts have been made by the Korean government, but the number of complaints related with the noise between floors has been gradually increasing. Therefore, through the field measurements by house type, the current state of noise was understood. To do this, the noise between floors was measured in an apartment household and a multiplex house to perform a comparative analysis. As the result, the differences in the noise between the two house types were clarified. The findings of this research are expected to contribute to reduction of the noise between floors in an apartment building in the future.

scholarly journals Aerosol chemical and optical properties over the Paris area within ESQUIF project

2006 ◽  
Vol 6 (11) ◽  
pp. 3257-3280 ◽  
Author(s):  
A. Hodzic ◽  
R. Vautard ◽  
P. Chazette ◽  
L. Menut ◽  
B. Bessagnet
Keyword(s):  
Optical Properties ◽  
Secondary Organic Aerosols ◽  
Organic Aerosols ◽  
Dust Particles ◽  
Aerosol Size Distribution ◽  
Aerosol Composition ◽  
Aerosol Mass ◽  
Coarse Mode ◽  
Paris Area ◽  
Flight Trajectories

Abstract. Aerosol chemical and optical properties are extensively investigated for the first time over the Paris Basin in July 2000 within the ESQUIF project. The measurement campaign offers an exceptional framework to evaluate the performances of the chemistry-transport model CHIMERE in simulating concentrations of gaseous and aerosol pollutants, as well as the aerosol-size distribution and composition in polluted urban environments against ground-based and airborne measurements. A detailed comparison of measured and simulated variables during the second half of July with particular focus on 19 and 31 pollution episodes reveals an overall good agreement for gas-species and aerosol components both at the ground level and along flight trajectories, and the absence of systematic biases in simulated meteorological variables such as wind speed, relative humidity and boundary layer height as computed by the MM5 model. A good consistency in ozone and NO concentrations demonstrates the ability of the model to reproduce the plume structure and location fairly well both on 19 and 31 July, despite an underestimation of the amplitude of ozone concentrations on 31 July. The spatial and vertical aerosol distributions are also examined by comparing simulated and observed lidar vertical profiles along flight trajectories on 31 July and confirm the model capacity to simulate the plume characteristics. The comparison of observed and modeled aerosol components in the southwest suburb of Paris during the second half of July indicates that the aerosol composition is rather correctly reproduced, although the total aerosol mass is underestimated by about 20%. The simulated Parisian aerosol is dominated by primary particulate matter that accounts for anthropogenic and biogenic primary particles (40%), and inorganic aerosol fraction (40%) including nitrate (8%), sulfate (22%) and ammonium (10%). The secondary organic aerosols (SOA) represent 12% of the total aerosol mass, while the mineral dust accounts for 8%. The comparison demonstrates the absence of systematic errors in the simulated sulfate, ammonium and nitrates total concentrations. However, for nitrates the observed partition between fine and coarse mode is not reproduced. In CHIMERE there is a clear lack of coarse-mode nitrates. This calls for additional parameterizations in order to account for the heterogeneous formation of nitrate onto dust particles. Larger discrepancies are obtained for the secondary organic aerosols due to both inconsistencies in the SOA formation processes in the model leading to an underestimation of their mass and large uncertainties in the determination of the measured aerosol organic fraction. The observed mass distribution of aerosols is not well reproduced, although no clear explanation can be given.

scholarly journals Understanding the anthropogenic influence on formation of biogenic secondary organic aerosols in Denmark via analysis of organosulfates and related oxidation products

2014 ◽  
Vol 14 (17) ◽  
pp. 8961-8981 ◽  
Author(s):  
Q. T. Nguyen ◽  
M. K. Christensen ◽  
F. Cozzi ◽  
A. Zare ◽  
A. M. K. Hansen ◽  
...  
Keyword(s):  
Organic Acids ◽  
Long Range ◽  
Secondary Organic Aerosols ◽  
Global Radiation ◽  
Organic Aerosols ◽  
Photochemical Reactions ◽  
Common Mechanism ◽  
Aerosol Acidity ◽  
Local Impacts ◽  
Concentration Levels

Abstract. Anthropogenic emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx) may affect concentration levels and composition of biogenic secondary organic aerosols (BSOA) through photochemical reactions with biogenic organic precursors to form organosulfates and nitrooxy organosulfates. We investigated this influence in a field study from 19 May to 22 June, 2011 at two sampling sites in Denmark. Within the study, we identified a substantial number of organic acids, organosulfates and nitrooxy organosulfates in the ambient urban curbside and semi-rural background air. A high degree of correlation in concentrations was found among a group of specific organic acids, organosulfates and nitrooxy organosulfates, which may originate from various precursors, suggesting a common mechanism or factor affecting their concentration levels at the sites. It was proposed that the formation of those species most likely occurred on a larger spatial scale, with the compounds being long-range transported to the sites on the days with the highest concentrations. The origin of the long-range transported aerosols was investigated using the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model in addition to modeled emissions of related precursors, including isoprene and monoterpenes using the global Model of Emissions of Gases and Aerosols from Nature (MEGAN) and SO2 emissions using the European Monitoring and Evaluation Program (EMEP) database. The local impacts were also studied by examining the correlation between selected species, which showed significantly enhanced concentrations at the urban curbside site and the local concentrations of various gases, including SO2, ozone (O3), NOx, aerosol acidity and other meteorological conditions. This investigation showed that an inter-play of the local parameters such as the aerosol acidity, NOx, SO2, relative humidity (RH), temperature and global radiation seemed to affect the concentration level of those species, suggesting the influence of aqueous aerosol chemistry. The local impacts, however, seemed minor compared to the regional impacts. The total concentrations of organosulfates and nitrooxy organosulfates, on average, contributed to approximately 0.5–0.8% of PM1 mass at the two sampling sites.

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