Indonesia contains large areas of peatland that have been drained
and cleared of natural vegetation, making them susceptible to burning. Peat
fires emit considerable amounts of carbon dioxide, ...particulate matter (PM)
and other trace gases, contributing to climate change and causing regional
air pollution. However, emissions from peat fires are uncertain, due to
uncertainties in emission factors and fuel consumption. We used the Weather
Research and Forecasting model with chemistry and measurements of PM
concentrations to constrain PM emissions from Indonesian fires during 2015,
one of the largest fire seasons in recent decades. We estimate primary
PM2.5 (particles with diameters less than 2.5 µm) emissions from
fires across Sumatra and Borneo during September–October 2015 were 7.33 Tg, a factor 3.5 greater than those in the Fire Inventory from NCAR (FINNv1.5),
which does not include peat burning. We estimate similar dry fuel
consumption and CO2 emissions to those in the Global Fire Emissions
Database (GFED4s, including small fires) but PM2.5
emissions that are a factor of 1.8 greater, due to updated PM2.5 emission factors for Indonesian peat.
Fires were responsible for an additional 3.12 Tg of secondary organic
aerosol formation. Through comparing simulated and measured PM
concentrations, our work provides independent support of these updated
emission factors. We estimate peat burning contributed 71 % of total
primary PM2.5 emissions from fires in Indonesia during September–October
2015. We show that using satellite-retrieved soil moisture to modify the
assumed depth of peat burn improves the simulation of PM, increasing the
correlation between simulated and observed PM from 0.48 to 0.56. Overall,
our work suggests that peat fires in Indonesia produce substantially greater
PM emissions than estimated in current emission inventories, with
implications for the predicted air quality impacts of peat burning.
Crucially, one should not expect software to automate well simply because it is mature and from a reliable source—a prime example of this is Microsoft Office, which Microsoft specifically advises is ...not supported to be run unattended in a robotic process automation (RPA) environment 14. ...your software project must have some high-level project documentation, describing what your project is intended to do and who it will be useful for. ...your project must include interface-level documentation. First and foremost, your software project must use source control software, such as Git 24 or Subversion 25.
Hay fever affects people differently and can change over a lifetime, but data is lacking on how environmental factors may influence this. This study is the first to combine atmospheric sensor data ...with real-time, geo-positioned hay fever symptom reports to examine the relationship between symptom severity and air quality, weather and land use. We study 36145 symptom reports submitted over 5 years by over 700 UK residents using a mobile application. Scores were recorded for nose, eyes and breathing. Symptom reports are labelled as urban or rural using land-use data from the UK's Office for National Statistics. Reports are compared with AURN network pollution measurements and pollen and meteorological data taken from the UK Met Office. Our analysis suggests urban areas record significantly higher symptom severity for all years except 2017. Rural areas do not record significantly higher symptom severity in any year. Additionally, symptom severity correlates with more air quality markers in urban areas than rural areas, indicating that differences in allergy symptoms may be due to variations in the levels of pollutants, pollen counts and seasonality across land-use types. The results suggest that a relationship exists between urban surroundings and hay fever symptoms.
Polar stratospheric cloud microphysics and chemistry Lowe, Douglas; MacKenzie, A. Robert
Journal of atmospheric and solar-terrestrial physics,
2008, 2008-1-00, 20080101, Letnik:
70, Številka:
1
Journal Article
Recenzirano
The solid and liquid particles which constitute polar stratospheric clouds (PSCs) are of manifold importance to the meteorology of the stratosphere. The heterogeneous reactions which take place on ...and within these particles release halogens from relatively inert reservoir species into forms which can destroy ozone in the polar spring. In addition, solid PSC particles are instrumental in the physical removal of nitrogen oxides (denitrification) and water (dehydration) of regions of the polar stratosphere. Denitrification, in particular, allows extended ozone destruction by slowing the conversion of chlorine radicals back into reservoir species.
We review the historical development of PSC studies, with particular emphasis on results from the last decade, encompassing developments in observations, in laboratory experiments, and in theoretical treatments. The technical challenge of measuring sufficient of the parameters describing any given PSC, to allow its microphysics to be understood, has driven forward balloon-borne, aircraft, and satellite instrumentation. The technical challenge of finding suitable laboratory proxies for PSCs, in order to observe the microphysics under controlled conditions, has resulted in a wide variety of experimental designs, some of which maximise the probability of observing phase change, others which mimic the surface–volume ratios of PSCs more closely. The challenge to theory presented by PSCs has resulted in improvements in the thermodynamics of concentrated inorganic solutions of volatile compounds, and a new general theory of freezing of water ice from concentrated aqueous solutions. Of the major processes involving PSCs, heterogeneous reaction probabilities for ternary HNO
3/H
2SO
4/H
2O solutions, and heterogeneous freezing to produce nitric-acid hydrates, are the least well understood.
In recent years, quantifying the impacts of detrimental air quality has become a global priority for researchers and policy makers. At present, the systems and methodologies supporting the collection ...and manipulation of this data are difficult to access. To support studies quantifying the interplay between common gaseous and particulate pollutants with meteorology and biological particles, this paper presents a comprehensive data-set containing daily air quality readings from the Automatic Urban and Rural Network, and pollen and weather data from Met Office monitoring stations, in the years 2016 to 2019 inclusive, for the United Kingdom. We describe (1) the sources from which the data were collected, (2) the methods used for the data cleaning process and (3) how issues related to missing values and sparse regional coverage were addressed. The resulting data-set is designed to be used 'as is' by those using air quality data for research; we also describe and provide open access to the methods used for curating the data to allow modification of or addition to the data-set.
The fast development of a secondary aerosol layer was observed over megacities in eastern Asia during summertime. Within three hours, from midday to early afternoon, the contribution of secondary ...aerosols above the planetary boundary layer (PBL) increased by a factor of three to five, and the coatings on black carbon (BC) also increased and enhanced its absorption efficiency by 50%. This tended to result from the intensive actinic flux received above the PBL which promoted photochemical reactions. The absorption of BC could be further amplified by the strong reflection of solar radiation over the cloud top across the PBL. This enhanced heating effect of BC introduced by combined processes (intensive solar radiation, secondary formation and cloud reflection) may considerably increase the temperature inversion above the PBL. This mechanism should be considered when evaluating the radiative impact of BC, especially for polluted regions receiving strong solar radiation.
Fine particulate matter (PM2.5) and surface ozone (O3) are major air pollutants in megacities such as Delhi, but the design of suitable mitigation strategies is challenging. Some strategies for ...reducing
PM2.5 may have the notable side effect of increasing O3. Here, we demonstrate a numerical framework for investigating the impacts of
mitigation strategies on both PM2.5 and O3 in Delhi. We use
Gaussian process emulation to generate a computationally efficient surrogate for a regional air quality model (WRF-Chem). This allows us to perform global sensitivity analysis to identify the major sources of air pollution and to generate emission-sector-based pollutant response surfaces to inform mitigation policy development. Based on more than 100 000 emulation runs during the pre-monsoon period (peak O3 season), our global sensitivity analysis shows that local traffic emissions from the Delhi city region and regional transport of pollution emitted from the National Capital Region (NCR) surrounding Delhi are dominant factors influencing PM2.5 and O3 in Delhi. They together govern the O3 peak and PM2.5 concentration during daytime. Regional transport contributes about 80% of the PM2.5 variation during the night. Reducing traffic emissions in Delhi alone (e.g. by 50 %) would reduce PM2.5 by 15 %–20 % but lead to a 20 %–25 % increase in O3. However, we show that reducing NCR regional emissions by 25 %–30 % at the same time would further reduce PM2.5 by 5 %–10 % in Delhi and avoid the O3 increase. This study provides scientific evidence to support the need for joint coordination of controls on local and regional scales to achieve effective reduction in PM2.5 whilst minimising the risk of O3 increase in Delhi.
Air quality in India during the winter months is particularly bad, due to the meteorological conditions limiting dispersal of pollutants. However, investigations of this period using regional air ...quality models have, so far, been limited. Air quality simulations, using the Weather Research and Forecasting with Chemistry (WRF-Chem) model, at a high grid resolution of 12 km × 12 km, have been carried out for the 2015–16 winter period over the Indian subcontinent. Gas and aerosol chemistry are simulated using the CBM-Z and MOSAIC (4-bin) modules. Emissions from the EDGAR-HTAPv2.2 database are used, scaled to the simulation year based on changes in activity data for each Indian state, which increases national emissions of PM2.5, BC, OC, NOx, SO2 and NMVOCs by 2.6, 0.3, 0.5, 6, 13.5 and 3.6 Gg/day, respectively, in winter. Model performance was evaluated with respect to ground-based observations of PM2.5, CO, NO2 and O3 from available monitoring stations in the cities Ahmedabad, Bangalore, Chennai, Delhi, Agra, Lucknow, Patna, Mumbai, Kolkata, and Hyderabad. PM2.5 predictions at most of the monitoring cities fell within the excellent model performance criteria (Mean Fractional Bias range − 0.15 to 0.11). The NO2 concentrations were reproduced well by the model, with a Mean Fractional Bias range of −0.17 to 0.25. CO concentrations were generally underpredicted, but with relatively smaller biases over northern Indian cities. Ozone was reasonably reproduced at Delhi, but modelled day time peaks are much higher than observations in the other cities (~ 42–62%). Patterns of diurnal cycles of pollutants were found to be broadly similar for both observations and WRF-Chem predictions. The 24 h averaged PM2.5 mass loading over most Indian cities and states were found to exceed the Indian National Ambient Air Quality Standard (NAAQS). PM2.5, CO and NO2 mass loadings were highest in northern and eastern India, particularly over the Indo-Gangetic Plain. Overall in this study, wintertime pollution loading in India is reproduced well by WRF-Chem. However, creating diurnal emission cycles based on local activity data, updated national emission inventories for recent years at higher resolution, and extra air quality monitoring stations, especially in rural areas, are needed to increase the accuracy and validation of model predictions, to better inform policy making.
•Wintertime high resolution air quality simulation over India using WRF-Chem v3.9.1.•Applied chemically complex gas-aerosol (CBM-Z, MOSAIC-4bin) chemistry.•Model performance for PM2.5 fell within excellent criteria at most Indian cities.•Model predicted and observed diurnal cycles of pollutant were found broadly similar.•Higher wintertime pollution loading is found over the IGP than the rest of India.
Parameterizations for calculating the equilibrium vapor pressure of the semivolatile inorganic gases, HNO3, HCl, and NH3, above an aqueous aerosol are presented. The hybrid Partial Derivative Fitted ...Taylor Expansion (PD‐FiTE) approach uses optimized model parameters describing the interaction between different inorganic ions, resulting in comparable computational performance with existing reduced methods while remaining accurate. Comparisons with the most accurate inorganic activity coefficient model available indicate that PD‐FiTE performs very well over the parameterization space of the system H+‐NH4+‐Na+‐SO42−‐HSO4−‐NO3−‐Cl− at 298.15 K. The linear additive framework allows the inclusion of further species. However, including the ability to describe the interaction between inorganic and organic components will be presented in a future publication. Coupling PD‐FiTE to a coupled box model of gaseous chemistry and aerosol microphysics in a test case investigating marine aerosol passing through a polluted environment demonstrates its robustness and ability to capture fine details of important phenomena such as the outgassing of HCl in response to HNO3 uptake by sea‐salt particles.
The physical properties of black carbon (BC) including the mass loading, size distribution and mixing state were in-situ characterized by aircraft measurements using a single particle soot photometer ...(SP2) in the lower troposphere over Beijing area. The flights were conducted in both late spring and winter during the daytime with well-developed planetary boundary layer (PBL). The BC mass in the PBL (BCPBL) in late spring showed no apparent vertical gradient nor correlation with the PBL height (PBLH) due to strong convective mixing; in winter the BCPBL was more concentrated near ground and anti-correlated with the PBLH due to dilution effect of the dominant cleaner northerly air masses at higher altitude. The BC mass loading at height h, C(h) within the PBL can be extended from the surface level (C0) in late spring; for levels above the PBL, C(h) can be parameterized by applying an exponential decline function C(h) = C0*exp(h/hs), with the scale height (hs) of 0.31 ± 0.16 km and 0.66 ± 0.24 km for late spring and winter respectively. This parameterization excluded the profiles for: turbulent conditions when the BC mass was efficiently vented upwards and diluted, expressed as C(h) = C0 up to the top of the PBL; or in periods of strong southerly advection, when the entire column was significantly influenced by regional transport from the polluted south regions. The BC core mass median diameters (MMD) were commonly populated at 205–220 nm in both seasons, with additional mode of MMD ∼195 nm also frequently observed in late spring. The bulk relative coating thickness of BC (coated diameter divided by uncoated core diameter Dp/Dc) in the PBL mostly populated at 2.0–2.2 but at ∼1.2–1.6 in the lower free troposphere (FT). The mass absorption cross section of BC at 550 nm (MAC550), constrained by the SP2 measurements, was largely influenced by the coating thickness, was relatively consistent in the PBL at ∼8.6 m2 g−1, but reduced to 7–7.5 m2 g−1 in the FT or turbulent condition due to decreased coatings. The BC was found to exhibit smaller particle size in the FT but larger in the PBL, which may imply larger BC have been scavenged by low-level clouds. The BC particles trapped in the PBL or regionally transported from polluted region represent the most absorbing element in the particulate matter population and should be particularly considered in evaluating the radiative forcing impact of aerosols over this region.
•Vertical profiles of black carbon physical properties in the lower troposphere were in-situ characterized over Beijing.•Black carbon at different layers was influenced by seasonal emission and meteorological conditions.•These results will improve modelling on black carbon radiative forcing and constrain remote sensing absorption measurement.
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