Browsing by Author "Robinson, Andrew D."

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    Atmospheric isoprene measurements reveal larger-than-expected Southern Ocean emissions
    (Springer Nature, 2024-03-22) Ferracci, Valerio; Weber, James; Bolas, Conor G.; Robinson, Andrew D.; Tummon, Fiona; Rodríguez-Ros, Pablo; Cortés-Greus, Pau; Baccarini, Andrea; Jones, Roderic L.; Galí, Martí; Simó, Rafel; Schmale, Julia; Harris, Neil
    Isoprene is a key trace component of the atmosphere emitted by vegetation and other organisms. It is highly reactive and can impact atmospheric composition and climate by affecting the greenhouse gases ozone and methane and secondary organic aerosol formation. Marine fluxes are poorly constrained due to the paucity of long-term measurements; this in turn limits our understanding of isoprene cycling in the ocean. Here we present the analysis of isoprene concentrations in the atmosphere measured across the Southern Ocean over 4 months in the summertime. Some of the highest concentrations ( >500 ppt) originated from the marginal ice zone in the Ross and Amundsen seas, indicating the marginal ice zone is a significant source of isoprene at high latitudes. Using the United Kingdom Earth System Model we show that current estimates of sea-to-air isoprene fluxes underestimate observed isoprene by a factor >20. A daytime source of isoprene is required to reconcile models with observations. The model presented here suggests such an increase in isoprene emissions would lead to >8% decrease in the hydroxyl radical in regions of the Southern Ocean, with implications for our understanding of atmospheric oxidation and composition in remote environments, often used as proxies for the pre-industrial atmosphere.
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    Development of a low-maintenance measurement approach to continuously estimate methane emissions: a case study
    (Elsevier, 2016-12-18) Riddick, Stuart N.; Hancock, B. R.; Robinson, Andrew D.; Connors, Sarah; Davies, S.; Allen, Grant; Pitt, Joseph; Harris, Neil R. P.
    The chemical breakdown of organic matter in landfills represents a significant source of methane gas (CH4). Current estimates suggest that landfills are responsible for between 3% and 19% of global anthropogenic emissions. The net CH4 emissions resulting from biogeochemical processes and their modulation by microbes in landfills are poorly constrained by imprecise knowledge of environmental constraints. The uncertainty in absolute CH4 emissions from landfills is therefore considerable. This study investigates a new method to estimate the temporal variability of CH4 emissions using meteorological and CH4 concentration measurements downwind of a landfill site in Suffolk, UK from July to September 2014, taking advantage of the statistics that such a measurement approach offers versus shorter-term, but more complex and instantaneously accurate, flux snapshots. Methane emissions were calculated from CH4 concentrations measured 700 m from the perimeter of the landfill with observed concentrations ranging from background to 46.4 ppm. Using an atmospheric dispersion model, we estimate a mean emission flux of 709 μg m−2 s−1 over this period, with a maximum value of 6.21 mg m−2 s−1, reflecting the wide natural variability in biogeochemical and other environmental controls on net site emission. The emissions calculated suggest that meteorological conditions have an influence on the magnitude of CH4 emissions. We also investigate the factors responsible for the large variability observed in the estimated CH4 emissions, and suggest that the largest component arises from uncertainty in the spatial distribution of CH4 emissions within the landfill area. The results determined using the low-maintenance approach discussed in this paper suggest that a network of cheaper, less precise CH4 sensors could be used to measure a continuous CH4 emission time series from a landfill site, something that is not practical using far-field approaches such as tracer release methods. Even though there are limitations to the approach described here, this easy, low-maintenance, low-cost method could be used by landfill operators to estimate time-averaged CH4 emissions and their impact downwind by simultaneously monitoring plume advection and CH4 concentrations.
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    Estimating the size of a methane emission point source at different scales: from local to landscape
    (European Geosciences Union (EGU) / Copernicus Publications, 2017-06-29) Riddick, Stuart N.; Connors, Sarah; Robinson, Andrew D.; Manning, Alistair J.; Jones, Pippa S. D.; Lowry, David; Nisbet, Euan; Skelton, Robert L.; Allen, Grant; Pitt, Joseph; Harris, Neil
    High methane (CH4) mixing ratios (up to 4 ppm) have occurred sporadically at our measurement site in Haddenham, Cambridgeshire, since July 2012. Isotopic measurements and back trajectories show that the source is the Waterbeach Waste Management Park 7 km SE of Haddenham. To investigate this further, measurements were made on 30 June and 1 July 2015 at other locations nearer to the source. Landfill emissions have been estimated using three different approaches at different scales; near source using the WindTrax inversion dispersion model, middle distance using a Gaussian plume (GP) model and at the landscape scale using the Numerical Atmospheric Modelling Environment (NAME) Inversion Technique for Emission Modelling (InTEM) inversion. The emission estimates derived using the WindTrax and Gaussian plume (GP) approaches agree well for the period of intense observations. Applying the Gaussian plume approach to all periods of elevated measurements seen at Haddenham produces year-round and monthly landfill emission estimates with an estimated annual emission of 11.6 GgCH(4) yr(-1). The monthly emission estimates are highest in winter (2160 kg h(-1) in February) and lowest in summer (620 kg h(-1) in July). These data identify the effects of environmental conditions on landfill CH4 production and highlight the importance of year-round measurements to capture seasonal variability in CH4 emission.
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    Estimating the size of a methane emission point-source at different scales: from local to landscape
    (Copernicus Publications, 2016-11-22) Riddick, Stuart N.; Connors, Sarah; Robinson, Andrew D.; Manning, Alistair J.; Jones, Pippa S. D.; Lowry, David; Nisbet, Euan; Skelton, Robert L.; Allen, Grant; Pitt, Joseph; Harris, Neil
    High methane (CH4) mixing ratios (up to 4 ppm) have occurred sporadically at our measurement site in Haddenham, Cambridgeshire since July 2012. Isotopic measurements and back trajectories show that the source is the Waterbeach Waste management park 7 km SE of Haddenham. To investigate this further, measurements were made on June 30th and July 1st 2015 at other locations nearer to the source. Landfill emissions have been estimated using three different approaches (WindTrax, Gaussian plume, and NAME InTEM inversion) applied to the measurements made close to source and at Haddenham. The emission estimates derived using the WindTrax and Gaussian plume approaches agree well for the period of intense observations. Applying the Gaussian plume approach to all periods of elevated measurements seen at Haddenham produces year-round and monthly landfill emission estimates. The estimated annual emissions vary between 11.6 and 13.7 Gg CH4 yr−1. The monthly emission estimates are highest in winter (2160 kg hr−1 in February) and lowest in summer (620 kg hr−1 in July). These data identify the effects of environmental conditions on landfill CH4 production and highlight the importance of year-round measurement to capture seasonal variability in CH4 emission. We suggest the landscape inverse modelling approach described in this paper is in good agreement with more labour-intensive near-source approaches and can be used to identify point-sources within an emission landscape to provide high-quality emission estimates.
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    iDirac: a field-portable instrument for long-term autonomous measurements of isoprene and selected VOCs
    (European Geosciences Union, 2020-02-19) Bolas, Conor G.; Ferracci, Valerio; Robinson, Andrew D.; Mead, Mohammed Iqbal; Nadzir, Mohd Shahrul Mohd; Pyle, John A.; Jones, Roderic L.; Harris, Neil
    The iDirac is a new instrument to measure selected hydrocarbons in the remote atmosphere. A robust design is central to its specifications, with portability, power efficiency, low gas consumption and autonomy as the other driving factors in the instrument development. The iDirac is a dual-column isothermal oven gas chromatograph with photoionisation detection (GC-PID). The instrument is designed and built in-house. It features a modular design, with the novel use of open-source technology for accurate instrument control. Currently configured to measure biogenic isoprene, the system is suitable for a range of compounds. For isoprene measurements in the field, the instrument precision (relative standard deviation) is ±10 %, with a limit of detection down to 38 pmol mol−1 (or ppt). The instrument was first tested in the field in 2015 during a ground-based campaign, and has since shown itself suitable for deployment in a variety of environments and platforms. This paper describes the instrument design, operation and performance based on laboratory tests in a controlled environment as well as during deployments in forests in Malaysian Borneo and central England.
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    Seasonal and long term variations of surface ozone concentrations in Malaysian Borneo
    (Elsevier, 2016-08-27) Latif, Mohd Talib; Dominick, Doreena; Ahamad, Fatimah; Ahamad, Nur Shuhada; Khan, Md Firoz; Juneng, Liew; Xiang, Chung Jing; Nadzir, Mohd Shahrul Mohd; Robinson, Andrew D.; Ismail, Marzuki; Mead, Mohammed Iqbal; Harris, Neil
    Malaysian Borneo has a lower population density and is an area known for its lush rainforests. However, changes in pollutant profiles are expected due to increasing urbanisation and commercial-industrial activities. This study aims to determine the variation of surface {O3} concentration recorded at seven selected stations in Malaysian Borneo. Hourly surface {O3} data covering the period 2002 to 2013, obtained from the Malaysian Department of Environment (DOE), were analysed using statistical methods. The results show that the concentrations of {O3} recorded in Malaysian Borneo during the study period were below the maximum Malaysian Air Quality Standard of 100 ppbv. The hourly average and maximum {O3} concentrations of 31 and 92 ppbv reported at Bintulu (S3) respectively were the highest among the {O3} concentrations recorded at the sampling stations. Further investigation on {O3} precursors show that sampling sites located near to local petrochemical industrial activities, such as Bintulu (S3) and Miri (S4), have higher NO2/NO ratios (between 3.21 and 5.67) compared to other stations. The normalised {O3} values recorded at all stations were higher during the weekend compared to weekdays (unlike its precursors) which suggests the influence of {O3} titration by {NO} during weekdays. The results also show that there are distinct seasonal variations in {O3} across Borneo. High surface {O3} concentrations were usually observed between August and September at all stations with the exception of station {S7} on the east coast. Majority of the stations (except {S1} and S6) have recorded increasing averaged maximum concentrations of surface {O3} over the analysed years. Increasing trends of {NO2} and decreasing trends of {NO} influence the yearly averaged maximum of {O3} especially at S3. This study also shows that variations of meteorological factors such as wind speed and direction, humidity and temperature influence the concentration of surface O3.
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    Spatial-temporal variations in surface ozone over Ushuaia and the Antarctic region: observations from in situ measurements, satellite data, and global models
    (Springer, 2017-11-08) Mohd Nadzir, Mohd Shahrul; Ashfold, Matthew J.; Khan, Md Firoz; Robinson, Andrew D.; Bolas, Conor; Latif, Mohd Talib; Wallis, Benjamin M.; Mead, Mohammed Iqbal; Abdul Hamid, Haris Hafizal; Harris, Neil; Ahmad Ramly, Zamzam Tuah; Lai, Goh Thian; Liew, Ju Neng; Ahamad, Fatimah; Uning, Royston; Abu Samah, Azizan; Maulud, Khairul Nizam; Suparta, Wayan; Zainudin, Siti Khalijah; Abdul Wahab, Muhammad Ikram; Mujahid, Aazani; Morris, Kenobi Isima; Dal Sasso, Nicholas; Sahani, Mazrura; Müller, Moritz; Yeok, Foong Swee; Abdul Rahman, Nasaruddin
    The Antarctic continent is known to be an unpopulated region due to its extreme weather and climate conditions. However, the air quality over this continent can be affected by long-lived anthropogenic pollutants from the mainland. The Argentinian region of Ushuaia is often the main source area of accumulated hazardous gases over the Antarctic Peninsula. The main objective of this study is to report the first in situ observations yet known of surface ozone (O3) over Ushuaia, the Drake Passage, and Coastal Antarctic Peninsula (CAP) on board the RV Australis during the Malaysian Antarctic Scientific Expedition Cruise 2016 (MASEC’16). Hourly O3 data was measured continuously for 23 days using an EcoTech O3 analyzer. To understand more about the distribution of surface O3 over the Antarctic, we present the spatial and temporal of surface O3 of long-term data (2009–2015) obtained online from the World Meteorology Organization of World Data Centre for greenhouse gases (WMO WDCGG). Furthermore, surface O3 satellite data from the free online NOAA-Atmospheric Infrared Sounder (AIRS) database and online data assimilation from the European Centre for Medium-Range Weather Forecasts (ECMWF)-Monitoring Atmospheric Composition and Climate (MACC) were used. The data from both online products are compared to document the data sets and to give an indication of its quality towards in situ data. Finally, we used past carbon monoxide (CO) data as a proxy of surface O3 formation over Ushuaia and the Antarctic region. Our key findings were that the surface O3 mixing ratio during MASEC’16 increased from a minimum of 5 ppb to ~ 10–13 ppb approaching the Drake Passage and the Coastal Antarctic Peninsula (CAP) region. The anthropogenic and biogenic O3 precursors from Ushuaia and the marine region influenced the mixing ratio of surface O3 over the Drake Passage and CAP region. The past data from WDCGG showed that the annual O3 cycle has a maximum during the winter of 30 to 35 ppb between June and August and a minimum during the summer (January to February) of 10 to 20 ppb. The surface O3 mixing ratio during the summer was controlled by photochemical processes in the presence of sunlight, leading to the depletion process. During the winter, the photochemical production of surface O3 was more dominant. The NOAA-AIRS and ECMWF-MACC analysis agreed well with the MASEC’16 data but twice were higher during the expedition period. Finally, the CO past data showed the surface O3 mixing ratio was influenced by the CO mixing ratio over both the Ushuaia and Antarctic regions. Peak surface O3 and CO hourly mixing ratios reached up to ~ 38 ppb (O3) and ~ 500 ppb (CO) over Ushuaia. High CO over Ushuaia led to the depletion process of surface O3 over the region. Monthly CO mixing ratio over Antarctic (South Pole) were low, leading to the production of surface O3 over the Antarctic region.