J. R. Drummond

Dalhousie University, Halifax, Nova Scotia, Canada

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Publications (343)430.5 Total impact

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    ABSTRACT: We present measurements of a long-range smoke transport event recorded on 20–21 July 2011 over Halifax, Nova Scotia, Canada, during the Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites (BORTAS-B) campaign. Ground-based Fourier transform spectrometers and photometers detected air masses associated with large wild-land fires burning in eastern Manitoba and western Ontario. We investigate a plume with high trace gas amounts but low amounts of particles that preceded and overlapped at the Halifax site with a second plume with high trace gas loadings and significant amounts of particulate material. We show that the first plume experienced a meteorological scavenging event, but the second plume had not been similarly scavenged. This points to the necessity to account carefully for the plume history when considering long-range transport since simultaneous or near-simultaneous times of arrival are not necessarily indicative of either similar trajectories or meteorological history. We investigate the origin of the scavenged plume, and the possibility of an aerosol wet deposition event occurring in the plume ∼ 24 h prior to the measurements over Halifax. The region of lofting and scavenging is only monitored on an intermittent basis by the present ob-serving network, and thus we must consider many different pieces of evidence in an effort to understand the early dynamics of the plume. Through this discussion we also demonstrate the value of having many simultaneous remote-sensing measurements in order to understand the physical and chemical behaviour of biomass burning plumes.
    ATMOSPHERIC CHEMISTRY AND PHYSICS 08/2014; 14:8449-8460. · 5.51 Impact Factor
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    ABSTRACT: We present measurements of a long range smoke transport event recorded on 20–21 July 2011 over Halifax, Nova Scotia, Canada, during the Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites (BORTAS-B) campaign. Ground-based Fourier transform spectrometers and photometers detected air masses associated with large wildland fires burning in eastern Manitoba and western Ontario. We investigate a plume with high trace gas amounts but low amounts of particles that preceded and overlapped at the Halifax site with a second plume with high trace gas loadings and significant amounts of particulate material. We show that the first plume experienced a meteorological scavenging event but the second plume had not been similarly scavenged. This points to the necessity to account carefully for the plume history when considering long range transport since simultaneous or near-simultaneous times of arrival are not necessarily indicative of either similar trajectories or meteorological history. We investigate the origin of the scavenged plume, and the possibility of an aerosol wet deposition event occurring in the plume ~24 h prior to the measurements over Halifax. The region of lofting and scavenging is only monitored on an intermittent basis by the present observing network, and thus we must consider many different pieces of evidence in an effort to understand the early dynamics of the plume. Through this discussion we also demonstrate the value of having many simultaneous remote-sensing measurements in order to understand the physical and chemical behaviour of biomass burning plumes.
    ATMOSPHERIC CHEMISTRY AND PHYSICS DISCUSSIONS. 02/2014; 14:3395-3426.
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    ABSTRACT: In August 2010, simultaneous enhancements of aerosol optical depth and total columns of carbon monoxide (CO), hydrogen cyanide (HCN), and ethane (C2H6) were observed at the Polar Environment Atmospheric Research Laboratory (PEARL, 80.05°N, −86.42°W, 0.61 km above sea level, Eureka, Nunavut, Canada). Moderate Resolution Imaging Spectroradiometer (MODIS) hot spots, Ozone Monitoring Instrument (OMI) aerosol index maps, and Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) back-trajectories were used to attribute these enhancements to an intense boreal fire event occurring in Russia. A ground-based Fourier Transform InfraRed (FTIR) spectrometer at PEARL provided vertically integrated measurements of trace gases transported in smoke plumes. We derived HCN and C2H6 equivalent emission ratios with respect to CO of 0.0054 ± 0.0022 and 0.0108 ± 0.0036, respectively, and converted them into equivalent emission factors of 0.66 ± 0.27 g kg−1 and 1.47 ± 0.50 g kg−1 (in grams of gas per kilogram of dry biomass burnt, with one-sigma uncertainties). These emission factors add new observations to the relatively sparse datasets available and can be used to improve the simulation of biomass burning fire emissions in chemical transport models. These emission factors for the boreal forest are in agreement with the mean values recently reported in a compilation study.
    Atmosphere-ocean 12/2013; 51(5). · 1.67 Impact Factor
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    ABSTRACT: We present the results of total column measurements of CO, C2 H6 and fine-mode aerosol optical depth (AOD) during the “Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites” (BORTAS-B) campaign over eastern Canada. Ground-based observations, using Fourier transform spectrometers (FTSs) and sun photometers, were carried out in July and August 2011. These measurements were taken in Halifax, Nova Scotia, which is an ideal location to monitor the outflow of boreal fires from North America, and also in Toronto, Ontario. Measurements of fine-mode AOD enhancements were highly correlated with enhancements in coincident trace gas (CO and C2H6) observations between 19 and 21 July 2011, which is typical for a smoke plume event. In this paper, we focus on the identification of the origin and the transport of this smoke plume. We use back trajectories calculated by the Canadian Meteorological Centre as well as FLEXPART forward trajectories to demonstrate that the enhanced CO, C2H6 and fine-mode AOD seen near Halifax and Toronto originated from forest fires in northwestern Ontario that occurred between 17 and 19 July 2011. In addition, total column measurements of CO from the satellite-borne Infrared Atmospheric Sounding Interferometer (IASI) have been used to trace the smoke plume and to confirm the origin of the CO enhancement. Furthermore, the enhancement ratio – that is, in this case equivalent to the emission ratio (ERC2 H6 /CO) – was estimated from these ground- based observations. These C2 H6 emission results from boreal fires in northwestern Ontario agree well with C2H6 emission measurements from other boreal regions, and are relatively high compared to fires from other geographical regions. The ground-based CO and C2H6 observations were compared with outputs from the 3-D global chemical trans- port model GEOS-Chem, using the Fire Locating And Modeling of Burning Emissions (FLAMBE) inventory. Agreement within the stated measurement uncertainty (∼ 3 % for CO and ∼ 8 % for C2H6) was found for the magnitude of the enhancement of the CO and C2H6 total columns between the measured and modelled results. However, there is a small shift in time (of approximately 6 h) of arrival of the plume over Halifax between the results.
    ATMOSPHERIC CHEMISTRY AND PHYSICS 10/2013; 13:10227-10241. · 5.51 Impact Factor
  • P. F. Fogal, Lisa M. LeBlanc, James R. Drummond
    Arctic. 09/2013; 66(3):377.
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    ABSTRACT: We describe the design and execution of the BORTAS (Quantifying the impact of BOReal forest fires on Tropospheric oxidants using Aircraft and Satellites) experiment, which has the overarching objective of understanding the chemical aging of airmasses that contain the emission products from seasonal boreal wildfires and how these airmasses subsequently impact downwind atmospheric composition. The central focus of the experiment was a two-week deployment of the UK BAe-146-301 Atmospheric Research Aircraft (ARA) over eastern Canada. The planned July 2010 deployment of the ARA was postponed by 12 months because of activities related to the dispersal of material emitted by the Eyjafjallajo¨kull volcano. However, most other planned model and measurement activities, including ground-based measurements at the Dalhousie University Ground Station (DGS), enhanced ozonesonde launches, and measurements at the Pico Atmospheric Observatory in the Azores, went ahead and constituted phase A of the experiment. Phase B of BORTAS in July 2011 included the same measurements, but included the ARA, special satellite observations and a more comprehensive measurement suite at the DGS. The high-frequency aircraft data provided a comprehensive snapshot of the pyrogenic plumes from wildfires. The coordinated ground-based and sonde data provided detailed but spatially-limited information that put the aircraft data into context of the longer burning season. We coordinated aircraft vertical profiles and overpasses of the NASA Tropospheric Emission Spectrometer and the Canadian Atmospheric Chemistry Experiment. These space-borne data, while less precise than other data, helped to relate the two-week measurement campaign to larger geographical and longer temporal scales. We interpret these data using a range of chemistry models: from a near-explicit gas-phase chemical mechanism, which tests out under standing of the underlying chemical mechanism, to regional and global 3-D models of atmospheric transport and lumped chemistry, which helps to assess the performance of the simplified chemical mechanism and effectively act as intermediaries between different measurement types. We also present an overview of some of the new science that has originated from this project from the mission planning and execution to the analysis of the ground-based, aircraft, and space-borne data.
    ATMOSPHERIC CHEMISTRY AND PHYSICS 07/2013; 13:6239-6261. · 5.51 Impact Factor
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    ABSTRACT: This presentation will describe the use of ground-based FTIR spectroscopy to measure atmospheric composition. It will focus on measurements made at the UofT Atmospheric Observatory and the high-Arctic PEARL facility, and introduce a new Canadian FTIR network.
    Fourier Transform Spectroscopy; 06/2013
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    ABSTRACT: The Extended-range Atmospheric Emitted Radiance Interferometer (E-AERI) was installed at the Polar Environment Atmospheric Research Laboratory (PEARL) at Eureka, Nunavut, Canada in October 2008. Spectra from the E-AERI provide information about the radiative balance and budgets of trace gases in the Canadian high Arctic. Measurements are taken every 7 min year-round, including polar night when the solar-viewing spectrometers at PEARL are not operated. This allows E-AERI measurements to fill the gap in the PEARL dataset during the four months of polar night. Measurements were taken year-round in 2008-2009 at the PEARL Ridge Lab, which is 610 m a.s.l. (above sea-level), and from 2011 onwards at the Zero-Altitude PEARL Auxiliary Lab (0PAL), which is at sea level 15 km from the Ridge Lab. Total columns of O3, CO, CH4, and N2O have been retrieved using a modified version of the SFIT2 retrieval algorithm adapted for emission spectra. This provides the first ground-based nighttime measurements of these species at Eureka. Changes in the total columns driven by photochemistry and dynamics are observed. Analyses of E-AERI retrievals indicate accurate spectral fits (root-mean-square residuals consistent with noise) and a 10-15% uncertainty in the total column, depending on the trace gas. O3 comparisons between the E-AERI and a Bruker IFS 125HR Fourier transform infrared (FTIR) spectrometer, three Brewer spectrophotometers, two UV-visible ground-based spectrometers, and a System D'Analyse par Observations Zenithales (SAOZ) at PEARL are made from 2008-2009 and for 2011. 125HR CO, CH4, and N2O columns are also compared with the E-AERI measurements. Mean relative differences between the E-AERI and the other spectrometers are 1-10% (14% is for the un-smoothed profiles), which are less than the E-AERI's total column uncertainties. The E-AERI O3 and CO measurements are well correlated with the other spectrometers (r > 0.92 with the 125HR). The 24 h diurnal cycle and 365-day seasonal cycle of CO are observed and their amplitudes are quantified by the E-AERI (6-12 and 46%, respectively). The seasonal variability of H2O has an impact on the retrievals, leading to larger uncertainties in the summer months. Despite increased water vapour at the lower-altitude site 0PAL, measurements at 0PAL are consistent with measurements at PEARL.
    Atmospheric Measurement Techniques 06/2013; 6(6):1549-1565. · 3.21 Impact Factor
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    ABSTRACT: Wild fires started by lightning are a significant source of carbonaceous aerosols and trace gases to the atmosphere. Careful observations of biomass burning plumes are required to quantify the long range transport and chemical evolution of the outflow from these fires. During the summer of 2011 an international effort - the Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites (BORTAS) project - led by the University of Edinburgh, evaluated the chemistry and dynamics of Boreal biomass burning plumes through aircraft, satellite, and ground-based measurements. The Dalhousie Ground Station (DGS), located in Halifax, Nova Scotia, provided ground support to the BORTAS campaign. Two Fourier Transform Spectrometers (FTSs) provided solar absorption measurements of trace gases while two photometers provided aerosol optical depths. On 20 July 2011 a plume of elevated carbon monoxide and other trace gases was detected by the FTS instruments at the DGS; however, particulate data gathered from the co-located sun photometer and the Dalhousie Raman Lidar system showed no enhancement of fine-mode aerosol for the initial 7 hours of the event. After that time, particulates increased in abundance and a peak aerosol optical depth of 2.3 was measured on 21 July. FLEXPART trajectory analyses suggest that this plume originated in fires that were burning in Northwestern Ontario and Eastern Manitoba from 17 to 19 July. Despite the sparse observing network in the region, there is ample evidence of a significant lofting event via the same meso-scale convective system that tempered the burning on the 19th. We will provide an overview of this event and present evidence that precipitation scavenging was the most likely mechanism for the observed aerosol/trace gas anomaly. Support for this this research was provided by the Canadian Space Agency (CSA) and the Natural Sciences and Engineering Research Council of Canada.
    04/2013;
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    ABSTRACT: The Measurement of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation (MAESTRO) spectrophotometer on the SCISAT satellite is a simple, compact instrument for the measurement of atmospheric extinction, ozone, nitrogen dioxide and other trace gases in the stratosphere and upper troposphere as part of the Atmospheric Chemistry Experiment (ACE) mission. The following pages provide an overview of the instrument from its heritage and performance requirements to its realization, including optical design, pre_launch and on_orbit performance and includes some retrieved profiles of O3, NO2 and aerosol.
    The atmospheric chemistry experiment ACE at 10, 1 edited by P.F Bernath, 02/2013: chapter Chapter 5: pages 81-101; A. Deepak Publishing., ISBN: 978-0-937194--54-6
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    ABSTRACT: The Atmospheric Chemistry Experiment (ACE) Measurement of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation (MAESTRO) instrument on the SCISAT satellite collects solar occultation spectra that can be used to derive profiles of atmospheric pressure and temperature using absorption the A- and B-band bands of molecular oxygen. These retrievals are performed with a global fit that simultaneously fits all spectra from a single occultation to determine a density profile, which is then used to determine pressure and temperature. The forward model uses a fast line-by-line calculation and correlated-k technique to accurately model atmospheric absorption and the nonlinear saturation effects in the occultation geometry. The algorithm is applied to several occultation observations in Arctic winter, spring, and the tropics, and during the Eureka 2004 and 2005 ACE validation campaigns. Comparisons with the ACE-FTS (Fourier Transform Spectrometer) and coincident radiosondes show mean biases between MAESTRO profiles of 2 to 5% in pressure and less than 5 K in temperature.
    The atmospheric chemistry experiment ACE at 10, 1 edited by P.F Bernath, 02/2013: chapter Chaper 18: pages 261-270; A. Deepak Publishing., ISBN: 978-0-937194--54-6
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    ABSTRACT: The Extended-range Atmospheric Emitted Radiance Interferometer (E-AERI) was installed at the Polar Environment Atmospheric Research Laboratory (PEARL) at Eureka, Nunavut, Canada in October 2008. Spectra from the E-AERI provide information about the radiative balance and budgets of trace gases in the Canadian high Arctic. Measurements are taken every seven minutes year-round, including polar night when the solar-viewing spectrometers at PEARL are not operated. This allows E-AERI measurements to fill the gap in the PEARL dataset during the four months of polar night. Measurements were taken year-round in 2008-2009 at the PEARL Ridge Lab, which is 610 m above sea-level, and from 2011-onwards at the Zero-Altitude PEARL Auxiliary Lab (0PAL), which is 15 km from the Ridge Lab at sea level. Total columns of O3, CO, CH4, and N2O have been retrieved using a modified version of the SFIT2 retrieval algorithm adapted for emission spectra. This provides the first nighttime measurements of these species at Eureka. Changes in the total columns driven by photochemistry and dynamics are observed. Analyses of E-AERI retrievals indicate accurate spectral fits (root-mean-square residuals < 1.5%) and a 10-15% uncertainty in the total column, depending on the trace gas. O3 comparisons between the E-AERI and a Bruker IFS 125HR Fourier transform infrared (FTIR) spectrometer, three Brewer spectrophotometers, two UV-visible ground-based spectrometers, and a System D'Analyse par Observations Zenithales (SAOZ) at PEARL are made from 2008-2009 and for 2011. 125HR CO, CH4, and N2O columns are also compared with the E-AERI measurements. Mean relative differences between the E-AERI and the other spectrometers are 1-14% (depending on the gas), which are less than the E-AERI's total column uncertainties. The E-AERI O3 and CO measurements are well correlated with the other spectrometers; the best correlation is with the 125HR (r > 0.92). The 24-h diurnal cycle and 365-day seasonal cycle of CO are observed and their amplitudes are quantified by the E-AERI (6-12% and 46%, respectively). The seasonal variability of H2O has an impact on the retrievals, leading to larger uncertainties in the summer months. Despite increased water vapour at the lower-altitude site 0PAL, measurements at 0PAL are consistent with measurements at PEARL.
    Atmospheric Measurement Techniques Discussions. 01/2013; 6(1):547-586.
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    ABSTRACT: Atmospheric carbon monoxide (CO) distributions are controlled by anthropogenic emissions, biomass burning, transport and oxidation by reaction with the hydroxyl radical (OH). Quantifying trends in CO is therefore important for understanding changes related to all of these contributions. Here we present a comprehensive record of satellite observations from 2000 through 2011 of total column CO using the available measurements from nadir-viewing thermal infrared instruments: MOPITT, AIRS, TES and IASI. We examine trends for CO in the Northern and Southern Hemispheres along with regional trends for Eastern China, Eastern USA, Europe and India. We find that all the satellite observations are consistent with a modest decreasing trend ∼-1% yr-1 in total column CO over the Northern Hemisphere for this time period and a less significant, but still decreasing trend in the Southern Hemisphere. Although decreasing trends in the United States and Europe have been observed from surface CO measurements, we also find a decrease in CO over E. China that, to our knowledge, has not been reported previously. Some of the interannual variability in the observations can be explained by global fire emissions, but the overall decrease needs further study to understand the implications for changes in anthropogenic emissions.
    Atmospheric Chemistry and Physics 01/2013; 13(2):837-850. · 4.88 Impact Factor
  • Glen Lesins, Thomas J. Duck, James R. Drummond
    Journal of Climate 12/2012; 25(23):8277-8288. · 4.36 Impact Factor
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    ABSTRACT: The Extended-range Atmospheric Emitted Radiance Interferometer (E-AERI) is a moderate resolution (1 cm-1) Fourier transform infrared spectrometer for measuring the absolute downwelling infrared spectral radiance from the atmosphere between 400 and 3000 cm-1. The extended spectral range of the instrument permits monitoring of the 400-550 cm-1 (20-25 μm) region, where much of the infrared surface cooling currently occurs in the dry air of the Arctic. The E-AERI provides information about radiative balance, trace gases, and cloud properties in the Canadian high Arctic. The instrument was installed at the Polar Environment Atmospheric Research Laboratory (PEARL) Ridge Lab at Eureka, Nunavut, in October 2008. Measurements are taken every seven minutes year-round (precipitation permitting), including polar night when the solar-viewing spectrometers are not operated. A similar instrument, the University of Idaho's Polar AERI (P-AERI), was installed at the Zero-altitude PEARL Auxiliary Laboratory (0PAL), 15 km away from the Ridge Lab, from March 2006 to June 2009. During the period of overlap, these two instruments provided calibrated radiance measurements from two different altitudes. Retrievals of total columns of various trace gases are being evaluated using a prototype version of the retrieval algorithm SFIT2 modified to analyze emission features. In contrast to solar absorption measurements of atmospheric trace gases, which depend on sunlit clear-sky conditions, the use of emission spectra allows measurements year-round (except during precipitation events or when clouds are present). This capability allows the E-AERI to provide temporal coverage throughout the four months of polar night and to measure the radiative budget throughout the entire year. This presentation will describe the new E-AERI instrument, its performance evaluations, and clear sky vs. cloudy measurements.
    Proc SPIE 11/2012;
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    ABSTRACT: The advanced E-Region Wind Interferometer (ERWIN II) combines the imaging capabilities of a CCD detector with the wide field associated with field widened Michelson interferometry. This instrument is capable of simultaneous multi-directional wind observations for three different airglow emissions (oxygen green line (O(1S)), the PQ(7) and PP(7) emission lines in the O2(0-1) atmospheric band and P1(3) emission line in the (6,2) hydroxyl Meinel band) on a three minute cadence. In each direction, for 45 s measurements for typical airglow brightness the instrument is capable of line-of-sight wind precisions of ~ 1 m s-1 for hydroxyl and O(1S) and ~ 4 m s-1 for O2. This precision is achieved using a new data analysis algorithm which takes advantage of the imaging capabilities of the CCD detector along with knowledge of the instrument phase variation as a function of pixel location across the detector. This instrument is currently located in Eureka, Nunavut as part of the Polar Environment Atmospheric Research Laboratory (PEARL). The details of the physical configuration, the data analysis algorithm, the measurement calibration and validation of the observations are described. Field measurements which demonstrate the capabilities of this instrument are presented. To our knowledge, the wind determinations with this instrument are the most accurate and have the highest observational cadence for airglow wind observations of this region of the atmosphere and match the capabilities of other wind measuring techniques.
    Atmospheric Measurement Techniques 11/2012; 5(6):8271-8311. · 3.21 Impact Factor
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    ABSTRACT: In spring 2011, the Arctic polar vortex was stronger than in any other year on record. As the polar vortex started to break up in April, ozone and NO2 columns were measured with UV-visible spectrometers above the Polar Environment Atmospheric Research Laboratory (PEARL) in Eureka, Canada (80.05° N, 86.42° W) using the differential optical absorption spectroscopy (DOAS) technique. These ground-based column measurements were complemented by Ozone Monitoring Instrument (OMI) and Optical Spectrograph and Infra-Red Imager System (OSIRIS) satellite measurements, Global Modeling Initiative (GMI) simulations, and dynamical parameters. On 8 April 2011, NO2 columns above PEARL from the DOAS, OMI, and GMI datasets were approximately twice as large as in previous years. On this day, temperatures and ozone volume mixing ratios above Eureka were high, suggesting enhanced chemical production of NO2 from NO. Additionally, GMI NOx and N2O fields suggest that downward transport along the vortex edge and horizontal transport from lower latitudes also contributed to the enhanced NO2. The anticyclone that transported lower-latitude NOx above PEARL became frozen-in and persisted in dynamical and GMI N2O fields until the end of the measurement period on 31 May 2011. Ozone isolated within this frozen-in anticyclone (FrIAC) in the middle stratosphere was depleted due to reactions with the enhanced NOx. Ozone loss was calculated using the passive tracer technique, with passive ozone profiles from the Lagrangian Chemistry and Transport Model, ATLAS. At 600 K, ozone losses between 1 December 2010 and 20 May 2011 reached 4.2 parts per million by volume (ppmv) (58%) and 4.4 ppmv (61%), when calculated using GMI and OSIRIS ozone profiles, respectively. This middle-stratosphere gas-phase ozone loss led to a more rapid decrease in ozone column amounts in April/May 2011 compared with previous years. Ground-based, OMI, and GMI ozone total columns within the FrIAC all decreased by more than 100 DU from 15 April to 20 May. Two lows in the ozone columns were also investigated and were attributed to a vortex remnant passing above Eureka at ~500 K on 12/13 May and an ozone mini-hole on 22/23 May.
    Atmospheric Chemistry and Physics 08/2012; 12(8):20033-20072. · 4.88 Impact Factor
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    ABSTRACT: The Canadian Network for the Detection of Atmospheric Change and Environment Canada DIAL lidar located at the Polar Environment Atmospheric Research Laboratory (PEARL) in Eureka, Nunavut has been upgraded to measure water vapour mixing ratio profiles at 150 m vertical resolution. The system is capable of measuring water vapour in the dry arctic atmosphere up to the tropopause region. Measurements were obtained in the February to March polar sunrise during 2007, 2008 and 2009 as part of the Canadian Arctic ACE Validation Campaign. Before such measurements can be used to address important questions in understanding dynamics and chemistry, the lidar measurements must be calibrated against an independent determination of water vapour. Here, radiosonde measurements of relative humidity have been used to calibrate the lidar measurements. It was found that the calibration varied significantly between each campaign. However, the calibration of the lidar during an individual polar sunrise campaign agrees with the local radiosonde measurements to better than 12% below 6 km altitude. To independently validate the calibration of the lidar derived from the radiosondes, comparisons are made between the calibrated lidar measurements and water vapour measurements from the Atmospheric Chemistry Experiment satellite-borne Fourier Transform Spectrometer. The comparisons between the lidar and satellite for both campaign averages and single overpasses show favourable agreement between the two instruments and help validate the comparison with the radiosondes.
    Atmospheric Measurement Techniques 08/2012; 5(4):5665-5689. · 3.21 Impact Factor
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    ABSTRACT: As a consequence of dynamically variable meteorological conditions, springtime Arctic ozone levels exhibit significant interannual variability in the lower stratosphere. In winter 2011, the polar vortex was strong and cold for an unusually long time. Our research site, located at Eureka, Nunavut, Canada (80.05° N, 86.42° W), was mostly inside the vortex from October 2010 until late March 2011. The Bruker 125HR Fourier transform infrared spectrometer installed at the Polar Environment Atmospheric Research Laboratory at Eureka acquired measurements from 23 February to 6 April during the 2011 Canadian Arctic Atmospheric Chemistry Experiment Validation Campaign. These measurements showed unusually low ozone, HCl, and HNO3 total columns compared to the previous 14 yr. To remove dynamical effects, we normalized these total columns by the HF total column. The normalized values of the ozone, HCl, and HNO3 total columns were smaller than those from previous years, and confirmed the occurrence of chlorine activation and chemical ozone depletion. To quantify the chemical ozone loss, a three-dimensional chemical transport model, SLIMCAT, and the passive subtraction method were used. The chemical ozone depletion was calculated as the mean percentage difference between the measured ozone and the SLIMCAT passive ozone, and was found to be 35%.
    ATMOSPHERIC CHEMISTRY AND PHYSICS 04/2012; 12(8):3821-3835. · 5.51 Impact Factor

Publication Stats

3k Citations
430.50 Total Impact Points

Institutions

  • 2006–2014
    • Dalhousie University
      • Department of Physics and Atmospheric Science
      Halifax, Nova Scotia, Canada
  • 1985–2012
    • University of Toronto
      • Department of Physics
      Toronto, Ontario, Canada
  • 2005
    • National Center for Atmospheric Research
      • Division of Atmospheric Chemistry
      Boulder, Colorado, United States
    • National Institute of Standards and Technology
      Maryland, United States
  • 1998
    • University of Colorado at Boulder
      • Department of Chemistry and Biochemistry
      Boulder, CO, United States