A5057056367- Atmospheric chemistry and aerosols
- Atmospheric aerosols and clouds
- Atmospheric Ozone and Climate
- Atmospheric and Environmental Gas Dynamics
- Air Quality and Health Impacts
- Aeolian processes and effects
- Marine and coastal ecosystems
- Radioactive contamination and transfer
- Maritime Transport Emissions and Efficiency
- Air Quality Monitoring and Forecasting
- Advanced Aircraft Design and Technologies
- Meteorological Phenomena and Simulations
- Ocean Acidification Effects and Responses
- Vehicle emissions and performance
- Climate change and permafrost
- Particle Dynamics in Fluid Flows
- Odor and Emission Control Technologies
- Arctic and Russian Policy Studies
- Spacecraft and Cryogenic Technologies
- Icing and De-icing Technologies
- Arctic and Antarctic ice dynamics
- Methane Hydrates and Related Phenomena
- Oil Spill Detection and Mitigation
- Silicone and Siloxane Chemistry
- Toxic Organic Pollutants Impact
Dalhousie University
2015-2024
Washington University in St. Louis
2022-2024
Abstract. This paper introduces and evaluates the second version of global aerosol-climate model ECHAM-HAM. Major changes have been brought into model, including new parameterizations for aerosol nucleation water uptake, an explicit treatment secondary organic aerosols, modified emission calculations sea salt mineral dust, coupling microphysics to a two-moment stratiform cloud scheme, alternative wet scavenging parameterizations. These revisions extend model's capability represent details...
Abstract. Motivated by the need to predict how Arctic atmosphere will change in a warming world, this article summarizes recent advances made research consortium NETCARE (Network on Climate and Aerosols: Addressing Key Uncertainties Remote Canadian Environments) that contribute our fundamental understanding of aerosol particles as they relate climate forcing. The overall goal has been use an interdisciplinary approach encompassing extensive field observations range chemical transport, earth...
Abstract. Atmospheric marine aerosol particles impact Earth's albedo and climate. These can be primary or secondary come from a variety of sources, including sea salt, dissolved organic matter, volatile compounds, sulfur-containing compounds. Dimethylsulfide (DMS) emissions contribute greatly to the global biogenic sulfur budget, its oxidation products mass, specifically as sulfuric acid methanesulfonic (MSA). Further, is known nucleating compound, MSA may able participate in nucleation when...
Abstract. Measurements at high-Arctic sites (Alert, Nunavut, and Mt. Zeppelin, Svalbard) during the years 2011 to 2013 show a strong similar annual cycle in aerosol number size distributions. Each year both sites, of aerosols with diameters larger than 20 nm exhibits minimum October two maxima, one spring associated dominant accumulation mode (particles 100 500 diameter) second summer Aitken diameter). Seasonal-mean effective diameter from measurements ranges about 180 260 winter. This study...
Abstract. Wet deposition processes are highly efficient in the removal of aerosols from atmosphere, and thus strongly influence global aerosol concentrations, clouds, their respective radiative forcings. In this study, physically detailed size-dependent below-cloud scavenging parameterizations for rain snow implemented ECHAM5-HAM aerosol-climate model. Previously, by was simply a function mode, then scaled rainfall rate. The snowfall rate alone. mean optical depth, sea salt burden sensitive...
Abstract Arctic observations show large decreases in the concentrations of sulfate and black carbon (BC) aerosols since early 1980s. These near‐term climate‐forcing pollutants perturb radiative balance atmosphere may have played an important role recent warming. We use GEOS‐Chem global chemical transport model to construct a 3‐D representation that is generally consistent with their trends from 1980 2010. Observations at surface sites significant BC mass 2–3% per year. find anthropogenic...
Abstract. A diagnostic cloud nucleation scavenging scheme, which determines stratiform ratios for both aerosol mass and number distributions, based on droplet, ice crystal concentrations, is introduced into the ECHAM5-HAM global climate model. This scheme coupled with a size-dependent in-cloud impaction parameterization droplet-aerosol, crystal-aerosol collisions. The scavenged in clouds found to be primarily (>90%) by processes all species, except dust (50%). attributed impaction. 99% of...
The Arctic region is vulnerable to climate change and able affect global climate. summertime atmosphere pristine strongly influenced by natural regional emissions, which have poorly understood impacts related atmospheric particles clouds. Here we show that ammonia from seabird-colony guano a key factor contributing bursts of newly formed particles, are observed every summer in the near-surface at Alert, Nunavut, Canada. Our chemical-transport model simulations indicate pan-Arctic...
Abstract. Continuous hourly measurements of gas-phase ammonia (NH3(g)) were taken from 13 July to 7 August 2014 on a research cruise throughout Baffin Bay and the eastern Canadian Arctic Archipelago. Concentrations ranged 30 650 ng m−3 (40–870 pptv) with highest values recorded in Lancaster Sound (74°13′ N, 84°00′ W). Simultaneous total ammonium ([NHx]), pH temperature ocean melt ponds used compute compensation point (χ), which is ambient NH3(g) concentration at surface–air fluxes change...
Abstract. Aerosols have important impacts on air quality and climate, but the processes affecting their removal from atmosphere are not fully understood poorly constrained by observations. This makes modelled aerosol lifetimes uncertain. In this study, we make use of an observational constraint provided radionuclide measurements investigate causes differences within a set global models. During Fukushima Dai-Ichi nuclear power plant accident March 2011, radioactive isotopes cesium-137 (137Cs)...
Abstract The Arctic warms nearly four times faster than the global average, and aerosols play an increasingly important role in climate change. In Arctic, sea salt is a major aerosol component terms of mass concentration during winter spring. However, mechanisms production remain unclear. Sea are typically thought to be relatively large size but low number concentration, implying that their influence on cloud condensation nuclei population properties generally minor. Here we present...
Abstract. Dimethyl sulfide (DMS) plays a major role in the global sulfur cycle. In addition, its atmospheric oxidation products contribute to formation and growth of aerosol particles, thereby influencing cloud condensation nuclei (CCN) populations thus formation. The pristine summertime Arctic atmosphere is strongly influenced by DMS. However, DMS mixing ratios have only rarely been measured Arctic. During July–August, 2014, we conducted first high time resolution (10 Hz) ratio measurements...
Abstract. Summertime Arctic aerosol size distributions are strongly controlled by natural regional emissions. Within this context, we use a chemical transport model with size-resolved microphysics (GEOS-Chem-TOMAS) to interpret measurements of from the Canadian Archipelago during summer 2016, as part “NETwork on Climate and Aerosols: Addressing key uncertainties in Remote Environments” (NETCARE) project. Our simulations suggest that condensation secondary organic (SOA) precursor vapors...
Abstract. Black carbon (BC) particles in the atmosphere have important impacts on climate. The amount of BC must be carefully quantified to allow evaluation climate effects this type aerosol. In study, we present treatment aerosol developmental version 4th generation Canadian Centre for Climate modelling and analysis (CCCma) atmospheric general circulation model (AGCM). focus work is conversion insoluble soluble/mixed by physical chemical ageing. Physical processes include condensation...
Abstract. An explicit and detailed representation of in-droplet in-crystal aerosol particles in stratiform clouds has been introduced the global aerosol-climate model ECHAM5-HAM. The new scheme allows an evaluation cloud cycling aerosols estimation relative contributions nucleation collision scavenging, as opposed to evaporation hydrometeors processing by clouds. On average particle is cycled through 0.5 times. leads important changes simulated fraction scavenged clouds, consequently wet...
Abstract. The uncertainties associated with the wet removal of aerosols entrained above convective cloud bases are investigated in a global aerosol-climate model (ECHAM5-HAM) under set limiting assumptions for aerosols. negligible scavenging and vigorous (either through activation, size-dependent impaction scavenging, or prescribed fractions standard model). To facilitate this process-based study, an explicit representation cloud-droplet-borne ice-crystal-borne aerosol mass number, purpose...
Abstract. In this paper, we investigate the coagulation of interstitial aerosol particles (particles too small to activate cloud droplets) with drops, a process often ignored in aerosol-climate models. We use GEOS-Chem-TOMAS (Goddard Earth Observing System-Chemistry TwO-Moment Aerosol Sectional) global chemical transport model microphysics calculate changes size distribution, cloud-albedo indirect effect, and direct effect due process. find that inclusion clouds lowers total particle number...
Abstract From 17–22 August 2017 simultaneous enhancements of ammonia (NH 3 ), carbon monoxide (CO), hydrogen cyanide (HCN), and ethane (C 2 H 6 ) were detected from ground‐based solar absorption Fourier transform infrared (FTIR) spectroscopic measurements at two high‐Arctic sites: Eureka (80.05°N, 86.42°W) Nunavut, Canada, Thule (76.53°N, 68.74°W), Greenland. These attributed to wildfires in British Columbia the Northwest Territories Canada using FLEXPART back‐trajectories fire locations...
Abstract Collection efficiency E experiments for aerosol particles scavenged by cloud droplets were carried out in the newly built Collision Ice Nucleation Chamber (CLINCH). Pure water having radii between 12.8 and 20.0 μm allowed to fall freely collide a laminar flow with lithium metaborate 0.05 0.33 μm. At bottom of chamber, captured collected using cup impactor. The solution was analyzed mass inductively coupled plasma spectrometry. Evaporation taken into account since relative humidity...
Atmospheric models of secondary organic aerosol (OA) (SOA) typically rely on parameters derived from environmental chambers. Chambers are subject to experimental artifacts, including losses (1) particles the walls (PWL), (2) vapors wall (V2PWL), and (3) directly (VWL). We present a method for deriving artifact-corrected SOA translating these volatility basis set (VBS) use in chemical transport (CTMs). Our process involves combining box model that accounts chamber artifacts (Statistical...
Abstract. Aerosol removal processes control global aerosol abundance, but the rate of that remains uncertain. A recent study aerosol-bound radionuclide measurements after Fukushima Daiichi nuclear power plant accident documents 137Cs (e-folding) times 10.0–13.9 days, suggesting mean lifetimes in range 3–7 days models might be too short by a factor two. In this study, we attribute discrepancy to differences between e-folding and lifetimes. We implement simulation 133Xe into GEOS-Chem chemical...
Abstract Historically, cargo ships have been powered by low-grade fossil fuels, which emit particles and particle-precursor vapors that impact human health climate. We used a global chemical-transport model with online aerosol microphysics (GEOS-Chem-TOMAS) to estimate the climate impacts of four emission-control policies: (1) 85% reduction in sulfur oxide (SO x ) emissions (Sulf); (2) SO black carbon (BC) (Sulf-BC); (3) , BC, organic (OA) (Sulf-BC-OA); (4) OA, nitrogen (NO (Sulf-BC-OA-NO )....
Abstract. Aerosols over Earth's remote and spatially extensive ocean surfaces have important influences on planetary climate. However, these aerosols their effects remain poorly understood, in part due to the remoteness limited observations regions. In this study, we seek understand factors that shape marine aerosol size distributions composition northwest Atlantic Ocean region. We use GEOS-Chem model with TwO-Moment Aerosol Sectional (TOMAS) microphysics algorithm interpret measurements...
Abstract. Wet deposition processes are highly efficient in the removal of aerosols from atmosphere, and thus strongly influence global aerosol concentrations, clouds, their respective radiative forcings. In this study, physically detailed size-dependent below-cloud scavenging parameterizations for rain snow implemented ECHAM5-HAM aerosol-climate model. Previously, by was simply a function mode, then scaled rainfall rate. The snowfall rate alone. mean optical depth, sea salt burden sensitive...
Abstract. This paper introduces and evaluates the second version of global aerosol-climate model ECHAM-HAM. Major changes have been brought into model, including new parameterizations for aerosol nucleation water uptake, an explicit treatment secondary organic aerosols, modified emission calculations sea salt mineral dust, coupling microphysics to a two-moment stratiform cloud scheme, alternative wet scavenging parameterizations. These revisions extend model's capability represent details...