A5041380453- Atmospheric chemistry and aerosols
- Atmospheric Ozone and Climate
- Atmospheric and Environmental Gas Dynamics
- Air Quality and Health Impacts
- Mercury impact and mitigation studies
- Atmospheric aerosols and clouds
- Toxic Organic Pollutants Impact
- Vehicle emissions and performance
- Arctic and Antarctic ice dynamics
- Air Quality Monitoring and Forecasting
- Methane Hydrates and Related Phenomena
- Cryospheric studies and observations
- Planetary Science and Exploration
- Isotope Analysis in Ecology
- Marine and coastal ecosystems
- Maritime Transport Emissions and Efficiency
- Chemical Analysis and Environmental Impact
- Advanced Aircraft Design and Technologies
- Groundwater and Isotope Geochemistry
- Water Quality Monitoring and Analysis
- Smart Materials for Construction
- Ocean Acidification Effects and Responses
- Meteorological Phenomena and Simulations
- Astro and Planetary Science
- Heavy metals in environment
University of Washington
2016-2025
Seattle University
2016-2024
University of Washington Bothell
2018
California State University, Monterey Bay
2018
University of California, San Diego
2018
Tofwerk (Switzerland)
2018
NOAA Air Resources Laboratory
2009
Harvard University
1998-2002
Planetary Science Institute
1998-2002
Harvard University Press
1997-2000
Abstract. We combine in situ measurements of sea salt aerosols (SS) from open ocean cruises and ground-based stations together with aerosol optical depth (AOD) observations MODIS AERONET, the GEOS-Chem global chemical transport model to provide new constraints on SS emissions over world's oceans. find that using Gong (2003) source function overestimates cruise coarse mode mass concentrations by factors 2–3 at high wind speeds cold waters Southern, North Pacific Atlantic Oceans. Furthermore,...
We use space-based observations of NO2 columns from the Global Ozone Monitoring Experiment (GOME) to derive monthly top-down NOx emissions for 2000 via inverse modeling with GEOS-CHEM chemical transport model. Top-down sources are partitioned among fuel combustion (fossil and biofuel), biomass burning soils by exploiting spatio-temporal distribution remotely sensed fires a priori information on location regions dominated combustion. The inventory is combined an obtain optimized posteriori...
We use a global 3‐D model of atmospheric mercury (GEOS‐Chem) to interpret worldwide observations total gaseous (TGM) and reactive (RGM) in terms the constraints they provide on chemical cycling deposition mercury. Our simulation including source 7000 Mg yr −1 TGM lifetime 0.8 years reproduces magnitude large‐scale variability at land sites. However, it cannot capture high from ship cruises, implying problem either measurements or our fundamental understanding sources. Observed seasonal...
Ambient fine particulate matter (PM2.5) is the world's leading environmental health risk factor. Reducing PM2.5 disease burden requires specific strategies that target dominant sources across multiple spatial scales. We provide a contemporary and comprehensive evaluation of sector- fuel-specific contributions to this 21 regions, 204 countries, 200 sub-national areas by integrating 24 global atmospheric chemistry-transport model sensitivity simulations, high-resolution satellite-derived...
We develop a mechanistic representation of land‐atmosphere cycling in global 3‐D ocean‐atmosphere model mercury (GEOS‐Chem). The resulting land‐ocean‐atmosphere is used to construct preindustrial and present biogeochemical cycles mercury, examine the legacy past anthropogenic emissions, map enrichment factors for deposition, attribute deposition United States. Land emission includes prompt recycling recently deposited (600 Mg −1 day), soil volatilization (550 ), evapotranspiration ). spatial...
Abstract. We use observations from the April 2008 NASA ARCTAS aircraft campaign to North American Arctic, interpreted with a global 3-D chemical transport model (GEOS-Chem), better understand sources and cycling of hydrogen oxide radicals (HOx≡H+OH+peroxy radicals) their reservoirs (HOy≡HOx+peroxides) in springtime Arctic atmosphere. find that standard gas-phase mechanism overestimates observed HO2 H2O2 concentrations. Computation HOx HOy budgets on basis also indicates large missing sink...
Significance Exposure to fine particulate matter is a leading cause of premature deaths and illnesses globally. In the eastern United States, substantial cuts in sulfur dioxide nitrogen oxides emissions have considerably lowered sulfate nitrate concentrations for all seasons except winter. Simulations that reproduce detailed airborne observations wintertime atmospheric chemistry over States indicate formation limited by availability oxidants acidity particles, respectively. These limitations...
Formaldehyde (HCHO) is the most important carcinogen in outdoor air among 187 hazardous pollutants (HAPs) identified by U.S. Environmental Protection Agency (EPA), not including ozone and particulate matter. However, surface observations of HCHO are sparse EPA monitoring network could be prone to positive interferences. Here we use 2005-2016 summertime column data from OMI satellite instrument, validated with high-quality aircraft oversampled on a 5 × km2 grid, map concentrations across...
Abstract Nocturnal dinitrogen pentoxide (N 2 O 5 ) heterogeneous chemistry impacts regional air quality and the distribution lifetime of tropospheric oxidants. Formed from oxidation nitrogen oxides, N is heterogeneously lost to aerosol with a highly variable reaction probability, γ ), dependent on composition ambient conditions. Reaction products include soluble nitrate (HNO 3 or NO − nitryl chloride (ClNO ). We report first‐ever derivations wintertime aircraft measurements in critically...
Abstract Natural emissions of air pollutants from the surface play major roles in quality and climate change. In particular, nitrogen oxides (NO x ) emitted soils contribute ~15% global NO emissions, sea salt aerosols are a player chemistry marine atmosphere, biogenic dominant source non-methane volatile organic compounds at scale. These natural often estimated using nonlinear parameterizations, which sensitive to horizontal resolutions inputted meteorological ancillary data. Here we use...
Abstract. Aerosol interactions with clouds represent a significant uncertainty in our understanding of the Earth system. Deep convective may respond to aerosol perturbations several ways that have proven difficult elucidate observations. Here, we leverage two busiest maritime shipping lanes world, which emit particles and their precursors into an otherwise relatively clean tropical marine boundary layer, make headway on influence deep clouds. The recent 7-fold change allowable fuel sulfur by...
The concentrations of the hydrogen radicals OH and HO2 in middle upper troposphere were measured simultaneously with those NO, O3, CO, H2O, CH4, non-methane hydrocarbons, ultraviolet visible radiation field. data allow a direct examination processes that produce O3 this region atmosphere. Comparison calculations based on their production from water vapor, ozone, methane demonstrate these sources are insufficient to explain observed radical troposphere. photolysis carbonyl peroxide compounds...
Continuous CO measurements were obtained at Cheeka Peak Observatory (CPO, 48.3°N, 124.6°W, 480 m), a coastal site in Washington state, between 9 March 2001 and 31 May 2002. We analyze these observations as well ground sites throughout the North Pacific using GEOS‐CHEM global tropospheric chemistry model to examine seasonal variations of Asian long‐range transport. The reproduces observed levels, their cycle day‐to‐day variability, with 5–20 ppbv negative bias winter/spring 5–10 positive...
During the summer of 2003, biomass fires burned a large area Siberia, largest in at least 10 years. We used NRL Aerosol Analysis and Prediction System (NAAPS) model to forecast transport smoke from these fires. Transport airmasses North America was confirmed by aircraft surface observations. The resulted enhancements background CO O 3 23–37 5–9 ppbv, respectively, sites Alaska, Canada Pacific Northwest. From burned, we estimate that Siberian generated 68 Tg 0.82 NO x (as N). In addition,...
We develop a mechanistic representation of land-atmosphere cycling in global 3-D ocean-atmosphere model mercury (GEOS-Chem). The resulting land-ocean-atmosphere is used to construct preindustrial and present biogeochemical cycles mercury, examine the legacy past anthropogenic emissions, map enrichment factors for deposition, attribute deposition United States. Land emission includes prompt recycling recently deposited (600 Mg -1 day), soil volatilization (550 ), evapotranspiration ). spatial...
We present results from a new global atmospheric mercury model coupled with mixed layer slab ocean. The ocean describes the interactions of atmosphere and deep ocean, as well conversion between elemental, divalent, nonreactive species. Our mean aqueous concentrations 0.07 pM 0.80 reactive, 1.51 total agree observations. provides 14.1 Mmol yr −1 source to atmosphere, at upper end previous estimates. Re‐emission previously deposited constitutes 89% this flux. Ocean emissions are largest in...
The factors controlling the concentrations of HO x radicals (= OH + peroxy) in upper troposphere (8–12 km) are examined using concurrent aircraft observations OH, 2 , H O CH 3 OOH, and made during Subsonic Assessment Ozone Nitrogen Oxide Experiment (SONEX) at northern midlatitudes fall. These observations, complemented by measurements O, NO, peroxyacetyl nitrate (PAN), HNO 4 CO, acetone, hydrocarbons, actinic fluxes, aerosols, allow a highly constrained mass balance analysis larger chemical...
We measured gaseous elemental mercury (GEM), particulate (PHg), and reactive (RGM), along with CO, ozone, aerosol scatter at the Mount Bachelor Observatory (2.7 km above sea level), Oregon, from May to August 2005. The mean concentrations (at standard conditions) were 1.54 ng/m 3 5.2 pg/m 43 (RGM). RGM enhancements, up 600 , occurred night linked a diurnal pattern of upslope downslope flows that mixed in boundary layer air during day free tropospheric night. During night, was inversely...
We use space‐based observations of NO 2 columns from the Global Ozone Monitoring Experiment (GOME) to map spatial and seasonal variations x emissions over Africa during 2000. The GOME show not only enhanced tropospheric biomass burning dry season but also comparable enhancements soil rainy Sahel. These occur in strong pulses lasting 1–3 weeks following onset rain, affect 3 million km semiarid sub‐Saharan savanna. Surface International Atmospheric Chemistry (IGAC)/Deposition Biochemically...
The origin of NO x in the upper troposphere over central United States is examined using aircraft observations obtained during SUCCESS campaign April–May 1996. Correlations between y (sum and its oxidation products) CO at 8–12 km altitude indicate that originates primarily from convective transport polluted boundary layer air. Lightning emissions appear to be only minor sources . Chemical steady state model calculations constrained by local underestimate measured /NO concentration ratio a...
Abstract. Sea salt aerosols (SSA) are generated via air bubbles bursting at the ocean surface as well by wind mobilization of saline snow and frost flowers over sea-ice-covered areas. The relative magnitude these sources remains poorly constrained polar regions, affecting our ability to predict their impact on halogen chemistry, cloud formation, climate. We implement a blowing flower emission scheme in GEOS-Chem global chemical transport model, which we validate against multiyear (2001–2008)...
Abstract Most intensive field studies investigating aerosols have been conducted in summer, and thus, wintertime aerosol sources chemistry are comparatively poorly understood. An mass spectrometer was flown on the National Science Foundation/National Center for Atmospheric Research C‐130 during Wintertime INvestigation of Transport, Emissions, Reactivity (WINTER) 2015 campaign northeast United States. The fraction boundary layer submicron that organic (OA) about a factor 2 smaller than 2011...
Abstract. We have developed a new nested-grid mercury (Hg) simulation over North America with 1/2° latitude by 2/3° longitude horizontal resolution employing the GEOS-Chem global chemical transport model. Emissions, chemistry, deposition, and meteorology are self-consistent between nested domains. Compared to model (4° 5° longitude), shows improved skill at capturing high spatial temporal variability of Hg wet deposition observed Mercury Deposition Network (MDN) in 2008–2009. The resolves...