A5085665747- Atmospheric chemistry and aerosols
- Atmospheric aerosols and clouds
- Atmospheric Ozone and Climate
- Air Quality and Health Impacts
- Atmospheric and Environmental Gas Dynamics
- Air Quality Monitoring and Forecasting
- Methane Hydrates and Related Phenomena
- Climate Change and Geoengineering
- Climate change and permafrost
- Climate variability and models
- Aeolian processes and effects
- European history and politics
- Advanced Data Processing Techniques
- Environmental Chemistry and Analysis
- Water Treatment and Disinfection
- German History and Society
- Extraction and Separation Processes
- Vehicle emissions and performance
- Environmental Impact and Sustainability
- Italian Fascism and Post-war Society
- Climate Change and Health Impacts
- Sustainable Industrial Ecology
- Time Series Analysis and Forecasting
- Advanced Chemical Sensor Technologies
- Environmental Policies and Emissions
Harvard University
2016-2023
Harvard University Press
2020-2023
Harvard Global Health Institute
2022-2023
United States Department of State
2022-2023
Planetary Science Institute
2016-2022
Princeton University
2016
Abstract. In his study, we use a combination of multivariate statistical methods to understand the relationships PM2.5 with local meteorology and synoptic weather patterns in different regions China across various timescales. Using June 2014 May 2017 daily total observations from ∼ 1500 monitors, all deseasonalized detrended focus on synoptic-scale variations, find strong correlations selected meteorological variables (e.g., positive correlation temperature but negative sea-level pressure...
Abstract PM 2.5 during severe winter haze in Beijing, China, has reached levels as high 880 μg/m 3 , with sulfur compounds contributing significantly to composition. This been traditionally assumed be sulfate, although atmospheric chemistry models are unable account for such large sulfate enhancements under dim conditions. Using a 1‐D model, we show that well‐characterized but previously overlooked of aqueous‐phase HCHO and S(IV) cloud droplets form S(IV)‐HCHO adduct, hydroxymethane...
Abstract. Wet processes, including aqueous-phase chemistry, wet scavenging, and surface uptake during dry deposition, are important for global modeling of aerosols aerosol precursors. In this study, we improve the treatments these processes in Goddard Earth Observing System with chemistry (GEOS-Chem) v12.6.0, pH calculations cloud, rain, surfaces, fraction cloud available rainout efficiencies various types clouds, empirical washout by rain snow, deposition. We compare simulated mass...
Abstract. Cloud water acidity affects the atmospheric chemistry of sulfate and organic aerosol formation, halogen radical cycling, trace metal speciation. Precipitation including post-depositional inputs adversely soil freshwater ecosystems. Here, we use GEOS-Chem model to simulate global distributions cloud precipitation as well total acid ecosystems from wet deposition. The accounts for strong acids (H2SO4, HNO3, HCl), weak (HCOOH, CH3COOH, CO2, SO2), bases (NH3 dust sea salt alkalinity)....
Abstract Sulfur compounds are an important constituent of particulate matter, with impacts on climate and public health. While most sulfur observed in matter has been assumed to be sulfate, laboratory experiments reveal that hydroxymethanesulfonate (HMS), adduct formed by aqueous phase chemical reaction dissolved HCHO SO 2 , may easily misinterpreted measurements as sulfate. Here we present observational modeling evidence for a ubiquitous global presence HMS. We find filter samples collected...
Significance Particulate matter, often formed via cloud processing, strongly influences the Earth’s climate and air quality. Particle composition depends on anthropogenic biogenic emissions. Thus, in order to understand change, knowledge of difference between preindustrial current conditions is critical. Under conditions, multifunctional organic hydroperoxides, which are strong oxidants have ability contribute particulate matter formation, higher concentrations atmosphere. In this work, we...
Abstract Severe PM 2.5 air pollution in China and the First Grand National Standard (FGNS), implemented 2016 (annual concentration target of less than 35 µg m −3 ), necessitate urgent reduction strategies. This study applied nested‐grid version Goddard Earth Observing System (GEOS) chemical transport model (GEOS‐Chem) to quantify 2000–2050 changes quality related direct radiative forcing (DRF) China, based on future emission under representative pathway (RCP) scenarios RCP2.6, RCP4.5,...
Abstract. Geostationary satellite measurements of aerosol optical depth (AOD) over East Asia from the Ocean Color Imager (GOCI) and Advanced Himawari (AHI) instruments can augment surface monitoring fine particulate matter (PM2.5) air quality, but this requires better understanding AOD–PM2.5 relationship. Here we use GEOS-Chem chemical transport model to analyze critical variables determining relationship by simulation observations satellite, aircraft, ground-based datasets. This includes...
Since 2013, Chinese policies have dramatically reduced emissions of particulates and their gas-phase precursors, but the implications these reductions for aerosol-radiation interactions are unknown. Using a global, coupled chemistry-climate model, we examine how radiative impacts air pollution in winter months 2012 2013 affect local meteorology changes may, turn, influence surface concentrations PM2.5, particulate matter with diameter <2.5 μm. We then investigate decreasing through 2016 2017...
Abstract. Hydroxymethanesulfonate (HMS) has recently been identified as an abundant organosulfur compound in aerosols during winter haze episodes northern China. It also detected other regions although the concentrations are low. Because of sparse field measurements, global significance HMS and its spatial seasonal patterns remain unclear. Here, we modify add to implementation chemistry GEOS-Chem chemical transport model conduct multiple simulations. The accounts for cloud entrainment...
Solar radiation management (SRM) is a climate engineering strategy to reduce temperature increases due global change. The most well-researched SRM methodology stratospheric aerosol injection (SAI), which involves increasing the concentration of particles in stratosphere amount solar reaching Earth’s surface. considered and heavily researched for SAI sulfate. has been extensively modeled using various scenarios investigated data from previous volcanic eruptions, provide an analog effects SAI....
Abstract Tropospheric reactive gaseous chlorine (Cl y ) impacts the atmosphere's oxidation capacity with implications for chemically reduced gases such as methane. Here we use Greenland ice‐core records of chlorine, sodium, and acidity, global model simulations to show how tropospheric Cl has been impacted by anthropogenic emissions since 1940s. We that contribution nonsea‐salt significantly influenced total its trends after The modeled regional 170% increase from preindustrial 1970s was...
Abstract Recent field studies have documented a surprisingly strong and consistent methane sink in arctic mineral soils, thought to be due high‐affinity methanotrophy. However, the distinctive physiology of these methanotrophs is poorly represented mechanistic models. We developed new model, constrained by microcosm experiments, simulate activity methanotrophs. The model was tested against soil core‐thawing experiments field‐based measurements fluxes compared conventional Our simulations...
Abstract. Geostationary satellite sensors over East Asia (GOCI and AHI) are now providing continuous mapping of aerosol optical depth (AOD) at 550 nm to improve monitoring fine particulate matter (PM2.5) air quality. Here we evaluate our understanding the physical relationships between AOD PM2.5 by using GEOS-Chem atmospheric chemistry model simulate observations from multiple sources: 1) joint NASA-NIER Korea – United States Air Quality aircraft campaign South (KORUS-AQ; May–June 2016); 2)...
Abstract Studies of the impacts solar geoengineering have mostly ignored tropospheric chemistry. By decreasing sunlight reaching Earth's surface, may help mitigate anthropogenic climate change, but changing also alters rates chemical reactions throughout troposphere. Using GEOS‐Chem atmospheric chemistry model, we show that stratospheric aerosol injection (SAI) with sulfate, a frequently studied method, can perturb composition over span 10 years, increasing oxidative capacity by 9% and...
Abstract. Wet processes, including aqueous phase chemistry, wet scavenging, and surface uptakes during dry deposition, are important for global modeling of aerosol precursors aerosols. In this study, we improved the treatments these processes in GEOS-Chem v12.6.0, pH calculation cloud, rain, surface, fraction cloud available rainout efficiencies various types empirical washout by rain snow, deposition. We compared simulated mass concentrations aerosols with monitoring networks over United...
Abstract. Cloudwater acidity affects the atmospheric chemistry of sulfate and organic aerosol formation, halogen radical cycling, trace metal speciation. Rainwater including post-depositional inputs adversely soil freshwater ecosystems. Here we use GEOS-Chem model to simulate global distributions cloud- rainwater acidity, total acid ecosystems from wet deposition. The accounts for strong acids (H2SO4, HNO3, HCl), weak (HCOOH, CH3COOH, CO2, SO2), bases (NH3, dust sea salt alkalinity). We...
Abstract. In this study, we use a combination of multivariate statistical methods to understand the relationships PM2.5 with local meteorology and synoptic weather patterns in different regions China across various timescales. Using June 2014 May 2017 daily total observations from ~ 1500 monitors, all deseasonalized detrended focus on synoptic-scale variations, find strong correlations selected meteorological variables (e.g., positive correlation temperature but negative sea-level pressure...