A5039609700- Atmospheric chemistry and aerosols
- Atmospheric and Environmental Gas Dynamics
- Atmospheric Ozone and Climate
- Air Quality and Health Impacts
- Vehicle emissions and performance
- Air Quality Monitoring and Forecasting
- Atmospheric aerosols and clouds
- Fire effects on ecosystems
- Military History and Strategy
- Military and Defense Studies
- Radical Photochemical Reactions
- Historical and Contemporary Political Dynamics
- Radioactive contamination and transfer
- Wind and Air Flow Studies
- Landslides and related hazards
- Municipal Solid Waste Management
- Vietnamese History and Culture Studies
- Hygrothermal properties of building materials
- Mobile and Web Applications
- Military Strategy and Technology
- Wireless Sensor Networks for Data Analysis
- African history and culture studies
- Soil Moisture and Remote Sensing
- Geology and Paleoclimatology Research
- Military Defense Systems Analysis
Environmental Protection Agency
2013-2024
Research Triangle Park Foundation
2013-2024
Michigan Technological University
2006-2017
Environmental Protection Agency
2017
University of Michigan
2010-2012
The University of Texas at Austin
1981
Abstract The radiative properties of soot particles depend on their morphology and mixing state, but evolution during transport is still elusive. Here we report observations from an electron microscopy analysis individual transported in the free troposphere over long distances to remote Pico Mountain Observatory Azores North Atlantic. Approximately 70% were highly compact those 26% thinly coated. Discrete dipole approximation simulations indicate that this compaction results increase single...
Extensive wildfires burned in northern North America during summer 2004, releasing large amounts of trace gases and aerosols into the atmosphere. Emissions from these frequently impacted PICO‐NARE station, a mountaintop site situated 6–15 days downwind fires Azores Islands. To assess impacts boreal wildfire emissions on levels aerosol black carbon (BC), nitrogen oxides O 3 America, we analyzed measurements CO, BC, total reactive (NO y ), NO x + 2 ) made June to September 2004 combination...
We report summertime measurements of CO and O 3 obtained during 2001–2003 at the PICO‐NARE mountaintop station in Azores. Frequent events elevated mixing ratios were observed. On basis backward trajectories arriving free troposphere global simulations biomass burning plumes, we attribute nearly all these to North American pollution outflow long‐range transport emissions. There was a high degree interannual variability levels: median [CO] ranged from 65 ppbv 2001 104 2003. The highest...
Ground level ozone concentrations ([O 3 ]) typically show a direct linear relationship with surface air temperature. Three decades of California measurements provide evidence statistically significant change in the ozone-temperature slope (Δ m O3- T ) under extremely high temperatures (> 312 K). This Δ leads to plateau or decrease [O ], reflecting diminished role nitrogen oxide sequestration by peroxyacetyl nitrates and reduced biogenic isoprene emissions at temperatures. Despite...
Abstract. Free tropospheric aerosol was sampled at the Pico Mountain Observatory located 2225 m above mean sea level on Island of Azores archipelago in North Atlantic. The observatory is ~ 3900 km east and downwind America, which enables studies free air transported over long distances. Aerosol samples collected filters from June to October 2012 were analyzed characterize organic carbon, elemental inorganic ions. average ambient concentration 0.9 ± 0.7 μg m−3. On average, components...
We examine the ozone production from boreal forest fires based on a case study of wildfires in Alaska and Canada summer 2004. The model simulations were performed with chemistry transport model, MOZART‐4, evaluated by comparison comprehensive set aircraft measurements. In analysis we use measurements carbon monoxide (CO) (O 3 ) at PICO‐NARE station located Azores within pathway North American outflow. modeled mixing ratios used to test robustness enhancement ratio ΔO /ΔCO (defined as excess...
Abstract. We have analysed the sensitivity of tropospheric ozone distribution over North America and Atlantic to boreal biomass burning emissions during summer 2010 using GEOS-Chem 3-D global chemical transport model observations from in situ satellite instruments. show that is consistent with Pico Mountain Observatory Azores, ozonesondes across Canada, Tropospheric Emission Spectrometer (TES) Infrared Atmospheric Sounding Instrument (IASI) Mean biases between observed mixing ratio free...
Abstract Long‐range transported free tropospheric particles can play a significant role on heterogeneous ice nucleation. Using optical and electron microscopy we examine the physicochemical characteristics of nucleating (INPs). Particles were collected substrates from troposphere at remote Pico Mountain Observatory in Azores Islands, after long‐range transport aging over Atlantic Ocean. We investigate four specific events to study formation potential by with different ages patterns. use...
We use the FLEXPART Lagrangian particle dispersion model and observations from PICO‐NARE station to identify analyze transport of North American anthropogenic emissions central Atlantic lower free troposphere (FT) during July 2003. adequately captured occurrence CO events, simulating all but 1 16 observed events while producing only 3 not observed. Low‐level (below km) was responsible for most events. Three case studies this type are presented. Export boundary layer in these result eastward...
Building emission inventories for the fires in boreal regions remains a challenging task with significant uncertainties methods used. In this work, we assess impact of seasonal trends fuel consumption and flaming/smoldering ratios on emissions species dominated by flaming combustion (e.g., NO x ) smoldering CO). This is accomplished using measurements CO y at free tropospheric Pico Mountain observatory central North Atlantic during active fire seasons 2004 2005. ΔNO /ΔCO enhancement aged...
Summertime observations of O 3 and CO made at the PICO‐NARE station during 2001, 2003, 2004 are used to assess impact boreal forest fires on distribution mixing ratios in midlatitude Northern Hemisphere (NH) lower free troposphere (FT). Backward trajectories were select measurements impacted by outflow from high‐latitude regions. Measurements these periods segregated into two subsets: those obtained with without apparent significant upwind fire emissions. Periods affected emissions...
Abstract. We describe the design and execution of BORTAS (Quantifying impact BOReal forest fires on Tropospheric oxidants over Atlantic using Aircraft Satellites) experiment, which has overarching objective understanding chemical aging air masses that contain emission products from seasonal boreal wildfires how these subsequently downwind atmospheric composition. The central focus experiment was a two-week deployment UK BAe-146-301 Atmospheric Research (ARA) eastern Canada, based out...
The R-LINE model, which was released in 2013 as a stand-alone model for roadway-type applications and based on set of newly developed dispersion curves, exhibited favorable performance limited evaluations (Heist et. al, 2013, Snyder et al. Venkatram 2013). In 2019, the incorporated RLINE source type EPA's preferred near-field AERMOD. Since its inclusion AERMOD, has been tested compared to other AERMOD types using multiple data sets transportation studies. outcome these tests is need revisit...
Upslope flows caused by mechanical forcing in strong synoptic winds or buoyant driven solar heating under weak can influence the air composition at mountaintop observatories. Using meteorological and trace gas measurements PICO‐NARE observatory on Pico mountain (Azores Islands, North Atlantic Ocean), frequency impact of such orographic a small, volcanic, subtropical island was examined. To determine origin mechanically lifted air, upstream kinetic energy balanced against potential gained...
A study of the impacts on respiratory health 2007 wildland fires in and around San Diego County, California is presented. This helps to address impact fire emissions human by modeling exposure potential proximate populations atmospheric particulate matter (PM) from vegetation fires. Currently, there no standard methodology model forecast effects PM plumes fires, part this due a lack for rigorously relating two. The contribution research specifically targets that absence explicitly emission,...
Abstract. The Pico Mountain Observatory, located at 2225 m a.s.l. in the Azores Islands, was established 2001 to observe long-range transport from North America central Atlantic. In previous research conducted observatory, ozone enhancement (> 55 ppbv) American outflows observed, and efficient production these postulated. This study is focused on determining causes for high d[O3] / d[CO] values (~1 ppbv ppbv−1) observed summers of 2009 2010. folded retroplume technique, developed by Owen...
Measurements of NO, NO 2 , and y (total reactive nitrogen oxides) made at the Pico Mountain station, 38.47°N, 28.40°W, 2.2 km above sea level, from July 2002 to August 2005 are used characterize seasonal diurnal variations oxides in background lower free troposphere (FT) over central North Atlantic Ocean. These observations reveal a well‐defined cycle (NO x = + ), with higher mixing ratios during summertime. Observed levels consistent long‐range transport emissions, significant removal en...
Measurements of nonmethane hydrocarbons (NMHC) at the Pico Mountain observatory 2225 m asl on Island, Azores, Portugal, from August 2004 to 2005 (in part overlapping with field campaign International Consortium Atmospheric Research Transport and Transformation study) were used investigate NMHC sources seasonal oxidation chemistry in central North Atlantic region. Levels anthropogenic characteristic marine free troposphere. Their concentrations low compared continental sites higher northern...
Transport of North American anthropogenic and boreal wildfire emissions is a large source nitrogen oxides over the Atlantic region. To characterize influence transport these on levels central lower free troposphere (FT) their further implications for hemispheric O 3 , we analyze measurements NO x (NO + 2 ), total reactive y CO, made at Pico Mountain station (38.47°N 28.40°W, 2.2 km above sea level) in Azores archipelago from July 2002 to August 2005. pollution America causes significant...
Santa Ana winds have been implicated as a major driver of large wildfires in southern California. While numerous anecdotal reports exist, there is little quantitative analysis peer-reviewed literature on how this weather phenomenon influences fire progression rates. We analysed within 158 events California function meteorologically defined conditions between 2001 and 2009. Our results show quantitatively that burned area per day 3.5–4.5 times larger days than non-Santa days. definition...
Abstract. In situ measurements of carbon monoxide (CO) and ozone (O3) at the Pico Mountain Observatory (PMO) located in Azores, Portugal, are analyzed together with results from an atmospheric chemical transport model (GEOS-Chem) satellite remote sensing data (AIRS (Atmospheric Infrared Sounder) for CO, TES (Tropospheric Emission Spectrometer) O3) to examine evolution free-troposphere CO O3 over North Atlantic 2001–2011. GEOS-Chem captured seasonal cycles well but significantly...