Carlsbad Caverns National Park Air Quality Study 2019

This data set includes fine particle and gas precursor measurements from Carlsbad Caverns National Park. The study was designed to examine the influence of regional sources, including urban emissions, oil and gas development, wildfires, and soil dust on air quality in the park. Field measurements of aerosols, trace gases and deposition were conducted from 25 July through 5 September 2019.Carlsbad Caverns National Park in southeastern New Mexico is adjacent to the Permian Basin, one of the most productive oil and gas regions in the country. The 2019 Carlsbad Caverns Air Quality Study (CarCavAQS) was designed to examine the influence of regional sources, including urban emissions, oil and gas development, wildfires, and soil dust on air quality in the park. Field measurements of aerosols, trace gases, and deposition were conducted from 25 July through 5 September 2019.This work was supported by the National Park Service Q5 [P20AC00679]

Les Houches 2015: Physics at TeV Colliders Standard Model Working Group Report

This Report summarizes the proceedings of the 2015 Les Houches workshop on Physics at TeV Colliders. Session 1 dealt with (I) new developments relevant for high precision Standard Model calculations, (II) the new PDF4LHC parton distributions, (III) issues in the theoretical description of the production of Standard Model Higgs bosons and how to relate experimental measurements, (IV) a host of phenomenological studies essential for comparing LHC data from Run I with theoretical predictions and projections for future measurements in Run II, and (V) new developments in Monte Carlo event generators.Comment: Proceedings of the Standard Model Working Group of the 2015 Les Houches Workshop, Physics at TeV Colliders, Les Houches 1-19 June 2015. 227 page

Scaling Patterns for QCD Jets

Jet emission at hadron colliders follows simple scaling patterns. Based on perturbative QCD we derive Poisson and staircase scaling for final state as well as initial state radiation. Parton density effects enhance staircase scaling at low multiplicities. We propose experimental tests of our theoretical findings in Z+jets and QCD gap jets production based on minor additions to current LHC analyses.Comment: 36 pages, 16 figure

Volatile organic compounds and ozone in Rocky Mountain National Park during FRAPPÉ

The 2014 Front Range Air Pollution and Photochemistry Éxperiment (FRAPPÉ) aimed to better characterize summertime air quality in the Northern Front Range Metropolitan Area (NFRMA) and its impact on surrounding areas. As part of this study, measurements of gas- and particle-phase species were collected in Rocky Mountain National Park (ROMO), located in the mountains west of the urban northern Front Range corridor from July to October 2014. We report on measurements of ozone from two locations in the park and a suite of volatile organic compounds (VOCs) measured using a continuous real-time gas chromatography (GC) system and a quadrupole proton-transfer-reaction mass spectrometer (PRT-MS) at the ROMO Longs Peak (ROMO-LP) air quality site. We also measured VOCs using canister samples collected along transects connecting the NFRMA and ROMO. These datasets show that ROMO is impacted by NFRMA emission sources, and high observed mixing ratios of VOCs associated with oil and gas extraction (e.g. ethane) and urban sources (e.g. ethene and C2Cl4) occur during periods of upslope transport. Hourly ozone mixing ratios exceeded 70&thinsp;ppb during six events. Two of the six events were largely associated with VOCs from the oil and gas sector, three high ozone events were associated with a mixture of VOCs from urban and oil and gas sources, and one high ozone event was driven by a stratospheric intrusion. For the high ozone events most associated with emissions from oil and gas activities, we estimate that VOCs and NOx from sources along the Front Range contributed ∼20&thinsp;ppbv of additional ozone.</p

Isotopic characterization of aerosol organic carbon components over the eastern United States

Author Posting. © American Geophysical Union, 2012. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 117 (2012): D13303, doi:10.1029/2011JD017153.Carbon isotopic signatures (δ13C, Δ14C) of aerosol particulate matter total organic carbon (TOC) and operationally defined organic carbon (OC) components were measured in samples from two background sites in the eastern U.S. TOC and water-soluble OC (WSOC) δ13C values (−27 to −24‰) indicated predominantly terrestrial C3 plant and fossil derived sources. Total solvent extracts (TSE) and their aliphatic, aromatic, and polar OC components were depleted in δ13C (−30 to −26‰) relative to TOC and WSOC. Δ14C signatures of aerosol TOC and TSE (−476 to +25‰) suggest variable fossil contributions (~5–50%) to these components. Aliphatic OC while comprising a small portion of the TOC (<1%), was dominated by fossil-derived carbon (86 ± 3%), indicating its potential utility as a tracer for fossil aerosol OC inputs. In contrast, aromatic OC contributions (<1.5%) contained approximately equal portions contemporary (52 ± 8%) and fossil (48 ± 8%) OC. The quantitatively significant polar OC fraction (6–25% of TOC) had fossil contributions (30 ± 12%) similar to TOC (26 ± 7%) and TSE (28 ± 9%). Thus, much of both of the fossil and contemporary OC is deduced to be oxidized, polar material. Aerosol WSOC consistently showed low fossil content (<8%) relative to the TOC (5–50%) indicating that the majority of fossil OC in aerosol particulates is insoluble. Therefore, on the basis of solubility and polarity, aerosols are predicted to partition differently once deposited to watersheds, and these chemically distinct components are predicted to contribute in quantitatively and qualitatively different ways to watershed carbon biogeochemistry and cycling.ASW was partially supported by a Graduate Fellowship from the Hudson River Foundation during the course of this study. Additional funding for this work came from a NOSAMS student internship award, a fellowship award from Sun Trust Bank administered through the VIMS Foundation, a student research grant from VIMS, and the following NSF awards: DEB Ecosystems grant DEB-0234533, Chemical Oceanography grant OCE-0327423, and Integrated Carbon Cycle Research Program grant EAR-0403949 to JEB; and Chemical Oceanography grant OCE-0727575 to RMD and JEB.2013-01-0

Aerosol decadal trends - Part 1: In-situ optical measurements at GAW and IMPROVE stations

Currently many ground-based atmospheric stations include in-situ measurements of aerosol physical and optical properties, resulting in more than 20 long-term (>10 yr) aerosol measurement sites in the Northern Hemisphere and Antarctica. Most of these sites are located at remote locations and monitor the aerosol particle number concentration, wavelength-dependent light scattering, backscattering, and absorption coefficients. The existence of these multi-year datasets enables the analysis of long-term trends of these aerosol parameters, and of the derived light scattering A° ngstro¨m exponent and backscatter fraction. Since the aerosol variables are not normally distributed, three different methods (the seasonal Mann-Kendall test associated with the Sen’s slope, the generalized least squares fit associated with an autoregressive bootstrap algorithm for confidence intervals, and the least-mean square fit applied to logarithms of the data) were applied to detect the long-term trends and their magnitudes. To allow a comparison among measurement sites, trends on the most recent 10 and 15 yr periods were calculated. No significant trends were found for the three continental European sites. Statistically significant trends were found for the two European marine sites but the signs of the trends varied with aerosol property and location. Statistically significant decreasing trends for both scattering and absorption coefficients (mean slope of −2.0%yr−1) were found for most North American stations, although positive trends were found for a few desert and high-altitude sites. The difference in the timing of emission reduction policy for the Europe and US continents is a likely explanation for the decreasing trends in aerosol optical parameters found for most American sites compared to the lack of trends observed in Europe. No significant trends in scattering coefficient were found for the Arctic or Antarctic stations, whereas the Arctic station had a negative trend in absorption coefficient. The high altitude Pacific island station of Mauna Loa presents positive trends for both scattering and absorption coefficients

A critical review of filter transmittance measurements for aerosol light absorption, and <i>de novo</i> calibration for a decade of monitoring on PTFE membranes

<p>The IMPROVE (Interagency Monitoring of PROtected Visual Environments) network monitors the attenuation of light by PM_2.5 samples (fine particulate matter, D_aero = 2.5 μm) routinely collected on polytetrafluoroethylene (PTFE) filters throughout the United States. The results of this measurement have long been reported as an indicator of absorption, with no rigorous calibration as such. Filter-based absorption measurements more conventionally employ optically thick quartz- or glass-fiber collection media, for which a substantial calibration literature offers algorithms to correct for particle scattering and filter loading effects. PTFE membranes are optically thinner and less homogeneous than the fiber media, but they avoid interference from adsorbed organic gases that is associated with quartz and glass fiber media. IMPROVE's measurement system is a hybrid of integrating sphere and integrating plate that records the light backscattered as well as transmitted by each filter. This article introduces and validates a theory-based model for calibration and data reduction that accounts for particle scattering effects as well as variations in filter optics. Tests based on historical analyses of field blanks and recent reanalyses of archived samples establish that the current system has operated with a stable calibration since 2003.</p> <p>The newly calibrated IMPROVE absorption values correlate strongly with the refractory carbon fraction reported by thermal-optical analysis as “elemental” (EC). EC is sometimes treated as the only significant light absorber in PM_2.5, but the general decline observed between 2005 and 2014 in IMPROVE EC was not accompanied by a comparable decline in IMPROVE absorption. Absorption also exhibits a distinct association with Fe concentrations, which at IMPROVE sites are attributable mainly to mineral dusts and have generally held steady or risen since 2003. An increased relative contribution by mineral dusts can explain some, but not all, of the observed difference between recent absorption and EC trends.</p

Present and future nitrogen deposition to national parks in the United States: critical load exceedances

National parks in the United States are protected areas wherein the natural habitat is to be conserved for future generations. Deposition of anthropogenic nitrogen (N) transported from areas of human activity (fuel combustion, agriculture) may affect these natural habitats if it exceeds an ecosystem-dependent critical load (CL). We quantify and interpret the deposition to Class I US national parks for present-day and future (2050) conditions using the GEOS-Chem global chemical transport model with 1/2° × 2/3° horizontal resolution over North America. We estimate CL values in the range 2.5–5 kg N ha⁻¹ yr⁻¹ for the different parks to protect the most sensitive ecosystem receptors. For present-day conditions, we find 24 out of 45 parks to be in CL exceedance and 14 more to be marginally so. Many of these are in remote areas of the West. Most (40–85%) of the deposition originates from NO_x emissions (fuel combustion). We project future changes in N deposition using representative concentration pathway (RCP) anthropogenic emission scenarios for 2050. These feature 52–73% declines in US NO_x emissions relative to present but 19–50% increases in US ammonia (NH₃) emissions. Nitrogen deposition at US national parks then becomes dominated by domestic NH₃ emissions. While deposition decreases in the East relative to present, there is little progress in the West and increases in some regions. We find that 17–25 US national parks will have CL exceedances in 2050 based on the RCP8.5 and RCP2.6 scenarios. Even in total absence of anthropogenic NO_x emissions, 14–18 parks would still have a CL exceedance. Returning all parks to N deposition below CL by 2050 would require at least a 50% decrease in US anthropogenic NH₃ emissions relative to RCP-projected 2050 levels