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The state-of-the-science Community Multiscale Air Quality (CMAQ) Modeling System has recently been extended for hemispheric-scale modeling applications (referred to as H-CMAQ). In this study, satellite-constrained estimation of the degassing SO2 emissions from 50 volcanoes over the Northern Hemisphere is incorporated into H-CMAQ, and their impact on tropospheric sulfate aerosol (SO42-) levels is assessed for 2010. The volcanic degassing improves predictions of observations from the Acid Deposition Monitoring Network in East Asia (EANET), the United States Clean Air Status and Trends Network (CASTNET), and the United States Integrated Monitoring of Protected Visual Environments (IMPROVE). Over Asia, the increased SO42- concentrations were seen to correspond to the locations of volcanoes, especially over Japan and Indonesia. Over the USA, the largest impacts that occurred over the central Pacific were caused by including the Hawaiian Kilauea volcano, while the impacts on the continental USA were limited to the western portion during summertime. The emissions of the Soufrière Hills volcano located on the island of Montserrat in the Caribbean Sea affected the southeastern USA during the winter season. The analysis at specific sites in Hawaii and Florida also confirmed improvements in regional performance for modeled SO42- by including volcanoes SO2 emissions. At the edge of the western USA, monthly averaged SO42- enhancements greater than 0.1 µgm-3 were noted within the boundary layer (defined as surface to 750 hPa) during June–September. Investigating the change on SO42- concentration throughout the free troposphere revealed that although the considered volcanic SO2 emissions occurred at or below the middle of free troposphere (500 hPa), compared to the simulation without the volcanic source, SO42- enhancements of more than 10 % were detected up to the top of the free troposphere (250 hPa). Our model simulations and comparisons with measurements across the Northern Hemisphere indicate that the degassing volcanic SO2 emissions are an important source and should be considered in air quality model simulations assessing background SO42- levels and their source attribution. [ABSTRACT FROM AUTHOR]

In this communication, a new compact multiple‐input‐multiple‐output (MIMO) antenna design with frequency and port reconfigurable feature has been presented. The design consists of four orthogonally placed annular ring‐shaped UWB monopole elements. Wideband to narrowband switching of each monopole element is done by PIN diodes placed between the fed line and stepped‐impedance resonating stubs (SIRS). The reconfigurable frequency states are: UWB, mid‐band 5G and WLAN. In narrowband, frequency spectrum is tunable using varactor diodes placed at middle of SIRS. The antenna ports can be tuned to operate as 4‐port, or 2‐port MIMO and it is also possible that all the ports operate at different frequency simultaneously. The concept is proved by simulation and measurement results which includes S‐parameters, radiation patterns, gains, and envelop correlation coefficients. [ABSTRACT FROM AUTHOR]

The state-of-the-science Community Multiscale Air Quality (CMAQ) Modeling System has recently been extended for hemispheric-scale modeling applications (referred to as H-CMAQ). In this study, satellite-constrained estimation of the degassing SO2 emissions from 50 volcanos over the northern hemisphere is incorporated into H-CMAQ, and their impact on tropospheric sulfate aerosol (SO42-) levels is assessed for 2010. The volcanic degassing improves predictions of observations from the Acid Deposition Monitoring Network in East Asia (EANET), the United States Clean Air Status and Trends Network (CASTNET), and the United States Integrated Monitoring of Protected Visual Environments (IMPROVE). Over Asia, the increased SO42- concentrations were seen to correspond to the locations of volcanoes, especially over Japan and Indonesia. Over the U.S.A., the largest impacts occurred over the central Pacific caused by including the Hawaiian Kilauea volcano while the impacts on the continental U.S.A. were limited to the western portion during summertime. The emissions of the Soufriere Hills volcano located on Montserrat Island in the Caribbean Ocean affected the southeastern U.S.A. during the winter season. The analysis at specific sites in Hawaii and Florida also confirmed improvements in regional performance for modeled SO42- by including volcanoes SO2 emissions. At the edge of the western U.S.A., monthly-averaged SO42- enhancements greater than 0.1 µg/m³ were noted within the boundary layer (defined as surface to 750 hPa) during June-September. Investigating the change on SO42- concentration throughout the free troposphere revealed that although the considered volcanic SO2 emissions occurred at or below the middle of free troposphere (500 hPa), compared to the simulation without the volcanic source, SO42- enhancements of more than 10% were detected up to the top of the free troposphere (250 hPa). Our model simulations and comparisons with measurements across the Northern Hemisphere indicate that the degassing volcanic SO2 emissions are an important source impacting airborne sulfur budgets and should be considered in air quality model simulations assessing background SO42- levels and their source attribution. [ABSTRACT FROM AUTHOR]

In this study, an 8-port multibeam ultrawideband multi-input-multi-output (UWB-MIMO) antenna having pattern and polarisation diversity is investigated for Wireless Personal-Area Network access points. The proposed antenna consists of two different types of slot radiators, each of them provides four directive beams. The novelty of the proposed design is the achievement of a compact 8-port UWB-MIMO antenna using a common ground plane. Eight additional grounded slits are used in this design to enhance isolation. Antenna elements are placed in such a way that two adjacent antennas contribute different patterns. Results show that all the eight antenna elements cover complete UWB (3.1 to 10.6 GHz) with port isolation better than 15 dB. Proposed design offers gain better than 2 dB with envelop correlation coefficient lower than 0.1 from all ports. [ABSTRACT FROM AUTHOR]

With the evolution of technology search and rescue operations are now been executed with the help of mobile robots. Wired mobile robot deployment is very cumbersome and constrained. Thus, the need arises for appropriate wireless technology that may support the same or even better functionality. ZigBee is gaining popularity as supporting technology to facilitate the working of mobile robots for search and rescue operations. This is because ZigBee based nodes utilize the industrial, scientific, and medical frequency band that supports a data rate up to 250 kbps. This paper presents a packet forwarding mechanism for ZigBee based mobile wireless sensor network nodes. The results achieved through the reported work shows that the packet loss rate comes around to be 2 percent resulting in a 98 percent successful packet reception at the receiver end. [ABSTRACT FROM AUTHOR]

In this paper, a compact coplanar waveguide (CPW) fed ultra-wide band (UWB) multi input multi output (MIMO) antenna is proposed. The antenna consists of two antiparallel hexagonal ring monopole elements. Circular arcs shaped grounded stubs are used to enhance the isolation, both the arcs are connected through stub to make common ground. Tapering of the slots of CPW feed line at feed point, and grounded slots are introduced for impedance matching over UWB. The proposed antenna is fabricated and impedance bandwidth, isolation, radiation pattern, and gain are measured. Moreover, envelop correlation coefficient (ECC) results are given. Proposed antenna structure operates in the frequency range 3–12 GHz with a fractional bandwidth of 120% keeping isolation better than 15 dB. The antenna has a compact size of 45 × 25 mm 2 . [ABSTRACT FROM AUTHOR]

BACKGROUND: Air quality across the northern hemisphere over the past two decades has witnessed dramatic changes, with continuous improvement in developed countries in North America and Europe, but a contrasting sharp deterioration in developing regions of Asia. OBJECTIVE: This study investigates the historical trend in the long-term exposure to PM[sub 2.5] and PM[sub 2.5]-related premature mortality (PM[sub 2.5]-mortality) and its response to changes in emission that occurred during 1990-2010 across the northern hemisphere. Implications for future trends in human exposure to air pollution in both developed and developing regions of the world are discussed. METHODS: We employed the integrated exposure-response model developed by Health Effects Institute to estimate the PM[sub 2.5]-mortality. The 1990-2010 annual average PM[sub 2.5] concentrations were obtained from the simulations using the WRF-CMAQ model. Emission mitigation efficiencies of sulfur dioxide (SO[sub 2]), nitrogen oxides (NO[sub x]), ammonia (NH3), and primary PM are estimated from the PM[sub 2.5]-mortality responses to the emission variations. RESULTS: Estimated PM[sub 2.5]-mortalities in East Asia and South Asia increased by 21% and 85% respectively, from 866,000 and 578,000 in 1990, to 1,048,000 and 1,068,000 in 2010. PM[sub 2.5]-mortalities in developed regions (i.e., Europe and high-income North America) decreased substantially by 67% and 58% respectively. CONCLUSIONS: Over the past two decades, correlations between population and PM[sub 2.5] have become weaker in Europe and North America due to air pollution controls but stronger in East Asia due to deteriorating air quality. Mitigation of primary PM appears to be the most efficient way for increasing health benefits (i.e., providing the largest mortality reduction per unit emissions). However, reductions in emissions of NH[sub 3] are needed to maximize the effectiveness of NO[sub x] emission controls. CITATION: Wang J, Xing J, Mathur R, Pleim JE, Wang S, Hogrefe C, Gan CM, Wong DC, Hao J. 2017. Historical trends in PM[sub 2 5]-related premature mortality during 1990-2010 across the northern hemisphere. Environ Health Perspect 125:400-408; http://dx.doi.org/10.1289/EHP298 [ABSTRACT FROM AUTHOR]

Background: Mantle cell lymphoma (MCL) is an aggressive and incurable form of non-Hodgkin's lymphoma. Despite initial intense chemotherapy, up to 50 % of cases of MCL relapse often in a chemoresistant form. We hypothesized that the recently identified MCL-initiating cells (MCL-ICs) are the main reason for relapse and chemoresistance of MCL. Cancer stem cell-related pathways such as Wnt could be responsible for their maintenance and survival. Methods: We isolated MCL-ICs from primary MCL cells on the basis of a defined marker expression pattern (CD34-CD3-CD45+CD19-) and investigated Wnt pathway expression. We also tested the potential of Wnt pathway inhibitors in elimination of MCL-ICs. Results: We showed that MCL-ICs are resistant to genotoxic agents vincristine, doxorubicin, and the newly approved Burton tyrosine kinase (BTK) inhibitor ibrutinib. We confirmed the differential up-regulation of Wnt pathway in MCL-ICs. Indeed, MCL-ICs were particularly sensitive to Wnt pathway inhibitors. Targeting β-catenin-TCF4 interaction with CCT036477, iCRT14, or PKF118-310 preferentially eliminated the MCL-ICs. Conclusions: Our results suggest that Wnt signaling is critical for the maintenance and survival of MCL-ICs, and effective MCL therapy should aim to eliminate MCL-ICs through Wnt signaling inhibitors. [ABSTRACT FROM AUTHOR]

Background: Mantle cell lymphoma (MCL) is an aggressive and incurable form of non-Hodgkin’s lymphoma. Despite initial intense chemotherapy, up to 50 % of cases of MCL relapse often in a chemoresistant form. We hypothesized that the recently identified MCL-initiating cells (MCL-ICs) are the main reason for relapse and chemoresistance of MCL. Cancer stem cell-related pathways such as Wnt could be responsible for their maintenance and survival. Methods: We isolated MCL-ICs from primary MCL cells on the basis of a defined marker expression pattern (CD34-CD3-CD45+CD19-) and investigated Wnt pathway expression. We also tested the potential of Wnt pathway inhibitors in elimination of MCL-ICs. Results: We showed that MCL-ICs are resistant to genotoxic agents vincristine, doxorubicin, and the newly approved Burton tyrosine kinase (BTK) inhibitor ibrutinib. We confirmed the differential up-regulation of Wnt pathway in MCL-ICs. Indeed, MCL-ICs were particularly sensitive to Wnt pathway inhibitors. Targeting β-catenin-TCF4 interaction with CCT036477, iCRT14, or PKF118-310 preferentially eliminated the MCL-ICs. Conclusions: Our results suggest that Wnt signaling is critical for the maintenance and survival of MCL-ICs, and effective MCL therapy should aim to eliminate MCL-ICs through Wnt signaling inhibitors. [ABSTRACT FROM AUTHOR]

Non-Hodgkin lymphomas (NHLs) are characterized by specific abnormalities that alter cell cycle regulation, DNA damage response, and apoptotic signaling. It is believed that cancer cells are particularly sensitive to cell death induced by tumor necrosis factor α–related apoptosis-inducing ligand (TRAIL). However, many cancer cells show blocked TRAIL signaling due to up-regulated expression of anti-apoptotic factors, such as cFLIP. This hurdle to TRAIL’s tumor cytotoxicity might be overcome by combining TRAIL-based therapy with drugs that reverse blockages of its apoptotic signaling. In this study, we investigated the impact of a pan-methyltransferase inhibitor (3-deazaneplanocin A, or DZNep) on TRAIL-induced apoptosis in aggressive B-cell NHLs: mantle cell, Burkitt, and diffuse large B-cell lymphomas. We characterized TRAIL apoptosis regulation and caspase activation in several NHL-derived cell lines pre-treated with DZNep. We found that DZNep increased cancer cell sensitivity to TRAIL signaling by promoting caspase-8 processing through accelerated cFLIP degradation. No change in cFLIP mRNA level indicated independence of promoter methylation alterations in methyltransferase activity induced by DZNep profoundly affected cFLIP mRNA stability and protein stability. This appears to be in part through increased levels of cFLIP-targeting microRNAs (miR-512-3p and miR-346). However, additional microRNAs and cFLIP-regulating mechanisms appear to be involved in DZNep-mediated enhanced response to extrinsic apoptotic stimuli. The capacity of DZNep to target cFLIP expression on multiple levels underscores DZNep’s potential in TRAIL-based therapies for B-cell NHLs. [ABSTRACT FROM AUTHOR]

Information about the Integrated Meteorology And Chemistry Modeling workshop that was held in Chapel Hill, North Carolina on October 12, 2012 is presented. Topics include the various applications of integrated meteorology and chemistry modeling including climate modeling, air quality modeling and numerical weather prediction. The workshop featured the speaker Jerome Fast of the U.S. Pacific Northwest National Laboratory who shared his views on the use of integrating met-chem modeling.

Abstract: The maintenance of genome integrity is essential for the proper function and survival of all organisms. Human cells have evolved prompt and efficient DNA damage response to eliminate the detrimental effects of DNA lesions. The DNA damage response involves a complex network of processes that detect and repair DNA damage, in which long non-coding RNAs (lncRNAs), a new class of regulatory RNAs, may play important roles. Recent studies have identified a large number of lncRNAs in mammalian transcriptomes. However, little is known about the regulation and function of lncRNAs in the DNA damage response. In the present study, we demonstrate that one specific lncRNA, ANRIL, is transcriptionally up-regulated by the transcription factor E2F1 in an ATM-dependent manner following DNA damage, and elevated levels of ANRIL suppress the expression of INK4a, INK4b and ARF at the late-stage of DNA damage response, allowing the cell to return to normal at the completion of the DNA repair. [Copyright &y& Elsevier]

Faithful transmission of genetic material in eukaryotic cells requires not only accurate DNA replication and chromosome distribution but also the ability to sense and repair spontaneous and induced DNA damage. To maintain genomic integrity, cells undergo a DNA damage response using a complex network of signaling pathways composed of coordinate sensors, transducers and effectors in cell cycle arrest, apoptosis and DNA repair. Emerging evidence has suggested that miRNAs play a crucial role in regulation of DNA damage response. In this review, we discuss the recent findings on how miRNAs interact with the canonical DNA damage response and how miRNA expression is regulated after DNA damage. [Copyright &y& Elsevier]

In the recent years, knowledge about cancer biomarkers has increased tremendously providing great opportunities for improving the management of cancer patients by enhancing the efficiency of detection and efficacy of treatment. Recent technological advancement has enabled the examination of many potential biomarkers and renewed interest in developing new biomarkers. Biomarkers of cancer could include a broad range of biochemical entities, such as nucleic acids, proteins, sugars, lipids, and small metabolites, cytogenetic and cytokinetic parameters as well as whole tumour cells found in the body fluid. A comprehensive understanding of the relevance of each biomarker will be very important not only for diagnosing the disease reliably, but also help in the choice of multiple therapeutic alternatives currently available that is likely to benefit the patients. This review provides a brief account on various biomarkers for diagnosis, prognosis and therapeutic purposes, which include markers already in clinical practice as well as various upcoming biomarkers. [ABSTRACT FROM AUTHOR]

Abstract: The National Air Quality Forecast Capacity (NAQFC) system, which links NOAA’s North American Mesoscale (NAM) meteorological model with EPA’s Community Multiscale Air Quality (CMAQ) model, provided operational ozone (O3) and experimental fine particular matter (PM2.5) forecasts over the continental United States (CONUS) during 2008. This paper describes the implementation of a real-time Kalman Filter (KF) bias-adjustment technique to improve the accuracy of O3 and PM2.5 forecasts at discrete monitoring locations. The operational surface-level O3 and PM2.5 forecasts from the NAQFC system were post-processed by the KF bias-adjusted technique using near real-time hourly O3 and PM2.5 observations obtained from EPA’s AIRNow measurement network. The KF bias-adjusted forecasts were created daily, providing 24-h hourly bias-adjusted forecasts for O3 and PM2.5 at all AIRNow monitoring sites within the CONUS domain. The bias-adjustment post-processing implemented in this study requires minimal computational cost; requiring less than 10 min of CPU on a single processor Linux machine to generate 24-h hourly bias-adjusted forecasts over the entire CONUS domain. The results show that the real-time KF bias-adjusted forecasts for both O3 and PM2.5 have performed as well as or even better than the previous studies when the same technique was applied to the historical O3 and PM2.5 time series from archived AQF in earlier years. Compared to the raw forecasts, the KF forecasts displayed significant improvement in the daily maximum 8-h O3 and daily mean PM2.5 forecasts in terms of both discrete (i.e., reduced errors, increased correlation coefficients, and index of agreement) and categorical (increased hit rate and decreased false alarm ratio) evaluation metrics at almost all locations during the study period in 2008. [Copyright &y& Elsevier]

The main use of air quality forecast (AQF) models is to predict ozone (O3) exceedances of the primary O3 standard for informing the public of potential health concerns. This study presents the first evaluation of the performance of the Eta-CMAQ air quality forecast model to predict a variety of widely used seasonal mean and cumulative O3 exposure indices associated with vegetation using the U.S. AIRNow O3 observations. These exposure indices include two concentration-based O3 indices, M7 and M12 (the seasonal means of daytime 7-h and 12-h O3 concentrations, respectively), and three cumulative exposure-based indices, SUM06 (the sum of all hourly O3 concentrations≥0.06ppm), W126 (hourly concentrations weighed by a sigmoidal weighting function), and AOT40 (O3 concentrations accumulated over a threshold of 40ppb during daylight hours). During a three-month simulation (July–September 2005), the model over predicted the M7 and M12 values by 8–9ppb, or a NMB value of 19% and a NME value of 21%. The model predicts a central belt of high O3 extending from Southern California to Middle Atlantic where the seasonal means, M7 and M12 (the seasonal means of daytime 7-h and 12-h O3 concentrations), are higher than 50ppbv. In contrast, the model is less capable of reproducing the observed cumulative indices. For AOT40, SUM06 and W126, the NMB and NME values are two- to three-fold of that for M7, M12 or peak 8-h O3 concentrations. The AOT40 values range from 2 to 33ppmh by the model and from 1 to 40ppmh by the monitors. There is a significantly higher AOT40 value experienced in the United States in comparison to Europe. The domain-wide mean SUM06 value is 14.4ppmh, which is about 30% higher than W126, and 40% higher than AOT40 calculated from the same 3-month hourly O3 data. This suggests that SUM06 and W126 represent a more stringent standard than AOT40 if either the SUM06 or the W126 was used as a secondary O3 standard. Although CMAQ considerably over predicts SUM06 and W126 values at the low end, the model under predicts the extreme high exposure values (>50ppmh). Most of these extreme high values are found at inland California sites. Based on our analysis, further improvement of the model is needed to better capture cumulative exposure indices. [Copyright &y& Elsevier]

The integrated process rates (IPRs) estimated by the Eta–CMAQ model at grid cells along the trajectory of the air mass transport path were analyzed to quantitatively investigate the relative importance of physical and chemical processes for O3 formation and evolution over the northeastern U.S. during the 2004 International Consortium for Atmospheric Research on Transport and Transformation (ICARTT) period. The Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model is used to determine the back trajectory of air masses reaching the northeast by linking a downwind receptor to upwind source areas. The process analysis is applied to a high O3 episode occurring on July 22, 2004 at three selected sites in the northeastern U.S. The process analysis at the location of the site shows that during the daytime, the O3 concentrations in the surface layer are mainly enhanced by the vertical diffusion of O3-rich air from aloft, followed by horizontal advection (HADV) and chemical production (CHEM), whereas dry deposition (DDEP) and vertical advection (ZADV) mainly deplete O3 concentrations at the sites of Valley Central (VC), NY and Castle Spring (CS), NH. By integrating the effects of each process over the depth of the daytime planetary boundary layer (PBL), it was found that at the VC site, CHEM and HADV contributed about 53% and 41%, respectively, to O3 levels within the PBL. This confirms the significance of regional transport of O3 from the industrialized areas into the Northeast. On the other hand, the process analysis results for O3 formation in moving air masses indicate that on July 22, large chemical production of O3 along the transport path over the polluted urban regions leads to significant increase in O3 in the air mass reaching the VC site, whereas the low chemical production of O3 along the transport path over the low... [Copyright &y& Elsevier]

It has been reported that ambient ozone (O3), either alone or in concurrence with acid rain precursors, accounts for up to 90% of US crop losses resulting from exposure to all major air pollutants. Crop damage due to O3 exposure is of particular concern as ambient O3 concentrations remain high in many major food-producing regions. Assessing O3 damage to crops is challenging due to the difficulties in determining the reduction in crop yield that results from exposure to surface O3, for which monitors are limited and mostly deployed in non-rural areas. This work explores the potential benefits of using operational air quality forecast (AQF) data to estimate rural O3 exposure. Using the results from the first nationwide AQF as a case study, we demonstrate how the O3 data provided by AQF can be combined with concurrent crop information to assess O3 damages to soybeans in the United States. We estimate that exposure to ambient O3 reduces the US soybean production by 10% in 2005. [Copyright &y& Elsevier]

Traditional categorical metrics used in model evaluations are “clear cut” measures in that the model’s ability to predict an “exceedance” is defined by a fixed threshold concentration and the metrics are defined by observation–forecast sets that are paired both in space and time. These metrics are informative but limited in evaluating the performance of air quality forecast (AQF) systems because AQF generally examines exceedances on a regional scale rather than a single monitor. New categorical metrics—the weighted success index (WSI), area hit (aH), and area false-alarm ratio (aFAR)—are developed. In the calculation of WSI, credits are given to the observation–forecast pairs within the observed exceedance region (missed forecast) or the forecast exceedance region (false alarm), depending on the distance of the points from the central line (perfect observation–forecast match line or 1:1 line on scatterplot). The aH and aFAR are defined by matching observed and forecast exceedances within an area (i.e., model grid cells) surrounding the observation location. The concept of aH and aFAR resembles the manner in which forecasts are usually issued. In practice, a warning is issued for a region of interest, such as a metropolitan area, if an exceedance is forecast to occur anywhere within the region. The application of these new categorical metrics, which are supplemental to the traditional counterparts (critical success index, hit rate, and false-alarm ratio), to the Eta Model–Community Multiscale Air Quality (CMAQ) forecast system has demonstrated further insight into evaluating the forecasting capability of the system (e.g., the new metrics can provide information about how the AQF system captures the spatial variations of pollutant concentrations). [ABSTRACT FROM AUTHOR]

Two geometrical and two advection-equivalent spatial interpolation schemes were tested in providing lateral boundary conditions to a nested grid domain. Geometric interpolation schemes used in this study are a zeroth-order and a quadratic scheme, while the two advection-equivalent interpolation schemes were based on upwind and Bott's advection schemes. The test problem involves an initially cone-shaped distribution of a scalar advected from a coarse to a fine grid. Simulation results were compared to the exact solution to study magnitude and phase characteristics of each scheme. Results indicated that Bott's advection-equivalent interpolation scheme provided better interface conditions and, consequently, a more accurate transition of the signal from a coarse to a fine grid. [ABSTRACT FROM AUTHOR]

In this article, a compact half‐hexagonal ultra‐wide band multiple‐input‐multiple‐output (MIMO) antenna is presented. The key feature of the antenna is its novel isolation improvement technique which includes grounded stub along with dual grounded circular ring resonator. The antenna contains two counter facing half‐hexagonal monopoles having hybrid isolation circuit. The antenna has a compact size of 20 × 34 mm2, with operating frequency band of 3‐11 GHz where port isolation is better than 20 dB in most of the band. The MIMO performance is ensured by calculating envelop correlation coefficient and mean effective gain ratio for isotropic, indoor, and outdoor environment. The performance of the antenna with multilayer printed circuit board having large dual ground plane and device housing is also studied. Results show that the proposed MIMO antenna is a good candidate for handheld devices for wireless personal‐area networks application. [ABSTRACT FROM AUTHOR]

This study assesses the impact of the lightning nitric oxide (LNO) production schemes in the Community Multiscale Air Quality (CMAQ) model on ground-level air quality as well as aloft atmospheric chemistry through detailed evaluation of model predictions of nitrogen oxides (NOx) and ozone (O3) with corresponding observations for the US. For ground-level evaluations, hourly O3 and NOx values from the U.S. EPA Air Quality System (AQS) monitoring network are used to assess the impact of different LNO schemes on model prediction of these species in time and space. Vertical evaluations are performed using ozonesonde and P-3B aircraft measurements during the Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) campaign conducted in the Baltimore–Washington region during July 2011. The impact on wet deposition of nitrate is assessed using measurements from the National Atmospheric Deposition Program's National Trends Network (NADP NTN). Compared with the Base model (without LNO), the impact of LNO on surface O3 varies from region to region depending on the Base model conditions. Overall statistics suggest that for regions where surface O3 mixing ratios are already overestimated, the incorporation of additional NO from lightning generally increased model overestimation of mean daily maximum 8 h (DM8HR) O3 by 1–2 ppb. In regions where surface O3 is underestimated by the Base model, LNO can significantly reduce the underestimation and bring model predictions close to observations. Analysis of vertical profiles reveals that LNO can significantly improve the vertical structure of modeled O3 distributions by reducing underestimation aloft and to a lesser degree decreasing overestimation near the surface. Since the Base model underestimates the wet deposition of nitrate in most regions across the modeling domain with the exception of the Pacific Coast, the inclusion of LNO leads to reduction in biases and errors and an increase in correlation coefficients at almost all the NADP NTN sites. Among the three LNO schemes described in Kang et al. (2019), the hNLDN scheme, which is implemented using hourly observed lightning flash data from National Lightning Detection Network (NLDN), performs best for comparisons with ground-level values, vertical profiles, and wet deposition of nitrate; the mNLDN scheme (the monthly NLDN-based scheme) performed slightly better. However, when observed lightning flash data are not available, the linear regression-based parameterization scheme, pNLDN, provides an improved estimate for nitrate wet deposition compared to the base simulation that does not include LNO. [ABSTRACT FROM AUTHOR]

This study assesses the impact of the lightning NOX (LNOX) production schemes in the CMAQ model (Kang et al., 2019) on ground-level air quality as well as aloft atmospheric chemistry through detailed evaluation of model predictions of nitrogen oxides (NOx) and ozone (O3) with corresponding observations for the U.S. For ground-level evaluations, hourly O3 and NOx from the US EPA's AQS monitoring network are used to assess the impact of different LNOx schemes on model prediction of these species in time and space. Vertical evaluations are performed using ozonesonde and P-3B aircraft measurements during the DISCOVER-AQ campaign conducted in the Baltimore/Washington region during July 2011. The impact on wet deposition of nitrate is assessed using measurements from the National Atmospheric Deposition Program's National Trends Network (NADP/NTN). Compared with the base model (without LNOx), the impact of LNOx on surface O3 varies from region to region depending on the base model conditions. Overall statistics suggest that for regions where surface O3 mixing ratios are already overestimated, the incorporation of additional NOx from lightning generally increased model overestimation of mean daily maximum 8-hr (DM8HR) O3 by 1-2ppb. In regions where surface O3 is underestimated by the base model, LNOx can significantly reduce the underestimation and bring model predictions close to observations. Analysis of vertical profiles reveals that LNOx can significantly improve the vertical structure of modeled O3 distributions by reducing underestimation aloft, and to a lesser degree decreasing overestimation near the surface. Since the base model underestimates the wet deposition of nitrate in most regions across the modeling domain except the Pacific Coast, the inclusion of LNOx leads to reduction in biases and errors and an increase in correlation coefficients at almost all the NADP/NTN sites. Among the three LNOx schemes described in Kang et al. (2019), the hNLDN scheme, which is implemented using hourly observed lightning flash data from National Lightning Detection Network (NLDN), performs best for the ground-level, vertical profiles, and wet deposition comparisons except that for the accumulated wet deposition of nitrate, the mNLDN scheme (the monthly NLDN-based scheme) performed slightly better. However, when observed lightning flash data are not available, the linear regression-based parameterization scheme, pNLDN, provides an improved estimate for LNOx compared to the base simulation that does not include LNOx. [ABSTRACT FROM AUTHOR]

We examined the impact of dimethylsulfide (DMS) emissions on sulfate concentrations over the continental U.S. by using the Community Multiscale Air Quality (CMAQ) model version 5.4 and performing annual simulations without and with DMS emissions for 2018. DMS emissions enhance sulfate not only over seawater but also over land, although to a lesser extent. On an annual basis, the inclusion of DMS emissions increase sulfate concentrations by 36% over seawater and 9% over land. The largest impacts over land occur in California, Oregon, Washington, and Florida, where the annual mean sulfate concentrations increase by ~25%. The increase in sulfate causes a decrease in nitrate concentration due to limited ammonia concentration, especially over seawater, and an increase in ammonium concentration with a net effect of increased inorganic particles. The largest sulfate enhancement occurs near the surface (over seawater), and the enhancement decreases with altitude, diminishing to 10–20% at an altitude of ~5 km. Seasonally, the largest enhancement in sulfate over seawater occurs in summer, and the lowest in winter. In contrast, the largest enhancements over land occur in spring and fall due to higher wind speeds that can transport more sulfate from seawater into land. [ABSTRACT FROM AUTHOR]

Impacts of aerosol cooling are not limited to changes in surface temperature since modulation of atmospheric dynamics resulting from the increased stability can deteriorate local air quality and impact human health. Health impacts from two manifestations of the aerosol direct effects (ADE) are estimated in this study: (1) the effect on surface temperature and (2) the effect on air quality through atmospheric dynamics. Average mortalities arising from the enhancement of surface PM2.5 concentration due to ADE in East Asia, North America and Europe are estimated to be 3-6 times higher than reduced mortality from decreases of temperature due to ADE. Our results suggest that mitigating aerosol pollution is beneficial in decreasing the impacts of climate change arising from these two manifestations of ADE health impacts. Thus, decreasing aerosol pollution gets direct benefits on health, and indirect benefits on health through changes in local climate and not offsetting changes associated only with temperature modulations as traditionally thought. The modulation of air pollution due to ADE also translates into an additional human health dividend in regions (e.g., U.S. Europe) with air pollution control measures but a penalty for regions (e.g., Asia) witnessing rapid deterioration in air quality. [ABSTRACT FROM AUTHOR]

The objective of this study is to determine the adequacy of using a relatively coarse horizontal resolution (i.e. 36 km) to simulate long-term trends of pollutant concentrations and radiation variables with the coupled WRF-CMAQ model. WRF-CMAQ simulations over the continental United State are performed over the 2001 to 2010 time period at two different horizontal resolutions of 12 and 36 km. Both simulations used the same emission inventory and model configurations. Model results are compared both in space and time to assess the potential weaknesses and strengths of using coarse resolution in long-term air quality applications. The results show that the 36 km and 12 km simulations are comparable in terms of trends analysis for both pollutant concentrations and radiation variables. The advantage of using the coarser 36 km resolution is a significant reduction of computational cost, time and storage requirement which are key considerations when performing multiple years of simulations for trend analysis. However, if such simulations are to be used for local air quality analysis, finer horizontal resolution may be beneficial since it can provide information on local gradients. In particular, divergences between the two simulations are noticeable in urban, complex terrain and coastal regions. [ABSTRACT FROM AUTHOR]

Comparison of lightning flash data from the National Lightning Detection Network (NLDN) and from the World Wide Lightning Location Network (WWLLN) over the contiguous United States (CONUS) for the 2016–2018 period reveals temporally and spatially varying flash rates that would influence lightning NOx (LNOx) production due to known detection efficiency differences especially during summer months over land (versus over ocean). However, the lightning flash density differences between the two networks show persistent seasonal patterns over geographical regions (e.g., land versus ocean). Since the NLDN data are considered to have higher accuracy (lightning detection with >95% efficiency), we developed scaling factors for the WWLLN flash data based on the ratios of WWLLN to NLDN flash data over time (months of year) and space. In this study, sensitivity simulations using the Community Multiscale Air Quality (CMAQ) model are performed utilizing the original data sets (both NLDN and WWLLN) and the scaled WWLLN flash data for LNOx production over the CONUS. The model performance of using the different lightning flash datasets for ambient O3 and NOx mixing ratios that are directly impacted by LNOx emissions and the wet and dry deposition of oxidized nitrogen species that are indirectly impacted by LNOx emissions is assessed based on comparisons with ground-based observations, vertical profile measurements, and satellite products. During summer months, the original WWLLN data produced less LNOx emissions (due to its lower lightning detection efficiency) compared to the NLDN data, which resulted in less improvement in model performance than the simulation using NLDN data as compared to the simulation without any LNOx emissions. However, the scaled WWLLN data produced LNOx estimates and model performance comparable with the NLDN data, suggesting that scaled WWLLN may be used as a substitute for the NLDN data to provide LNOx estimates in air quality models when the NLDN data are not available (e.g., due to prohibitive cost or lack of spatial coverage). [ABSTRACT FROM AUTHOR]

Aerosols can influence the climate indirectly by acting as cloud condensation nuclei and/or ice nuclei, thereby modifying cloud optical properties. In contrast to the widespread global warming, the central and south central United States display a noteworthy overall cooling trend during the 20th century, with an especially striking cooling trend in summertime daily maximum temperature (Tmax) (termed the U.S. "warming hole"). Here we used observations of temperature, shortwave cloud forcing (SWCF), longwave cloud forcing (LWCF), aerosol optical depth and precipitable water vapor as well as global coupled climate models to explore the attribution of the "warming hole". We find that the observed cooling trend in summer Tmax can be attributed mainly to SWCF due to aerosols with offset from the greenhouse effect of precipitable water vapor. A global coupled climate model reveals that the observed "warming hole" can be produced only when the aerosol fields are simulated with a reasonable degree of accuracy as this is necessary for accurate simulation of SWCF over the region. These results provide compelling evidence of the role of the aerosol indirect effect in cooling regional climate on the Earth. Our results reaffirm that LWCF can warm both winter Tmax and Tmin. [ABSTRACT FROM AUTHOR]

Resistance to Fas-mediated apoptosis is associated with poor cancer outcomes and chemoresistance. To elucidate potential mechanisms of defective Fas signaling, we screened primary lymphoma cell extracts for Fas-associated proteins that would have the potential to regulate Fas signaling. An activation-resistant Fas complex selectively included nucleolin. We confirmed the presence of nucleolin-Fas complexes in B-cell lymphoma cells and primary tissues, and the absence of such complexes in B-lymphocytes from healthy donors. RNA-binding domain 4 and the glycine/arginine-rich domain of nucleolin were essential for its association with Fas. Nucleolin colocalized with Fas on the surface of B-cell lymphoma cells. Nucleolin knockdown sensitized BJAB cells to Fas ligand (FasL)-induced and Fas agonistic antibody-induced apoptosis through enhanced binding, suggesting that nucleolin blocks the FasL-Fas interaction. Mice transfected with nucleolin were protected from the lethal effects of agonistic anti-mouse Fas antibody (Jo2) and had lower rates of hepatocyte apoptosis, compared with vector and a non-Fas-binding mutant of nucleolin. Our results show that cell surface nucleolin binds Fas, inhibits ligand binding, and thus prevents induction of Fas-mediated, apoptosis in B-cell lymphomas and may serve as a new therapeutic target. [ABSTRACT FROM AUTHOR]

Abstract: Since the Community Multiscale Air Quality modeling system (CMAQ) and the Weather Research and Forecasting with Chemistry model (WRF/Chem) use different approaches to simulate the interaction of meteorology and chemistry, this study compares the CMAQ and WRF/Chem air quality simulation results for a month-long retrospective study period (August 2006) over the eastern United States, including comparisons with data from several observation networks. To help improve the comparability of the two models, the 2005 Carbon Bond chemical mechanism (CB05) was implemented into WRF/Chem. In addition, the same emissions, initial and boundary conditions have been used in both models to inter-compare simulated ozone (O3) from the WRF-driven CMAQ and WRF/Chem models. Results reveal that ground-level O3 from both models is biased high, especially in the central South and Ohio River Valley; however, WRF/Chem predicts roughly 10% more O3 aloft (1000–2500m AGL) than CMAQ. Different model configurations due to the choice of land surface model (LSM), planetary boundary layer (PBL) physics scheme, and convective cloud parameterization contributed to the differences seen in simulated O3, but most important were the different treatments of the radiative effects of clouds by their respective photolysis schemes. [Copyright &y& Elsevier]

Abstract: This paper provides a performance evaluation of the real-time, CONUS-scale National Air Quality Forecast Capability (NAQFC) that supported, in part, its transition into operational status. This evaluation focuses primarily on discrete forecasts for the maximum 8-h O3 concentrations covering the 4-month period, June through September, 2007, using measurements obtained from EPA''s AIRNow network. Results indicate that the 2007 NAQFC performed as well or better than previous configurations, despite the expansion of the forecast domain into the western half of the nation that is dominated by complex terrain. The mean, domain-wide, season-long correlation was 0.70. When examined over time, the domain-wide correlations exhibit a fairly consistent nature, with values exceeding 0.60 (0.70) over 90% (55%) of the days. The NAQFC systematically over-predicted the 8-h O3 concentrations, continuing a trend established by earlier NAQFC configurations, though to a lesser degree. The summer-long mean forecast value of 53.2ppb was 4.2ppb higher than the observed value, resulting in a domain-wide Normalized Mean Bias (NMB) of 8.7%. Most of the over-prediction is associated with observed concentrations less than 50ppb. In fact the model tends to under-predict when concentrations exceed 70ppb. As with the bias, the error associated with the latest configuration was also lower. The summer-long Root Mean Square Error of 13.0ppb (Normalized Mean Error (NME)=20.4%) represented marked improvements over earlier forecasts. Examination of the spatial distribution of both the NMB and NME reveals that the NAQFC was generally within 25% for the NME and 25% for the NMB over a majority of the domain. Several areas of poorer performance, where the NMB and NME often exceed 25% and in some cases 50%, were noted. These areas include southern California, where the NAQFC tended to under-predict concentrations (especially on weekends) and the southeast Atlantic and Gulf coasts regions, where the model over-predicted. Subsequent analysis revealed that the incorrect temporal allocation of precursor emissions was likely the source of the under-prediction in southern California, while inaccurate simulation of PBL heights likely contributed to the over-prediction in the coastal regions. [Copyright &y& Elsevier]

Predictions of nitrous acid from the Community Multiscale Air Quality modeling system are compared with the measurements from the 2001 Northeast Oxidant and Particle Study. Four different sources of nitrous acid were considered in the study: gas-phase reactions, direct emissions, a heterogeneous reaction, and a surface photolysis reaction. When only gas-phase reactions were considered in the model, the diurnally averaged mean bias, the normalized mean bias, the root mean square error, and the normalized mean error of the model were −1.01ppbv, −98%, 1.05ppbv, and 98%, respectively. However, the diurnally averaged mean bias, normalized mean bias, the root mean square error, and the normalized mean error of the model improved to −0.42ppbv, −41%, 0.45ppbv, and 41%, respectively, when all sources were considered. Model results suggest that the heterogeneous reaction and the surface photolysis reaction are the most important sources of nitrous acid in the atmosphere, accounting for about 86% of the predicted nitrous acid. Emissions and the gas-phase reactions were relatively minor sources and accounted for only 14% of the predicted nitrous acid. Model predictions suggest that the heterogeneous reaction is the most significant source of nitrous acid at night, while the surface photolysis reaction is the most significant source during the day. The addition of these sources increased the diurnally averaged hydroxyl radicals and ozone by 10% and 1.4ppbv, respectively. [Copyright &y& Elsevier]

Abstract: The National Oceanic and Atmospheric Administration (NOAA), in partnership with the United States Environmental Protection Agency (EPA), are developing an operational, nationwide Air Quality Forecasting (AQF) system. An experimental phase of this program, which couples NOAA''s Eta meteorological model with EPA''s Community Multiscale Air Quality (CMAQ) model, began operation in June of 2004 and has been providing forecasts of ozone (O3) concentrations over the northeastern United States. An important component of this AQF system has been the development and implementation of an evaluation protocol. Accordingly, a suite of statistical metrics that facilitates evaluation of both discrete- and categorical-type forecasts was developed and applied to the system in order to characterize its performance. The results reveal that the AQF system performed reasonably well in this inaugural season (mean domain wide correlation coefficient=0.59), despite anomalously cool and wet conditions that were not conducive to the formation of O3. Due in part to these conditions, the AQF system overpredicted concentrations, resulting in a mean bias of +10.2ppb (normalized mean bias=+22.8%). In terms of error, the domain-wide root mean square error averaged 15.7ppb (normalized mean error=28.1%) for the period. Examination of the discrete and categorical metrics on a daily basis revealed that the AQF system''s level of performance was closely related to the synoptic-scale meteorology impacting the domain. The model performed very well during periods when anticyclones, characterized by clear skies, dominated. Conversely, periods characterized by extensive cloud associated with fronts and/or cyclones, resulted in poor model performance. Subsequent analysis revealed that factors associated with CMAQ''s cloud cover scheme contributed to this overprediction. Accordingly, changes to the cloud schemes are currently underway that are expected to significantly improve the AQF system''s performance in anticipation of its second year of operation. [Copyright &y& Elsevier]

In airsheds that contain high volatile organic compounds (VOCs) and low NOx (=NO+NO2) concentrations, ozone (O3) production may be significantly suppressed by NOx reactions that lead to the formation of organic nitrates. O3 and its precursors (VOCs and NOx) ambient levels simulated using a regional-scale photochemical model, called Multiscale Air Quality Simulation Platform, are analyzed and compared to observed data from three southeast United States national parks. [Copyright &y& Elsevier]

The two-way coupled Weather Research and Forecasting and Community Multiscale Air Quality (WRF-CMAQ) model has been developed to more realistically represent the atmosphere by accounting for complex chemistry–meteorology feedbacks. In this study, we present a comparative analysis of two-way (with consideration of both aerosol direct and indirect effects) and offline coupled WRF v3.4 and CMAQ v5.0.2 over the contiguous US. Long-term (5 years from 2008 to 2012) simulations using WRF-CMAQ with both offline and two-way coupling modes are carried out with anthropogenic emissions based on multiple years of the U.S. National Emission Inventory and chemical initial and boundary conditions derived from an advanced Earth system model (i.e., a modified version of the Community Earth System Model/Community Atmospheric Model). The comprehensive model evaluations show that both two-way WRF-CMAQ and WRF-only simulations perform well for major meteorological variables such as temperature at 2 m, relative humidity at 2 m, wind speed at 10 m, precipitation (except for against the National Climatic Data Center data), and shortwave and longwave radiation. Both two-way and offline CMAQ also show good performance for ozone (O3) and fine particulate matter (PM 2.5). Due to the consideration of aerosol direct and indirect effects, two-way WRF-CMAQ shows improved performance over offline coupled WRF and CMAQ in terms of spatiotemporal distributions and statistics, especially for radiation, cloud forcing, O3 , sulfate, nitrate, ammonium, elemental carbon, tropospheric O3 residual, and column nitrogen dioxide (NO2). For example, the mean biases have been reduced by more than 10 W m -2 for shortwave radiation and cloud radiative forcing and by more than 2 ppb for max 8 h O3. However, relatively large biases still exist for cloud predictions, some PM 2.5 species, and PM 10 that warrant follow-up studies to better understand those issues. The impacts of chemistry–meteorological feedbacks are found to play important roles in affecting regional air quality in the US by reducing domain-average concentrations of carbon monoxide (CO), O3 , nitrogen oxide (NOx), volatile organic compounds (VOCs), and PM 2.5 by 3.1 % (up to 27.8 %), 4.2 % (up to 16.2 %), 6.6 % (up to 50.9 %), 5.8 % (up to 46.6 %), and 8.6 % (up to 49.1 %), respectively, mainly due to reduced radiation, temperature, and wind speed. The overall performance of the two-way coupled WRF-CMAQ model achieved in this work is generally good or satisfactory and the improved performance for two-way coupled WRF-CMAQ should be considered along with other factors in developing future model applications to inform policy making. [ABSTRACT FROM AUTHOR]

Utilizing a state-of-the-art mobile laboratory in conjunction with a dynamic flow-through chamber system, nitric oxide concentrations [NO] were measured and NO fluxes were calculated during the summer, winter and spring of 1999/ 2000. The field site where these measurements were conducted was an agricultural soil amended with biosolids from a municipal wastewater treatment facility. These NO flux values were then used to assess the impact of including biosolid amended soils as a land-use class in an air quality model. The average NO flux from this biosolid amended soil was found to be exponentially dependent on soil temperature [NO Flux (ng N m[sup -2] s[sup -1]) = 1.07 exp(0.14 T[sub soil]); R² = 0.81NO Flux = 71.3 ng N m[sup -2] s[sup -1] at 30°C]. Comparing this relationship to results of the widely applied biogenic emissions inventory system (BEIS2) model revealed that for this field site, if the BEIS2 model was used, the NO emissions would have been underestimated by a factor of 26. Using this newly developed NO flux algorithm, combined with North Carolina Division of Water Quality statistics on how many biosolid amended acres are permitted per county, county-based NO inventories from these biosolid amended soils were calculated. Results from this study indicate that county-level biogenic NO emissions can increase by as much as 18% when biosolid amended soils are included as a land-use class. The multiscale air quality simulation platform (MAQSIP) was then used to determine differences in ozone (O[sub 3]) and odd-reactive nitrogen compounds (NO[sub y]) between models run with and without the biosolid amended acreages included in the inventory. Results showed that during the daytime, when atmospheric mixing heights are typically at their greatest, any increase in O[sub 3] or NO[sub y] concentrations predicted by the model were small (< 3%). In some locations during late evening/early morning hours, ozone was found to be consumed by as much as 11%. [ABSTRACT FROM AUTHOR]

Air quality modeling for research and regulatory applications often involves executing many emissions sensitivity cases to quantify impacts of hypothetical scenarios, estimate source contributions, or quantify uncertainties. Despite the prevalence of this task, conventional approaches for perturbing emissions in chemical transport models like the Community Multiscale Air Quality (CMAQ) model require extensive offline creation and finalization of alternative emissions input files. This workflow is often time-consuming, error-prone, inconsistent among model users, difficult to document, and dependent on increased hard disk resources. The Detailed Emissions Scaling, Isolation, and Diagnostic (DESID) module, a component of CMAQv5.3 and beyond, addresses these limitations by performing these modifications online during the air quality simulation. Further, the model contains an Emission Control Interface which allows users to prescribe both simple and highly complex emissions scaling operations with control over individual or multiple chemical species, emissions sources, and spatial areas of interest. DESID further enhances the transparency of its operations with extensive error-checking and optional gridded output of processed emission fields. These new features are of high value to many air quality applications including routine perturbation studies, atmospheric chemistry research, and coupling with external models (e.g., energy system models, reduced-form models). [ABSTRACT FROM AUTHOR]

The Community Multiscale Air Quality (CMAQ) model version 5.3 (CMAQ53), released to the public in August 2019 and followed by version 5.3.1 (CMAQ531) in December 2019, contains numerous science updates, enhanced functionality, and improved computation efficiency relative to the previous version of the model, 5.2.1 (CMAQ521). Major science advances in the new model include a new aerosol module (AERO7) with significant updates to secondary organic aerosol (SOA) chemistry, updated chlorine chemistry, updated detailed bromine and iodine chemistry, updated simple halogen chemistry, the addition of dimethyl sulfide (DMS) chemistry in the CB6r3 chemical mechanism, updated M3Dry bidirectional deposition model, and the new Surface Tiled Aerosol and Gaseous Exchange (STAGE) bidirectional deposition model. In addition, support for the Weather Research and Forecasting (WRF) model's hybrid vertical coordinate (HVC) was added to CMAQ53 and the Meteorology-Chemistry Interface Processor (MCIP) version 5.0 (MCIP50). Enhanced functionality in CMAQ53 includes the new Detailed Emissions Scaling, Isolation and Diagnostic (DESID) system for scaling incoming emissions to CMAQ and reading multiple gridded input emission files. Evaluation of CMAQ531 was performed by comparing monthly and seasonal mean daily 8 h average (MDA8) O 3 and daily PM 2.5 values from several CMAQ531 simulations to a similarly configured CMAQ521 simulation encompassing 2016. For MDA8 O 3 , CMAQ531 has higher O 3 in the winter versus CMAQ521, due primarily to reduced dry deposition to snow, which strongly reduces wintertime O 3 bias (2–4 ppbv monthly average). MDA8 O 3 is lower with CMAQ531 throughout the rest of the year, particularly in spring, due in part to reduced O 3 from the lateral boundary conditions (BCs), which generally increases MDA8 O 3 bias in spring and fall (∼0.5 µgm-3). For daily 24 h average PM 2.5 , CMAQ531 has lower concentrations on average in spring and fall, higher concentrations in summer, and similar concentrations in winter to CMAQ521, which slightly increases bias in spring and fall and reduces bias in summer. Comparisons were also performed to isolate updates to several specific aspects of the modeling system, namely the lateral BCs, meteorology model version, and the deposition model used. Transitioning from a hemispheric CMAQ (HCMAQ) version 5.2.1 simulation to a HCMAQ version 5.3 simulation to provide lateral BCs contributes to higher O 3 mixing ratios in the regional CMAQ simulation in higher latitudes during winter (due to the decreased O 3 dry deposition to snow in CMAQ53) and lower O 3 mixing ratios in middle and lower latitudes year-round (due to reduced O 3 over the ocean with CMAQ53). Transitioning from WRF version 3.8 to WRF version 4.1.1 with the HVC resulted in consistently higher (1.0–1.5 ppbv) MDA8 O 3 mixing ratios and higher PM 2.5 concentrations (0.1–0.25 µgm-3) throughout the year. Finally, comparisons of the M3Dry and STAGE deposition models showed that MDA8 O 3 is generally higher with M3Dry outside of summer, while PM 2.5 is consistently higher with STAGE due to differences in the assumptions of particle deposition velocities to non-vegetated surfaces and land use with short vegetation (e.g., grasslands) between the two models. For ambient NH 3 , STAGE has slightly higher concentrations and smaller bias in the winter, spring, and fall, while M3Dry has higher concentrations and smaller bias but larger error and lower correlation in the summer. [ABSTRACT FROM AUTHOR]

Air quality modeling for research and regulatory applications often involves executing many emissions sensitivity cases to quantify impacts of hypothetical scenarios, estimate source contributions or quantify uncertainties. Despite the prevalence of this task, conventional approaches for perturbing emissions in chemical transport models like the Community Multiscale Air Quality (CMAQ) model require extensive offline creation and finalization of alternative emissions input files. This workflow tends to be time-consuming, error-prone, inconsistent among model users and difficult to document while consuming increased computer storage space. The Detailed Emissions Scaling, Isolation, and Diagnostic (DESID) module, a component of CMAQv5.3 and beyond, addresses these limitations by performing these modifications online during the air quality simulation. Further, the model contains an Emission Control Interface which allows users to prescribe both simple and highly complex emissions scaling operations with control over individual or multiple chemical species, emissions sources, and spatial areas of interest. DESID further enhances the transparency of its operations with extensive error-checking and optional gridded output of processed emission fields. These new features are of high value to many air quality applications including routine perturbation studies, atmospheric chemistry research, and coupling with external models (e.g. energy system models, reduced-form models). [ABSTRACT FROM AUTHOR]

Regional air quality models are widely being used to understand the spatial extent and magnitude of the ozone non-attainment problem and to design emission control strategies needed to comply with the relevant ozone standard through direct emission perturbations. In this study, we examine the manageable portion of ground-level ozone using two simulations of the Community Multiscale Air Quality (CMAQ) model for the year 2010 and a probabilistic analysis approach involving 29 years (1990–2018) of historical ozone observations. The modeling results reveal that the reduction in the peak ozone levels from total elimination of anthropogenic emissions within the model domain is around 13–21 ppb for the 90th−100th percentile range of the daily maximum 8-hr ozone concentrations across the contiguous United States (CONUS). Large reductions in the 4th highest 8-hr ozone are seen in the regions of West (interquartile range (IQR) of 17–33%), South (IQR 22–34%), Central (IQR 19–31%), Southeast (IQR 25–34%), and Northeast (IQR 24–37%). However, sites in the western portion of the domain generally show smaller reductions even when all anthropogenic emissions are removed, possibly due to the strong influence of global background ozone, including sources such as intercontinental ozone transport, stratospheric ozone intrusions, wildfires, and biogenic precursor emissions. Probabilistic estimates of the exceedances for several hypothetical thresholds of the 4th highest 8-hr ozone indicate that, in some areas, exceedances of such hypothetical thresholds may occur even with no anthropogenic emissions due to the ever-present atmospheric stochasticity and the current global tropospheric ozone burden. Implications: Because air pollution is intricately linked to adverse health effects, National Ambient Air Quality Standards (NAAQS) have been established for criteria pollutants to safeguard human health and the environment. Areas not in compliance with the relevant standards are required to develop plans and policies to reduce their air pollution levels. Regional-scale air quality models are currently being used routinely to inform policies to identify the emissions reduction required to meet and maintain the NAAQS throughout the country. This paper examines the feasibility of the 4th highest ozone, which is used to derive the ozone design value for NAAQS, complying with various current and hypothetical 8-hr ozone thresholds over CONUS based on the information embedded in 29 years of historical ozone observations and two modeling scenarios with and without anthropogenic emissions loading. [ABSTRACT FROM AUTHOR]

The Community Multiscale Air Quality (CMAQ) model version 5.3 (CMAQ53), released to the public in August 2019 and followed by version 5.3.1 (CMAQ531) in December 2019, contains numerous science updates, enhanced functionality, and improved computation efficiency relative to the previous version of the model, 5.2.1 (CMAQ521). Major science advances in the new model include a new aerosol module (AERO7) with significant updates to secondary organic aerosol (SOA) chemistry; updated chlorine chemistry; updated detailed bromine/iodine chemistry; updated simple halogen chemistry; addition of dimethyl sulfide (DMS) chemistry in the CB6r3 chemical mechanism; updated M3Dry bi-directional deposition model; and the new Surface Tiled Aerosol and Gaseous Exchange (STAGE) bi-directional deposition model. In addition, support for the Weather Research and Forecasting (WRF) model's hybrid vertical coordinate (HVC) system was added to CMAQ53 and the Meteorology-Chemistry Interface Processor (MCIP) version 5.0 (MCIP50). Enhanced functionality in CMAQ53 includes the new Detailed Emissions Scaling, Isolation and Diagnostic (DESID) system for scaling incoming emissions to CMAQ and reading multiple gridded input emission files. Evaluation of CMAQ53 was performed by comparing monthly and seasonal mean daily 8-hr average (MDA8) O3 and PM2.5 values from several CMAQ531 simulations to a similarly configured CMAQ521 simulation encompassing 2016. For MDA8 O3, CMAQ531 has higher O3 in the winter versus CMAQ521, due primarily to reduced dry deposition to snow, which strongly reduces wintertime O3 bias. MDA8 O3 is lower with CMAQ531 throughout the rest of the year, particularly in spring, due in part to reduced O3 from the lateral boundary conditions (BCs), which generally increases MDA8 O3 bias in spring and fall. For daily 24-hr average PM2.5, CMAQ531 has lower concentrations on average in spring and fall, higher concentrations in summer, and similar concentrations in winter as CMAQ521, which slightly increases bias in spring and fall and reduces bias in summer. Comparisons isolating updates to several specific aspects of the modeling system, namely the lateral BCs, meteorology model version, and the deposition model used, were also performed. Transitioning from a hemispheric CMAQ (HCMAQ) version 5.2.1 simulation to a HCMAQ version 5.3 simulation to provide lateral BCs contributes to higher O3 mixing ratios in the regional CMAQ simulation in higher latitudes during winter (due to the decreased O3 dry deposition to snow in CMAQ53) and lower O3 mixing ratios in mid and lower latitudes year-round (due to reduced O3 over the ocean with CMAQ53). Transitioning from WRF version 3.8 to WRF version 4.1.1 with the HVC system resulted in consistently higher (1.0-1.5 ppbv) MDA8 O3 mixing ratios and higher PM2.5 concentrations (0.1-0.25 µg m-3) throughout the year. Finally, comparisons of the M3Dry and STAGE deposition models showed that MDA8 O3 is generally higher with M3Dry outside of summer, while PM2.5 is consistently higher with STAGE due to differences in the assumptions of particle deposition velocities to some surfaces between the two models. For ambient NH3, STAGE has slightly higher concentrations and smaller bias in the winter, spring, and fall, while M3Dry has higher concentrations and smaller bias, but larger error and lower correlation, in the summer. [ABSTRACT FROM AUTHOR]

The downward transport of ozone (O 3) stemming from the stratosphere-to-troposphere exchange (STE) can be a significant contributor to background O 3. Such enhancement of background O 3 may also influence ground-level PM 2.5 , particularly in polluted regions which have abundant precursor emissions. In this study, we quantified the STE impact on tropospheric O 3 and its subsequent influence on surface PM 2.5 across the northern hemisphere. The sensitivity analyses was conducted by using a comprehensive hemispheric atmospheric modeling system. Results suggest the surface PM 2.5 concentration can be considerably enhanced by the STE in polluted regions including East China, East US, and Europe, mostly in winter and spring. In winter, the PM 2.5 concentrations in East China, East US, and Europe are estimated to be enhanced by 1.3%, 3.5% and 5.5% due to the STE. The STE-enhanced PM 2.5 concentrations are typically higher on high pollution days suggesting likely increasing contributions in regions with the growing pollution levels. During the heavy polluted days, the PM 2.5 concentrations in East China can be enhanced by 2.289 μg/m3 in winter and 2.034 μg/m3 in spring due to the STE. The STE-enhanced PM 2.5 also exhibits strong diurnal variations following a pattern similar to the total PM 2.5 concentration, with high increasing ratio in the morning and low at afternoon, suggesting that the enhancement is most pronounced during peak pollution events. The STE-enhanced PM 2.5 is exclusively contributed by the increase of nitrate, ammonium, and secondary organic aerosol which in-turn are strongly influenced by the atmospheric oxidation capacity. • STE-driven O 3 downward transport can lead to non-trivial enhancement of surface PM 2.5 • STE-enhanced PM 2.5 is most pronounced in polluted regions. • STE enhances peak PM 2.5 thereby further exacerbating high pollution levels. • STE-enhanced PM 2.5 is exclusively caused by an increase of secondary aerosols. • STE enhancement on SOA becomes more important during heavier polluted period. [ABSTRACT FROM AUTHOR]

The two-way coupled Weather Research and Forecasting and Community Multiscale Air Quality (WRF-CMAQ) model has been developed to more realistically represent the atmosphere by accounting for complex chemistry-meteorology feedbacks. In this study, we present a comparative analysis of two-way (with consideration of both aerosol direct and indirect effects) and offline coupled WRF v3.4 and CMAQ v5.0.2 over the contiguous U.S. Long-term (five-year of 2008-2012) simulations using WRF-CMAQ with both offline and two-way coupling modes are carried out with anthropogenic emissions based on multiple years of the U.S. National Emission Inventory and chemical initial and boundary conditions derived from an advanced Earth system model (i.e., a modified version of the Community Earth System Model/Community Atmospheric Model). The comprehensive model evaluations show that both two-way WRF-CMAQ and WRF-only simulations perform well for major meteorological variables such as temperature at 2 m, relative humidity at 2 m, wind speed at 10 m, and precipitation (except for against the National Climatic Data Center data) as well as shortwave/longwave radiation. Both two-way and offline CMAQ also show good performance for ozone (O3) and fine particulate matter (PM2.5). Due to the consideration of aerosol direct and indirect effects, two-way WRF-CMAQ shows improved performance over offline-coupled WRF and CMAQ in terms of spatiotemporal distributions and statistics, especially for radiation, cloud forcing, O3, sulfate, nitrate, ammonium, and elemental carbon as well as tropospheric O3 residual and column nitrogen dioxide (NO2). For example, the mean biases have been reduced by more than 10 W m-2 for shortwave radiation and cloud radiative forcing and by more than 2 ppb for max 8-h O3. However, relatively large biases still exist for cloud predictions, some PM2.5 species, and PM10, which warrant follow-up studies to better understand those issues. The impacts of chemistry-meteorological feedbacks are found to play important roles in affecting regional air quality in the U.S. by reducing domain-average concentrations of carbon monoxide (CO), O3, nitrogen oxide (NOx), volatile organic compounds (VOCs), and PM2.5 by 3.1 % (up to 27.8 %), 4.2 % (up to 16.2 %), 6.6 % (up to 50.9 %), 5.8 % (up to 46.6 %), and 8.6 % (up to 49.1 %), respectively, mainly due to reduced radiation, temperature, and wind speed. The overall performance of the two-way coupled WRF-CMAQ model achieved in this work is generally good or satisfactory and the improved performance for two-way coupled WRF-CMAQ should be considered along with other factors in developing future model applications to inform policy making. [ABSTRACT FROM AUTHOR]

BACKGROUND: Reductions in ambient concentrations of fine particulate matter (PM2.5) have contributed to reductions in cardiovascular (CV) mortality. OBJECTIVES: We examined changes in CV mortality attributed to reductions in emissions from mobile, point, areal, and nonroad sources through changes in concentrations of PM2.5 and its major components [nitrates, sulfates, elemental carbon (EC), and organic carbon (OC)] in 2,132 U.S. counties between 1990 and 2010. METHODS: Using Community Multiscale Air Quality model estimated PM2.5 total and component concentrations, we calculated population-weighted annual averages for each county. We estimated PM2.5 total- and component-related CV mortality, adjusted for county-level population characteristics and baseline PM2.5 concentrations. Using the index of Emission Mitigation Efficiency for primary emission-to-particle pathways, we expressed changes in particle-related mortality in terms of precursor emissions by each sector. RESULTS: PM2.5 reductions represented 5.7% of the overall decline in CV mortality. Large point source emissions of sulfur dioxide accounted for 6.685 [95% confidence interval (CI): 5.703, 7.667] fewer sulfate-related CV deaths per 100,000 people. Mobile source emissions of primary EC and nitrous oxides accounted for 3.396 (95% CI: 2.772, 4.020) and 3.984 (95% CI: 2.472, 5.496) fewer CV deaths per 100,000 people respectively. Increased EC and OC emissions from areal sources increased carbon-related CV mortality by 0.788 (95% CI: -0:540, 2.116) and 0.245 (95% CI: -0:697, 1.187) CV deaths per 100,000 people. DISCUSSION: In a nationwide epidemiological study of emission sector contribution to PM2.5related mortality, we found that reductions in sulfurdioxide emissions from large point sources and nitrates and EC emissions from mobile sources contributed the largest reduction in particle-related mortality rates respectively. [ABSTRACT FROM AUTHOR]

Bromine and iodine chemistry has been updated in the Community Multiscale Air Quality (CMAQ) model to better capture the influence of natural emissions from the oceans on ozone concentrations. Annual simulations were performed using the hemispheric CMAQ model without and with bromine and iodine chemistry. Model results over the Northern Hemisphere show that including bromine and iodine chemistry in CMAQ not only reduces ozone concentrations within the marine boundary layer but also aloft and inland. Bromine and iodine chemistry reduces annual mean surface ozone over seawater by 25%, with lesser ozone reductions over land. The bromine and iodine chemistry decreases ozone concentration without changing the diurnal profile and is active throughout the year. However, it does not have a strong seasonal influence on ozone over the Northern Hemisphere. Model performance of CMAQ is improved by the bromine and iodine chemistry when compared to observations, especially at coastal sites and over seawater. Relative to bromine, iodine chemistry is approximately four times more effective in reducing ozone over seawater over the Northern Hemisphere (on an annual basis). Model results suggest that the chemistry modulates intercontinental transport and lowers the background ozone imported to the United States. • Bromine and iodine chemistry reduces ozone. • Iodine chemistry is more effective in reducing ozone than the bromine chemistry. • Bromine and iodine chemistry affects background ozone. • Bromine and iodine chemistry improves model performance. [ABSTRACT FROM AUTHOR]

This work describes the lightning nitric oxide (LNO) production schemes in the Community Multiscale Air Quality (CMAQ) model. We first document the existing LNO production scheme and vertical distribution algorithm. We then describe updates that were made to the scheme originally based on monthly National Lightning Detection Network (mNLDN) observations. The updated scheme uses hourly NLDN (hNLDN) observations. These NLDN-based schemes are good for retrospective model applications when historical lightning data are available. For applications when observed data are not available (i.e., air quality forecasts and climate studies that assume similar climate conditions), we have developed a scheme that is based on linear and log-linear parameters derived from regression of multiyear historical NLDN (pNLDN) observations and meteorological model simulations. Preliminary assessment for total column LNO production reveals that the mNLDN scheme overestimates LNO by over 40 % during summer months compared with the updated hNLDN scheme that reflects the observed lightning activity more faithfully in time and space. The pNLDN performance varies with year, but it generally produced LNO columns that are comparable to hNLDN and mNLDN, and in most cases it outperformed mNLDN. Thus, when no observed lightning data are available, pNLDN can provide reasonable estimates of LNO emissions over time and space for this important natural NO source that influences air quality regulations. [ABSTRACT FROM AUTHOR]

Atmospheric oxidation of natural and anthropogenic volatile organic compounds (VOCs) leads to secondary organic aerosol (SOA), which constitutes a major and often dominant component of atmospheric fine particulate matter (PM2.5). Recent work demonstrates that rapid autoxidation of organic peroxy radicals (RO2) formed during VOC oxidation results in highly oxygenated organic molecules (HOM) that efficiently form SOA. As NOx emissions decrease, the chemical regime of the atmosphere changes to one in which RO2 autoxidation becomes increasingly important, potentially increasing PM2.5, while oxidant availability driving RO2 formation rates simultaneously declines, possibly slowing regional PM2.5 formation. Using a suite of in situ aircraft observations and laboratory studies of HOM, together with a detailed molecular mechanism, we show that although autoxidation in an archetypal biogenic VOC system becomes more competitive as NOx decreases, absolute HOM production rates decrease due to oxidant reductions, leading to an overall positive coupling between anthropogenic NOx and localized biogenic SOA from autoxidation. This effect is observed in the Atlanta, Georgia, urban plume where HOM is enhanced in the presence of elevated NO, and predictions for Guangzhou, China, where increasing HOM-RO2 production coincides with increases in NO from 1990 to 2010. These results suggest added benefits to PM2.5 abatement strategies come with NOx emission reductions and have implications for aerosol–climate interactions due to changes in global SOA resulting from NOx interactions since the preindustrial era. [ABSTRACT FROM AUTHOR]