Multi-scale modeling study of the source contributions to near-surface ozone and sulfur oxides levels over California during the ARCTAS-CARB period

Chronic high surface ozone (O_3) levels and the increasing sulfur oxides (SO_x = SO_2 + SO_4) ambient concentrations over South Coast (SC) and other areas of California (CA) are affected by both local emissions and long-range transport. In this paper, multi-scale tracer, full-chemistry and adjoint simulations using the STEM atmospheric chemistry model are conducted to assess the contribution of local emission sourcesto SC O_3 and to evaluate the impacts of transported sulfur and local emissions on the SC sulfur budgetduring the ARCTAS-CARB experiment period in 2008. Sensitivity simulations quantify contributions of biogenic and fire emissions to SC O_3 levels. California biogenic and fire emissions contribute 3–4 ppb to near-surface O_3 over SC, with larger contributions to other regions in CA. During a long-range transport event from Asia starting from 22 June, high SO_x levels (up to ~0.7 ppb of SO_2 and ~1.3 ppb of SO_4) is observed above ~6 km, but they did not affect CA surface air quality. The elevated SO_x observed at 1–4 km is estimated to enhance surface SO_x over SC by ~0.25 ppb (upper limit) on ~24 June. The near-surface SO_x levels over SC during the flight week are attributed mostly to local emissions. Two anthropogenic SO_x emission inventories (EIs) from the California Air Resources Board (CARB) and the US Environmental Protection Agency (EPA) are compared and applied in 60 km and 12 km chemical transport simulations, and the results are compared withobservations. The CARB EI shows improvements over the National Emission Inventory (NEI) by EPA, but generally underestimates surface SC SO_x by about a factor of two. Adjoint sensitivity analysis indicated that SO_2 levels at 00:00 UTC (17:00 local time) at six SC surface sites were influenced by previous day maritime emissions over the ocean, the terrestrial emissions over nearby urban areas, and by transported SO_2 from the north through both terrestrial and maritime areas. Overall maritime emissions contribute 10–70% of SO2 and 20–60% fine SO_4 on-shore and over the most terrestrial areas, with contributions decreasing with in-land distance from the coast. Maritime emissions also modify the photochemical environment, shifting O_3 production over coastal SC to more VOC-limited conditions. These suggest an important role for shipping emission controls in reducing fine particle and O_3 concentrations in SC

A regional scale modeling analysis of aerosol and trace gas distributions over the eastern Pacific during the INTEX-B field campaign

The Sulfur Transport and dEposition Model (STEM) is applied to the analysis of observations obtained during the Intercontinental Chemical Transport Experiment-Phase B (INTEX-B), conducted over the eastern Pacific Ocean during spring 2006. Predicted trace gas and aerosol distributions over the Pacific are presented and discussed in terms of transport and source region contributions. Trace species distributions show a strong west (high) to east (low) gradient, with the bulk of the pollutant transport over the central Pacific occurring between similar to 20 degrees N and 50 degrees N in the 2-6 km altitude range. These distributions are evaluated in the eastern Pacific by comparison with the NASA DC-8 and NSF/NCAR C-130 airborne measurements along with observations from the Mt. Bachelor (MBO) surface site. Thirty different meteorological, trace gas and aerosol parameters are compared. In general the meteorological fields are better predicted than gas phase species, which in turn are better predicted than aerosol quantities. PAN is found to be significantly overpredicted over the eastern Pacific, which is attributed to uncertainties in the chemical reaction mechanisms used in current atmospheric chemistry models in general and to the specifically high PAN production in the SAPRC-99 mechanism used in the regional model. A systematic underprediction of the elevated sulfate layer in the eastern Pacific observed by the C-130 is another issue that is identified and discussed. Results from source region tagged CO simulations are used to estimate how the different source regions around the Pacific contribute to the trace gas species distributions. During this period the largest contributions were from China and from fires in South/Southeast and North Asia. For the C-130 flights, which operated off the coast of the Northwest US, the regional CO contributions range as follows: China (35%), South/Southeast Asia fires (35%), North America anthropogenic (20%), and North Asia fires (10%). The transport of pollution into the western US is studied at MBO and a variety of events with elevated Asian dust, and periods with contributions from China and fires from both Asia and North America are discussed. The role of heterogeneous chemistry on the composition over the eastern Pacific is also studied. The impacts of heterogeneous reactions at specific times can be significant, increasing sulfate and nitrate aerosol production and reducing gas phase nitric acid levels appreciably (~50%)

Assessing the regional impacts of Mexico City emissions on air quality and chemistry

The impact of Mexico City (MCMA) emissions is examined by studying its effects on air quality, photochemistry, and on ozone production regimes by combining model products and aircraft observations from the MILAGRO experiment during March 2006. The modeled influence of MCMA emissions to enhancements in surface level NOx [NO subscript x], CO, and O3 [O subscript 3] concentrations (10–30% increase) are confined to distances <200 km, near surface. However, the extent of the influence is significantly larger at higher altitudes. Broader MCMA impacts (some 900 km Northeast of the city) are shown for specific outflow conditions in which enhanced ozone, NOy [NO subscript y], and MTBE mixing ratios over the Gulf of Mexico are linked to MCMA by source tagged tracers and sensitivity runs. This study shows that the "footprint" of MCMA on average is fairly local, with exception to reactive nitrogen, which can be transported long range in the form of PAN, acting as a reservoir and source of NOx [NO subscript x] with important regional ozone formation implications. The simulated effect of MCMA emissions of anthropogenic aerosol on photochemistry showed a maximum regional decrease of 40% in J[NO2→NO+O] [J [NO subscript 2 → NO + O]], and resulting in the reduction of ozone production by 5–10%. Observed ozone production efficiencies are evaluated as a function of distance from MCMA, and by modeled influence from MCMA. These tend to be much lower closer to MCMA, or in those points where modeled contribution from MCMA is large. This research shows that MCMA emissions do effect on regional air quality and photochemistry, both contributing large amounts of ozone and its precursors, but with caveat that aerosol concentrations hinder formation of ozone to its potential due to its reduction in photolysis rates.United States. National Aeronautics and Space AdministrationNational Science Foundation (U. S.) (ATM award 0528227

Main Trends in Regional Innovation Systems: An Author Co-citation Analysis

Regional Innovation Systems are increasingly attracting attention on behalf of accademics, practitioners and policy makers. This has produced a wide array of studies in the field, both regards the specific themes treated and the perspectives adopted. Though a number of sujective reviews of the field have been proposed, these tend to present the field according to the analysts' subjective biases and tends to meld what the field is with what the field should be. In order to overcome the limitations present in the subjective reviews proposed untill today, in this study we conduct an objective review of the main contributions to the Regional Innovation Systems fiels of studies

Event-sampling method with experimental design: A promising method for investigating microfoundational phenomena within family businesses

Over the past decades the field of family business has witnessed a surge in publications and experienced meaningful changes that have served to increase its legitimacy and establish the field as an independent area of academic inquiry. Along with these advancements, scholars have called for experimental research designs that can reveal the influence of individual-level, microfoundational phenomena underlying macro-level family business phenomena. Given the challenge of conducting such studies, the event-sampling method with experimental design (ESME) approach is highlighted as a new opportunity for family business scholars to further enrich their methodological toolbox. Fundamentally, the ESME approach is a longitudinal, repeated-sampling method with experimental design that provides researchers with the opportunity to investigate the effects of various micro-level phenomena within the family business. By facilitating the incorporation of familial variables and processual elements in family business research, the ESME approach can account for the longitudinal and dynamic interplay of family and family business phenomena. Overall, ESME is a method with the potential to help researchers answer many of the “how” questions that remain unanswered in the field of family business. A description of ESME is offered, relevant challenges and opportunities in family business research are identified, and best practices for ESME are shared to support the work of family business scholars

Creating authenticity in online learning and assessment: the use of emotion in mimetic simulation

Authentic assessment theory has identified critical elements and theorized benefits for student outcomes in management schools. More needs to be done, however, to empirically test relationships between different aspects of authenticity and student outcomes, particularly in the postgraduate online learning environment. In this paper we examine whether an online simulation-based learning and assessment design, using only standard learning management system (LMS) functionality, has measurable ‘authenticity’ in an online postgraduate business course. In addition, we assess whether the online simulation-based design is associated with improvements in student learning behaviors and learning outcomes. Last, we enquire into possible mechanisms for improving learning behaviors and outcomes, focusing on students’ ability to recognize emotion in the online simulation, as well as their ability to recognize their own emotional response. Using bespoke and constructively aligned simulation-based teaching, learning, and assessment activities, this paper analyses qualitative data collected through lecturer and student interviews and student work submitted online, as well as data analytics from the LMS in both control and experimental conditions. Seven critical elements of authentic assessment were identified by participants, including new aspects of authenticity specific to online simulations. Students watched lecture videos and viewed and participated in online discussion more frequently in the online simulation than in the control condition. Students indicated greater perceived mastery of, and confidence in, the learning outcomes and recognized emotional content and their own emotional reaction, as a mechanism for driving their learning behaviors. These findings make important contributions to authentic assessment theory and have practical implications for using online simulations in postgraduate study

Meteorological and air quality forecasting using the WRF-STEM model during the 2008 ARCTAS field campaign

In this study, the University of Iowa’s Chemical Weather Forecasting System comprising meteorological predictions using the WRF model, and off-line chemical weather predictions using tracer and full chemistry versions of the STEM model, designed to support the flight planning during the ARCTAS 2008 mission is described and evaluated. The system includes tracers representing biomass burning and anthropogenic emissions from different geographical emissions source regions, as well as air mass age indicators. We demonstrate how this forecasting system was used in flight planning and in the interpretation of the experimental data obtained through the case study of the summer mission ARCTAS DC-8 flight executed on July 9 2008 that sampled near the North Pole. The comparison of predicted meteorological variables including temperature, pressure, wind speed and wind direction against the flight observations shows that the WRF model is able to correctly describe the synoptic circulation and cloud coverage in the Arctic region The absolute values of predicted CO match the measured CO closely suggesting that the STEM model is able to capture the variability in observations within the Arctic region. The time–altitude cross sections of source region tagged CO tracers along the flight track helped in identifying biomass burning (from North Asia) and anthropogenic (largely China) as major sources contributing to the observed CO along this flight. The difference between forecast and post analysis biomass burning emissions can lead to significant changes (∼10–50%) in primary CO predictions reflecting the large uncertainty associated with biomass burning estimates and the need to reduce this uncertainty for effective flight planning

Impacts of transported background ozone on California air quality during the ARCTAS-CARB period – a multi-scale modeling study

Multi-scale tracer and full-chemistry simulations with the STEM atmospheric chemistry model are used to analyze the effects of transported background ozone (O&lt;sub&gt;3&lt;/sub&gt;) from the eastern Pacific on California air quality during the ARCTAS-CARB experiment conducted in June, 2008. Previous work has focused on the importance of long-range transport of O&lt;sub&gt;3&lt;/sub&gt; to North America air quality in springtime. However during this summer experiment the long-range transport of O&lt;sub&gt;3&lt;/sub&gt; is also shown to be important. Simulated and observed O&lt;sub&gt;3&lt;/sub&gt; transport patterns from the coast to inland northern California are shown to vary based on meteorological conditions and the O&lt;sub&gt;3&lt;/sub&gt; profiles over the oceans, which are strongly episodically affected by Asian inflows. Analysis of the correlations of O&lt;sub&gt;3&lt;/sub&gt; at various altitudes above the coastal site at Trinidad Head and at a downwind surface site in northern California, show that under long-range transport events, high O&lt;sub&gt;3&lt;/sub&gt; air-masses (O&lt;sub&gt;3&lt;/sub&gt;&gt;60 ppb) at altitudes between about 2 and 4 km can be transported inland and can significantly influence surface O&lt;sub&gt;3&lt;/sub&gt; 20–30 h later. These results show the importance of characterizing the vertical structure of the lateral boundary conditions (LBC) needed in air quality simulations. The importance of the LBC on O&lt;sub&gt;3&lt;/sub&gt; prediction during this period is further studied through a series of sensitivity studies using different forms of LBC. It is shown that the use of the LBC downscaled from RAQMS global model that assimilated MLS and OMI data improves the model performance. We also show that the predictions can be further improved through the use of LBC based on NASA DC-8 airborne observations during the ARCTAS-CARB experiment. These results indicate the need to develop observational strategies to provide information on the three-dimensional nature of pollutant distributions, in order to improve our capability to predict pollution levels and to better quantify the influence of these Asian inflows on the US west coast air quality