William C. Porter

Filter mediated design : generating coherence in (collaborative) design

Abstract Architectural design involves the integration of diverse, sometimes conflicting, concepts and requirements into a coherent single composition. This paper proposes a method for negotiating architectural design across domains, by examining issues of perception, generation and evaluation, and detailing a prototype in which these mechanisms are augmented using computational agents for achieving coherence and innovation in remote collaborative design. Filter Mediated Design is intended to explore the processes and strategies of constructing intelligent designs and design intelligence.

Considering the air quality impacts of bioenergy crop production: a case study involving Arundo donax.

The expanding production of bioenergy crops may impact regional air quality through the production of volatile organic compounds such as isoprene. To investigate the effects of isoprene-emitting crops on air quality, specifically ozone (O(3)) and secondary organic aerosol (SOA) formation, we performed a series of model runs using the Weather Research and Forecasting model with Chemistry (WRF/Chem) coupled with the Model of Emissions of Gases and Aerosols from Nature (MEGAN) simulating a proposed cropland conversion to the giant cane Arundo donax for biomass production. Cultivation of A. donax in the relatively clean air of northeastern Oregon resulted in an average increase in 8 h O(3) levels of 0.52 ppb, while SOA was largely unaffected (<+0.01 μg m(-3)). Conversions in U.S. regions with reduced air quality (eastern Texas and northern Illinois) resulted in average 8 h O(3) increases of 2.46 and 3.97 ppb, respectively, with daily increases up to 15 ppb in the Illinois case, and daytime SOA increases up to 0.57 μg m(-3). While cultivation of isoprene-emitting bioenergy crops may be appropriate at some scales and in some regions, other areas may experience increased O(3) and SOA, highlighting the need to consider isoprene emissions when evaluating potential regional impacts of bioenergy crop production.

Annual and weekly patterns of ozone and particulate matter in Jeddah, Saudi Arabia

Air pollution has been an increasing concern within the Kingdom of Saudi Arabia and other Middle Eastern countries. In this work the authors present an analysis of daily ozone (O3), nitrogen oxide (NOx), and particulate matter (<10 μm aerodynamic diameter; PM10) concentrations for two years (2010 and 2011) at sites in and around the coastal city of Jeddah, as well as a remote background site for comparison. Monthly and weekly variations, along with their implications and consequences, were also examined. O3 within Jeddah was remarkably low, and exhibited the so-called weekend effect—elevated O3 levels on the weekends, despite reduced emissions of O3 precursors on those days. Weekend O3 increases averaged between 12% and 14% in the city, suggesting that NOx/volatile organic compound (VOC) ratios within cities such as Jeddah may be exceptionally high. Sites upwind or far removed from Jeddah did not display this weekend effect. Based on these results, emission control strategies in and around Jeddah must carefully address NOx/VOC ratios so as to reduce O3 at downwind locations without increasing it within urban locations themselves. PM10 concentrations within Jeddah were elevated compared with North American cites of similar climatology, though comparable to other large cities within the Middle East. Implications: Daily concentrations of O3, PM10, and NOx in and around the city of Jeddah, Saudi Arabia, are analyzed and compared with those of other reference cities. Extremely low O3 levels, along with a significant urban weekend effect (higher weekend O3, despite reduced NOx concentrations), is apparent, along with high levels of PM10 within the city. Urban O3 in Jeddah was found to be lower than that of other comparable cities, but the strong weekend effect suggests that care must be taken to reduce downwind O3 levels without increasing them within the city itself. Further research into the emissions and chemistry contributing to the reduced O3 levels within the city is warranted.

Evaluation of ozone, nitrogen dioxide, and carbon monoxide at nine sites in Saudi Arabia during 2007

This paper presents a one-year record of in situ air-quality data from nine sites throughout Saudi Arabia. The data set is composed of hourly measurements of ozone (O3), nitrogen dioxide (NO2), and carbon monoxide (CO) at six of the largest cities in Saudi Arabia (Riyadh, Jeddah, Makkah, Yanbu, Dammam, Hafouf) and two remote locations in the mountainous southwestern region of Alsodah for the year 2007. The authors found that international O3 and CO standards were routinely exceeded throughout the year at many sites, and that exceedances increased during Ramadan (Sep. 12 – Oct. 13), the Islamic month of fasting when much of normal daily activity is shifted to nighttime hours. In general NO2 and CO levels were higher in Saudi cities compared to U.S. cities of comparable population, while O3 levels were lower. There was a general trend for O3 and NO2 to be negatively correlated in Saudi cities in contrast to U.S. cities where the correlation is positive, suggesting that ozone chemistry in Saudi Arabia is limited by volatile organic compound emissions. This may be caused by low biogenic emissions from vegetation. Pollutant levels were lower at most Saudi sites during the four day Hajj period (Dec. 18–21) but higher in Makkah which receives millions of visitors during Hajj. The authors also found that ozone levels were elevated during the weekend (Thursday & Friday) relative to weekday levels despite lower NO2, a phenomenon known as the “weekend effect.” As little air quality data is available from Saudi Arabia in the English-language literature, this data set fills a knowledge gap and improves understanding of air quality in an important but under-reported region of the world. Implications: Air quality measurements at nine sites in Saudi Arabia provide a detailed look at spatial and temporal patterns of ozone (O3), nitrogen dioxide (NO2), and carbon monoxide (CO). NO2 and CO levels increased in most cities during the fasting month of Ramadan, whereas O3 levels decreased. This led to an increased frequency of CO exceedances based on international standards. NO2 and CO also increased in Makkah during the Hajj pilgrimage. In general, NO2 and O3 levels were anticorrelated at most sites, suggesting that O3 chemistry is limited by volatile organic compound emissions throughout much of Saudi Arabia.

Data mining to investigate the meteorological drivers for extreme ground level ozone events

This project aims to explore which combinations of meteorological conditions are associated with extreme ground level ozone conditions. Our approach focuses only on the tail by optimizing the tail dependence between the ozone response and functions of meteorological covariates. Since there is a long list of possible meteorological covariates, the space of possible models cannot be explored completely. Consequently, we perform data mining within the model selection context, employing an automated model search procedure. Our study is unique among extremes applications as optimizing tail dependence has not previously been attempted, and it presents new challenges, such as requiring a smooth threshold. We present a simulation study which shows that the method can detect complicated conditions leading to extreme responses and resists overfitting. We apply the method to ozone data for Atlanta and Charlotte and find similar meteorological drivers for these two Southeastern US cities. We identify several covariates which help to differentiate the meteorological conditions which lead to extreme ozone levels from those which lead to merely high levels.

Air quality in Yanbu, Saudi Arabia

ABSTRACT Yanbu, on the Red Sea, is an affluent Saudi Arabian industrial city of modest size. Substantial effort has been spent to balance environmental quality, especially air pollution, and industrial development. We have analyzed six years of observations of criteria pollutants O3, SO2, particles (PM2.5 and PM10) and the known ozone precursors—volatile organic compounds (VOCs) and nitrogen oxides (NOx). The results suggest frequent VOC-limited conditions in which ozone concentrations increase with decreasing NOx and with increasing VOCs when NOx is plentiful. For the remaining circumstances ozone has a complex non-linear relationship with the VOCs. The interactions between these factors at Yanbu cause measurable impacts on air pollution including the weekend effect in which ozone concentrations stay the same or even increase despite significantly lower emissions of the precursors on the weekends. Air pollution was lower during the Eids (al-Fitr and al-Adha), Ramadan and the Hajj periods. During Ramadan, there were substantial night time emissions as the cycle everyday living is almost reversed between night and day. The exceedances of air pollution standards were evaluated using criteria from the U.S. Environmental Protection Agency (EPA), World Health Organization (WHO), the Saudi Presidency of Meteorology and Environment (PME) and the Royal Commission Environmental Regulations (RCER). The latter are stricter standards set just for Yanbu and Jubail. For the fine particles (PM2.5), an analysis of the winds showed a major impact from desert dust. This effect had to be taken into account but still left many occasions when standards were exceeded. Fewer exceedances were found for SO2, and fewer still for ozone. The paper presents a comprehensive view of air quality at this isolated desert urban environment. Implications: Frequent VOC-limited conditions are found at Yanbu in Saudi Arabia that increase ozone pollution if NOx is are reduced. In this desert environment, increased nightlife produces the highest levels of VOCs and NOx at night rather than the day. The effects increase during Ramadan. Fine particles peak twice a day—the morning peak is caused by traffic and increases with decreasing wind, potentially representing health concerns, but the larger afternoon peak is caused by the wind, and it increases with increasing wind speeds. These features suggest that exposure to pollutants must be redefined for such an environment.

Reducing the negative human-health impacts of bioenergy crop emissions through region-specific crop selection

Environ. Res. Lett. 10 (2015) 054004 doi:10.1088/1748-9326/10/5/054004 LETTER OPEN ACCESS Reducing the negative human-health impacts of bioenergy crop emissions through region-specific crop selection RECEIVED 17 December 2014 REVISED 16 March 2015 William C Porter 1,4 , Todd N Rosenstiel 1 , Alex Guenther 2 , Jean-Francois Lamarque 3 and Kelley Barsanti 1 ACCEPTED FOR PUBLICATION 31 March 2015 PUBLISHED 6 May 2015 Portland State University, Portland, OR 97201, USA Pacific Northwest National Laboratory, Richland, WA 99354, USA National Center for Atmospheric Research, Boulder, CO 80305, USA Current address: Massachusetts Institute of Technology, Cambridge, MA 02139, USA. E-mail: wporter@mit.edu Keywords: bioenergy, air quality, climate change Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Supplementary material for this article is available online Abstract An expected global increase in bioenergy-crop cultivation as an alternative to fossil fuels will have consequences on both global climate and local air quality through changes in biogenic emissions of volatile organic compounds (VOCs). While greenhouse gas emissions may be reduced through the substitution of next-generation bioenergy crops such as eucalyptus, giant reed, and switchgrass for fossil fuels, the choice of species has important ramifications for human health, potentially reducing the benefits of conversion due to increases in ozone (O 3 ) and fine particulate matter (PM 2.5 ) levels as a result of large changes in biogenic emissions. Using the Community Earth System Model we simulate the conversion of marginal and underutilized croplands worldwide to bioenergy crops under varying future anthropogenic emissions scenarios. A conservative global replacement using high VOC- emitting crop profiles leads to modeled population-weighted O 3 increases of 5–27 ppb in India, 1–9 ppb in China, and 1–6 ppb in the United States, with peak PM 2.5 increases of up to 2 μg m −3 . We present a metric for the regional evaluation of candidate bioenergy crops, as well as results for the application of this metric to four representative emissions profiles using four replacement scales (10–100% maximum estimated available land). Finally, we assess the total health and climate impacts of biogenic emissions, finding that the negative consequences of using high-emitting crops could exceed 50% of the positive benefits of reduced fossil fuel emissions in value. 1. Introduction As bioenergy crops continue to replace both existing agricultural crops and natural landscapes, the choice of crop species will become increasingly important given their likely impacts on air quality and climate. The use of crops such as poplar, eucalyptus, and switchgrass as bioenergy feedstocks has increased globally over the past decade, and while ongoing adoption trends are highly dependent on both eco- nomic outcomes and policy decisions, significant increases are expected to continue (Energy Informa- tion Administration 2013). The large scale land-use changes associated with bioenergy production will have consequences on many aspects of environmental and human health, including food supply, watershed cleanliness, soil quality, and ecological diversity (e.g.