Browsing by Author "Escobar, Jaime"

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    Application of MM5/CALMET/CAMx in Santiago, Chile
    (2003) Jorquera, Héctor; Castro, Julio; Escobar, Jaime; Jakobs, Hermann
    The Comprehensive Air Quality Model with Extensions (CAMx) has been applied to two summer photochemical episodes in the greater metro area of Santiago, Chile. It is shown that the CAMx model predicts reasonably well the spatial gradients of gaseous pollutants and the weekly cycle of variation for CO and NOx. The emission estimates for CO seem to be quite on agreement with actual emissions in 2000. NOx emissions are more appropriate for the 1998 scenario, whereas for 2000 they seem to overestimate actual emissions, so the mobile sources emission factors need to be verified. The SO2 simulations indicate that there relevant sources not accounted for in the inventory. There are problems with the VOC emissions for the area sources, because the model predictions for ozone are quite below what is being observed, for all network stations in 1998, a scenario with reliable NOx simulated levels. For the 2000 scenario, this problem is worsened because of excessive ozone scavenging. When we use the results of a comprehensive VOC campaign to produce a synthetic VOC profile of emissions for the whole city, simulated ozone gets closer to ambient measurements for the 1998 scenario. For the 2000 scenario, the overestimation in the simulated NOx levels is large enough to prevent any significant ozone sensitivity with respect to VOC increases. All things considered, CAMx has passed the "proof of the concept" for studying photochemical episodes at Santiago, Chile. The major sources of uncertainty are the emission inventory estimates for NOx and VOC. As a second source of uncertainty, meteorology was not properly represented on the second half of the January 1998 episode, and there are some problems with the stations closer to the Andes foothills overnight, particularly regarding ozone nocturnal profiles, that deserve further research.
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    Do ecosystem insecurity and social vulnerability lead to failure of water security?
    (2021) Scott, Christopher A.; Zilio, Mariana I.; Harmon, Thomas; Zuniga-Teran, Adriana; Diaz-Caravantes, Rolando; Hoyos, Natalia; Perillo, Gerardo M. E.; Meza, Francisco; Varady, Robert G.; Neto, Alfredo Ribeiro; Velez, Maria Isabel; Martin, Facundo; Escobar, Jaime; Piccolo, M. Cintia; Mussetta, Paula; Montenegro, Suzana; Rusak, James A.; Pineda, Nicolas
    Achieving water security for humans and ecosystems is a pervasive challenge globally. Extensive areas of the Americas are at significant risk of water insecurity, resulting from global-change processes coupled with regional and local impacts. Drought, flooding, and water quality challenges pose significant threats, while at the same time, rapid urban expansion, competing water demands, river modifications, and expanding global markets for water-intensive agricultural products drive water insecurity. This paper takes a social-ecological systems perspective, aiming to identify examples and pathways towards resilient ecosystems and social development. It draws on lessons from two science-policy network projects, one focusing on water scarcity in arid and semi-arid regions of Argentina, Chile, Brazil, Peru, Mexico and the United States; and the second addressing river and lake basins as sentinels of climate variability and human effects on water quantity and quality in Canada, the United States, Argentina, Colombia, Uruguay and Chile. Together, these `complementary contrasts' provide an analytical basis to empirically examine stakeholder engagement, knowledge co-production and science-policy interaction supporting decision-making to achieve water security. The paper identifies four tenets for decision-making based on water-security-focused global-change science in the Americas: 1) Decision makers should focus on protecting ecosystems because water security (along with food and energy security) depend on them; 2) Water-use and allocation decisions ought to be made considering future environmental and societal vulnerabilities, especially climate projections; 3) Holistic approaches (at basin or other appropriate levels) are best suited to ensure social-ecological system resilience and reduce vulnerability; and 4) It is essential to support local/traditional livelihoods, and underserved populations to achieve equitable water security and ecosystem resilience.