La modernización de la flota de vehículos pesados a diésel vía retrofit (adaptación de sistemas de control de emisiones) representaría un paso pequeño, pero importante, hacia una mejora adicional de la calidad del aire en la Ciudad de México. 

Los vehículos pesados a diésel, a pesar de su pequeña contribución a la flota vehicular (menos del 6%), son responsables del 24% de las emisiones totales de partículas finas primarias. Por ello, realizamos un análisis de costo-efectividad de las tecnologías de control de emisiones para estos vehículos que circulan en la Ciudad de México. Nuestro análisis incluye la evaluación de la eficacia del control para reducir las emisiones de partículas primarias del diésel en la línea base; de los impactos de las reducciones de emisiones en las concentraciones ambientales de partículas finas primarias y la reducción de la exposición en la población; de los beneficios para la salud asociados con el control de emisiones y las mejoras en la calidad del aire, estimados como reducciones en la mortalidad prematura; de los costos de las posibles tecnologías de control, es decir, el costo del equipo, la instalación, el ahorro en el consumo de diésel, y el mantenimiento del equipo; y de la monetización de los beneficios netos estimados (comparación de beneficios y costos).

En la Ciudad de México hay más de 100,000 vehículos pesados en circulación que utilizan diésel; éstos se pueden agrupar en autobuses (RTP-transporte público, escolares y de personal, concesionados y Metrobús, con placa local; y de turismo y pasajeros con placa federal); camiones de carga (camiones de reparto de mercancías de tamaño mediano con placa local de entre 4.6 y 27.2 toneladas o placa federal de entre 11.8 y 14.9 toneladas); y tractocamiones (vehículos que pesan más de 27.2 toneladas, con placa local o federal).

En nuestro análisis consideramos tres tipos de tecnologías de control: el catalizador de oxidación de diésel (DOC); el filtro de partículas de diésel con regeneración activa (DPF-a); y el filtro de partículas de diésel con regeneración pasiva (DPF-p).

¿Qué encontramos?

Que la estrategia de retrofit con las tecnologías evaluadas es costo-efectiva para todos los autobuses, camiones de carga y tractocamiones. De llevar a cabo esta estrategia en todos los vehículos pesados que circulan en la Ciudad de México se podrían reducir 950 toneladas de emisiones de PM2.5, reducir las concentraciones de PM2.5 en alrededor de 1 µg/m3 y salvar cerca de 100 vidas / año. El costo anual sería de menos de 93 millones de dólares, mientras que los beneficios en salud representarían cerca de 250 millones de dólares al año.  

Por ello, alentamos a las autoridades de la Ciudad de México a considerar avanzar con el diseño e implementación de un programa de esta naturaleza.

In this talk I’ll discuss Atlantic hurricane activity. I’ll focus on the climate modes that influence Atlantic hurricane activity in various time-scales, from intra-seasonal to decadal. I’ll give an overview of seasonal  Atlantic hurricane forecasts and how they have changed since the 1980s. Sub-seasonal Atlantic hurricane forecasts have started to be developed, but the predictability at these time-scales still needs to be fully explored. I’ll finish by summarizing the current state of the knowledge in the relationship of climate change and Atlantic hurricanes and what we can expect in the future. 

It is imperative that we provide more accurate and consistent analysis of anthropogenic pollution emissions at scales that is relevant to air quality, energy, and environmental policy. 

For the first part of this talk, I will present three proof-of-concept studies that explore observational constraints from ground, aircraft, and satellite- derived measurements of atmospheric composition on bulk characteristics of anthropogenic combustion in megacities and fire regions. I will focus on jointly analyzing co-emitted combustion products such as CO2, NO2, CO, SO2, and aerosols. Each of these constituents exhibit distinct atmospheric signatures that depend on fuel type, combustion technology, process, practices and regulatory policies. Our results show that distinguishable patterns and relationships between the increases in concentrations across the megacity or large fire events due to emissions of these constituents enable us to: a) identify attributable trends in combustion activity and efficiency, and b) reconcile discrepancies between state- to country-based emission inventories and modeled concentrations of these constituents. For example, the decadal trends in enhancement ratios of these species reveal combustion emission pathways for China and United States that are not captured by current emission inventories and chemical reanalyses. This work motivates the need for continuous and preferably collocated satellite measurements of atmospheric composition (including CH4) for long-term megacity-scale emissions monitoring, in conjunction with ground-based networks and airborne field campaigns. Synergies between measurements of air quality (AQ) and greenhouse gases (GHG) will be discussed as well.

For the second part of this talk, I will present model-data inter-comparisons based on five relatively long term chemical reanalyses which have been reported from leading data assimilation and inverse modeling groups. Here, I present an assessment of the state of CO, OH, NOX, and O3 in the past decade (2005-2015) as inferred from these reanalyses using available ground-, aircraft- and satellite-based observations. These reanalyses represent a range of modeling and assimilation approaches, assimilating different sets of chemical observations for multiple species, and in several cases updating monthly emission estimates from various bottom-up inventories. This provides an unprecedented dataset to understand and characterize the uncertainties on the inferred estimates and their trends. I present the ensemble statistics (e.g., mean and spread) on the spatial and temporal patterns of species abundance and associated emissions at megacity to global scales. I will also elucidate and discuss outstanding biases relative to independent measurements. The ensemble of reanalyses allows us to identify representativeness and model errors, that cannot be fully address with a single modeling system and traditional evaluation diagnostics. This work serves as a step towards an inter-comparison project on current prediction systems for reactive gases similar to what has been done for greenhouse gases within the TransCom experiments for CO2 and CH4. The relevance of this activity will be discussed within the context of the new IGAC project (Analysis of eMIssions usinG Observations or AMIGO), which is directed towards a synthesis activity on research related to observations-based analysis techniques aim to better quantify emissions.

Las recientes negociaciones del Tratado de Libre Comercio de América del Norte (TLCAN) entre los Estados Unidos, México y Canadá han hecho visible la relación estrecha que existe en la manufactura automotriz y el comercio de los productos agrícolas. Desde su inicio en el 1994, el TLCAN ha transformado las condiciones socioeconómicas a lo largo de los 3,000 kilómetros de la frontera entre México y Estados Unidos, en parte por las grandes inversiones relacionadas con la infraestructura agrícola y manufacturera. Si bien el TLCAN incluye disposiciones para la protección del medio ambiente en ciertos sectores, se ha prestado poca atención al uso de los recursos naturales que han sido requeridos para la expansión económica. ¿Qué consecuencias ha tenido el TLCAN en los recursos de agua y uso del suelo en la frontera de Estados Unidos y México? Para abordar esta pregunta, cuantificamos los cambios en el uso del suelo durante el período de 1992 a 2011 y sus efectos sobre el suministro y demanda de agua en la zona trasfronteriza. Este esfuerzo requirió el uso de varios registros de datos de los gobiernos mexicano y estadounidense e imágenes satelitales y su combinación con un modelo de las condiciones hidrológicas para los paisajes naturales, agrícolas y urbanos de la frontera. El modelo simuló una región que consta de porciones de seis estados de EE.UU. y doce estados mexicanos, o aproximadamente 1.7 millones de kilómetros cuadrados, en una alta resolución espacial (6 kilómetros) y temporal (diaria) para generar estimaciones de los cambios en el uso del suelo después del TLCAN. Este trabajo es la primera evaluación integral de cómo se ha modificado la cobertura terrestre a lo largo de la frontera de Estados Unidos-México, su impacto en las demandas de agua de los diferentes sectores, y las implicaciones de estos cambios en la sustentabilidad regional.

Wildfires are predicted to increase with global climate change, resulting in longer fire seasons and larger areas burned. On the other hand, the use of fire to reduce or dispose of vegetative debris is a worldwide and long-standing practice, since it is a quick and inexpensive way to manage the large amounts of residues. However, the smoke from both sources affects human health, worsens air quality, and can trigger severe regional haze events. At both national and international levels, there is an increasing focus on the establishment of emission inventories and regulations of regional carbon emissions to the atmosphere. From the standpoint of atmospherically-based carbon monitoring programs, fires are challenging because they tend to be extremely variable in both space and time, they are expected to increase in number and severity, and because emission estimates depend on biofuel characteristics and combustion phase. In addition to high spatial and temporal variations in fuel loadings and lack of observational data, one of the most influential and variable parameters is the emission factor. Emission factors (EFs) of selected species for major biomes have recently been reviewed and summarized by Akagi et al. (2011). However, due to the variability and complexity of the burning conditions and limited on-site experiments, EFs for many biofuels are still uncertain. In addition, EFs measured in the laboratory may substantially differ from those obtained in the field. 

With the aim of quantifying and characterizing the emissions of trace gases and aerosol particles from representative wildfires and open agricultural burning events, the University of Aveiro has developed techniques to sample the smoke plumes under real conditions and to perform the detailed characterization of both the gas and particulate phases. The new datasets include carbon oxides, organic and inorganic volatile compounds, and a vast array of particulate constituents, including organic and elemental carbon (OC and EC), water soluble ions, metals and hundreds of individual organic compounds.  The comprehensive databases may be useful for numerical models to evaluate the impact of wildfires in the Mediterranean region, which is particularly uncover by this type of studies. This research may also contribute to improve source apportionment models allowing to estimate the input of wildfires to the atmospheric levels at specific monitoring sites. The results consolidate previous argumentations that smoldering emissions make a significant contribution to the total emissions, and therefore cannot be neglected. The smoke plume is mainly composed of fine particles containing carcinogenic (e.g. polycyclic aromatic hydrocarbons) and compounds that cause oxidative stress (e.g. phenolics). Thus, populations regularly exposed to fire smoke are at high health risk. Smoke particles are carbonaceous in nature with a clear dominance of OC and much higher OC/EC values than those reported in the literature for other sources. Since EC plays a key role in radiative forcing and considering the discrepancies between the various studies, the magnitude of the emission factor for EC remains uncertain and deserves further investigation.

Acknowledgements: The experimental work was performed within the project entitled “Contribution of biomass combustion to air pollutant emissions (BIOEMI)”, PTDC/AMB/65706/2006, funded by the Portuguese Science Foundation (FCT). The data treatment was partially carried out in the frame of the project “Chemical and toxicological SOurce PROfiling of particulate matter in urban air (SOPRO)”, POCI-01-0145-FEDER-029574, funded by FEDER, through COMPETE2020 – Programa Operacional Competitividade e Internacionalização (POCI), and by national funds (OE), through FCT/MCTES.

Reference: Akagi et al., 2011. Atmos. Chem.  Phys. 11, 4039-4072.

El mercurio es un elemento de reconocida toxicidad, tanto ambiental como por sus efectos sobre los seres humanos. Se trata, además, de un “contaminante global” o “global pollutant”, ya que su presencia puede hacerse transnacional a partir de una fuente discreta, debido a la gran movilidad atmosférica del vapor del elemento.

El mercurio presente en la atmósfera corresponde a tres variedades: mercurio elemental (Gaseous Elemental Mercury, GEM en la denominación anglosajona); mercurio gaseoso reactivo (Reactive Gaseous Mercury, RGM); y mercurio ligado a partículas (particule-bound Mercury, PBM); por su parte, el contenido total de mercurio en la atmósfera, incluyendo estas tres variedades, recibe la denominación de mercurio gaseoso total (TGM, total gaseous Mercury).

Las fuentes generadoras de la dispersión ambiental de mercurio pueden ser muy variadas, y tanto naturales como antropogénicas; de entre ellas se reconoce internacionalmente a la combustión de carbón como una de las más importantes, si no la que más.

En la presente ponencia se trata sobre los posibles orígenes de la presencia del mercurio en el aire, a partir de fuentes naturales y relacionadas con la actividad humana, sobre la realización de su cuantificación y control a través de equipos y procedimientos de medida, de la distribución del mercurio en distintos ambientes, y se analizan las consecuencias de la presencia del mercurio en aire al respecto de la salud humana.

The skills of the Isotopic Regional Spectral Model (IsoRSM) to reproduce weather and climate regional features of Central America were evaluated based upon meteorological records and a network of stable isotopes in precipitation. IsoRSM runs for a Central American domain were computed for the 1980-2016 period at a 10km grid with an hourly resolution. The performance of IsoRSM to capture the climatological behavior of monthly accumulated precipitation and surface temperature over a Central America were analyzed in comparison with long term available records. It was determined that the model captures reasonably well the annual cycle of rainfall, mean temperature and diurnal temperature range. Despite the interannual variability was captured, the range of the variations showed smaller skill scores. Hourly rainfall and the diurnal cycle of surface temperature were evaluated for Costa Rica using an hourly network of weather stations. The results show that the diurnal cycle of surface temperature is well represented but that the skills of the model find a limit in the complex topography of the country. The ability of the model to reproduce hourly rainfall was rather poor in comparison as the model fails to capture the intensity of locally forced rainfall. A contrast is observed in how the simulations present a better capture of the second peak of the rainy season which is mostly large scale forced. Still, the model shows a reasonable performance as it fairly captures the occurrence of extreme events. In terms of the analysis of the stable isotopic composition of water, the model outputs were evaluated for the 2012-2016 period, showing a fair representation of the average patterns. In addition, a short review on the application of water stable isotopes within the tropical America is presented in order to provide the basics for the interpretation of wate isotopic composition at different time scales and the relevance of isotopic information to analyse moisture transport patterns.

The talk first summaries the growth of mega-cites around the world, as well as the main environmental challenges facing such areas in a changing climate.  It next reviews the data analysis techniques that best illuminate the dynamical and physical processes that produce the unique climate and weather in cities.  It finally reviews the current state of urban-scale numerical weather and climate models. These reviews are illustrated by results from a variety of California, US, and international cities. It finishes with a review of the current challenges in this area of research.  

The speaker earned a PhD (1972) in Meteorology from NYU and is currently Prof. Emeritus at SJSU, where he had taught since 1969.  He is an AMS Fellow, has received Fulbright Fellow-ships (to Italy, Austria, Brazil), was on the WMO Commission on Urban Climatology, served on the BAAQMD Advisory Council, and received lifetime achievement awards in urban climate research from the AMS and the International Association for Urban Climate (both in 2008).  The 2017 AMS Urban Conference had named sessions for his 75th birthday and he received a 2017 Great Wall Friendship Award from the Major of Beijing.