Priority 2: Investigating the Interactions of the Atmosphere, the Broader Earth System and Human Society

MIRAGE-MILAGRO

Background

The export of pollutants from urban to regional and global environments is a major concern because of wide-ranging potential consequences for human health and cultivated and natural ecosystems, visibility degradation, weather modification, changes in radiative forcing, and tropospheric oxidation (self-cleaning) capacity. The need for a better scientific understanding of the origin and fate of these pollutants is one aspect of the 2006 NCAR Strategic Plan. NCAR scientists chose Mexico City for intensive study of pollution export because of its large size, excellent collaborations with local researchers, adequate infrastructure, and the availability of urban air quality monitoring networks and emissions inventories needed to specify the initial state of the exported air. This study, MIRAGE-Mex (Megacities Impacts on Regional And Global Environments ? Mexico City case study), involved an intensive observational period (IOP) of coordinated aircraft and ground-based measurements supported by extensive modeling and satellite observations. The overall scientific objectives of MIRAGE-Mex are:

• Characterization of the extent, persistence, and potential impacts of the Mexico City plume in the surrounding regions.
• Increased understanding of the evolution of gas-phase reactivity over the urban-to-regional-to-global scale transition.
• Increased understanding of the physical and chemical evolution of aerosols and their radiative properties over the urban-to-regional-to-global transition.
• Increased understanding of the gas-aerosol interactions over the urban-to-regional-to-global transition.

The MIRAGE-Mex results will provide the Mexican government with the first-ever assessment of the regional pollution problem surrounding Mexico City, and a better understanding of the relative importance of different sources (e.g. urban vs. biomass burning). Scientifically, the results will allow evaluation and improvement of predictive models of atmospheric composition. Because MIRAGE-Mex focuses on understanding processes (e.g. gas-aerosol-radiation interactions), the knowledge gained from MIRAGE-Mex will be, at least in part, applicable to other megacities for which measurements are sparse or non-existent.

Progress

The The Intensive Observation Period (IOP) took place 1-30 March 2006. Over the last several years, partnerships were established between MIRAGE-Mex and projects from other agencies, particularly DOE (MAX-Mex), NASA (INTEX-B), and the Mexican government (MCMA-2006), thus leveraging resources toward comprehensive, simultaneous, coordinated observations spanning urban, regional, and larger scales. Approximately 100 Mexican and 320 non-Mexican scientists participated in the MIRAGE-Mex IOP and coordinated projects. All of these projects were brought together under the MILAGRO (Megacity Initiative: Local and Global Research Observations) campaign, which served as an umbrella organization to coordinate the individual projects. Post-mission data analysis was carried out by individual researchers, and submitted to a central data archive by September, 2006.

Plans

Analysis and interpretation of this unique and rich data set is ongoing and expected to continue over the next several years. NCAR scientists hosted the First Science Meeting in October, 2006 where researchers presented their individual results and began collaborative analysis of multiple data sets. The Second Science Meeting will take place in Mexico, tentatively in May 2007. Numerous resultant publications are anticipated over the next two years, and plans are underway for collecting them as a special issue of a major international scientific journal. Special sessions are being planned for the Fall 2007 AGU and other international and national meetings.

For further detail, please read the full project report linked below.

ESSL Annual Report