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Harvard Forest Symposium Abstract 2012

• Title: Hourly and Seasonal Patterns of CO2 in the Atmosphere Over Boston, MA: An Assessment of Natural and Anthropogenic Drivers
• Primary Author: Brittain Briber (Boston University)
• Additional Authors: Allison Dunn (Worcester State University); Lucy Hutyra (Boston University); Robert Kaufmann (Boston University); J. William Munger (Harvard University)
• Abstract:

  Urban areas are playing an increasingly important role in the carbon cycle. Situated on less than 3% of the Earth’s landmass, cities are responsible for ~70% of anthropogenic emissions. Yet, our knowledge of carbon exchange in urban areas is limited since we currently cannot parse urban atmospheric CO2 mixing ratios into useful anthropogenic and biogenic components. Past urban CO2 research efforts have highlighted decreasing levels of atmospheric CO2 across urban to rural gradients (Idso et al. 2002) but have rarely assessed the drivers of observed mixing ratios. In this analysis, we compare CO2 mixing ratios over a one and a half year period at three locations across Boston’s urbanization gradient in order to better determine the meteorological, anthropogenic, and biogenic drivers of short and long term CO2 trends. Boston, Worcester, and Harvard Forest (HF), MA were analyzed and represent high density urban, semi-urban (adjacent to large tracts of forest), and predominantly rural landscapes, respectively. Contrasting our meteorological and atmospheric observations with these estimates across these three sites has enabled a better understanding of the varying source and sink functions at each location: annual mean CO2 mixing ratios are 408.2 ± 0.2, 401.5 ± 0.4, 393.0 ± 0.3ppm at Boston, Worcester, and HF, respectively and reflect increasing anthropogenic and decreasing biogenic influence across the Boston’s urbanization gradient. We also analyzed CO2 mixing ratios along a vertical gradient at the BU test site in order to 1) better identify urban exchange processes and 2) determine the appropriate instrument height for measuring CO2 mixing ratios given complex urban micrometeorology. This analysis is a first step in attributing observed CO2 mixing rations in urban areas to spatially explicit CO2 emissions.
  
  

• Research Category: Forest-Atmosphere Exchange
  Regional Studies