A53L-3372:
Long Term Trends in Carbon Dioxide Enhancements in an Urban Region
Friday, 19 December 2014
Logan Mitchell1, John C Lin2, David R Bowling3, Diane E Pataki2, Courtenay Strong2, Andrew Schauer4, Ryan Bares5, Susan E Bush3, Lacey Holland2, Derek Mallia2 and James R Ehleringer6, (1)University of Utah, Department of Atmospheric Sciences, Salt Lake City, UT, United States, (2)University of Utah, Salt Lake City, UT, United States, (3)University of Utah, Biology, Salt Lake City, UT, United States, (4)University of Washington, Seattle, WA, United States, (5)University of Utah, Atmospheric Sciences, Salt Lake City, UT, United States, (6)Univ Utah, Salt Lake City, UT, United States
Abstract:
Urban regions are characterized by highly concentrated emissions of greenhouse gases, accounting for an estimated ~70% of global fossil fuel CO2 emissions from energy usage. Traditional long-term measurement networks designed to constrain the global carbon budget have sites situated in remote regions far from urban centers, rendering such sites unable to resolve signatures of spatial and temporal variability from urban emissions. Here we present a unique, long-term record of CO2 concentrations at five locations ranging from rapidly growing to fully mature urban regions in Utah’s Salt Lake Valley, based on continuous measurements since 2001. Trends in concentration enhancements above background levels were found to vary throughout the valley, with mature urban areas (Salt Lake City) exhibiting declining CO2 enhancements and previously rural areas undergoing urban growth, having increasing CO2 enhancements. Furthermore, divergent trends were observed at different times of the day, potentially indicating long-term changes in emissions from different contributing sources. Multiple hypotheses to explain the trends in CO2 enhancements will be discussed, including changes in socioeconomic (e.g., population, traffic, energy efficiency) and meteorological (e.g., atmospheric mixing heights, temperatures) factors. This spatially distributed long-term CO2 monitoring network also provides a case study for understanding factors relevant to the design of urban trace gas observatories.
