Project at a Glance

Title: Impact of Climate Change on the Frequency and Intensity of Low-Level Temperature Inversions in California

Principal Investigator / Author(s): Iacobellis, Sam and Dan Cayan, Joel Norris and Masao Kanamitsu

Contractor: Scripps Institution of Oceanography, University of California San Diego

Contract Number: 06-319

Research Program Area: Climate Change

Topic Areas: Greenhouse Gas Control, Greenhouse Gas Emissions, Impacts


Low-Level atmospheric temperature inversions (where temperature increases with height) inhibit vertical movement of air and can thereby increase the concentrations of air pollutants emitted near the ground. As the climate and regional circulation patterns change, the frequency and intensity of low-level temperature inversions will likely be affected. This research examined temperature inversions in California on various temporal scales (diurnal, synoptic, seasonal, and inter-annual) with a focus on two major air basins in California: SJVAB and SoCAB. Historical radiosonde and surface-based observations from 1960 through 2007 were analyzed while projections of inversion strength were produced for the time period 2010-2099 in the SJVAB and SoCAB. Climate model projections indicate increasing trends in elevated inversion strength into the next century at both air basins, ranging from 0.2C to 1.6C for the SJVAB and 0.5C to 1.3C for the SoCAB. The increases in inversion strength are projected to become substantial (relative to historical levels and variability) by 2060, and to worsen air quality within both the SJVAB and the SoCAB. The results of this research project would help to answer questions on the impacts of climate change on air quality. A better understanding of future changes in the temperature structure and other meteorological parameters is needed to help ARB staff prepare for future regional air quality plans in California.

For questions regarding this research project, including available data and progress status, contact: Research Division staff at (916) 445-0753

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