Observed Relationships Between Large-Scale Patterns of Climate Variability and Atmospheric Carbon Dioxide.

EPA Grant Number: F6B10064
Title: Observed Relationships Between Large-Scale Patterns of Climate Variability and Atmospheric Carbon Dioxide.
Investigators: Hawes, Amy K
Institution: Colorado State University
EPA Project Officer: Lee, Sonja
Project Period: August 1, 2006 through July 31, 2009
Project Amount: $105,016
RFA: STAR Graduate Fellowships (2006) RFA Text |  Recipients Lists
Research Category: Air Quality and Air Toxics , Academic Fellowships , Fellowship - Atmospheric Sciences , Climate Change


The purpose of this study is to examine how two major patterns of large-scale climate variability, the so-called Northern and Southern Annular Modes, are related to variations in atmospheric carbon dioxide concentrations. Both patterns exert substantial influence on surface climate in their respective hemispheres, and both patterns have exhibited trends over the past few decades. Nevertheless, it remains unknown to what extent the climate impacts of these patterns feedback onto the global carbon cycle. In addition to exploring the effects of the annular modes on the carbon cycle, I will also study how increasing human emissions of carbon dioxide and chlorofluorocarbons impact the atmospheric circulation.


Using atmospheric carbon dioxide measurements from the NOAA Global Monitoring Division, I will first look for statistical relationships between the times series of the annular modes and atmospheric carbon dioxide at various stations around the globe. I will also examine the mechanisms responsible for any observed relationships by investigating the links between the annular modes and atmospheric inversion model CO2 flux estimates, sea surface temperature fields and near-surface wind fields.

Expected Results:

Because the Northern Annular Mode effects high-latitude temperatures, it may impact the uptake of carbon dioxide from the terrestrial biosphere through changes in the length of the growing season. Due to lack of nearby land regions with significant vegetation in the Southern Hemisphere, the Southern Annular Mode is thought to impact atmospheric carbon dioxide via air-sea flux exchange. Based on preliminary results, I predict that the annular modes are indeed coupled to variations in atmospheric CO2 in a manner consistent with these theories.

Supplemental Keywords:

annular mode, carbon dioxide, global carbon cycle, climate variability, chlorofluorocarbons,, RFA, Scientific Discipline, Air, Environmental Chemistry, climate change, Air Pollution Effects, Environmental Monitoring, Atmospheric Sciences, Atmosphere, atmospheric carbon dioxide, carbon dioxide, circulation model, greenhouse gases, climate variability

Progress and Final Reports:

  • 2007
  • 2008
  • Final