CO2 transport over complex terrain

Jielun Sun, Sean P. Burns, Anthony C. Delany, Steven P. Oncley, Andrew A. Turnipseed, Britton B. Stephens, Donald H. Lenschow, Margaret A. LeMone, Russell K. Monson, Dean E. Anderson

Research output: Contribution to journalArticlepeer-review

78 Scopus citations


CO2 transport processes relevant for estimating net ecosystem exchange (NEE) at the Niwot Ridge AmeriFlux site in the front range of the Rocky Mountains, Colorado, USA, were investigated during a pilot experiment. We found that cold, moist, and CO2-rich air was transported downslope at night and upslope in the early morning at this forest site situated on a ∼5% east-facing slope. We found that CO2 advection dominated the total CO2 transport in the NEE estimate at night although there are large uncertainties because of partial cancellation of horizontal and vertical advection. The horizontal CO2 advection captured not only the CO2 loss at night, but also the CO2 uptake during daytime. We found that horizontal CO2 advection was significant even during daytime especially when turbulent mixing was not significant, such as in early morning and evening transition periods and within the canopy. Similar processes can occur anywhere regardless of whether flow is generated by orography, synoptic pressure gradients, or surface heterogeneity as long as CO2 concentration is not well mixed by turbulence. The long-term net effect of all the CO2 budget terms on estimates of NEE needs to be investigated.

Original languageEnglish (US)
Pages (from-to)1-21
Number of pages21
JournalAgricultural and Forest Meteorology
Issue number1-2
StatePublished - Jul 9 2007
Externally publishedYes


  • Canopy
  • Carbon dioxide
  • Complex terrain
  • Drainage flow

ASJC Scopus subject areas

  • Global and Planetary Change
  • Forestry
  • Agronomy and Crop Science
  • Atmospheric Science


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