Fluxes of energy and carbon dioxide over a suburban area of Vancouver, BC

• Main Author: Walsh, Cindy Jennifer
• Language: English
• Published: 2010
• Online Access: http://hdl.handle.net/2429/17707

In this study, a relatively long-term (August 2001 - December 2002) measurement campaign o f radiation, energy and atmospheric CO₂ fluxes was conducted in a fairly homogeneous suburb of Vancouver, British Columbia (Sunset site). Examination of radiative flux densities revealed that the incoming and outgoing short and longwave radiation followed expected patterns throughout the year, and at the diurnal time scale. Energy fluxes demonstrated more complex patterns. Sensible heat dominated throughout the year. Latent heat was lower than expected. The reasons for this are difficult to determine with confidence but are thought to be at least partially related to low data coverage during the winter. The Sunset site has also become more built over the years with natural surfaces transformed into impervious surfaces that more readily accept heat. The role of heat storage played an important role in the energy balance at the diurnal time scale. The annual pattern of CO₂ followed expected seasonal trends, with the lowest concentrations recorded in the summer corresponding to the peak in photosynthesis. Diurnal trends of CO₂ concentrations appear to be at least partly linked to the pattern of fossil fuel consumption. A characteristic peak in concentrations at the diurnal time scale was seen in the morning that coincided with the morning rush hour. The pattern of CO₂ fluxes proved more difficult to interpret. Examination of annual CO₂ flux patterns revealed few negative fluxes indicating that the site was a source for CO₂ for most of the year. The diurnal pattern of CO₂ fluxes closely resembled patterns observed in other urban areas, but of particular interest at the Sunset site was an apparent relationship between wind direction and flux strength. Throughout the year, when the wind was coming from the direction of a nearby busy intersection, fluxes were higher than when the wind was coming from all other directions. This indicates that fluxes may not be well mixed at the sensor height. This directional bias was not observed in the fluxes of heat or water vapour indicating that there may be significant spatial differences in the sources of CO₂ and/or an inequality in the transfer efficiencies of different entities. === Arts, Faculty of === Geography, Department of === Graduate