#FLUX HOUSTON SOFTWARE#

Measured carbon fluxes peak during morning rush-hour traffic, especially when increasing stretches of the main commuter road fall into the footprint. On the other hand, anthropogenic CO2 emissions dominate over photosynthetic uptake all year round. The largely mature, dominantly oak urban canopy cover alleviates approximately 100 W m- 2 during typical summer days.

Significant differences are also observed with direction during summer, showing decreased Bowen ratios and lower CO2 emissions from sectors with a larger urban tree canopy cover in the footprint. Latent heat flux, however, is smaller outside the growing season, with an equivalent increase in winter storage fluxes, as expected. At this urban location it is balanced by roughly equal amounts of sensible heat, latent heat, and storage fluxes. Net radiation was also only marginally affected by surface heterogeneity. The latter is investigated through visible/near IR orthoimagery and LIDAR data, which are incorporated into a local GIS. Surface properties as calculated from the gradient measurements show the site to be surprisingly uniform, with displacement heights between 5 and 9 m and roughness lengths between 0.4 and 0.7 m, despite urban heterogeneity.

#FLUX HOUSTON SOFTWARE#

Two CSI data loggers and software control the measurements, and EdiRe software is used to analyze turbulence data and compute fluxes. A closed path IRGA is used for CO2 and water vapor fluxes, and independent instrumentation for criteria pollutant and VOC fluxes. Wind speed, temperature and relative humidity are recorded at five levels between 12 and 60 m above ground 3-D wind speed measurements, solar and net radiances, and trace gas sampling are established from the 60 m level. An existing radio communications tower 4 km north of downtown Houston was equipped with micrometeorological instrumentation and trace gas sampling lines in spring 2007. We describe the setup and some first year results of a new flux measurements tower in an urban area.

Flux houston