Fig. 1 Flux tower on the urban site on the campus of Cairo university

At all sites the radiation and the energy balance are measured. The radiation budget is measured using three CNR1 radiometer and stored in one minute intervals. Three ultrasonic anemometer, two Open Path Analyzer and a fast hygrometer - measuring at 20 Hz - are used for the estimation of the turbulent heat fluxes (sensible and latent heat flux). At the agricultural site and the desert site we use soil heat plates for the ground heat flux and soil thermistors measure the soil temperature at different depths. Additionally CO² fluxes are measured using the Open Path CO²/H₂O Gas Analyzer at the urban and the agricultural site.

These measurements are unique for a mega-city like Cairo in arid environments.

The output of this campaign will also be used for the calibration of the estimated radiation and heat fluxes using remote sensing data of the ASTER and ETM+ sensors.

Additionally active and  passive sampling techniques have been employed to obtain particle data from street level and background air pollution in greater Cairo. For this purpose one MiniVS  sampling the fine particle fraction PM2.5 and five passive samplers  (Sigma-2) for the coarse suspended particulate matter ( >2.5 µm ) have been installed.  Table 1 gives an overview over the instrumentation of the stations.

Tab. 1 Measured variables and instrumentation

* Open Path CO²/H₂O Gas Analyzer

Fig. 2 Eddy-covariance system with a CSAT-3 and a Krypton Hygrometer at the desert station "10th of ramadan"

On the following image the locations of the three sites - the urban station "Cairo Universtiy", the suburban/agricultural station "Bahtim" and the desert station "10th of Ramadan" - are shown on the background of a LANDSAT ETM+ rgb image.