Correlated humidity and temperature measurements in the urban atmospheric boundary layer

To investigate the effect of atmospheric turbulence on microwave communication links, temperature and water vapor pressure have been measured and radio refractivity has been computed in the atmospheric boundary layer of an urban site during different meteorological conditions. The cospectra between temperature (T) and water vapor pressure (e) have been found to be negative over the whole range of frequencies, or the low-frequency end of the cospectrum is of opposite sign relative to the high-frequency end. In both cases, cospectra follow a -5/3 law in the inertial subrange, in agreement with the theoretical predictions. The coherence spectra clearly show that the temperature and humidity fluctuations are highly coherent within the inertial subrange under both convective and stable conditions. The relative contribution of C sub(T) super(2) , C sub(e) sub(T) , and C sub(e) super(2) to the real refractive index structure parameter C sub(n) super(2) is examined and discussed.