Applications - Surface Based Remote Sensing of the Atmospheric Boundary Layer - page 107

The use of an enhanced radiometer, called HATPRO (Humidity And Temperature
PROfiler), has been described by Pospichal and Crewell ( 2007 ). HATPRO records
a set of 14 brightness temperatures every 2 s. From seven brightness temperatures
from channels between 51.26 and 58 GHz, it obtains composite temperature pro-
files from boundary layer scans at six different elevations and zenith observations.
These composite profiles will combine the advantages of both observation modes
and give a consistent temperature profile from 50 m above ground to the upper tropo-
sphere. No significant differences are to be expected in the lowest kilometre, which
is dominated by the boundary layer scans and above 2 km where all information
stems from zenith observations. The vertical resolution of the temperature profile
retrievals decreases from 10 m near the ground to about 300 m at 400 m height.
Figure 4.21 gives an example from HATPRO temperature measurements in West
Africa (Pospichal and Crewell 2007 ). In the lowest 500 m the retrieval accuracies
for temperature from elevation-scanning microwave measurements with instruments
such as HATPRO and spectral infrared measurements (such as AERI, see next sub-
section) are very similar (0.2-0.6 K). Above this level the accuracies of the AERI
retrieval are significantly more accurate (<1 K RMSE below 4 km, Löhnert et al.
2009 ).
Fig. 4.21 24 hour time-height cross section of temperature from measurements with the radiome-
ter HATPRO (from Pospichal and Crewell 2007 )