Comparison of Doppler spectral moments from TARA and disdrometers during rainfall experiments at CESAR

The Cabauw Experimental Site for Atmospheric Research (CESAR) is the national atmospheric remote sensing facility of The Netherlands. Several major Dutch universities and research institutes involved in atmospheric and land surface research have formed a research consortium and carry out collaborative research at CESAR (~ 25 km SW of Utrecht). One of the focal points of CESAR is the long-term monitoring of the macro- and microstructure of precipitation, with a view to an improved process representation in regional weather and climate models, and to provide a ground validation site for planned satellite precipitation missions (e.g. GPM). The development of improved rainfall retrieval algorithms for operational weather radars and atmospheric research radars is one of the central activities in this endeavour.

Here we focus on detailed comparisons of time series of Doppler spectral moments as measured by the 3 GHz doppler-polarimetric Transportable Atmospheric Research Radar (TARA) and several types of disdrometers (impact-, optical-, and video-) and a local rain gauge network during rainfall experiments organized at CESAR, in particular the CESAR Rainfall Experiment 2002 (C-Rex'02, Fall 2002) and the Baltex Bridge Cloud campaign, phase II (BBC-2, May 2003). We discuss the influence of sampling errors on disdrometer estimates of the Doppler spectral moments and the influence of the vertical wind and turbulence on radar measurements of these moments. Finally, we employ the measured time series to test a recently proposed rainfall retrieval algorithm based on Doppler spectral moments (Uijlenhoet et al., this conference).