IDRA reflectivity measurements from 2008 and 2009 are publicly available in NetCDF format in the CESAR database.
Beside the IDRA data, you will find in the CESAR database a large variety of atmospheric measurements carried out at Cabauw.
CESAR stands for Cabauw Experimental Site for Atmospheric Research. It is a consortium of eight institutes and universities from The Netherlands. The goal of the consortium is to operate and maintain with CESAR a unique observational facility with a comprehensive set of remote sensing and in-situ equipment to characterize the state of the atmosphere, its radiative properties and the interaction with the land surface.