Assessing the Quality of Water Vapor Radiometer Data from Onsala during the CONT11 Geodetic VLBI Campaign

Other conference contribution, 2012

Two water vapour radiometers (WVRs), called Astrid and Konrad, were operated during the CONT11 campaign at the Onsala Space Observatory. A well known feature of WVRs is that their algorithm brakes down when there are large drops of water affecting the observations. Without any independent information one has to rely on the WVR data themselves to detect rain and remove the corresponding low quality results. In order to assess this technique we operated different types of rain sensors during CONT11: a zenith looking Doppler rain radar, three optical, and three capacitive sensors. The first 8.25 days had frequent rain events whereas the last 7.75 days where significantly drier. We summarize the data set acquired by the WVRs and the rain detectors. The inferred time series of the equivalent zenith wet delay (ZWD) and linear horizontal gradients are compared to the corresponding estimates from GPS data (acquired at the IGS station ONSA) and the VLBI data themselves.