The dataset contains daily nc-files of the Cloudnet ice water content during Polarstern cruise PS106 based on:- 35.5 GHz Cloud radar MIRA.The data is retrieved using the instrument synergystic approach Cloudnet (Illingworth, 2007 doi:10.1175/BAMS-88-6-883 ).This variable was calculated from the 35.5-GHz radar reflectivity factor after correction for gaseous attenuation, and temperature taken from a forecast model, using the following empirical formula:log10(iwc[g m-3]) = 0.000242Z[dBZ]T[degC] + 0.0699Z[dBZ] + -0.0186T[degC] + -1.63 (Hogan, 2006 doi:10.1175/JAM2340.1 ).In this formula Z is taken to be defined such that all frequencies of radar would measure the same Z in Rayleigh scattering ice. However, the radar is more likely to have been calibrated such that all frequencies would measure the same Z in Rayleigh scattering liquid cloud at 0 degrees C. The measured Z is therefore multiplied by|K(liquid,0degC,35GHz)|^2/0.93 = 0.9441before applying this formula.The formula has been used where the \"categorization\" data has diagnosed that the radar echo is due to ice, but note that in some cases supercooled drizzle will erroneously be identified as ice. Missing data indicates either that ice cloud was present but it was only detected by the lidar so its ice water content could not be estimated, or that there was rain below the ice associated with uncertain attenuation of the reflectivities in the ice.Note that where microwave radiometer liquid water path was available it was used to correct the radar for liquid attenuation when liquid cloud occurred below the ice; this is indicated a value of 3 in the iwc_retrieval_status variable. There is some uncertainty in thisprodedure which is reflected by an increase in the associated values in the iwc_error variable.When microwave radiometer data were not available and liquid cloud occurred below the ice, the retrieval was still performed but its reliability is questionable due to the uncorrected liquid water attenuation. This is indicated by a value of 2 in the iwc_retrieval_status variable, and an increase in the value of the iwc_error variable.

This is an updated version of this data set: https://doi.pangaea.de/10.1594/PANGAEA.900246