Quality control and calibration of Faroe Bank Channel bottom temperature

This report documents quality control and calibration of temperature measurements made with moored instruments close to the bottom over the sill of the Faroe Bank Channel. This task is especially important for the early part of the period, before Microcats or similar high-precision instruments were in regular use for temperature measurement or for later periods when these instruments for some reason were not in operation. A preliminary version of the bottom temperature data was presented in Hansen et al. (2016), but new information and a more dedicated approach has allowed revisions of the data that reduce the uncertainties. Havstovan maintains two ADCP moorings, termed FB and FC, over the sill of the channel. Most of the temperature measurements are from mooring FB, but there is also a considerable amount of data from FC and that mooring is somewhat deeper and monitors slightly colder water. We discuss the difference between the two data sets and how the FB data may be adjusted to be more representative for the coldest bottom water of the channel, which at the same time is the densest water entering the North Atlantic.