A monthly summary of summit weather has been available here for many years. Beginning with October 2013 the mean values for air temperature and relative humidity will be from a different sensor, and thus are not strictly comparable with those from prior months. Although the difference is likely to be only a few tenths of a degree, users should be aware of the change.
The reason for the change is that we decided to remove the fan-aspirated sensor during October fieldwork. The radiation shield housing this sensor had known systematic errors, and our technique of intermittent aspiration created additional problems. So, after 3 years of overlap with the CRN-compatible shield and sensors (T and RH), the time had come to remove this instrument.