by K. Richard, Sept 8, 2022 in NoTricksZone
The accuracy of the long-term global instrumental temperature record – especially the data obtained before the 1970s – wholly rests on the assumption that sailors obtained precisely reliable temperature measurements as they pulled wooden or canvas buckets out of the water from ships at random depths, locations, and times of day. They didn’t.
It has long been known that pulling a bucket out of the water from a ship is rooted in serious error, rendering the sea surface temperature (SST) data obtained nearly useless. Ashford (1948) summarized some of the more salient reliability problems with this method of measurement.
• The initial temperature of the bucket is generally different from that of the sea.
• The water in the bucket may change its temperature before the reading is taken owing to the processes of heat exchange and evaporation.
• The initial temperature of the thermometer is generally different from that of the sample.
• The thermometer is liable to scale errors.
• Owing to thermal lag, the thermometer may take an appreciable time to indicate the true temperature of the sample.
• If the thermometer is removed from the bucket when taking the reading, it may no longer indicate the true water temperature.
• The temperature may be read incorrectly.