Phase 2A: Ship based Sea Surface Temperature (SST) Comparison

A successful SST inter comparison was carried out on the Cunard Queen Mary 2 between the 11th September to 5th November 2015.

The two instruments participating in the SST Field Inter-Comparison Experiment (FICE) were the Rutherford Appleton Laboratory SISTeR (Scanning Infrared Sea Surface Temperature Radiometer) and the University of Southampton ISAR (Infrared Sea Surface Temperature Autonomous Radiometer).

Images from the comparison are shown below:

Left: SISTeR and ISAR side by side on the port side QM2 bridge roof. Right: SISTeR (left) and ISAR (right)


Rain Gauges

An issue with the optical rain gauges – both instruments use the same model – reduced the usable SST data to the 18th October 2015 and 5th November 2015. The problem was the rain gauge body is semi-transparent and one rain gauge did see the optical beam from the other which meant it was measuring rain at all times. The issue was fixed with a metal plate between the rain gauges as shown below.

Rain gauge fix

Overall we discovered that rain gauges seem to have very high values at times – data from the rain gauge experiments are shown below:

Illustrated above are the high values (left) and the tests with a shielded and unshielded rain gauge (right).

The comparison showed that the mean SST difference of the two instruments is 50 to 60 mK, which is within their stated uncertainty of 100mK.

Below shows (top) the SST mean data of SISTeR and ISAR as a scatter plot and histogram and (bottom) also the location of the data.

SST data comparison between ISAR-003(I) and SISTeR A (S) on the Queen Mary 2, 18th October 2015 and 5th November 2015.


ISAR-SISTeR Ship Track

SST mean difference between SISTeR and ISAR.

The second part of the inter comparison was to compare the uncertainties of the two instruments which is still ongoing. The early results how that the magnitude of uncertainties is smaller for SISTeR and larger for ISAR and while the Type A uncertainties seem to agree fairly well the type B uncertainties differ for both instruments with their current uncertainty models.


2017 SISTeR radiometer cruises

The figures below show the sea surface temperature recorded in two recent measurement campaigns using the SISTeR radiometer: cruises 13 (January to May 2017) and 14 (data shown is from May – July 2017).

The coloured lines in the ocean indicate the measured sea service temperature (see scale for temperature chart).

SISTeR A cruise 13

SISTeR A cruise 14


International Shipborne Radiometer Network

The International Shipborne Radiometer Network (ISRN) sets out to develop and promote an international network of ocean and remote sensing scientists who share a particular interest in promoting and improving the use of shipborne infrared radiometers for measuring sea surface temperature (SST) at the skin of the ocean, comparable to measurements made by satellite infrared radiometers. For further information, please visit: