Remote sensing Measuring Sea Surface Temperatures (SST) using ship-borne radiometers What is a radiometer? A radiometer is a thermometer, which measures the temperature of the ocean using the infra-red radiation (heat) emitted from the surface. Why do we want accurate Sea Surface Temperature information? SST holds the key to understanding many aspects of the Great Barrier Reef (GBR). Fish distributions, abundance and species variety are strongly influenced by temperature. SST is also a major cause of stress in corals. During 1998, 2002 & 2004 significant areas of the GBR were bleached due to elevated water temperature. Corals that survived produced less spawn the next year and disease increased. Seagrass beds were "burned" affecting grazing herbivores such as dugongs. Seabird breeding seasons have also collapsed during these periods of high temperatures. The information gathered from satellite images and this radiometer will help shed light on the impact SST has on the Great Barrier Reef. A radiometer being built and tested by Paul Millers in the electronic and mechanical workshops at AIMS. Photo: AIMS How do radiometers work? The measurements made by the radiometer are similar to those made by the satellite sensors but are not affected by "looking" through the atmosphere, which can be a source of error due to aerosols such as dust, cloud and water vapour. The purpose of the radiometer system is to make satellite SST readings taken across the Great Barrier Reef accurate. It has an internal calibration system and is linked to a mobile phone modem to allow daily download of the data and programming from AIMS headquarters at Cape Ferguson (near Townsville). There is also a sensor in the engine room where the engine intake water temperature is measured. A sensor called a pyrgeometer on the back upper deck measures the "background" infra-red radiation from the atmosphere. An integrated GPS ensures the data collected can be matched in space and time to the satellite measurements. On March 9th 2006 AIMS commissioned a unique on-board radiometer on a Fantasea Cruises tourist boat that travels daily between Airlie Beach in Central Queensland to the Reefworld pontoon on Hardy Reef, a journey of approximately 75km. This radiometer samples sea surface temperatures critical to coral bleaching and climate research. Media release Fantasea Cruises’ new onboard radiometer will aid vital climate research The automated radiometer, custom built by AIMS, is perched above the bridge of Fantasea One and enables scientists to be updated on sea surface temperatures (SST) while they are working hundreds of kilometres away in their laboratories at Cape Ferguson (near Townsville). To date it is the only ship-borne radiometer worldwide working regularly in the tropics, which makes the readings significant for climate change scientists globally. AIMS radiometer viewed from the top deck of Fantasea One. Image: Mike Mahoney Contact Craig Steinberg - Remote Sensing Manager     March 9, 2006

December 18, 2008