IMOS Radiometry Task Team (IRTT)
Background and rationale
Given Australia’s vast ocean territory, satellites form an important means by which to establish baselines and assess spatial and temporal patterns of change. The Ocean Colour Radiometry missions have the capacity to deliver publicly available data at spatial resolution from 250m to 1km on daily time-‐steps, and have been used to describe large-‐scale patterns in ocean properties for the last several decades. IMOS currently serve such products to the Australian research community, with an emphasis on tailored local products, which are not necessarily available from the space agencies owning the satellite missions.
Algorithms used to derive ocean properties from remote sensing reflectance have largely been developed using in situ data collected in locations distant from Australia (large northern hemisphere bias). Validation of some satellite products for regional application has already demonstrated that global algorithms are not sufficient to accurately describe ocean properties. To address this, researchers are using alternative approaches that involve measuring the inherent and apparent optical properties (IOPs and AOPs) of the upper ocean, alongside ocean biogeochemical properties, to develop regionally specific satellite algorithms.
Measurements of radiometric quantities, from which apparent optical properties (AOPs) are derived, are performed by IMOS from a variety of platforms (ships and fixed stations) and using different instruments (essentially the DALECs and the SeaPrism at Lucinda). Ensuring consistency of these different measurements is essential, but has not been done systematically. The rationale of this task team is to collate these radiometric data sets and to assess the (lack of) consistency among various data streams
The objective is to perform activities that can ultimately improve usability of IMOS radiometric data sets for research purposes as well as for validation of satellite ocean colour products.
Another objective is to develop a plan for the evolution of radiometry measurements in IMOS for the next decade. This can be summarised as follows:
- Evaluate the degree of consistency or inconsistency among existing sea-‐going radiometers used in the IMOS and wider Australian bio-‐optical community, through dedicated laboratory and field experiments
- If needed, improve consistency among these instruments
- Develop a plan for the evolution of radiometry measurements in IMOS for the next decade