Building an accurate bird’s-eye view

One of the main problems facing Australians who use remotely sensed data in scientific environmental research and analysis is the gaps in the record, in time or space, or both, and simple difficulties accessing data held in space agencies or national mapping agencies. Sometimes when there is no local data available, or the quality of local data isn’t good enough, scientists have extrapolated from data from the northern hemisphere, where more research has been done. However, Australia faces some unique environmental problems, and northern data is not a good proxy for these.

Because of these problems, any pictures scientists paint of the environmental health of a region or the whole continent are, with the best will in the world, inaccurate. And this affects those people on the ground making land-management and policy decisions, because they can only work from the information available.

This is where AusCover comes in: the role of the facility, which is a national network of experts coordinated by CSIRO Marine and Atmospheric Research (CMAR), is to build comprehensive datasets describing various characteristics of the land-surface across Australia, for example the level of ground cover or burnt areas throughout the seasons and across the country. Several of these datasets are sitting on interconnected computer servers around the country. Researchers can access them to answer questions about environmental change and how it affects ecosystems with much more confidence.

Once AusCover is fully operational, it will provide series of remotely sensed ecosystem data taken over time, as well as map products based on biophysical data collected from satellites and airborne craft; and high-resolution datasets of selected data, for use in further remote-sensing research, that cover several of the TERN supersites. The facility also performs quality control on satellite and airborne data, by collecting field data to calibrate instruments and software and validate the data they collect and process. All the data and map products will be provided free, and will be available all day every day through the AusCover portal.

One invaluable historical dataset that was not easily accessible to the wider ecosystem research community is the long series of monthly satellite ‘snapshots’ of the state of green cover across the continent, which are derived from a series of US satellites originally designed as basic weather satellites. It reaches back to the 1980s, and clearly shows the impacts of El Niño and La Niña years on the continent’s carbon sink strength and ecosystem productivity.

Another dataset that was previously difficult to access is the derived historical time series of bushfire scars across the continent. These data allow ecologists to piece together a history of ecosystem disturbance, natural and human-induced, and its recovery. This is critical to understanding the incredibly complex mosaic of landscapes, habitats and associated species diversity that is observed on the ground.

Other AusCover products and activities that are already having an impact on Australian ecosystem science and management are:

  • remotely sensed data to support the assessment of carbon stocks stored in vegetation biomass
  • satellite imagery used to inform land-management decisions
  • the Persistent Green-Vegetation Fraction 2000–2010, a map product providing robust estimates of areas where green vegetation persists over time
  • burnt-area mapping used to assess the extent of fires and support the measurement of carbon emissions from fires 
  • mapping the severity of fires in northern Australia
  • collaboration with Google Earth Outreach to make detailed satellite imagery accessible to everyone.

Published in TERN e-Newsletter December 2012

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