Credit
We at TERN acknowledge the Traditional Owners and Custodians throughout Australia, New Zealand and all nations. We honour their profound connections to land, water, biodiversity and culture and pay our respects to their Elders past, present and emerging.
Purpose
These decile datasets are an excellent way of identifying areas of low or high cover, relative to what is typical for that location and season.
Lineage
Further details are provided in the Methods section.
Data Creation
Rankings:
The seasonal fractional cover timeseries for the period Autumn (Mar-May) 1988 to Summer (Dec-Feb) 2012/2013 is used as a baseline. Every season is ranked against every available seasonal value within the baseline period, for the corresponding season, on a per-pixel basis.
Rankings are expressed as deciles, so a cover value which falls within the bottom 10% of values in the baseline period is given as decile 1, and a cover value which falls in the top 10% is given as decile 10. Two versions of this are created – one which ranks total cover (green + non-green), and one which ranks only the green fraction.
Because the seasonal composites are used, the data are representative of the season, and robust against outliers. The baseline period is sampled evenly across the whole period, so there is no bias towards the years with more imagery available.
Example:
For example, a total cover value for Spring 2013 is ranked against the total cover in all the Spring images in the baseline period. A green cover value in Spring 2013 is ranked against the green cover fractions in all the Spring images in the baseline period.
Seasonal fractional cover process:
Refer to the Methods section in Seasonal fractional cover - Landsat, JRSRP algorithm, Australia coverage https://portal.tern.org.au/22026