Brief description
These data describe the Australia-wide, monthly fraction of Photosynthetically Active Radiation absorbed by vegetation (fPAR) derived from Advance Very High Resolution Radiometer data spanning July 1981 to Oct 2011. FPAR is linearly related to fractional foliage cover. Here fPAR is split into that of persistent vegetation and of recurrent vegetation, which represent non-deciduous perennial vegetation and annual, ephemeral and deciduous vegetation, respectively. Data have been processed using the "invariant cover triangle" method to remove the majority of errors introduced by sensor calibration and change-over effects.Notes
Supplemental InformationPlease refer to the "AVHRR_VegData_readme_v5.txt" file.
Lineage
ENVI data are available from CSIRO DAP, https://doi.org/10.4225/08/50FE0CBE0DD06.Data Creation
Spatial resolution:
Pathfinder AVHRR Land (PAL) data (0.08 degree resolution), spanning July 1981-April 1994, have been combined with High Resolution Picture Transmission (HRPT) data (0.01 degree resolution), spanning February 1995-December 2006. When the HRPT data are supplied at 0.08 degree-equivalent resolution, the original 0.01 degree HRPT data have been resampled to 0.08 degrees by averaging the data into 64-pixel squares which approximately align with overlying PAL pixels.
Version history:
Version 3: Data produced using the method described in Donohue et al. (2008). This version was created in March 2008, and included minor refinements to V2 to address feedback from the Remote Sensing of Environment external reviewers.
Version 4: Update to the persistent and recurrent fPAR data (7 July 2008). A coding error was found in the program used to create the FTP version of the dataset. Whilst this would have only affected the persistent and recurrent data, all variables have been recalculated.
Version 5: Created as an update to version 4 extending it to October 2011. The global thresholds used to rescale NDVI to fPAR were recalculated for the HRPT (0.01) data. This means the fPAR data values for the months within the 1992-2006 period are likely to differ from values in the same months in version 4. All data from the GAC (0.08) data are the same as version 4.
Notes
CreditWe 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.
This dataset has been developed by the Time Series Remote Sensing Team, CSIRO Land and Water in conjunction with the Environmental Biology Group at the Australian National University. The original data were supplied by CSIRO Marine and Atmospheric Research. This work has been supported by the eWater CRC.
Data are suited to the analysis of long-term dynamics (trends) in vegetation cover. Data are monthly grids of 0.08 degree cell size from July 1981 onwards and of 0.01 degree from Feb 1995 onwards.
Data Quality Assessment Scope
local :
dataset
Data are derived from NOAA AVHRR Red and Near Infra-Red reflectances. Reflectances were calibrated using the invariant-cover-triangle methodology (Donohue et al., 2008). This method makes relative calibrations for both atmospheric interferences and sensor calibration errors to produce data suitable for long-term vegetation dynamics analyses. Refer to readme file for details. These data have been corrected specifically for use in looking at long-term dynamics. The majority of sensor calibration and sensor change-over errors have been removed as have most Rayleigh (molecular) and aerosol scattering. Water vapour absorption and viewing angle (i.e., BRDF) effects have not been removed from the data. Some months in the PAL data series have had data from portions of the country masked out due to poor data quality. These months and the approximate regions covered by masks are indicated in the list at the end of the readme file (see Donohue et al., 2007 for full details).
Data Quality Assessment Result
local :
Quality Result
No assessment of accuracy has been performed on this data although the greatest possible precision of AVHRR-derived NDVI/fPAR data is around 0.01-0.02. Spatial accuracy of the HRPT LAC data is to within half a pixel.
Created: 2013-01-29
Issued: 2021-09-22
Modified: 2024-06-20
Data time period: 1981-07-01 to 2011-10-31
text: Australia
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Point-of-truth metadata URL- URI : geonetwork.tern.org.au/geonetwork/srv/eng/catalog.search#/metadata/37788b5f-8084-4522-9fc8-9ae29d43c918
- global : 37788b5f-8084-4522-9fc8-9ae29d43c918
