The Global Long-term Microwave Vegetation Optical Depth Climate Archive VODCA

Related paper containing detailed description: Moesinger et al. (2020)

Vegetation optical depth (VOD) describes the attenuation of radiation by plants. VOD a function of frequency as well as vegetation water content, and by extension biomass. VOD has many possible applications in studies of the biosphere, such as biomass monitoring, drought monitoring, phenology analyzes or fire risk management.

We merged VOD observations from various spaceborne sensors (SSM/I, TMI, AMSR-E, AMSR2, WindSat) to create global long-term vod time series. Prior to aggregation the data has been rescaled to AMSR-E, removing systematic differences between them.

There is a product for C-band (~6.9 GHz, 2002 - 2018), X-band (10.7 GHz, 1997 - 2018) and Ku-band (~19 GHz, 1987 - 2017). The data is global sampled on a regular 0.25 degrees grid. Each product is available as daily global netcdf4 files.

Currently there is an issue with opening the file using ESA SNAP. As an alternative Panoply can be used to quickly visualize the data. 

An update of VODCA, addressing this issue and potentially including an extension of the dataset, is foreseen to be published on Zenodo early 2020.

Please contact us if you have any questions, problems or suggestions for improvement!

Files:

• "VODCA_C-band_2002-2018_v01.0.0.zip" (unzipped size: ~140 GB):
  • VODCA C-band files, sorted into yearly folders
• "VODCA_X-band_1997-2018_v01.0.0.zip" (unzipped size: ~180 GB):
  • VODCA X-band files, sorted into yearly folders
• "VODCA_Ku-band_1987-2017_v01.0.0.zip" (unzipped size: ~270 GB) :
  • VODCA Ku-band files, sorted into yearly folders
• "vodca_v01-0_K-band_2007-06-01.nc"
  • sample file of the Ku-band product
• "ESA-CCI-SOILMOISTURE-LAND_AND_RAINFOREST_MASK-fv04.2.nc"
  • Contains a global land mask, VODCA only has data for land locations. Source: https://github.com/TUW-GEO/smecv-grid

Variables of data in VODCA files:

• "VOD": Unitless, Vegetation Optical Depth of the respective band
• "sensor_flag": Bit-flag indicating which sensors contributed to each observation.
  • Values:
    • 1 = AMSR-E
    • 2 = AMSR2
    • 3 = SSM/I F8
    • 4 = SSM/I F11
    • 5 = SSM/I F13
    • 6 = TMI
    • 7 = WindSat
• "processing_flag": Bit-flag indicating irregularities during processing affecting the quality of the observations
  • Values:
    • 0 = Everything is fine
    • 10 = AMSR-2 7.3 GHz band is used instead of 6.9 GHz
    • 11 = Sensor is scaled to matched TMI instead of AMSR-E
    • 12 = Sensor scaled without temporally overlapping observations
• "time"/"lon"/"lat": Dimensions of the data.