The Global Long-Term Microwave Vegetation Optical Depth Climate Archive (VODCA)
Vegetation Optical Depth (VOD) describes the attenuation of radiation by plants. VOD is a function of frequency as well as vegetation water content, and by extension biomass. VOD has many possible applications in biosphere research, such as biomass monitoring, drought monitoring, phenology analysis or fire risk management. We merge VOD observations from various space sensors (SSM/I, TMI, AMSR-E, AMSR2, WindSat) to build a global long-term VOD time series. Before aggregation, the data have been rescaled according to AMSR-E, removing systematic differences between them.
There is a C-band (~6.9 GHz, 2002 - 2018), X-band (10.7 GHz, 1997 - 2018) and Ku-band (~19 GHz, 1987 - 2017) product. Data are globally sampled on a regular grid of 0.25 degrees.
Data variables in the VODCA file:
VOD: No unit, the vegetation optical depth of each band
sensor_flag: Bit-flag, indicating which sensor contributes 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 abnormal conditions during processing that affect observation quality
Values:
0 = everything works
10 = use AMSR-2 7.3 GHz band instead of 6.9 GHz
11 = scale of sensors matches TMI, not AMSR-E
12 = scale of sensors does not overlap observations in time
Disclaimer: Full or partial descriptions of datasets are provided by the authors or their works.
Dataset preprocessing
The dataset is provided as a compressed NetCDF file, which includes sub-datasets for VOD, sensor flags, and processing flags. Datasets including sub-datasets were exported as individual tif files, which were then stacked in band order of VOD, sensor flags, and processing flags.
| Bands | Band Name | Unit |
|---|---|---|
| b1 | VOD | Unitless |
| b2 | Sensor Flag | Refer to variable description |
| b3 | Processing Flag | Refer to variable description |
Dataset citation¶
Moesinger, Leander, Dorigo, Wouter, De Jeu, Richard, Van der Schalie, Robin, Scanlon, Tracy, Teubner, Irene, & Forkel, Matthias. (2019).
The Global Long-term Microwave Vegetation Optical Depth Climate Archive VODCA (1.0) [Data set].
Zenodo. https://doi.org/10.5281/zenodo.2575599
Paper Citation¶
Moesinger, Leander, Wouter Dorigo, Richard de Jeu, Robin van der Schalie, Tracy Scanlon, Irene Teubner, and Matthias Forkel.
"The global long-term microwave vegetation optical depth climate archive (VODCA)." Earth System Science Data 12, no. 1 (2020): 177-196.
Earth Engine Snippet¶
var cband = ee.ImageCollection("projects/sat-io/open-datasets/VODCA/C-BAND");
var kband = ee.ImageCollection("projects/sat-io/open-datasets/VODCA/K-BAND");
var xband = ee.ImageCollection("projects/sat-io/open-datasets/VODCA/X-BAND");
License¶
This work is licensed under a Creative Commons Attribution 4.0 International License. You are free to copy and redistribute the material in any medium or format, and to transform and build upon the material for any purpose, even commercially. You must give appropriate credit, provide a link to the license, and indicate if changes were made.
Created by : Moesinger, Leander, Wouter Dorigo, Richard de Jeu, Robin van der Schalie, Tracy Scanlon, Irene Teubner, and Matthias Forkel
Curated in GEE by: Samapriya Roy
Keywords: VOD, Vegetation Optical Depth, Biomass, Vegetation water content, Microwave Remote Sensing, Biosphere, Time Series, global, vegetation
Last updated : 2023-01-19