A new global ASCAT vegetation optical depth (VOD) product is available, named the ASCAT INRAE-BORDEAUX or ASCAT IB VOD product. This product is the improvement of the ASCAT IB VOD version 1 in Africa (Liu et al., 2021). The improvement lies in the implementation of a multi-temporal (MT) method and the incorporation of a cost function with constraints into the algorithm. The retrieval algorithm is based on the Water Cloud Model (WCM) including the Ulaby bare soil model. More information can be found in Documentation section.
Documentation section:
Global ASCAT IB VOD was developed by the INRAE-Bordeaux (IB) Remote Sensing Lab (Liu et al., 2023). Global ASCAT IB VOD is the active C-band vegetation optical depth (C-VOD) retrieved from ASCAT at a resolution of 25 x 25 km. The data was retrieved based on the Water Cloud Model (WCM) coupled with the Ulaby linear model.
Key Features: Global ASCAT IB VOD is independent of passive microwave observations. The main features of Global IB VOD are that (i) the ERA5-Land soil moisture (SM) dataset was used as an auxiliary SM dataset in the retrievals, (ii) pixel-based soil model parameters were mapped using Random Forest (RF), and (iii) a multi-temporal (MT) method and a cost function with constraints were implemented into the algorithm making the retrieval of VOD and vegetation scattering parameter simultaneously.
Product: Global ASCAT IB VOD provides 13 years (2008-2020) daily descending (overpass at 09:30 a.m. Local Solar Time) VOD, as well as the vegetation scattering parameter product in the NetCDF format with the WGS84 project.
Data Format:
lat:latitude
lon:longitude
vod: vegetation Optical Depth
vege: vegetation scattering parameter
doy: Day of year
Download link: https://doi.org/10.6084/m9.figshare.24321388.v1
Reference:
Liu, X., Wigneron, J.P., Wagner, W., Frappart, F., Fan, L., Vreugdenhil, M., Baghdadi, N., Zribi, M., Jagdhuber, T., Tao, S., Li, X., Wang, H., Wang, M., Bai, X., Mousa, B.G. and Ciais, P., 2023. A new global C-band vegetation optical depth product from ASCAT: Description, evaluation, and inter-comparison. Remote Sensing of Environment, 299, p.113850. https://doi.org/10.1016/j.rse.2023.113850
Liu, X., Wigneron, J.P., Fan, L., Frappart, F., Ciais, P., Baghdadi, N., Zribi, M., Jagdhuber, T., Li, X., Wang, M. and Bai, X., 2021. ASCAT IB: A radar-based vegetation optical depth retrieved from the ASCAT scatterometer satellite. Remote Sensing of Environment, 264, p.112587. https://doi.org/10.1016/j.rse.2021.112587
Questions?
Email: jean-pierre.wigneron@inrae.fr or xiangzhuo.liu@inrae.fr
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