A published data set provides new look at the pulse of nature
What was previously hidden by cloud cover became now visible through VODCA2GPP - the first microwave-based dataset of Gross Primary Productivity which describes global vegetation’s productivity since 1988.
The Climate and Environmental Remote Sensing Research Group (CLIMERS, opens an external URL in a new window) of TU Wien recently published the first gross primary production data set based on microwave remote sensing. The data set called VODCA2GPP is freely available to all researchers and those interested and can be downloaded from the research data repository of the TU Wien.
Gross Primary Productivity or: the Pulse of Nature
Gross Primary Productivity (GPP) is an essential variable in our global ecosystem: GPP describes the total amount of carbon that is bound by organisms. Plants “breathe” carbon dioxide (CO2) and convert this CO2 to biomass and energy through the process of photosynthesis. GPP therefore plays a key role in our ecosystems and can also be understood as the pulse of nature, as this animation illustrates:
By closely observing GPP, we can determine how our vegetation reacts to changing environmental conditions. Increasing atmospheric CO2 concentrations, for example, play a role, as do higher temperatures and changing forms of land use. Measuring GPP therefore makes a significant contribution to understanding the human impact on our environment.
Using Microwaves to look through the clouds
The (global) measurement of GPP was so far dependent on optical satellite sensors. Optical sensors "see" the world in the same wavelength range as we humans which allows them to estimate the vegetation’s productivity based on the greenness of the vegetation. This optical approach has been tried and tested for centuries and is relatively reliable, but it has one major disadvantage: optical sensors cannot look through clouds. This is particularly problematic considering that the most productive regions of the world (for example the tropics) are covered by a thick layer of clouds for most parts of the year.
For this reason, the Climate and Environmental Remote Sensing research group, headed by Prof. Wouter Dorigo, developed an alternative, microwave-based approach to determine global GPP a few years ago. As clouds are no obstacles for microwaves, microwave satellite sensors allow weather-independent and uninterrupted observation of our planet. Compared to optical satellites, microwave satellites do not observe the greenness of the vegetation but are sensitive to changes in the water content of the plants. This allows to draw conclusions about biomass and thus also about the productivity of the plants.
New insights through VODCA2GPP
With its innovative measurement methodology, VODCA2GPP has the potential to provide new insights into our global ecosystems. Some insights have already been gained from VDOCA2GPP. Initial analyses of VODCA2GPP have confirmed, for example, that global GPP has increased significantly in recent years. One reason for this increasing productivity of our ecosystem is the increased concentration of CO2 in the atmosphere. The detailed study of this and other anthropogenic effects on the global carbon cycle is more relevant than ever and requires high-quality data such as VODCA2GPP.
Free data access
In order to maximize the knowledge gained from remote sensing, the CLIMERS group is actively following an open data philosophy. VODCA2GPP is also freely available to all researchers and everyone interested in understanding our planet better. The data can be downloaded via the TU Data Repository website (https://doi.org/10.48436/1k7aj-bdz35, opens an external URL in a new window).
Further information on the methodology, quality, and analysis options of VODCA2GPP can be found in our recent publication (https://doi.org/10.5194/essd-14-1063-2022, opens an external URL in a new window).
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