Frequently Asked Questions
Which remote sensing products is the Biomass Proxy based on?
Biomass Proxy is a fusion of active microwave imagery from the European Space Agency (ESA) Sentinel-1 satellite and optical images from its Sentinel-2 satellites.
How does cloud cover affect the quality of the product?
Users get a new BP raster every day, independent of cloud cover. During persistent cloudy conditions, the spatial distribution of the signal can be affected due to the absence of updated cloud-free optical data.
What is the unit of measurement?
Each pixel has a value from zero to one which represents a relative measure of crop biomass.
What is the spatial resolution?
The size of the pixels in the raster is 10-m.
Does the Biomass saturate at high values?
Yes, the signal can get saturated when the vegetation cover is very dense (e.g. LAI > 5).
For what regions on Earth is the product available?
Due to the Sentinel-1B outage at the end of 2021, and until Sentinel-1C is launched and fully operational, the BP is only available where there is Sentinel-1A coverage (see map below).
Geometry for which Biomass Proxy is currently supported.
How does biomass compare with yield?
Biomass is an important indicator of crop yield. Nonetheless it is also different from yield depending on crop type. The biomass that is measured corresponds with the full column of above-ground biomass. The actual yield obtained is measured in units of production e.g. tons/hectare (which is not the same as kg/m2 corn plant, including the stems and the leaves). Often, through strong correlations with yield (>0.7), biomass can to a certain degree be translated to yield and has a predictive skill. As an example, the figure below shows the correlation between the BP and yield in soybean and maize fields in Nebraska, USA.
Linear correlation between measured yield and biomass proxy values during the growing period.
Does it work in pastures?
The Biomass Proxy can accurately monitor changes in biomass in areas of pasture and grasslands. However, the reduced frequency of SAR observations due to the outage of Sentinel-1B can result in differences between the dynamic changes in biomass due to grazing or mowing and the daily data delivered.
Has the product been validated?
The product has been extensively tested together with our launching customer (xarvio™ Digital Farming Solutions, BASF) in three regions – Europe, North America and South America. We are currently broadening the validation study with different scientific groups and will soon be able to share the results.
What are the effects of frozen ground / snow cover?
Frozen ground and snow cover impacts both optical and microwave signals. This has been accounted for and taken care of by the algorithm and now rarely affects the signal in the growing season.
Could harvest be detected?
Yes, field harvest events can clearly be seen in the timeseries of the Biomass Proxy. Since version 3, we have largely increased the accuracy of the timing in harvest detection.
How does the Biomass Proxy compare to NDVI? What are the advantages over NDVI?
Unlike Normalized Difference Vegetation Index (NDVI), which is not available on cloudy days and only measures spectral greenness, the Biomass Proxy measures the water content in the vegetation. NDVI is based on optical satellite data so is unavailable when it is cloudy. Biomass Proxy on the other hand also makes use of microwave data, so it is also available even when there is cloud cover. In addition, in crops with yellow flowers such as canola, the NDVI signal quickly declines after flowering. In contrast, the BP signal remains almost constant due to the persistence of water in the vegetation.
What makes the product unique?
There is no other fully operational product like the Biomass Proxy that observes biomass with this revisit time, accuracy and spatial resolution. The basis for the product is found in a wealth of experience in remote sensing, combining active microwave data from the European Space Agency (ESA) Sentinel-1 satellites and optical images from its Sentinel-2 satellites.
How is the data delivered?
Data is delivered through Planet’s Subscriptions API. You create a subscription per field or region of interest, each with a geojson geometry file and a requested date range for which the Biomass Proxy should be delivered (see API documentation for more details of how to create a subscription and to download the generated data).
Which geometry should I provide for a new subscription?
The geometry should match as closely as possible with the region of desired output (e.g. your field of interest). Since we process Biomass Proxy on a field-level, providing only a bounding box or a geometry buffered around your field may lead to a reduction in data quality and less representative biomass values.
When can I expect a new image? How soon after a satellite overpass is the data available?
A new update will be available in your account at 6am local solar time, every day, based on the most recent images from all of the satellite data sources.
How long is the historical record?
In addition to our NRT offering, we are also able to provide a historical archive of Biomass. Any service including historical data will include data from april 1st 2020 on. It is also possible to process the full archive back to 2017, at additional cost.
What is the cost/ how does pricing work?
Prices are set on the basis of per hectare, per year, and are determined by the size and duration of the customer commitment and the required historical record.
How can we (“prospect/customer”) validate the Biomass Proxy?
The Biomass Proxy could be validated against your or your customers’ in-field Biomass. We are happy to exchange data and work together with you on this sort of validation activity as part of a proof of concept study before a commercial deal.