Sentinel-2 L2A Image Service indices values too low

Question

I am using the Sentinel-2 L2A image service (https://sentinel.imagery1.arcgis.com/arcgis/rest/services/Sentinel2L2A/ImageServer) in ArcGIS Pro and Javascript client.

The values of the indices (from the available processing templates) are significantly lower than the values calculated from the raw downloaded Sentinel-2 L2A imagery.  For example, NDVI ("NDVI Raw" processing template) values are typically in the range of 0.1 to 0.2 lower than it should be.  I have also tried calculating the NDVI and other indices from the individual bands, but the result is the same.  Is there an issue with the baseline processing?

MOHAMEDALKAMEL · Answer

How can I extract Table  time-series zonal statistics of NDVI from Sentinel-2 live data in ArcGIS Online for each parcel or pivot in my dashboard project?

FC_Basson · Answer

Thanks @RWaterman for the clarification.  I'll make sure to follow any updates on the service.

RWaterman · Answer

Hi, yes, it sounds like you may be running into an issue with imagery post PB4.00 where the proper offset has not bee applied. This image service is sourced from the Microsoft Planetary Computer and you can read more about this here. For now, you will need to apply the appropriate offset as part of your workflow.

The Sentinel-2 Level-2A service is currently in beta. As part of our efforts to move this out of beta and into general availability, we will also be applying that offset on the service to normalize the data on the fly so that users will not need to worry about doing this. We anticipate releasing these changes in 2024 Q2. Further down the road, once Sentinel-2 Collection 1 imagery is available on Planetary Computer, that imagery will be provided through this service.