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David, Thanks for contacting us. See replies inline below: > GOES-R ABI L1b/L2 full disk and CONUS products are on the ABI fixed grid > projection. It is my understanding that Unidata has added support for > this projection (i.e. a Java library), at least to convert a point on > the fixed grid to a lat/lon and visa-versa. What I would like to find > out is whether THREDDS can: > > 1) Subset/sectorize these products based on lat/lon corner points. THREDDS has the NetCDF Subset Service (NCSS, see: https://www.unidata.ucar.edu/software/thredds/current/tds/reference/NetcdfSubsetServiceReference.html) which allows subsetting a dataset using lon/lat and time coordinates, as well as only asking for specific variables. > 2) Change the projection of these products on the full disk projection > to tropical mercator, lambert conformal, or polar stereographic. This is not supported on the thredds server--it only provides services in the data's native coordinates, lon/lat, or index-based subset. Reprojection is currently a task left to the client. We are investigating adding some generic server-side processing capabilities, of which this is a classic example, but this is very early investigations, and there is no timeline on when such features might appear in a release. > 3) Down-sample these products. NCSS supports specifying a stride for both horizontal spatial dimensions and time. This means you can get, for example, every 3rd point. > 4) Change the bit depth of the products' pixels. THREDDS does not do this, nor is it currently planned. > 5) The products contain data quality flag "images" that mirror the fixed > grid data arrays. Will the functions for 1) and 2) be available for > these data quality flag images? Assuming the data quality flag images are NetCDF4 variables, then NCSS will work on these as well. > 6) Will the CF-compliant geolocation metadata be modified appropriately > when functions 1) or 2) above are performed ? Yes, NCSS writes out CF-compliant files in general. > 7) Will the product level metadata fields (i.e. scalar variables, such > as number of good pixels in the image, be updated when functions for > 1) an d 2) above are performed? If I understand correctly, this metadata is not part of CF and is specific to the GOES-R ABI formatted files. As such, THREDDS would not currently handle this, nor is this currently on the roadmap. > 8) The standard names used for the coordinate variables in the native > GOES-R ABI L1b/L2 products are "projection_x_coordinate" and > "projection_y_coordinate". The units are supposed to be meters, but > the GOES-R product designers "cheated" and is using these standard > names with units of "radians". Is this going to cause a problem? I'm not sure. My gut says no, but that it will be straightforward to make it work. Such a problem is likely to be addressed once we start working with some real data. > 9) The other question I have is whether IDV has been revised to support > displaying GOES-R ABI L1b/L2 on the ABI fixed grid projection. For data accessed from THREDDS, the IDV will rely on the same netcdf-java code that power THREDDS. > 10) Lastly, if THREDDS is not currently capable of any of the functionality > described above, do you have plans to develop such functionality, and, > if so, when? All I can add is that we have plans to have a GOES-R receiver here. I'm sure once we have the data flowing we'll be smoothing the process of serving and processing the GOES-R data using THREDDS. This is especially true of problems that affect our internal clients (like IDV and THREDDS). I can't promise, however, that all of the issues discussed above will be solved. Ryan Ticket Details =================== Ticket ID: UIE-535383 Department: Support THREDDS Priority: Normal Status: Closed