The lat/lon layers are not reported in GDS2 L2P granules produced
by the NOAA Advanced Clear-Sky Processor for Ocean (ACSPO) SST system,
for new-generation geostationary sensors, including ABI onboard GOES-R
(GOES-16/17, aka "G16/17") and AHI onboard Himawari-8 ("H08") satellites.

Examples L2P data are found in PO.DAAC https://doi.org/10.5067/GHG16-2PO27
NCEI https://doi.org/10.25921/ayf6-c438 and NOAA CoastWatch
https://coastwatch.noaa.gov/cw/satellite-data-products/sea-surface-temperature/acspo-abi.html

Due to special L1b pre-processing on the ground called "geo-rectification",
lat/lon don't change for the same (i,j) geostationary pixel from image
to image, and can be easily calculated offline. Omitting these fixed
layers in data files decreases the filesize by a factor of 2 to 3.

This folder contains the geo_nav.py script which can be invoked as: 
geo_nav.py [path to GDS2 granule]
It calculates lat/lon's for each pixel in the GDS2 granule and
adds them to the input granule as two extra layers, "lat" and "lon".
If the "lat" and "lon" layers already exist in the input
GDS2 file, the script will print an error message and exit.

Precalculated lat/lon's for H08 are also provided in a file:
H08_140_7_E.nc -> H08 operational position at 140.7deg East (Oct 2014 - on)

In case of questions, email nesdis.star.acspo@noaa.gov