Earthdata Forum

Hi all,

I tried to reproject MODIS L2 data(AQUA_MODIS.20200227T052500.L2.OC.nc) to geotiff using Python, tired GCP but the result was a little misplaced. Also found that part of the lat and lon of the data is not monotonically increasing(see the picture attached), why is this and how should I deal with it while reprojecting?


Thanks,
Rachel

You have found the MODIS Bowtie effect. Since the MODIS sensor has 10 detectors that take data on each scan, the position of the edge pixels at the beginning and end of the scan overlap the previous and next scan. Here is a web page describing this in more detail:

https://oceancolor.gsfc.nasa.gov/docs/bowtie/modis/

If you want to map MODIS L2 data, I would suggest downloading Seadas and the Science software and using the program "mapgen" to bin and map the data to almost any projection you would like.

don

got it thanks