Subset MODIS L2 files for Arctic include data over dateline

[dbotis]

Hi,

I am trying to get MODISA L2 data over the Chukchi Sea and then mosaic by day. In my orders (extracted) I make sure to get things cut off east of the dateline, to avoid reprojection/mosaic issues that occur when trying to map data from both sides of the dateline. However, even though I set the west boundary at -179 or even -177, some of the files I receive bleed over into positive longitudes. This creates problems and gives weird results during my subsequent mosaic routine (via gpt). I can cut the files myself using the gpt subset operator, but when I do, the mosaic routine takes at least 10 times as long (~10-12 min/day), but the results do turn out better.

What is the best solution here? How can I avoid getting files in my orders with positive longitudes? Do I need to set the west bound of my orders farther east (-175?).

Any ideas are appreciated.

Dan

[OB.DAACx - SeanBailey]

Dan,

The L1 extraction will never eliminate all data outside the defined region, as it must retain the same length for all scan lines.  Additionally, there is a minimum size for a MODIS extract (so that it contains enough scans to be able to be calibrated).  So, you're stuck there unless you can move your region enough away from the dateline :cry:

Are you stuck with GPT for doing the mosaic?  If you use l2bin/l3mapgen you will avoid many of the the projection pitfalls you're encountering.

Sean