Earthdata Forum

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

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