Problem with area estimation using MOD09GA data

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tc4736900
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Problem with area estimation using MOD09GA data

by tc4736900 » Tue Sep 01, 2020 10:50 pm America/New_York

Hello all!

I am currently working on a project to map oil plumes in the Gulf of Mexico using MOD09GA data (MOD09GA.A2010137.h10v06.006.2015207160843 specifically) and I am confused about the actual pixel size of this data.

Taking the first pixel (x=1, y=1) as an example. In SNAP (Sentinal Toolbox Application) the length, width and area of this pixel is 595m, 463m and 0.389km^2. But when I import the same data into ARCGIS pro using the same coordinate system, the length, width and area of the same pixel became 463m, 463m and 0.21km^2.

I am so confused about which one is correct, can anyone help me with this? Thank you so much! (I have also posted this on STEP: https://forum.step.esa.int/t/problem-with-area-estimation/25045)

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gnwiii
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Problem with area estimation using MOD09GA data

by gnwiii » Wed Sep 02, 2020 7:12 am America/New_York

MOD09GA uses a sinusoidal projection.   ESA SNAP appears to overestimate areas when using this projection.   Since SeaDAS-7 and SNAP are both based on BEAM, it is likely that SeaDAS-7 shares this Area estimation is not exact on some CRS issue.

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