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Re: Fill value problem in MODIS Processing... [message #54547 is a reply to message #54545]

Tue, 26 June 2007 18:02

MarioIncandenza
Messages: 231
Registered: February 2005

Senior Member

> I am currently retrieving aerosole optical thickness from MODIS04
> Aerosole product of 2003 (Level 2, collection 4, and bands of 470,
> 550, and 660 nm).
>
> There are 702 *.hdf files in 2003 and I processed these in a batch
> mode. After I ran IDL/ENVI with these data and opened the output
> file, I found about 550 of 702 lines were processed into fill value
> (-9999.99), 120 lines were N/I ("not included in the swath"). Only 30
> lines were reasonable values.

Hi Harry,

I have done a lot with MOD04_L2 files in IDL, and maybe I can help. I
have some questions:

1) MOD04 Level 2, like all MODIS L2 products, is chopped into 5-minute
granules, 288 per day. Thus 720 files is not quite 3 days of data. How
are your 720 files selected?

2) What is your processing doing that it returns one value from each
granule? The most obvious guess is that it is looking for a specific
XY location in each granule. If so, your 4% rate of return might not
be unreasonable, again depending on how the 720 files you are picking
through were selected.

I have a routine for X|Y|T extraction of data from MOD04 files. If you
have some proficiency with IDL, it can probably be adapted to your
purposes, if you are interested.

Escape the common block!

--Edward H.

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[Message index]

		Re: Fill value problem in MODIS Processing... By: kim20026 on Tue, 26 June 2007 19:47
		Re: Fill value problem in MODIS Processing... By: kim20026 on Tue, 26 June 2007 18:55
		Re: Fill value problem in MODIS Processing... By: MarioIncandenza on Tue, 26 June 2007 18:02
		Re: Fill value problem in MODIS Processing... By: David Fanning on Tue, 26 June 2007 13:24
		Re: Fill value problem in MODIS Processing... By: James Kuyper on Wed, 27 June 2007 10:22
		Re: Fill value problem in MODIS Processing... By: James Kuyper on Wed, 27 June 2007 08:35

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