Search found 1220 matches

by OB.DAAC - SeanBailey
Fri Dec 03, 2021 7:35 am America/New_York
Forum: Questions/Comments
Question: Satellite PAR formula and Gregg-Carder light model
Replies: 3

Re: Satellite PAR formula and Gregg-Carder light model

Steph,
Well, I can't *deny* that approach is valid...it's effectively what the satellite algorithm is doing :D

Sean
by OB.DAAC - SeanBailey
Thu Dec 02, 2021 9:06 am America/New_York
Forum: Questions/Comments
Question: Processing using l2gen: several questions
Replies: 1

Re: Processing using l2gen: several questions

The mask_names attribute in the L2 metadata indicate which flags were masked during L2 processing. The flaguse parameter in l2bin indicates which flags to use when excluding data from binning. If a flag was set as a mask at L2, pixels with that flag set will be fill data, and if binned, will be excl...
by OB.DAAC - SeanBailey
Mon Nov 29, 2021 11:00 am America/New_York
Forum: Questions/Comments
Question: Satellite PAR formula and Gregg-Carder light model
Replies: 3

Re: Satellite PAR formula and Gregg-Carder light model

Yes. PAR is calculated internally in mW/cm2/um, and at the very end of the code:
/* Convert to E/D/m^2 */
if (par[ip] != BAD_FLT)
par[ip] *= 1.193;

So...dividing by 1.193 will get you back into radiance.

Sean
by OB.DAAC - SeanBailey
Mon Nov 29, 2021 10:41 am America/New_York
Forum: Questions/Comments
Question: Why does hicO's Lt(top of atmosphere) data exceed 1?
Replies: 7

Re: Why does hicO's Lt(top of atmosphere) data exceed 1?

If your netCDF reader already applied the scale_factor / add_offset, then you don't need to reapply it. I can confirm the file does include values much higher than 26.
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Screen Shot 2021-11-29 at 10.33.55 AM.png
Screen Shot 2021-11-29 at 10.33.55 AM.png (358.03 KiB) Not viewed yet
Regards,
Sean
by OB.DAAC - SeanBailey
Mon Nov 29, 2021 10:23 am America/New_York
Forum: Questions/Comments
Question: Seadas batch processing: Extracting l2flags and szen
Replies: 6

Re: Seadas batch processing: Extracting l2flags and szen

I still wonder if there is a way to process l2flags at level 3 using seadas No. The l2_flags are used by l2bin when selecting data to include (or more to the point, exclude) in the binning process. The l2bin flaguse parameter defines which l2_flags to set as masks when binning. You cannot bin the l...
by OB.DAAC - SeanBailey
Tue Nov 23, 2021 10:29 am America/New_York
Forum: Questions/Comments
Question: Why does hicO's Lt(top of atmosphere) data exceed 1?
Replies: 7

Re: Why does hicO's Lt(top of atmosphere) data exceed 1?

If correctly read, the Lts from both the HICO L1B files and the MODIS L1B files will be in W/m^2/um/sr and will be consistent. Looking at a typical HICO scene, I found plenty of data over clouds with values in the 300-400 W/m^2/um/sr range. The easiest way to get TOA reflectance for both MODIS and H...
by OB.DAAC - SeanBailey
Mon Nov 22, 2021 2:30 pm America/New_York
Forum: Questions/Comments
Question: L3 Browser extract data error
Replies: 10

Re: L3 Browser extract data error

The error:
Input listing file: "" not found.
...is the key.

Make sure your input list file does not have any blank lines. The code will try to read that blank line as a file and fail exactly as you see it failing.

Sean
...yeah, we probably should fix the code to deal with blank lines...
by OB.DAAC - SeanBailey
Thu Nov 18, 2021 4:15 pm America/New_York
Forum: Questions/Comments
Question: missing (?) scripts in our SeaDAS 8.1.0 ocssw installation
Replies: 2

Re: missing (?) scripts in our SeaDAS 8.1.0 ocssw installation

Jacques,
Yes, as you discovered we have moved the scripts into bin and (for most) removed the .py extension.

Sorry if this caused you any confusion!

Sean
by OB.DAAC - SeanBailey
Wed Nov 17, 2021 4:14 pm America/New_York
Forum: Questions/Comments
Question: Question about Lt results of Landsat8 OLI
Replies: 1

Re: Question about Lt results of Landsat8 OLI

Roxani, The l2gen code uses the reflectance formula and computes Lt from that. Similar to the approach described here: https://www.usgs.gov/core-science-systems/nli/landsat/using-usgs-landsat-level-1-data-product There is also a correction applied for the various focal plane modules and an overall v...
by OB.DAAC - SeanBailey
Wed Nov 17, 2021 2:38 pm America/New_York
Forum: Questions/Comments
Question: Optical Water Type (OWT) product in Seadas/l2gen
Replies: 3

Re: Optical Water Type (OWT) product in Seadas/l2gen

The Rrs above to below calcluation is based on the Lee approach as used in QAA:
rrs(λ) = Rrs(λ)/(0.52 + 1.7 Rrs(λ))

That likely isn't the issue...but not going to say it definitely isn't ;)

Now that we are aware that there is an issue (thanks!) it will (eventually) be fixed.

Regards,
Sean