The forum is locked.
The Ocean Color Forum has transitioned over to the Earthdata Forum (https://forum.earthdata.nasa.gov/). The information existing below will be retained for historical reference. Please sign into the Earthdata Forum for active user support.
from what I understand of previous posts, HICO wavebands are intergrated to MERIS bands for level2 processing.
I assume this is performed upstream (prior atmospheric corrections).
Can you specify which procedure you use to perform spectral integration?
There is no band integration involved. Currently, the HICO reader in our processing code
simply selects the HICO bands nearest to the MERIS bands. Yes, this is done prior to
We are not currently processing HICO beyond L1 browse imagery and have made no attempt
yet at calibrating the instrument for doing so. On our exceptionally long list of things to do is
to modify our processing code to be able to handle hyperspectral instruments like HICO.
If you want to see how we're currently handling HICO, the reader code is available in the
source package for SeaDAS (or just for web browsing, here)
I am processing HICO L1b data using Seadas 7, and an IDL code as a wrapper from L1 to L3. I understand that HICO processing "simulates" the MERIS bands. However, I would wish to clarify the following:
1. Is the HICO processing set up under SEADAS 7 meant to generate exactly the same products list like MERIS.
2. I have noted that requesting for processing of some OC products with the HICO bands fails (actually Seadas 7 halts), e.g. tsm_clark, chl_gsm; is it possible to generate such products from HICO bands?
SO, we only read in the bands that match the MERIS band set. This means that we can produce the same products with HICO
that we can produce with MERIS - although there may be some products that are not "HICO" aware and may not work (although
technically they could - e.g. par).
tsm_clark was removed as a product with 7.0.1 (although seems not completely enough, as it's selectable, but not produceable)
chl_gsm works for me...
Thanks, thats great info, I wish would actually go ahead and explain the 384, I am keen to understand a little bit more about HICO. Let me know what you would suggest as a thorough read on this.
Well, nice to meet you the other day at Cornell.
HICO can be commanded into a special calibration mode where it will record 384 spectral bands. There are only a few scenes like this.
I don't think the version of the code in the current SeaDAS release will handle these files, although our current development code does.
When we modify our code to be able to deal with hyperspectral data, we are likely to only handle the 128 band files.
The HICO sensor collects data from 350 to 1080 nm at 1.91 nm spectral resolution (384 bands).
In normal operating mode, these bands are binned spectrally by three at read-out, yielding the final 128 bands (at 5.7 nm spectral resolution) that are found in the data files. Binning the bands increases the signal-to-noise ratio.
As Sean mentioned, a high-resolution mode is used periodically for calibration purposes. This mode retains the original 1.91 nm resolution.
Further details about the HICO sensor are available from the HICO website:
You may particularly be interested in this page:
Are you aware of any SEADAS chlor-a algorithm that would be "best" suited for retrieving the product from HICO data in inland waters, e.g. a lake, or is all this at experimental stages?
I'm not familiar enough with inland waters to recommend a specific seadas chl routine (and it likely depends on your lake). However, there are numerous HICO projects underway that are specific to inland water bodies (mostly focusing on water quality). You will find that they all take different approaches, trying to take advantage of the hyperspectral nature of HICO. A list of known projects can be found on the HICO website projects page. Some of the projects have provided annual reports (found at the links labelled 2012_AR or 2014_AR) which may have helpful details of implementation and publications.
No, not yet anyway. We do not produce L2 files from HICO operationally, in part because we've not had time to assess the calibration.
Eventually, we will, but for now the gains are set to unity.
is SeaDAS processor now able to handle hyperspectral atmospheric correction and therefore generate hyperspectral marine reflectances?
Almost. The code released with SeaDAS v7.2 can process HICO with the full spectral resolution. The hicohs data tree needs to be put in place of the hico data tree for this to work.
It's still a work in progress, so no guarantees on the products it produces. Little things (like, oh say, water vapor corrections) are not quite up to snuff. No attempt at calibrating
the bands has been made, so caveat emptor.
Powered by mwForum 2.29.7 © 1999-2015 Markus Wichitill