Search found 8 matches

by clays_bio
Mon Jul 04, 2022 8:10 am America/New_York
Forum: Questions/Comments
Question: VIIRS striping and M1/M2 band comparisons to MODIS
Replies: 2

Re: VIIRS striping and M1/M2 band comparisons to MODIS

Hi Sean,

That's excellent news! Thanks for clearing that up. I'll check it out again after the reprocessing.

-Stephanie
by clays_bio
Thu Jun 30, 2022 1:33 pm America/New_York
Forum: Questions/Comments
Question: VIIRS striping and M1/M2 band comparisons to MODIS
Replies: 2

VIIRS striping and M1/M2 band comparisons to MODIS

Hi everyone, I'm comparing the VIIRS-SNPP times series to MODIS-Aqua and noticing an increase of striping in recent years (~2017-present). It's less noticeable in OCx chlorophyll-a, but very obvious in GSM (screenshot of 8day log10 chlorophyll images using the GSM_GS algorithm from Clay et al 2019, ...
by clays_bio
Thu Dec 02, 2021 11:01 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

Thanks Sean! I think my main confusion is the value that the satellite planar radiance represents, since I want to make sure I end up with the equivalent value modelled from Gregg-Carder. I was mixing up steps of integrating vs averaging and converting between energy and number of photons per waveba...
by clays_bio
Wed Nov 24, 2021 2:57 pm America/New_York
Forum: Questions/Comments
Question: Satellite PAR formula and Gregg-Carder light model
Replies: 3

Satellite PAR formula and Gregg-Carder light model

Hi everyone! I'm modelling hourly surface irradiance from 400-700nm using the Gregg-Carder model and trying to figure out how to properly convert it to the same units as the satellite PAR product so it can be scaled, but I'm having trouble following the steps in the PAR model. I would like to use th...
by clays_bio
Wed Mar 03, 2021 9:09 am America/New_York
Forum: Questions/Comments
Question: chlor_a Hu color index wavebands and coefficients
Replies: 5

Re: chlor_a Hu color index wavebands and coefficients

Awesome! I think that answers all my questions about it. In the future it would be good to have this info available on the chlor_a description page (formula for the conversion of the color index to chlorophyll and the current coefficients in use, the blending formula, and the link to the conv_rrs_to...
by clays_bio
Tue Mar 02, 2021 7:04 am America/New_York
Forum: Questions/Comments
Question: chlor_a Hu color index wavebands and coefficients
Replies: 5

Re: chlor_a Hu color index wavebands and coefficients

Thanks for your help! That clears up my question about the coefficients, but I'm still a little unclear about the non-SeaWiFS wavebands used in the algorithm: The chlor_a description page says the algorithm uses the instrument-specific wavebands closest to 443, 555, and 670... so for MODIS this shou...
by clays_bio
Thu Feb 25, 2021 6:49 pm America/New_York
Forum: Questions/Comments
Question: chlor_a Hu color index wavebands and coefficients
Replies: 5

chlor_a Hu color index wavebands and coefficients

Hi everyone!I'm trying to figure out how to implement NASA's chlor_a algorithm in R for MODIS-Aqua, SeaWiFS, and VIIRS-SNPP. The OCx part of it has been no problem, but I'm having trouble finding which wavebands and coefficients to use for the Hu color index algorithm. I've been look...
by clays_bio
Tue Oct 16, 2018 11:24 am America/New_York
Forum: Questions/Comments
Question: O'Reilly band ratio - Finding best coefficients with iterative minimization routines?
Replies: 1

O'Reilly band ratio - Finding best coefficients with iterative minimization routines?

Hello,I'm trying to assess the performance of the ocean colour band ratio algorithms for a couple different regions and sensors, and finding new optimal coefficients for different polynomial degrees using R. I started out simply using the lm() function to find the least squares polynomial throug...