Earthdata Forum

I wonder where can I find the spectral response function(SRF) of HICO? I've been trying all afternoon but I can't find it.

Ah, yes, that one would be hard to find without knowing exactly where it was...

It *should* be linked from here:
https://oceancolor.gsfc.nasa.gov/docs/rsr/rsr_tables/
but isn't yet. We began, but didn't finish, an update to that information. Hyperspectral sensors are tricky to display the way we've done for the multispectral....

Until we resolve that issue, you can find the file you seek here:

https://oceancolor.gsfc.nasa.gov/docs/r ... ico_RSR.nc

Regards,
Sean

Hi Sean,

Many thanks for your detailed answer !
I wonder what is the difference between the 'Relative Spectral Response'(RSR) and 'Spectral response function'(SRF) ?I looked at the MODIS spectral response function,Each band corresponds to a filter response.But I checked HICO's RSR, its size is 9000*128（wavelength*bands).I don't understand what the RSR means,and how can I convert RSR to SRF?

Thanks,
Comet

'Relative Spectral Response'(RSR) and 'Spectral response function'(SRF) are just two ways to say the same thing. One might argue that an RSR is inherently normalized, while if one uses the term SRF it is not implicitly normalized - although to use it properly would be to normalize it. So in practice the terms are interchangeable.

The HICO RSRs are provided at 0.1nm resolution between 300-1200nm (900nm at 0.1nm = 9000 elements), one spectrum per band in the HICO instrument (128 bands). HICO is a spectrometer, while MODIS is a filter radiometer. The RSR (or SRF) for both defines the instrument response at each band to input irradiance across the spectrum.

For an example of how these RSRs are used to derived band averaged quantities, see https://oceancolor.gsfc.nasa.gov/reproc ... 9/sources/

Regards,
Sean

Hi Sean,

I would like to ask again what is the band width of Hico? The use of spectral response functions involves λ1 and λ2 in different band ranges. I checked the website and only said "sampled at 5.7nm". Is 5.7nm the band width or the central wavelength interval?

Thanks,
Comet

Hello Comet,

There are also information pages for each mission on the OceanColor web. You can navigate to Missions > HICO and eventually you would come across this page on HICO Sensor and Data Characteristics

Hi Sean，
The website provides RSR of many sensors. However, the RSR of seawifs is different with others.
specifically, the max value of seawifs is over 1 (even 25) and others are lower than 1. How to convert RSR of seawifs?

Normalize it to the max value.
Sean