DSCOVR Options

[ljk4-1]

ADMIN NOTE: Please note that this topic was unavoidably poltical before the 'No Politics' rule. Please restrict future comments to the mission/spacecraft/news updates etc.

WHAT'S NEW Robert L. Park Friday, 6 Jan 06 Washington, DC
DEEP SPACE CLIMATE OBSERVATORY KILLED.
http://bobpark.physics.umd.edu/index.html

[scalbers]

Nice analysis by fredk. The DSCOVR Team reportedly did make some color improvements to the natural color web images a few years ago, though this eclipse image shows some improvements could still help. Perhaps looking at the available calibrated radiance / reflectance data would give some further insight. As mentioned it's unusual for DSCOVR to have to deal with color of low intensity regions except right near the limb at times. Sometimes I like to look for colors of clouds along the barely visible terminator. Hopefully scattered light doesn't vary with wavelength in the camera system.

The various effects including limb darkening of various wavelengths are somewhat accounted for (and something I hope to improve) in my simulated sky and Earth images. Just subjectively I think the redder color shows up visually when experiencing a deep partial eclipse. If it didn't the combination of bluer color and dimmer light would look more unnatural and different from a normal sunset sequence of lighting.

In this GOES animation the land looks a bit redder, more than the clouds though here also it isn't a perfectly true color processing.

https://col.st/4fqw2

[fredk]

Perhaps looking at the available calibrated radiance / reflectance data would give some further insight. As mentioned it's unusual for DSCOVR to have to deal with color of low intensity regions except right near the limb at times. Sometimes I like to look for colors of clouds along the barely visible terminator. Hopefully scattered light doesn't vary with wavelength in the camera system.

Thanks for the links. Yeah the raw epic data are 32-bit floating-point, and have no problem seeing deep into the penumbra. Here's an example during the eclipse - this is the 443nm channel, clipped on the fully-lit clouds to show detail in the shadow:

But converting three visible channels to a colour image is non-trivial, unless the team has laid out the details for their procedure somewhere.

The various effects including limb darkening of various wavelengths are somewhat accounted for (and something I hope to improve) in my simulated sky and Earth images.

Do you mean by "limb darkening" the extra absorption/scattering near the Earth's limb as viewed from the sun?

Just subjectively I think the redder color shows up visually when experiencing a deep partial eclipse. If it didn't the combination of bluer color and dimmer light would look more unnatural and different from a normal sunset sequence of lighting.

Interesting thought. I'll have to pay more attention to colours if I make it to the path of April's eclipse...