I am trying to estimate the downward longwave forcing from clouds. I have in-situ measurements of the direct and diffuse components of the incoming shortwave radiation, and I also have the top-of-atmosphere incoming shortwave flux (from reanaslysis).

In my scenario the cloud cover is 100% but its thickness is unknown, although I have radiosonde profiles of the temperature/pressure/humidity.

My theory is that the higher the ratio of diffuse:direct radiation, the thicker the cloud is. Also, the less global (direct+diffuse) shortwave radiation there is compared to the incident radiation, the thicker it is. If I know the incoming shortwave flux, and the shortwave coming out, I can partition the rest of the power into absorbed and reflected - can I estimate how much gets turned to longwave and beamed down with some assumptions? I'm thinking particularly that I could use the temperature profile?

Clearly this assumption would neglect the upward longwave power from the ground that is re-emmitted downwards from the cloud deck.



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