Questions about "skin temperature" definitions

Start by comparing the cited papers and the existing names surface_skin_temperature, skin_temperature, and skin_temperature_at_surface_over_ocean. Clarify whether the proposed _at_surface and _at_TOA definitions are distinct from temperature_at_TOA, then document an agreed naming definition that can resolve #150.

In the current names, the variable skin_temperature is mixed between having a surface_ prefix and not. Our desire is to remove the "surface_" part as superfluous, but it does seem like there may be a subtle difference between surface_skin_temperature and plain skin_temperature, and those differences may even depend on the field. We need to clarify the definition of these terms before resolving #150.

Examples

This older paper uses "skin temperature" to refer to the satellite-derived temperature of the surface (also referred to as "radiometric temperature"). Likewise this 2010 paper goes into some depth on the definitions used for various surface temperatures, including "skin temperature" as being synonymous with "radiometric surface temperature".

However, this 2016 paper defines "skin temperature" as synonymous with "TOA temperature", citing two textbooks Principles of Planetary Climate (2010) and Atmospheric Radiation (1989), the latter of which I was able to verify via Google Books.

The former is the familiar definition to me, but that does not mean other definitions are invalid.

To make things even more complicated, there seems to be yet another definition used in ocean observation contexts: sea_surface_skin_temperature is defined as the IR radiatively-derived temperature of the upper ∼500 μm of the water, as opposed to other definitions that are a property of the near-surface air. It is also unclear to me whether existing variables such as skin_temperature_at_surface_over_ocean are referring to the oceanic radiative definition described here, or the atmospheric radiative definition above.

Proposed definitions

Due to the potential ambiguity, I would propose that skin_temperature always contain a clarifying suffix. Since we already have _at_surface and _at_toa suffixes defined, I propose we use those:

• skin_temperature_at_surface: the "radiometric surface temperature" definition
• skin_temperature_at_TOA: the "TOA temperature" definition
• (if needed) sea_surface_skin_temperature: The SST skin temperature defined above.

But a follow-up question is, is skin_temperature_at_TOA meaningfully different from temperature_at_TOA? I am not sure if there is a potential difference between those definitions in an observational vs modeling context.