I want to estimate the long-term or annual heat transfer coefficient for the earth's surface in a particular area where the mean annual air surface temperature is about 13$^\circ$C, and the mean ground surface temperature is about 15$^\circ$C. How can I do this?
The general expression is $h=\frac{Q}{A \cdot \Delta T}$. So I suppose the heat flux term $Q$ is some sort of sum of the earth's outward flux and the sun's inward flux (I have a good estimate of the former: ~70mW/m^2, but I don't know the latter for this latitude. The latitude is about 37 degrees south.)
