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In the context of the land surface, the ground absorbs heat from radiation (also some times from precipitation and advection), and releases heat through evapotranspiration, advection and radiation, and run-off. If it were a closed system, you would expect the net heat loss/gain to be zero (at least on a reasonably long time scale, that irons out daily and seasonal cycles, and noise). However, there is also heat from the mantle to consider, and also heat conduction to the oceans.

Are there other avenues for heat loss or gain from the soil? Are any of these significant in a climatological context? Or should the total heat flux into (or out of) the ground from the atmosphere be equal to zero (or close enough for practical purposes, over time scales longer than a year)?

naught101
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It depends what your practical purposes are. Maybe you can treat it as 0. But in general, no, because it is not closed, due to geothermal heat flux, and anthropogenic imbalances. Also, even if assuming 0, that would be over long time scales and integrated over the earth surface. There are spatial heterogeneities.

mankoff
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  • Hey mankoff: True that. I removed the meteorological tag, and clarified the question: I'm interested in timescales that are long enough to make the seasonal cycle (and perhaps also intra-decadal variability) irrelevant. And I'm interested in the soil to only ~10m deep, max. – naught101 Jan 08 '15 at 13:35
  • I think there are still large spatial variations. There will be local net- and net+ depending on the local groundcover - desert v. rainforest v. urban, areas with groundwater flowing up/down, etc. – mankoff Jan 08 '15 at 15:10