Rate of Geothermal Temperature T_G({\bf r}) change along True Vertical Direction:
(1) | {\rm Grad} \, T_G({\bf r}) = \frac{\partial T_G}{\partial z} |
The difference between Geothermal Temperature Gradient (GradT) and Unbiased Geothermal Temperature Gradient (GT) is that the former accounts for the effects of the seasonal/daily temperature variations ( which are mostly noticeable above Neutral Temperature Layer ).
The most common value of Geothermal Temperature Gradient away from tectonic plate boundaries is: GT = 0.025 ÷ 0.035 °C/m.
See Also
Geology / Geothermal Temperature Field
[ Unbiased Geothermal Temperature Gradient (GT) ] [ Geothermal Temperature Profile (TG) ]