Rate of Geothermal Temperature change along True Vertical Direction :

{\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: G_T = 0.025 ÷ 0.035 °C/m.

See Also

Geology / Geothermal Temperature Field

[ Unbiased Geothermal Temperature Gradient (GT) ] [ Geothermal Temperature Profile (TG) ]