bulk average
From Glossary of Meteorology
A meteorological variable averaged over the vertical depth of a layer, such as the convective mixed layer.
For layers that are already relatively uniform with height, the bulk average is often used as an idealized value of that variable throughout the layer. For example, the potential temperature is often nearly constant with height in the mixed layer, so the vertical profile is often idealized to be exactly constant, with value equal to the bulk average potential temperature.
