M. Coates et J. Ferris, THE RADIATIVELY DRIVEN NATURAL-CONVECTION BENEATH A FLOATING PLANT LAYER, Limnology and oceanography, 39(5), 1994, pp. 1186-1194
If part of a water body is shaded while an adjacent part is warmed by
direct sunlight, contrasting thermal gradients develop. This different
ial heating generates a surface flow from the illuminated into the sha
ded portion of the water body. One example of this situation is macrop
hytes floating on the surface of a small lake. The macrophytes shade t
he underlying water, and if there is open water adjacent to this shade
d region, then differential heating may be expected. We show that the
presence of the roots of small floating plants displaces the intrusion
downward but does not prevent its formation. Further, we show that re
lations describing the differential absorption mechanism in the absenc
e of macrophyte roots remain valid with roots present. Using these rel
ationships, we calculate that an intrusion generated by differential h
eating may contribute significantly to replacement of nutrients taken
up by the macrophytes.