Abstract
We investigate the steady dynamical response of the atmosphere on the
equatorial β-plane to a steady, localized, mid-tropospheric heating
source. Following Part I which investigated the case of an equatorial
diabatic heating, we explore the sensitivity of the Gill circulation to
the latitudinal location of the heating, together with the sensitivity
to its horizontal scale. Again, we focus on characteristics of the
response which would be particularly important if the circulation
interacted with the hydrologic and energy cycles. In the off-equatorial
case, the intensity of the overturning circulation has the same limit as
in the equatorial case for small horizontal extent of the diabatic
heating, which is also the limit in the non-rotating case and the
ƒ-plane case. The decrease in this intensity with increasing horizontal
scale of the diabatic heating is slightly faster in the off-equatorial
case than in the equatorial case, but slower than in the ƒ-plane case,
which shows that the β effect disrupts the rotational motion.
The low-level westerly jet is more intense than in the equatorial case,
with larger maximum wind and eastward mass transport that tend to
infinity for small horizontal extent of the diabatic heating. While the
latitudinal extent of the jet is not very sensitive to the latitude of
the diabatic heating, it is not symmetric with respect to the latitude
of the diabatic-heating center, unlike in the equatorial case: it
extends further equatorward than poleward of the diabatic-heating
center. It also extends further eastward than in the equatorial case.