Slide 8 of 29
Warm core implies an increase in temperature towards the center of the axis. However, due to the lower resolution of most synoptic scales models, they will generally fail to resolve the warm core characteristics of these waves. Analysis of potential temperature and/or temperature will show, most of the time, little to no variations on the horizontal temperature gradient.
But, tropical waves tend to pool moist air. Thus, the thermal ridge is easier to find if one analyzes equivalent potential temperature (and/or dew point temperature) rather than temperature. The equivalent potential temperature is a better indicator than temperature alone, since it combines the latent heat released during condensation with the sensible heat of the parcel of air.
The tropical waves are warm core systems, and they depend on the latent heat of condensation to feed/sustain their “engine”. This then proves the usefulness of equivalent potential temperature for the evaluation of the waves.