This zone is referred to as the zone of inter-tropical convergence, and it is neither symmetric nor centred around the equator. Rather, it is to be found over the oceans in the northern tropical regions. Frierson et al. used observational data and model simulations to show overturning circulation in the oceans, as well as associated energy transports, and their importance in boreal disposition of rainfall (Hickey, 2013).
Hemispheric asymmetry in the ITCZ is caused by the influence of tropical landmasses and their associated cloud fields, and atmospheric circulation on ocean currents and temperatures (Frierson et al, 2013). On average, the Southern hemisphere absorbs more energy than the Northern hemisphere from the atmosphere. The energetic imbalance that results between the two hemispheres is redressed by meridional overturning circulation of the ocean, which transports heat from the Southern Hemisphere northwards towards the equator to be released as atmospheric heat. The ITCZ is sensitive to heat redistribution through the meridional overturning circulation. Generally, in the tropics, energy at the surface is absorbed by the oceans and released into the extra-tropical regions. When these perturbations to the mean state are explored using a model, which removes the effects of continental landmasses, hemispheric asymmetry can also be induced within the ITCZ (Frierson et al, 2013).
This hypothesis that ITCZ asymmetry is determined by meridional overturning circulation can also be tested by imposing, between the extra-tropics and tropics on the two hemispheres, a symmetrical flux of surface heat. The results show that, within the extra-tropics, differences in hemispheric atmosphere-ocean flux of heat related to meridional overturning circulation are a necessity for asymmetry of ITCZ (Pike, 2013). It is still important to note that surface heat flux present in hemispheric imbalance is a result of continental