What is Brown Ocean effect?

February 5, 2015 3:49 PM | Skymet Weather Team

Hurricanes, Typhoons, Cyclones, which originate in their respective basins over Atlantic Ocean, Pacific Ocean and Indian Ocean, are names synonymous with cyclonic disturbances.

Invariably, these storms rapidly weaken after making landfall, for the obvious reason of getting starved of moisture and latent heat.

Cyclonic disturbances also weaken or dissipate while over the sea itself, when they come across unfavourable conditions like colder sea surface temperatures and large vertical wind shear. For the Indian seas, the frequency of dissipation is higher over the west Arabian Sea due to colder sea surface temperatures. There are also significant number of decaying of storms along the east coast of India, Bangladesh and Myanmar coast.

Contrary to the common belief of weakening of cyclonic disturbances on landfall, `Brown Ocean` effect could make them stronger on reaching land. `Brown Ocean` effect goes with the premise that moisture and warmth, the life line of storms, might as well sustain over land under favourable conditions. The research in this direction has revealed that some hurricanes could actually pick up energy from the subsoil moisture and surface heat of the earth, thereby, either sustaining or even gaining strength.

As per Skymet's assessment, the possibility of such events remain confined to only those pockets where the landmass gets enveloped with moisture rich environment. The Indian sub-continent is not at all conducive for such conditions and therefore, stands zero chance to witness any such incidents.

Indian seas, on an average, witness 4-5 cyclones every year with peak months being May and November. History of these cyclones for the last about 100 years reveal that there is not even a single incident where the storm intensified after crossing the coast. However, there are cases of tropical storms weakening after crossing the east coast and later reemerging in the Arabian Sea to gain severity of cyclones. The levels of sub-soil moisture along with heat content of Indian landmass does not subscribe to the theory of `Brown Ocean` effect.

 

 

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