Eight-and-a-half degrees north of the equator is where the peninsula of India meets the ocean. Our country stretches across 29 degrees of latitude but it is in the vast watery realm south of Kanyakumari that the Indian summer monsoon is brewed, slowly and inevitably. Over twice as many lines of latitude stretches the Indian Ocean, its equatorial belt and then its southern reaches, which continue into the deep and icy girdles of water around Antarctica.
From this vast aqueous quarter-planet the vapours are gathered, and these swirls of airborne water then look for the winds to transport them, first towards the mid-southern latitudes (Madagascar lies astride these, but they are are still a full ten degrees south of the lower coasts of Java) and then in the equatorial trough that spins like a motor. From here these enormous masses of water – half again the size of India at times – are hurled as if in slow motion towards our western coast.
And so to gauge imperfectly whether the wind lords of the farther Indian Ocean have decided to be kind to us we rely nowadays on our eyes in the sky, our weather satellites. What they tell us now is coded in electronic chirps made intelligible by the meteorologists and climatologists of the Indian Meteorological Department, the Ministry of Earth Sciences, the Indian Institute of Tropical Meteorology and the National Centre for Medium Range Weather Forecasting.
Our Indian summer monsoon is amongst the most complex of the planet’s earth-sea-sky interactions. We are told by the scientists, when they disengage from their equations, that the land retains a shorter climate ‘memory’ than the ocean. We are introduced to meridonal termperature gradients and seasonal migration of the inter-tropical convergence zone.
There is an abundance of exotic nomenclature: the Mascarene High, the orographic influence of the East African Highlands, the momentum of the Somali Jet, the ventilation effect of poleward precipitation. And then there is the hot star of the equatorial deeps, El Niño himself, whose domain is the central Pacific and who, when he awakes, demands that the equatorial Indian Ocean obey. He has awoken this year, but the ocean named after us is as unruly as ever.
When will El Niño’s whip really crack? The best models of the climate scientists cannot truly tell us. They and their teraflop calculating machines can only posit what is measured, and what remains unmeasured is still far greater. What we do however know about El Niño is that he does tend to suppress the monsoon. But this year’s El Niño may not resemble one of an earlier year, for where El Niño arises and rules is as important as when. Where the ocean surface warms up (several thousand kilometres parallel to the equator, several hundred kilometres wide) unusually strong rising air flows result.
When these flows descend (as they eventually must) they are generally dry and stable, and so the opposite of conditions needed for or monsoon rains. If they descend far away from India (as happened in 1997-98 when they dropped back into the eastern Pacific) our ocean will deliver and our monsoon will roll in. If they descend in the middle of the Pacific (which happened in 2002) our monsoon will resent the interference and hide. But El Niño is awake and pacing the Pacific. We must hope he does not look too far westwards. (RG)