The Indian Ocean Region is currently witnessing two cyclonic storms, TITLI and LUBAN. While the Arabian Sea hosts Cyclone Luban, which will cause no harm to India’s coastlines, Cyclone Titli, residing in the Bay of Bengal, poses a threat to the coasts of Odisha and North Andhra Pradesh. Both cyclones owe their monikers to Pakistan and Oman respectively. The Inter Tropical Convergence Zone (ITCZ) is shifting southwards towards the coast, generating disturbances in open waters. Interestingly, both cyclones are offshoots of this ITCZ shift. Along with these, another weather phenomenon happens to be in the Indian Ocean called Madden-Julian Oscillation (MJO), which could potentially visit the Indian waters soon, creating favourable weather conditions.
Inter Tropical Convergence Zone
The Intertropical Convergence Zone, or ITCZ as it is normally known, is an equatorial region encircling Earth. It’s where the northeast trade winds (Northern Hemisphere) and southeast trade winds (Southern Hemisphere) merge. This merger takes place due to the rise in humidity and buoyancy caused by the intense heat of the sun and the warm water currents in the ITCZ. Consequently, this buoyant air rises, expands, and cools down, causing continual thunderstorms and heavy rainfall due to released moisture. The ITCZ seasonally oscillates between the north and south in tune with the Sun’s movements. In the case of the Indian Ocean, this shift spans between 40°–45° of latitude, which significantly impacts rainfall leading to the tropical regions experiencing wet and dry seasons rather than the typical cold and warm seasons found at higher latitudes.
Madden-Julian Oscillation
The Madden-Julian Oscillation, in short MJO, is a large-scale fluctuation involving tropical circulation and rainfall. This oscillation, which circulates the globe along the equator within 30-60 days on average, is a dynamic system of wind, cloud, and pressure responsible for rainfall. It derives its name from Roland Madden and Paul Julian, the scientists who discovered it back in 1971. The active phase of MJO produces more than the average annual rainfall, while the suppressed phase results in less than the average rainfall. Although the effects of MJO are primarily seen within the tropical region (between 30 degrees North and South of the equator), the mid-latitude regions in both hemispheres are also influenced by it.
Cyclones and Their Impacts
Cyclones TITLI and LUBAN owe their genesis to the aforementioned meteorological phenomena. The fact that the Arabian Sea and the Bay of Bengal are simultaneously hosting cyclones of such magnitude is a rare occurrence. Of these, Cyclone Titli poses an imminent threat to the coasts of Odisha and North Andhra Pradesh, while Cyclone Luban, in the Arabian Sea, does not pose any imminent threat to India’s coastlines. Regardless, both these cyclones, being offshoots of the ITCZ, illustrate the profound impact of this crucial climatic convergence zone. Furthermore, with MJO in close proximity and likely to visit Indian waters, the conditions are ripe for more weather-related disturbances.
Cyclones such as these, fuelled by major climatic systems like the ITCZ and MJO, have substantial impacts on the regions they hit. These impacts range from heavy rainfalls, high speed winds, to potential flooding and other related damage. Therefore, close monitoring and preparation become key to minimising loss and damage. Such extreme weather events underscore the need for ongoing research and understanding about our planet’s complex climatic systems.
