Cylone’s Effect on Monsoon Onset
Context:
- The dynamics of the monsoons, as well as forecasts for when it will start and how it will change throughout the season, are further complicated by the effects of global warming on cyclogenesis over the Pacific and North Indian Oceans, warming over the North Indian Ocean, and late pre-monsoon cyclones and typhoons.
The result:
- Perhaps as a result of the warming Arctic Ocean’s impact on the winds over the Arabian Sea, cyclone forms are occurring earlier in the pre-monsoon cyclone season, closer to the start of the monsoon.
- Of course, the three tropical oceans—Indian, Atlantic, and Pacific—as well as the “atmospheric bridge” from the Arctic and the oceanic tunnel and atmospheric bridge from the Southern Ocean (commonly known as the Antarctic Ocean) also have an impact on the monsoon.
- A “tunnel” is a connection between two far marine zones, whereas a “bridge” is the interaction of two distant locations in the atmosphere.
Position of cyclone is important:
- The onset of the monsoon has been impacted by a few cyclones in the North Indian Ocean in both good and bad ways. The location of the cyclone is crucial in terms of the storm’s impact on the transition of the monsoon trough since the winds around cyclones circulate anticlockwise.
- As demonstrated by Cyclone Mocha, which formed in the first half of May and briefly intensified into a “super cyclonic storm,” backwinds blowing from the southwest to the northeast can pull the monsoon trough forward and aid in the monsoon’s onset if a cyclone is located further north in the Bay of Bengal.
- The Arabian Sea and the Bay of Bengal have both warmed by more than 1o C during the pre-monsoon season, which is a serious effect of the abnormal anticyclones since March.
Guchol, Mawar, and Biparjoy:
- At this moment, Cyclone Biparjoy does not interact much with the monsoon trough. However, typhoons in the northwest Pacific Ocean are intimately tied to both its late birth and the late onset of the monsoon.
- Typhoon Mawar was created on May 19 and was gone by June 3. Mawar, which is now the strongest typhoon to have formed in May, met the criteria to be classified as a “super typhoon.” It is also the most powerful cyclone so far in 2023.
- Currently active roughly east of the Philippines, tropical storm Guchol is expected to move northwest before turning northeast. These strong typhoons are ravenous creatures that seek out moisture everywhere.
Winds from the southwest:
- South westerly winds were created across portions of the Arabian Sea and the Bay of Bengal by Cyclone Mawar, which dragged winds across the equator into the North Indian Ocean.
- “South westerly” refers to a wind direction.
- It is a good thing that there are south westerly winds across the Arabian Sea since they deliver a lot of moisture to the Indian subcontinent.
- On the other hand, the monsoon suffers when south westerly winds blow over the Bay of Bengal.
- The southwest and west monsoon winds over the southern Bay of Bengal rush in, but they then turn around and move northwest towards India.
- It is possible to visualise the powerful south westerly winds across the Bay of Bengal as a very big highway with heavy traffic moving from the southwest over southern peninsular India and Sri Lanka to the South China Sea and the northwest Pacific Ocean, feeding the powerful typhoons there.
- The Andaman and Nicobar Islands are connected to India by the Bay of Bengal, and the monsoon trough is like a small automobile attempting to go across this congested and huge highway.
Conclusion:
- This intricate dance between global warming’s effects on cyclogenesis over the Pacific and North Indian Oceans, the warming over the North Indian Ocean, and the late pre-monsoon cyclones and typhoons combined is just another hindrance to the dynamics of the monsoons as well as to forecasts of the monsoon’s onset and its evolution throughout the season. The monsoon trough, once thought of as a relatively predictable system because of its yearly migration northwest ward and withdrawal southeast ward, is now being tossed around in the game of climate change football.
