Cyclones in the Arabian Sea: Why are they uncommon?

Cyclones in the Arabian Sea are less common than those in the Bay of Bengal due to several meteorological and geographical factors. Read here to learn why cyclones in the Arabian Sea are uncommon, yet the frequency has increased.

Cyclone Asna, a rare August cyclone currently lying off the Kutch coast in India, is notable for being land-born, which is an unusual phenomenon.

The name Asna, which means “the one to be acknowledged or praised”, has been given by Pakistan.

Typically, cyclones form over warm ocean waters and then move towards the land. However, Cyclone Asna originated over land, specifically around the Kutch area.

Cyclone Asna

The rarity of Cyclone Asna can be attributed to a combination of unique meteorological conditions.

• The formation of land-born cyclones is uncommon because the lack of moisture and heat over land generally prevents the development of such systems.
• However, in this case, the presence of certain atmospheric dynamics, such as a low-pressure system and the interaction with the monsoon trough, facilitated the formation of Cyclone Asna over land.

The implications of a land-born cyclone like Asna are significant for weather forecasting and disaster preparedness in the region.

• It challenges the typical models and expectations of cyclone formation and movement, requiring a reassessment of how such events are predicted and managed.
• This cyclone also highlights the variability and unpredictability of weather patterns, especially in the context of changing climate conditions.
• The formation of Cyclone Asna underscores the need for continued research and monitoring to better understand these rare and potentially dangerous weather phenomena.

Factors Influencing Cyclone Formation in the North Indian Ocean

The North Indian Ocean, particularly the Arabian Sea and the Bay of Bengal plays a critical role in India’s summer monsoon by providing a substantial amount of moisture.

This moisture is essential for generating the vast quantities of rainfall that define the monsoon season. However, the region is unique because, despite having warm tropical waters that are conducive to cyclone formation, it is the least active area for cyclones compared to other tropical ocean basins.

• Warm Ocean Temperatures: Warm seas, like those in the Arabian Sea and the Bay of Bengal, are typically conducive to cyclone formation because they provide the necessary heat and moisture for the development of cyclonic systems.
• Seasonal Variability: The North Indian Ocean experiences two cyclone seasons: pre-monsoon (April to June) and post-monsoon (October to December). Despite this, the overall number of cyclones is relatively low compared to other regions.
• Monsoon Winds: During the monsoon season, strong winds and high atmospheric stability inhibit cyclone formation. The southwest monsoon winds are too powerful for cyclones to develop and sustain themselves during the peak of the monsoon.
• Vertical Wind Shear: High vertical wind shear, which refers to the difference in wind speed and direction at different altitudes, is prevalent in this region. High shear can disrupt the organization of cyclones, making it difficult for them to intensify.
• Land Interaction: The proximity of the Bay of Bengal and the Arabian Sea to landmasses like India, Bangladesh, and Myanmar often means that cyclones quickly make landfall, losing their energy and intensity due to friction with the land surface.
• Oceanic and Atmospheric Circulation: The unique oceanic and atmospheric circulation patterns in this region, such as the presence of the Madden-Julian Oscillation (MJO) and the Indian Ocean Dipole (IOD), influence the frequency and intensity of cyclones. These phenomena can either suppress or enhance cyclone activity depending on their phase and strength.

Cyclones in the Arabian Sea

Cyclones in the Arabian Sea are less common compared to those in the Bay of Bengal due to several meteorological and geographical factors:

1. Temperature and Humidity: The Arabian Sea has historically been cooler and less humid than the Bay of Bengal. Warm sea surface temperatures are crucial for the formation and intensification of cyclones, and the Arabian Sea typically does not maintain the consistently high temperatures needed. However, with the ongoing impact of climate change, the Arabian Sea is warming, which has led to an increase in cyclone activity in recent years.
2. Wind Shear: The Arabian Sea often experiences higher wind shear, which can disrupt the formation of cyclones. Wind shear refers to the change in wind speed and direction with height, and strong wind shear can tear apart the developing structure of a cyclone, preventing it from intensifying.
3. Geographical Constraints: The Arabian Sea is smaller and more enclosed than the Bay of Bengal, limiting the space for cyclones to develop and intensify. The Bay of Bengal, on the other hand, has a more open geography that allows cyclones to draw energy from the warm waters and grow in size and intensity.
4. Monsoon Influence: The southwest monsoon, which affects the Arabian Sea region, generally occurs during the peak cyclone season (June to September). The monsoon winds can disrupt the organization of cyclones, making it less likely for strong storms to form during this period.
5. Historical Data: Historically, most cyclones in the Indian Ocean region have formed in the Bay of Bengal due to the above factors. The Bay of Bengal has also been the preferred path for storms moving from the Andaman Sea and Southeast Asia, whereas the Arabian Sea has been less conducive to cyclone formation.

Increase in cyclones in the Arabian Sea

In recent years, the Arabian Sea has witnessed a noticeable increase in the frequency and intensity of cyclones. This change is largely attributed to evolving climate patterns, including rising sea surface temperatures and altered atmospheric conditions. Traditionally, the Bay of Bengal has been more prone to cyclones than the Arabian Sea, but recent trends show a significant shift.

For example, Cyclone Tauktae in May 2021 was one of the most severe cyclones to impact the Arabian Sea in recent history.

Several factors are driving this change:

• Warming Sea Surface Temperatures: The Arabian Sea has been warming faster than the Bay of Bengal. Warmer waters provide more energy to developing storms, leading to more powerful and sustained cyclones.
• Changing Wind Patterns: Variations in wind shear, which influences the formation and intensification of cyclones, have also contributed to the increasing intensity of storms in the Arabian Sea.
• Monsoon Delays: Shifts in the timing of the Indian monsoon can impact cyclone formation. Delays in the monsoon can leave the Arabian Sea more exposed to cyclonic activity during peak periods of warm sea surface temperatures.
• Climate Change: Broadly, global climate change is believed to be exacerbating extreme weather events, including cyclones, by altering the natural patterns of temperature, precipitation, and oceanic circulation.

This increase in cyclonic activity poses significant challenges for coastal regions in India, Pakistan, and other countries bordering the Arabian Sea, as they may face more frequent and severe storms, with implications for disaster preparedness and infrastructure resilience.

Conclusion

The North Indian Ocean’s cyclone activity is shaped by a complex interplay of factors that both promote and suppress cyclogenesis.

While the warm seas are a potential hotbed for cyclone formation, the region’s unique meteorological and geographical conditions often limit the number of cyclones.

However, with ongoing climate change, these dynamics may shift, leading to changes in cyclone patterns and impacts.

Frequently Asked Questions (FAQs)

Q. How many cyclones have been recorded in the Arabian Sea?

Ans: Around 64 known tropical cyclones have originated in the Arabian Sea which mostly affected the Yemen and Oman regions.

Q. What is the strongest cyclone in the Arabian Sea?

Ans: Super Cyclonic Storm Gonu was an extremely powerful tropical cyclone that became the strongest cyclone on record in the Arabian Sea. The second named tropical cyclone of the 2007 North Indian Ocean cyclone season, Gonu developed from a persistent area of convection in the eastern Arabian Sea on June 1, 2007.

Q. What is the name of a recent cyclone in the Arabian Sea?

Ans: Cyclone Asna is the first cyclonic storm in the Arabian Sea in August since 1976.

Emerging from the Arabian Sea, Cyclone Tauktae, the first cyclonic storm of 2021, hit southern Gujarat on May 17, 2021, classified as a Very Severe Cyclonic Storm, resulting in casualties in Maharashtra, Karnataka, and Gujarat.

Related articles:

• Important Geophysical phenomena
• Tornado: Gow is it different from cyclone?
• How are tropical cyclones named?

-Article by Swathi Satish