North Indian Ocean tropical cyclone

File:Luban and Titli 2018-10-10 0745Z–0926Z.jpg (left) and Titli (right) over the Arabian Sea and the Bay of Bengal in October 2018]]

The basin is divided into two sub-basins {{Snd}} the Bay of Bengal and the Arabian Sea.{{Cite web|title=2021 North Indian Ocean Cyclone Season|url=https://disasterphilanthropy.org/disaster/2021-north-indian-ocean-cyclone-season/|access-date=June 5, 2021|website=disasterphilanthropy.org}}

The Bay of Bengal, located in the northeast of the Indian Ocean. The basin is abbreviated BOB by the India Meteorological Department (IMD).{{Cite web|title=Acronyms|url=http://www.rsmcnewdelhi.imd.gov.in/acronyms.php|access-date=June 5, 2021|website=www.rsmcnewdelhi.imd.gov.in}} The United States's Joint Typhoon Warning Center unofficially designates as B to classify storms formed in the Bay of Bengal.{{cite web|url=https://www.metoc.navy.mil/jtwc/products/io0221web.txt|title=TROPICAL CYCLONE 02B (TWO) WARNING NR 001|website=www.metoc.navy.mil|author= |publisher=Joint Typhoon Warning Center|location=Pearl Harbor, Hawaii|date=May 24, 2021|access-date=May 24, 2021|archive-url=https://web.archive.org/web/20210524042107/https://www.metoc.navy.mil/jtwc/products/io0221web.txt|archive-date=May 24, 2021}} The Bay of Bengal's coast is shared among India, Bangladesh, Myanmar, Sri Lanka and western part of Thailand.{{Cite web|title=Bay of Bengal {{!}} bay, Indian Ocean|url=https://www.britannica.com/place/Bay-of-Bengal|access-date=June 3, 2021|website=Encyclopædia Britannica}} This sub-basin is the most active and produces some of the deadliest cyclones of all time.{{Cite web|date=May 26, 2021|title=Why Bay of Bengal is hotbed of worst tropical cyclones? As Yaas hits Odisha, here's all you need to know|url=https://www.financialexpress.com/lifestyle/science/why-bay-of-bengal-is-hotbed-of-worst-tropical-cyclones-as-yaas-hits-odisha-heres-all-you-need-to-know/2259192/|access-date=June 5, 2021|website=The Financial Express}} The most intense cyclone in the bay was the 1999 Odisha cyclone.{{Cite web|title=Frequently Asked Questions on Tropical Cyclones|url=http://www.rsmcnewdelhi.imd.gov.in/images/pdf/faq.pdf|access-date=May 31, 2021|website=IMD}}

The Arabian Sea is a sea located in the northwest of the Indian Ocean. Tropical cyclones in the basin are abbreviated ARB by the India Meteorological Department (IMD). The United States's Joint Typhoon Warning Center unofficially designates as A to classify storms formed in the Arabian Sea.{{cite web|url=https://www.metoc.navy.mil/jtwc/products/io0121web.txt|title=TROPICAL CYCLONE 01A (ONE) WARNING NR 001|website=www.metoc.navy.mil|author= |publisher=Joint Typhoon Warning Center|location=Pearl Harbor, Hawaii|date=May 14, 2021|access-date=May 14, 2021|archive-url=https://web.archive.org/web/20210514100035/https://www.metoc.navy.mil/jtwc/products/io0121web.txt|archive-date=May 14, 2021}} The Arabian Sea's coast is shared among Pakistan, India, Yemen, Oman, UAE, Iran, Sri Lanka, Maldives and Somalia.{{Cite web|date=April 10, 2011|title=History of cyclones in the Arabian sea|url=https://pakistanweatherportal.com/2011/04/10/history-of-cyclones-in-the-arabian-sea/|access-date=May 30, 2021|website=Pakistan Weather Portal (PWP)}} Monsoons are characteristic of the Arabian Sea and responsible for the yearly cycling of its waters. In summer, strong winds blow from the southwest to the northeast, bringing rain to the Indian subcontinent. Cyclones are less frequent in the Arabian Sea, but the basin can produce strong tropical cyclones. Cyclone Gonu was the strongest and the costliest recorded tropical cyclone in the basin.{{Cite web|date=June 7, 2007|title=Tropical Cyclone Gonu|url=https://earthobservatory.nasa.gov/images/18446/tropical-cyclone-gonu|access-date=May 30, 2021|website=earthobservatory.nasa.gov}}

The systematic scientific studies of tropical systems in the Bay of Bengal and Arabian Sea was started during the 19th century by Henry Piddington.{{cite report|url=http://www.rsmcnewdelhi.imd.gov.in/images/pdf/archive/best-track/bestrack.pdf|title=Best track data of tropical cyclonic disturbances over the north Indian Ocean|date=July 14, 2009|publisher=India Meteorological Department|access-date=October 31, 2015}} Piddington utilised meteorological logs of vessels that navigated the seas and published a series of memoirs, in the Journal of the Asiatic Society of Bengal between 1839 and 1858. These memoirs gave accounts and tracks of individual storms in the Bay of Bengal and the Arabian Sea.

During the 2004 post monsoon season the IMD started to name tropical cyclones within the basin, with the first one named Cyclone Onil during September 2004.{{cite report|url=http://www.rsmcnewdelhi.imd.gov.in/images/pdf/archive/rsmc/2004.pdf|date=January 2005|page=2|archive-url=https://web.archive.org/web/20150402104124/http://www.rsmcnewdelhi.imd.gov.in/images/pdf/archive/rsmc/2004.pdf|title=Report on Cyclonic Disturbances over North Indian Ocean during 2014|author=RSMC — Tropical Cyclones New Delhi|archive-date=April 2, 2015|url-status=live}} During 2015 a modification to the intensity scale took place, with the IMD and WMO calling a system with 3-minute maximum sustained wind speeds between {{convert|90|kn|km/h mph|round=5}} and {{convert|120|kn|km/h mph|round=5}} an extremely severe cyclonic storm.{{cite conference|page=10|url=https://www.wmo.int/pages/prog/www/tcp/documents/3JS_Reportdraft_FINAL.pdf|title=Third Joint Session of Panel on Tropical Cyclones & Typhoon Committee February 9–13, 2015|location=Bangkok, Thailand|url-status=live|archive-date=April 19, 2016|publisher=World Meteorological Organization|archive-url=https://web.archive.org/web/20160419055649/https://www.wmo.int/pages/prog/www/tcp/documents/3JS_Reportdraft_FINAL.pdf}}

A study analysing the spring season of tropical cyclones in the Bay of Bengal found increases in both pre-monsoon precipitation and tropical cyclone intensity as a result of enhanced large-scale monsoon circulation after 1979. The deepened monsoon trough in the Bay of Bengal not only affects cyclone frequency and timing, but also acts to direct more cyclones towards Myanmar. Increased anthropogenic aerosols likely contributed to such a regional climate change.{{Cite journal|last1=Wang|first1=Shih-Yu|last2=Buckley|first2=Brendan M.|last3=Yoon|first3=Jin-Ho|last4=Fosu|first4=Boniface|date=2013|title=Intensification of premonsoon tropical cyclones in the Bay of Bengal and its impacts on Myanmar|journal=Journal of Geophysical Research: Atmospheres|volume=118|issue=10|pages=4373–4384|doi=10.1002/jgrd.50396|bibcode=2013JGRD..118.4373W |issn=2169-8996|doi-access=free|url=https://academiccommons.columbia.edu/doi/10.7916/D8D50Z1H/download}}

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On average only five to six tropical cyclones form in the basin each year. Tropical cyclones form in the months of March to June and October to December, with peaks at May and November. Most of these storms form in the Bay of Bengal: either in the southeastern Bay of Bengal, in the Andaman Sea, or as a remnant of a typhoon from the South China Sea, and a few in the Arabian Sea. High sea surface temperatures and humidity makes the bays more favourable to tropical cyclone development.{{Cite web|title=Why Bay of Bengal is hotbed of world's worst tropical cyclones?|url=https://www.getbengal.com/details/why-bay-of-bengal-is-hotbed-of-worlds-worst-tropical-cyclones|access-date=June 2, 2021|website=Get Bengal}} There are many tropical cyclones in the West Pacific; this may be another reason for increased{{clarify|date=August 2022}} tropical cyclogenesis in the Bay, as it shares a fair portion of the increased quota of ACE. Meanwhile, the storms in the Arabian Sea mostly form over south-eastern part of the Arabian Sea or a remnant of a tropical cyclone from the Bay of Bengal, however the frequency of cyclogenesis in the Arabian Sea is generally less, due to cooler sea surface temperature and high wind shear. However a strong positive Indian Ocean Dipole may cause an increase of tropical cyclogenesis than usual{{clarify|date=August 2022}} which was seen in the 2019 season.{{Cite web|title=What is the Indian Ocean Dipole? Explain its connection with the Indian monsoons – Civilsdaily|date=31 October 2018 |url=https://www.civilsdaily.com/mains/what-is-the-indian-ocean-dipole-explain-its-connection-with-the-indian-monsoons/|access-date=June 2, 2021}} Very few tropical cyclones develop in the months of June to September (Monsoon months) because of high vertical wind shear. These storms form in the Bay of Bengal and peak as depressions or deep depressions before making landfall in Odisha or West Bengal. Another reason is the low life span in the sea{{clarify|date=August 2022}} which also avoids the intensification of these low-pressure systems.

Most of the storms move in a north-westerly direction and starts curving either towards southwest or northeast. There's a higher frequency of recurving towards northeast rather going southwest. In the Arabian Sea these storms mostly move in north-westerly direction targeting the Arabian Peninsula, however in some case these storm moves north-eastwards after crossing the 15°N latitude and strikes the Gujarati coast. In the Bay of Bengal, storms generally moves north-westwards until reaching the east coast and then moves north-eastwards.{{Cite web|title=Movement|url=http://www.rsmcnewdelhi.imd.gov.in/movement.php|access-date=May 30, 2021|website=www.rsmcnewdelhi.imd.gov.in}}

Intensification probability is maximum in the months of April, May and November in case of a depression becoming a cyclonic storm and severe cyclonic storm. More than half of the depressions intensify into a storm and a quarter intensify into a cyclone in these months.{{Cite web|title=Intensification|url=http://www.rsmcnewdelhi.imd.gov.in/intensification.php|access-date=May 30, 2021|website=www.rsmcnewdelhi.imd.gov.in}}

In the Arabian Sea, most storms dissipate offshore without making landfall, but a significant number of tropical cyclones also impact the west coast, particularly the states of Gujarat and Maharashtra. The remaining 11 percent makes landfall in either the Arabian Peninsula, Horn of Africa or Pakistan.{{Cite web|title=Landfall|url=http://www.rsmcnewdelhi.imd.gov.in/landfall.php|access-date=May 30, 2021|website=www.rsmcnewdelhi.imd.gov.in}} In rare cases, some storms make landfall in Iran, like Cyclone Gonu did in 2007.{{Cite web|title=WHO EMRO {{!}} Experience of cyclone Gonu in the Islamic Republic of Iran: lessons learned {{!}} Volume 16, issue 12 {{!}} EMHJ volume 16, 2010|url=http://www.emro.who.int/emhj-volume-16-2010/volume-16-issue-12/article-15.html|access-date=June 7, 2021|website=www.emro.who.int}} Other than Gonu, two storms: Cyclone Yemyin and Kyarr made some or major impact in Iran.{{Cite web|title=MODIS Web|url=https://modis.gsfc.nasa.gov/gallery/individual.php?db_date=2019-10-29|access-date=June 7, 2021|website=modis.gsfc.nasa.gov}}{{Cite web|title=NASA - Hurricane Season 2007: Tropical Cyclone 3B|url=https://www.nasa.gov/mission_pages/hurricanes/archives/2007/h2007_noname.html|access-date=June 7, 2021|website=www.nasa.gov}}

In the Bay of Bengal, most of the storms strikes either the Indian states of Odisha or West Bengal and a significant number of storms hit the states of Andhra Pradesh and Tamil Nadu. 30 percent of the cyclones strike the countries of Bangladesh, Sri Lanka and Myanmar while the remaining 13 percent just dissipates off shore without making landfall.

{{See also|Climate change}}

After a series of devastating cyclones in 2018, rising number of cyclones in the Arabian Sea in 2019 and a rising trend of rapid intensification in 2020 and 2021, many climatologists agree that climate change have caused these activities. On average, five cyclonic storms occur every year in the Arabian Sea. However, in 2019 eight cyclonic storms formed, becoming the record highest number of tropical cyclones in the sub-basin, which was tied with the 1902 season.{{Cite web|date=January 6, 2020|title=Statement on Climate of India during 2019|url=https://mausam.imd.gov.in/backend/assets/press_release_pdf/Statement_on_Climate_of_India_during_2019.pdf|access-date=June 5, 2021|website=IMD}}{{Cite web|title=Cyclone Tauktae shows why north Indian Ocean is now whacky|url=https://www.downtoearth.org.in/news/environment/cyclone-tauktae-shows-why-north-indian-ocean-is-now-whacky-77023|access-date=June 5, 2021|website=www.downtoearth.org.in|date=20 May 2021 }} Research has found that in recent decades the sea surface temperatures has risen up by {{convert|1.2|-|1.4|C-change|F-change|1}} in the Arabian Sea. During Cyclone Amphan’s rapid intensification, sea surface temperatures were as high as {{cvt|33|C}} in the Bay of Bengal, and parts of the Arabian Sea reached {{cvt|32|C}} before the formation of Cyclone Nisarga.{{Cite web|last=Sarkar|first=Soumya|date=June 5, 2020|title=Cyclones rise as climate change heats up Indian Ocean|url=https://indiaclimatedialogue.net/2020/06/05/cyclones-rise-as-climate-change-heats-up-indian-ocean/|archive-url=https://web.archive.org/web/20200618203332/https://indiaclimatedialogue.net/2020/06/05/cyclones-rise-as-climate-change-heats-up-indian-ocean/|url-status=usurped|archive-date=June 18, 2020|access-date=June 5, 2021|website=India Climate Dialogue}} According to the Union Ministry of Earth and Science, the frequency of very severe cyclonic storms has risen up by one per decade in last two decades, despite the decrease of the overall tropical cyclone frequency in the same period. Higher temperatures caused the cyclones to become more powerful and lead to tropical cyclone formation faster. Rising sea level also caused higher storm surge. Researchers also predict that cyclones will be deadlier and stronger as the trend of warming sea surface temperatures continue. Rising sea levels also may cause severe flooding, strong storm surge and inundation of coastal towns.

{{main|Pre-1890 North Indian Ocean cyclone seasons}}

{{main|1890s North Indian Ocean cyclone seasons}}

{{main|1900s North Indian Ocean cyclone seasons}}

{{main|1910s North Indian Ocean cyclone seasons}}

{{main|1920s North Indian Ocean cyclone seasons}}

{{main|1930s North Indian Ocean cyclone seasons}}

{{main|1940s North Indian Ocean cyclone seasons}}

{{main|1950s North Indian Ocean cyclone seasons}}

File:Nov319660819zESSA3MadrasCyclone.jpg

File:Cyclone 05B.jpg making landfall over Odisha in 1999.]]

File:Gonu 2007-06-04 0900Z.jpg at its peak in 2007.]]

File:Kyarr 2019-10-27 0858Z.jpg was the first super cyclone since 2007.]]

File:Amphan 2020-05-18 0745Z.jpg was the costliest cyclone in the basin to strike land.]]

• The most intense tropical cyclone of the basin was the 1999 Odisha Cyclone. It was the strongest tropical cyclone to hit the Indian state of Odisha. The maximum recorded wind speed was {{cvt|260|km/h|round=5}} with minimum barometric pressure of {{cvt|912|mbar|inHg|sigfig=4|comma=off}}.{{Cite web|date=May 12, 2019|title=Cyclone Fani: How 2019 was different from 1999 super cyclone|url=https://indianexpress.com/article/opinion/columns/cyclone-fani-why-2019-was-not-1999-imd-odisha-coast-5723260/|access-date=June 3, 2021|website=The Indian Express}}
• The costliest tropical cyclone was Cyclone Amphan, which struck the West Bengal coast on May 20, 2020. The recorded damage cost was {{US$}}13.2 billion,{{Cite web |last=Rajaram |first=Vedika Sud,Prema |date=2020-05-22 |title=Cyclone Amphan caused an estimated $13.2 billion in damage: government source |url=https://www.cnn.com/2020/05/22/weather/cyclone-amphan-damage-intl-hnk/index.html |access-date=2024-05-27 |website=CNN |language=en}} beating the previous record of Cyclone Nargis which was {{US$}}12 billion.{{Cite web |date=2022-03-31 |title=Asian bloc to handle Burma aid {{!}} The Star |website=Toronto Star |archive-url=https://web.archive.org/web/20220331095752/https://www.thestar.com/news/world/2008/05/19/asian_bloc_to_handle_burma_aid.html |access-date=2024-05-27 |url=https://www.thestar.com/news/world/2008/05/19/asian_bloc_to_handle_burma_aid.html |archive-date=31 March 2022 }}
• The deadliest tropical cyclone was the 1970 Bhola Cyclone, which caused over 500,000 fatalities in the Ganges-Brahmaputra delta region alone. It made landfall in the Tazumuddin Upazila in East Pakistan (now known as Bangladesh).{{Cite web|title=Fifty Years of the Cyclone That Triggered a Civil War and Created Bangladesh|url=https://thewire.in/history/cyclone-bhola-mujibur-rahman-bangladesh-liberation-yahya-khan-pakistan|access-date=June 3, 2021|website=The Wire}}{{Cite web|title=Hurricanes: Science and Society: 1970- The Great Bhola Cyclone|url=http://www.hurricanescience.org/history/storms/1970s/greatbhola/|access-date=June 3, 2021|website=www.hurricanescience.org}}
• The smallest tropical cyclone was Cyclone Ogni, which struck the Andhra Pradesh coast on October 30, 2008. The cyclone's diameter was only {{cvt|100|km}}.{{Cite web|date=January 2007|title=REPORT ON CYCLONIC DISTURBANCES OVER NORTH INDIAN OCEAN DURING 2006|url=https://mausam.imd.gov.insection/nhac/dynamic/RSMC%20-2006.pdf|url-status=live|archive-url=https://web.archive.org/web/20130412041004/http://www.imd.gov.in/section/nhac/dynamic/RSMC%20-2006.pdf|archive-date=April 12, 2013|access-date=June 4, 2021|website=IMD}}
• The largest tropical cyclone was the 1999 Odisha Cyclone, which struck the coast of Odisha.{{Cite web|title=Anemometer Failed to Read Wind Speed of 1999 Cyclone|url=https://www.outlookindia.com/newswire/story/anemometer-failed-to-read-wind-speed-of-1999-cyclone/813197|access-date=June 4, 2021|website=www.outlookindia.com/}}
• The wettest tropical cyclone was Severe Cyclonic Storm ARB 01 (2004). One of the weather stations recorded {{cvt|184|cm}} between May 5{{Spaced en dash}}7, 2004.{{Cite journal|date=August 2009|title=Alarming Rise in the Number and Intensity of Extreme Point Rainfall Events over the Indian Region under Climate Change Scenario|url=https://www.tropmet.res.in/~lip/Publication/RR-pdf/RR-123.pdf|journal=Indian Institute of Tropical Meteorology|pages=19}}

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{{Natural disasters in India}}

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{{DEFAULTSORT:North Indian Ocean Cyclone Seasons}}