Tropical cyclones in the Arabian Sea have intensified due to earlier monsoon onset

Sep 24, 2012
This shows Tropical Cyclone Benilde in the Indian Ocean in December 2011. Credit: Image courtesy Goddard Space Flight Center

The tropical cyclones in the Arabian Sea during the pre-monsoon season (May – June) have intensified since 1997 compared to 1979 - 1997. This has been attributed to decreased vertical wind shear due to the dimming effects of increased anthropogenic black carbon and sulfate emissions in the region. The decrease in vertical wind shear, however, is not the result of these emissions, but due to a 15-day on average earlier occurrence of tropical cyclones, according to a study spearheaded by Bin Wang at the International Pacific Research Center, University of Hawaii at Manoa and published in "Brief Communications Arising" in the September 20, 2012, issue of Nature.

"About 90% of the pre-monsoon occur during a small widow in late spring. The mean date during which the cyclones with maximum intensity occur has advanced from June 8 in the earlier period to May 24 in the second period," explains Bin Wang. "This advance has been accompanied by a significant decrease in vertical wind shear, which leads to tropical cyclone intensification, because large is most destructive to intensification."

"The ultimate reason for this earlier occurrence of storms and their intensification is the tendency we have noticed for the southwesterly monsoon to begin earlier in recent years," says Wang. "This earlier monsoon onset is related to the greater warming of the Asian landmass than the ocean and thus an increased temperature ocean–land contrast over the last years. This greater temperature difference may strengthen the monsoon and create more favorable conditions for the formation of tropical cyclones."

"All the changes that we see in the pre-monsoon storms and the earlier monsoon onset since the late 90s, can be the result either of natural variability, namely the Interdecadal Pacific Oscillation, or of warming effects due to greater , but not the effect of increased aerosols. Only time and more research will tell."

Explore further: Lava creeps toward road on Hawaii's Big Island

More information: Bin Wang, Shibin Xu, and Liguang Wu: Intensified Arabian Sea tropical storms: Brief Communications Arising, Nature, Sept. 20, 2012, 489.

Related Stories

Climate change and the South Asian summer monsoon

Jun 24, 2012

The vagaries of South Asian summer monsoon rainfall impact the lives of more than one billion people. A review in Nature Climate Change (June 24 online issue) of over 100 recent research articles concludes that w ...

Imani on the weakening on weekend

Mar 26, 2010

This isn't a good weekend for keeping tropical cyclones alive, as Tropical Storm Omais is becoming extra-tropical in the northwestern Pacific Ocean and Tropical Storm Imani appears doomed over the weekend in the Southern ...

Recommended for you

Icelandic volcano sits on massive magma hot spot

Oct 24, 2014

Spectacular eruptions at Bárðarbunga volcano in central Iceland have been spewing lava continuously since Aug. 31. Massive amounts of erupting lava are connected to the destruction of supercontinents and ...

NASA sees Tropical Storm Ana still vigorous

Oct 24, 2014

NASA's TRMM satellite saw that Tropical Storm Ana was still generating moderate rainfall is it pulled away from Hawaii. The next day, NASA's Aqua satellite saw that wind shear was having an effect on the ...

User comments : 4

Adjust slider to filter visible comments by rank

Display comments: newest first

JoeBlue
1 / 5 (2) Sep 24, 2012
Of course, it's all caused by humans.....
NotParker
1 / 5 (2) Sep 24, 2012
"All the changes that we see in the pre-monsoon storms and the earlier monsoon onset since the late 90s, can be the result either of natural variability, namely the Interdecadal Pacific Oscillation, or of warming effects due to greater greenhouse gas emissions"

WOW! They admit it could be the PDO!!!!!!!

They will be punished by the AGW cult.
Husky
not rated yet Sep 24, 2012
yeh, but what causes the PDO, yup right, warming of the stratosphere....
NotParker
1 / 5 (1) Sep 24, 2012
yeh, but what causes the PDO, yup right, warming of the stratosphere....


"MacDonald and Case[19] reconstructed the PDO back to 993 using tree rings from California and Alberta. The index shows a 50-70 year periodicity but this is a strong mode of variability only after 1800, a persistent negative phase occurred during medieval times (993-1300) which is consistent with la nina conditions reconstructed in the tropical Pacific[20] and multi-century droughts in the South-West United States"

http://en.wikiped...illation