Context

• The intensity of severe cyclonic storms in the North Indian Ocean region has shown an increasing trend in the past four decades, says a recent study by Indian Scientists.

Findings

• The increasing intensity of severe cyclonic storms with major socioeconomic implications was due to atmospheric parameters like

1. higher relative humidity, especially at mid atmospheric level,
2. weak vertical wind shear as well as
3. warm sea surface temperature (SST).
4. suppressed outgoing longwave radiation (OLR)

• It was found that the above factors are distinct during pre-monsoon seasons of La Niña, and that favors the genesis of severe cyclone formation over this region.
• Environmental variables such as SST, wind streamlines, Vertical Velocity, and Specific Humidity exhibited comparable contributions towards cyclogenesis during both El Niño and La Niña phases.
• This indicates the role of global warming in bringing about this increasing trend.
• The impact of global warming due to climate change and its effect on extreme weather events such as frequency and high-intensity tropical cyclones formed over global ocean basins is a matter of concern.
• High-intensity cyclones have become more frequent in the North Indian Ocean, causing significant risk and vulnerability to the coastal regions.
• The study reported an increased amount of water vapor content in the troposphere, and during the past 38 years at 1.93 times as compared to the base year 1979.
• During the past two decades (2000-2020), the La Niña years experienced almost double the number of intense cyclones compared to the El Niño years.
• An increasing trend in the climatological distribution of water vapor content was also seen during these years, with peaks localized over the Andaman Sea and North China Sea regions in conjunction with the increased frequency of severe cyclones.

Significance

• The new findings from this study are expected to augment advanced research in tropical cyclone activity for North Indian Ocean region and also provide the scope for a detailed investigation on the possible linkages and teleconnection with other climate indices over the North Indian Ocean.

https://www.pib.gov.in/PressReleasePage.aspx?PRID=1740252

Download PDF