South China Sea summer monsoon onset

November 9, 2016, Institute of Atmospheric Physics, Chinese Academy of Sciences

The South China Sea summer monsoon (SCSSM) greatly influences the socioeconomics of the regions it affects. Its onset mechanism is therefore a popular topic among atmospheric science researchers. However, due to the complexity of the interactions among land, ocean, atmosphere and topography, the definition of the SCSSM onset date is quite controversial and remains uncertain.

In a paper published in Atmospheric and Oceanic Science Letters in October 2016, Dr. Bian HE from Institute of Atmospheric Physics, Chinese Academy of Sciences and his colleagues studied the SCSSM onset during 1997 to 2014.They proposed four indices that depict the SCSSM onset from both the dynamical and thermal perspectives. Three distinct onset types were identified: among the 18 years studied, nine were normal onset years, characterized by a well-established westerly wind and associated precipitation over the South China Sea (SCS); eight were intermittent onset years, in which monsoon precipitation does not occur continuously following the establishment of the westerly wind over the SCS; and one year, 2014, was a delayed onset year, in which the western Pacific subtropical high dominated over the SCS after the seasonal transition and prevented the monsoon onset.

A comparison of the first two types suggested that a positive SST gradient in the northern Indian Ocean and local SST warming in the SCS are two key factors in the normal SCSSM onset type. With regard to the influence of the El Niño-Southern Oscillation background, there were four late onset years (1997, 1998, 2007 and 2010) that coincided with El Niño events, but only two early-onset years (1999 and 2012) out of the six years featuring La Niña events.

"Our further analysis suggested that the zonal thermal contrast across the Indian and western Pacific oceans modulates onset in La Niña years." Dr. HE concluded.

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

More information: Bian HE et al, Interannual variability in the onset of the South China Sea summer monsoon from 1997 to 2014, Atmospheric and Oceanic Science Letters (2016). DOI: 10.1080/16742834.2017.1237853

Provided by: Institute of Atmospheric Physics, Chinese Academy of Sciences

5 shares

Related Stories

Indian monsoon: Novel approach allows early forecasting

April 20, 2016

The Indian monsoon's yearly onset and withdrawal can now be forecasted significantly earlier than previously possible. A team of scientists developed a novel prediction method based on a network analysis of regional weather ...

Recommended for you

Meteorite source in asteroid belt not a single debris field

February 17, 2019

A new study published online in Meteoritics and Planetary Science finds that our most common meteorites, those known as L chondrites, come from at least two different debris fields in the asteroid belt. The belt contains ...

Diagnosing 'art acne' in Georgia O'Keeffe's paintings

February 17, 2019

Even Georgia O'Keeffe noticed the pin-sized blisters bubbling on the surface of her paintings. For decades, conservationists and scholars assumed these tiny protrusions were grains of sand, kicked up from the New Mexico desert ...

Archaeologists discover Incan tomb in Peru

February 16, 2019

Peruvian archaeologists discovered an Incan tomb in the north of the country where an elite member of the pre-Columbian empire was buried, one of the investigators announced Friday.

Where is the universe hiding its missing mass?

February 15, 2019

Astronomers have spent decades looking for something that sounds like it would be hard to miss: about a third of the "normal" matter in the Universe. New results from NASA's Chandra X-ray Observatory may have helped them ...

What rising seas mean for local economies

February 15, 2019

Impacts from climate change are not always easy to see. But for many local businesses in coastal communities across the United States, the evidence is right outside their doors—or in their parking lots.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.