Highlight of Recent Research on Indian Ocean Killer Cyclone Nargis
(Lin et al., Dept. of Atmospheric Sciences) by NASA and USA Today
The recent research results of Associate Professor I-I Lin (Dept. of Atmospheric Sciences, National Taiwan University, Taiwan) and co-authors on tropical cyclone Nargis was featured by NASA and the press release was issued on 26 February 2009 with subsequent reports by the Science Daily, USA Today, and other media. This paper, "Warm Ocean Anomaly, Air Sea Fluxes, and the Rapid Intensification of Tropical Cyclone Nargis"(2008) by I-I Lin, Chi-Hong Chen, Iam-Fei Pun, W. Timothy Liu, and Chun-Chieh Wu, was published in the February issue of the Geophysical Research Letters (36, L03817, doi:10.1029/2008GL035815). The paper explores the role a pre-existing warm ocean anomaly in the Indian Ocean played in the sudden intensification of the killer cyclone Nargis, which was was one of the most devastating natural disasters in recent years. On 1 May 2008, Nargis was observed to suddenly intensify from a relatively weak storm (category-1) to an intense category-4 storm within 24h. Immediately after reaching its peak, a landfall resulted and devastated Myanmar with a death toll exceeds 130,000 in addition to other tremendous social and economical losses.
Using combination of satellite altimetry data from NASA, recently-available in situ Argo floats data from the US NOAA (National Oceanic and Atmospheric Administration) and numerical modeling, Lin and the team (including Dr. W. Timothy Liu from NASA) found that due to the abnormally thick sub-surface ocean warm layer in the anomaly, the upper ocean heat content can increase significantly. Also, the presence of warm layer prohibits the cold water from the deeper ocean to be mixed to the surface. As such, ocean's negative feedback to cyclone's intensification is reduced and there is a 300% increase of the available air-sea sensible and latent heat fluxes to fuel Nargis'sudden intensification. More details can be found in the NASA press release and in Lin et al. (2009, GRL).