Global warming hiatus contributed to the increased occurrence of intense tropical cyclones in the coastal regions along East Asia

Jiuwei Zhao, Ruifen Zhan, Yuqing Wang
2018 Scientific Reports  
The recent global warming hiatus (GWH) was characterized by a La Niña-like cooling in the tropical Eastern Pacific accompanied with the Indian Ocean and the tropical Atlantic Ocean warming. Here we show that the recent GWH contributed significantly to the increased occurrence of intense tropical cyclones in the coastal regions along East Asia since 1998. The GWH associated sea surface temperature anomalies triggered a pair of anomalous cyclonic and anticyclonic circulations and equatorial
more » ... ly anomalies over the Northwest Pacific, which favored TC genesis and intensification over the western Northwest Pacific but suppressed TC genesis and intensification over the southeastern Northwest Pacific due to increased vertical wind shear and anticyclonic circulation anomalies. Results from atmospheric general circulation model experiments demonstrate that the Pacific La Niña-like cooling dominated the Indian Ocean and the tropical Atlantic Ocean warming in contributing to the observed GWH-related anomalous atmospheric circulation over the Northwest Pacific. Tropical cyclones (TCs) can cause enormously devastating losses of human life and property damages, especially for coastal areas, including China, Korea, and Japan over East Asia 1-3 . With the rapid increase in populations and economic growth, coastal countries in East Asia are likely to face greater risk during intense TC (ITC) events. Therefore, regional change in ITC activity in the coastal regions along East Asia over the western Northwest Pacific is a critical scientific and socioeconomic issue. A large increasing trend in the number and proportion of category 4-5 TCs has been observed over the main TC basins in recent decades 1,4-9 . This increase has often been linked to global warming 7,10-13 . Global warming not only induces the increase in sea surface temperature (SST) but also enhances the upper-ocean stratification due to the reduction of surface salinity by the upper-ocean freshening 11 . The latter in turn reduces the TC-induced vertical mixing and sea surface cooling and favors the intensification of ITCs 10, 11, 14, 15 . Recent studies have also reported a significant westward shift of the prevailing TC tracks over the Northwest Pacific with an increase in landfalling ITCs in recent three decades 3,16 . This westward shift of prevailing TC tracks has been attributed to the expansion of subtropical high over the Northwest Pacific and local ocean surface warming 3,17,18 . Since both the increase in landfalling ITCs and the westward shift in TC tracks over the Northwest Pacific imply the increasing threat by more ITCs to the coastal regions of the East Asian countries, it is important to further explore the regional change in ITC occurrences and understand possible mechanisms that contributed to the related regional change based on a perspective of global SST anomalies. The global surface warming over the 20th century was found to slow down during 1998-2013. This phenomenon was referred to as the global warming hiatus (GWH) and has been discussed in numerous studies [19] [20] [21] [22] [23] [24] [25] [26] . The GWH was shown to be characterized by a La Niña-like cooling in the tropical eastern Pacific (EP) accompanied with the Indian Ocean (IO) and the tropical Atlantic Ocean (AO) warming. Previous studies have proposed that the GWH could be triggered by the internal variability of the coupled ocean-atmospheric system, such as the Pacific Decadal Oscillation, or the external natural forcing, such as volcanic eruption and aerosols, Published: xx xx xxxx OPEN www.nature.com/scientificreports/ 2 Scientific REpoRTs | (2018) 8:6023 |
doi:10.1038/s41598-018-24402-2 pmid:29662073 pmcid:PMC5902566 fatcat:3lsvrcwcg5gn3dmpqt72lhl4si