Tropical cyclones - either known as hurricanes or typhoons depending on the region - have been moving faster over ocean basins since 1982, a new study reveals.
Researchers led by Sung-Hun Kim, a postdoctoral researcher from the MÄnoa School of Ocean and Earth Science and Technology (SOEST) at the University of Hawaii, have studied tropical cyclones more than three decades ago when satellites started providing more accurate, reliable data on the meteorological phenomenon.
They assessed the frequency and locations of storms, finding the patterns in tropical cyclone activity over the years. Furthermore, their study also showed that the North Atlantic region alone has seen more hurricanes, with tropical cyclone activities shifting closer to the Earth's poles for both the Atlantic and Pacific oceans.
PERTH, AUSTRALIA - MAY 25: The jetty of the Blue Boat House is seen submerged at Crawley on May 25, 2020, in Perth, Australia. Ex-Tropical Cyclone Mangga has brought heavy wind, rain, and waves along Western Australia's coastline after combining with other cold fronts to create unprecedented storm conditions. State Emergency Services have answered hundreds of calls for help with structural and roof damage since Sunday while thousands of homes and businesses have been left without power.
A Combination of Natural and Man-made Factors
Pao-Shin Chu, SOEST atmospheric sciences professor and a part of the research team, notes the ever-present threat of hurricanes every year for residents living in Hawaii. Close to 40 percent of the United States population lives in coastal areas, including those living in the archipelagic state.
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"For people in Hawaii, the threat of hurricanes is always there every year," Chu explained. He added that with faster hurricanes, people living in coastal communities, together with the emergency managers in charge of these places, would have less time to prepare for evacuation and response efforts.
Investigating the causes of increasing global mean tropical cyclone translation speed (TCTS) in the post-satellite era, with the researchers observing a mix of natural factors and anthropogenic reasons, most notably those related to climate change. TCTS is a factor that determines the impact of tropical cyclones. For example, slower-moving cyclones stay longer in its affected areas, such as the Typhoon Morakot that hit Taiwan in 2009, posting one of the highest recorded rainfall amounts in the area, according to previously published studies.
Following 36 Years of Cyclone Data
To conduct their study, TCTS and the position of the tropical cyclones were gathered from the International Best Track Archive for Climate Stewardship (IBTrACS) - a tracking archive of TC data - version 4, covering the period between 1982 and 2017. Researchers conducted the analysis at six-hour intervals that posted wind speeds of 34 knots or above. They did not include short-lived cyclones or those that lasted less than two days.
Researchers also covered six ocean basins in the study, observing an increasing trend across the South Pacific, the South Indian Ocean, and the Western North Pacific basins. They also noted, however, that the increase "is not statistically significant." As for the other three basins - North Atlantic, Eastern Pacific, and North Indian - show decreasing trends but were also considered "statistically insignificant." Together, these results suggest that the study's observed increase in the global mean TCTS speeds is not derived from local TCTS patterns.
Overall, the study revealed that the global mean tropical cyclone translation speed increased by about 0.31 kilometers per hour, per decade, for the previous 36 years covered in the study. Researchers intend to continue their study and further observe connections between climate variability and TC activities.
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