J8.3
Global warming and tropical cyclone landfall frequency in East Asia
Johnny C. L. Chan, City University of Hong Kong, Hong Kong, China
Recent apparently unusual occurrences of tropical cyclone (TC) landfall around the world (e.g. Hurricane Katrina in the US in 2005, 10 TCs making landfall in Japan in 2004, Tropical Cyclone Larry in Australia in 2006 and Typhoon Saomai in China in 2006) have brought up the question as to whether such occurrences will become more frequent as a result of global warming. To address this question, this paper reports the findings of a study of TC landfall frequency in the East Asia region where an average of 13 TCs make landfall each year (based on the data period 1945-2004), the largest for any ocean basin. Here, East Asia refers to all major landmasses within the domain 5-40N, 105-150E. The data are from various sources for the period 1945-2004. This dataset should not suffer from the problem of incompleteness that exists for TCs over the open ocean as every landfall would be well documented.
The land areas are divided into South East Asia (Vietnam, Philippines, South China), Middle East Asia (East China, including the Island of Taiwan), and North East Asia (Korean Peninsula and Japan). Time series of the annual number of landfalling TCs in each area are formed, both for all TCs having tropical storm intensity and for those reaching typhoon (TY) intensity at landfall.
The results show that none of the time series possesses any statistically significant trend, which suggests that global warming does not lead to more landfalls in any of the regions in Asia. Each time series show large interannual (2-8 years), interdecadal (8-16 years) and even multi-decadal (16-32 years) variations. In some periods, this number varies in unison among all regions of Asia. In others, one region might have above-normal number of landfalling TCs while the other regions have below-normal numbers. In general, at multi-decadal time scales, the number of TC or TY landfall in each region is well correlated with that of the total number of TCs or TYs over the western North Pacific. Some of the variations can be explained by similar variations in the Pacific Decadal Oscillation, El Nino or the Arctic Oscillation.
Recorded presentationJoint Session 8, Tropical Cyclones and Climate Change Part I
Monday, 21 January 2008, 1:30 PM-2:30 PM, R02-R03
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