Data rescue of historical typhoon tracks over the western north Pacific back to late 19th century Hisayuki Kubota Research Institute for Global Change, Japan Agency for Marine-Earth Science and Technology (JAMSTEC)
Background ・Typhoon activity appears to be affected by global warming (Oouchi et al. 2006). ・On the other hand, typhoon activity has natural interdecadal variability (Yumoto and Matsuura 2001) . ・Typhoon database is created over the Atlantic basin from 1851 (Landsea et al. 2004). ・However, over the WNP, typhoon database is available from 1945 by JTWC (Joint Typhoon Warning Center) best track data. Available global typhoon database 1945- 1851- 1949- 1877- 1877- by NCAR
Seasonality of typhoon track 1893-1918 Major four typhoon track dataset were used (Philippines, Japan, Hong Kong, and Zi-ka-Wei) Visher 1922 MWR
“For understanding the typhoon activity through the 20th century over the western north Pacific“ funded by the Grant-in-Aid for Scientific Research for Young Scientists (A) of the Ministry of Education, Culture, Sports, Science and Technology (MEXT) in Japan period : 2009-2011 budget: US$ 125,000 leader: Hisayuki Kubota (JAMSTEC) collaborators: Prof. Bin Wang (Univ. of Hawaii) Prof. Johnny Chan (City Univ. of Hong Kong) Dr. Mong-Ming Lu (Central Weather Bureau, Taiwan) Dr. KumiKataoka (Shumei Univ., Japan) Mr. Edwin W. L. Ginn (Hong Kong Observatory) Dr. Zhao Bingke (Shanghai Typhoon Institute)
Monthly Bulletins of Philippines Weather Bureau (1901-1940) stored in Hamilton Library at University of Hawaii (1891-1900 stored in JMA library) 300 stations observation data Typhoon tracks over the WNP Udias (1996) BAMS Introducing 19th-20th century meteorological observation over the world Philippine weather observation Spanish (from 1865) American (20th century) meteorologists
Typhoon track and surface isobar map on May 1913 Typhoon tracks were detected by using station observations, ship obs. reports, reports of typhoon eyes and damages.
Historical typhoon track data collected and digitized over the western north Pacific digitized collected available Hong Kong (Hong Kong Observatory) （1958 reedited） Shanghai(Zi-Ka-Wei) (Shanghai observatory) （1957 reedited） Philippines (Univ. Hawaii) Japan (JMA library)
Digital Tropical Cyclone tracks over the Western North Pacific from 1902 to 1940 Data source Monthly Bulletins of the Philippine Weather Bureau 1901-1940 Datasets TC (tropical cyclone) track locations Data files TYByyyymmdd.a.dat (for example: TYB19020706.a.dat) yyyymmdd: It is the first date of each TC track. • Data format • YYYYMMDDHH lat lon type flag • 1902 7 6 12 12.19 128.34 2 1 • 7 7 12 12.25 125.63 2 1 • 1902 7 8 12 12.57 123.54 2 1 • 1902 7 9 12 13.36 121.16 2 1 • 1902 7 10 12 14.70 118.30 2 1 • 7 11 12 17.09 114.66 2 1 • HH: Philippine local time (+8 hours GMT) This data is available at http://www.jamstec.go.jp/drc/maps/e/kadai/mon/mon_tt.html
flag1: types of TC 2: Tropical Storm or Typhoon (center pressure less than 750mmHg (about 1000 hPa)) 4: its intensity is unknown (Typhoon or Tropical Depression or Extra Tropical Cyclone) 8: Tropical Depression 1: report the TC heading direction flag2: Quality Check is performed 1: satisfied (compared to other best track data) 4: failed (high possibility of extra tropical cyclone) 6: questionable (possibility of tropical depression or extra tropical cyclone) 9: not checked (for flag1: 4, 8, and 1) I recommend of using only satisfied typhoon data with 2 in flag1 and 1 in flag2.
Typhoon definition compared by landfall numbers in the Philippines To check the reliability of the historical datasets • 1945-2005 when TS passed over Philippines Max wind speed >35kt (JTWC TS best track data) (JMA best track data used for comparison) • 1902-1939 when TS passed over Philippines ps <1000hPa observed at station using Monthly Bulletins of Philippines Weather Bureau Comparison between two definitions Typhoon landfall from 1951-1978 by “Tropical Cyclones Summaries from 1948 to 1978” by Bonjoc (1978) Max wind speed >35kt TS 124(JTWC), 124(JMA) Ps<1000 hPa107 105 (difference 13.7%, 15.3%) Kubota and Chan 2009
Remove extra tropical cyclones Satisfied tracks Failed tracks JTWC
Ensembles of multi typhoon track datasets Hong Kong Philippines Japan Shanghai
Quality check of the density of typhoon numbers over the WNP • Restrict the target area, within • 600km radius of each weather station • Check typhoon passage through • the perturbation of the station • pressure data 80% of typhoons passed target area (JTWC, JMA) Count enough numbers of typhoons throughout the year near Philippines from 1908 ▼ : typhoon by Philippines dataset ▼: typhoon by Hong Kong dataset ▼: typhoon by Japan dataset ▲ :typhoon landed Philippines
Density of historical typhoon numbers over the target area Until 1909 not satisfied 1910 Combination of 3 typhoon track dataset 1911-1939 Philippine Weather Bureau Central Meteorological Observatory Tokyo Japan After 1941 not satisfied Daily pressure data are available over the whole target area from 1907 to 1941
Historical daily rainfall dataset created from early 20th century Japan 1901-2009 Taiwan 1901-2009 Philippines 1901-2009 South Seas Bureau & WNP islands 1923-2009 Hong Kong 1884-2010
Typhoon numbers of the target area over the Western North Pacific MBP+combination JTWC JMA :10 years running mean 10-20N >20N <10N MBP, JTWC JMA
Summary • Historical typhoon tracks over the WNP were collected from Philippine Weather Bureau, Central Meteorological Observatory of Japan, Hong Kong Observatory, and Shanghai Observatory from late 19th century. • Digital dataset of typhoon track locations are created. • Quality check of the typhoon definition and typhoon density were performed. • Counting typhoon numbers over the target area is possible from 1910. • Typhoon numbers have interdecadal variability over the target area of WNP. However, low latitude typhoons have decreasing trend during the past 100 years.