Data rescue of historical typhoon tracks over the western north Pacific back to late 19 th 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 by NCAR Available global typhoon database

Seasonality of typhoon track Visher 1922 MWR Major four typhoon track dataset were used (Philippines, Japan, Hong Kong, and Zi-ka-Wei)

“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 : 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. Kumi Kataoka (Shumei Univ., Japan) Mr. Edwin W. L. Ginn (Hong Kong Observatory) Dr. Zhao Bingke (Shanghai Typhoon Institute)

Monthly Bulletins of Philippines Weather Bureau ( ) stored in Hamilton Library at University of Hawaii ( 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 Philippines (Univ. Hawaii) Japan (JMA library) Hong Kong (Hong Kong Observatory) （ 1958 reedited ） Shanghai(Zi-Ka-Wei) (Shanghai observatory) （ 1957 reedited ）

Philippine Weather Bureau Central Meteorological Observatory Tokyo Japan and Taiwan Hong Kong Observatory Zi-Ka-Wei (Shanghai) Observatory period Aug coverageWNP WNP up to 30NWNP typhoon definition less than 750mmHg (1000hPa) N/A more than 64kt and others N/A data Typhoon locations and date Typhoon locations and date, (some) center pressure Typhoon locations and date interval daily (some 6 hourly) 6 hourly interpolated daily reference Monthly Bulletins of Philippine Weather Bureau Geophysical Review , Wadachi 1952: Typhoon tracks , Xu, H. et al. 1973: 80 years typhoon track Chin, P. C., 1958: Tropical cyclones in the Western Pacific and China Sea area from 1884 to 1953 Gao 1957: Typhoon tracks and statistical analysis Historical typhoon track data over western north Pacific

Digital Tropical Cyclone tracks over the Western North Pacific from 1902 to 1940 Data source Monthly Bulletins of the Philippine Weather Bureau Datasets TC (tropical cyclone) track locations Data files TYByyyymmdd.a.dat (for example: TYB a.dat) yyyymmdd: It is the first date of each TC track. Data format YYYYMMDDHH lat lon type flag HH: Philippine local time (+8 hours GMT) This data is available at adai/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.

when TS passed over Philippines Max wind speed >35kt (JTWC TS best track data) (JMA best track data used for comparison) when TS passed over Philippines ps <1000hPa observed at station using Monthly Bulletins of Philippines Weather Bureau Comparison between two definitions Typhoon landfall from by “Tropical Cyclones Summaries from 1948 to 1978” by Bonjoc (1978) Max wind speed >35kt TS 124(JTWC), 124(JMA) Ps<1000 hPa (difference 13.7%, 15.3%) To check the reliability of the historical datasets Typhoon definition compared by landfall numbers in the Philippines Kubota and Chan 2009

Satisfied tracks Failed tracks JTWC Remove extra tropical cyclones

Ensembles of multi typhoon track datasets Hong Kong Philippines Japan Shanghai

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) ▼ : typhoon by Philippines dataset ▼ : typhoon by Hong Kong dataset ▼ : typhoon by Japan dataset ▲ :typhoon landed Philippines Count enough numbers of typhoons throughout the year near Philippines from 1908 Quality check of the density of typhoon numbers over the WNP

Density of historical typhoon numbers over the target area Until 1909 not satisfied 1910 Combination of 3 typhoon track dataset Philippine Weather Bureau 1940 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 20 th century Japan Taiwan Philippines South Seas Bureau & WNP islands Hong Kong

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 19 th 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 Typhoon numbers have interdecadal variability over the target area of WNP. However, low latitude typhoons have decreasing trend during the past 100 years.