Japanese early modern documentary based climate reconstruction

1. Japanese early modern documentarybased climate reconstruction Junpei Hirano(NIED), Masumi Zaiki(Seikei Univ), Takehiko Mikami(Teikyo Univ)

2. Background of documentary-based climate reconstruction in Japan • ・Knowledge of centennial-scale climate variations is essential • to evaluate potential impact of climate variations on human • history and environmental changes. • ・“Poor coverage of instrumental data outside Europe in the • 18th and early 19th centuries(Lamb,1995)”prevent us to • understand accurate picture of centennial-scale variations. • ・ Foundation of Japan Met Agency (JMA) in 1875. • Pre-1875: No meteorological data are available except for • some early instrumental records (Zaiki et al.,2006).

3. Background of documentary-based climate reconstruction in Japan(Continued) • JMA period • Pre-JMA period • Pre 1900 availability of meteorological data • in Japan ( by Zaiki et al., 2006)

4. Background of documentary-based climate reconstruction in Japan (continued) • Large number of daily weather documents in old diaries • during the 18th and the 19th centuries are available. • Documents have been used as useful proxy for • reconstructing centennial-scale climate variations. ✔Summer/winter temperature (Mizukoshi,1993； Mikami,1996; Hirano et al., 2012) ✔Typhoon frequency (Mizukoshi,1993；Grosman and Zaiki,2011) ✔Rainfall in Baiu season （Mizukoshi,1993 ； Murata,1988) • Date • Weather

5. Summer temperature reconstruction based on historical weather documents • ☑July temperature in Tokyois negatively correlated • with number of rainy days. • July mean temperature • Number of rainy days • Relationship between number of rainy days in July and • July mean temperature in Tokyo (Mikami,1996)

6. Summer temperature reconstruction based on historical weather documents (continued) • Reconstructed July mean temperature in Tokyo • for 1721-2010(after Mikami,1996)

7. Winter temperature reconstruction based on historical weather documents • ● • ☑Snowfall rate (number of snowfall /number of • precipitation ) in Yagamata is negatively correlated • with winter mean temperature (Hirano et al.,2012).

8. Winter temperature reconstruction based on historical weather documents (continued) • ☑Cold winters frequently appeared • during the early 19th century (Hirano et al.,2012)

9. Variation in summertime rainfall frequency in central Japan from 1700 to 1890 • Wet • Wet • Wet • Wet • ☑Wet period in the early 18th and the mid-19th centuries were detected in central Japan.

10. Comparison of summertime rainfall frequency with tree-ring based reconstruction. • Tree-ring data • Wet • Wet • Number of rainy days • ☑Wetsummer in the 18th and the mid 19th centuries • was detected from both documentary recordsand tree-ring data.

11. Historical Weather Database(HWDB). • ✓ Study group of historical climatologists have created • Historical Weather Database(HWDB). • ✓ Monthly based data are available on the • NOAA's National Climatic Data Center (NCDC) website. • https://www.ncdc.noaa.gov/paleo/study/5412

12. Historical Weather Database(HWDB) (Continued) • ✓Daily weather description in each diary was • categorizedinto 13 categories. • T1: Fine T2: Partly Cloudy T3: Cloudy T4: Shower • T5: Thunderstorm T6: Heavy Thunderstorm T7: Little Rain • T8: Rain T9: Heavy Rain TA: Hail, etc TB: Snow Shower • TC: Little Snow TD: Snow • ✓The database contains number of days for each • 13 weather typeper month. • Contents of database YEAR MN LOCATION T1 T2 T3 T4 T5 T6 T7 T8 T9 TA TB TC TD Z S4 1715 01 IKEDA 17 0 0 0 0 0 1 10 0 0 0 0 3 0 31 1716 01 IKEDA 28 0 0 0 0 0 1 2 0 0 0 0 0 0 31 1717 01 IKEDA 25 0 0 1 0 0 0 2 0 1 0 2 0 0 31 1718 01 IKEDA 21 0 1 0 0 0 2 6 0 0 0 0 1 0 31

13. Future issues • ✓ Mostof the documentary-based climate reconstruction • in Japan have been focused on climate variation within Japan. • ✓Furtherefforts are necessary to compare reconstructed • results in Japan those with the other East Asian region. • ✔These efforts could lead us to better understanding of • centennialscale climate variations over East Asia.