Comparison of winter daily weather patterns in Japan reconstructed from old diaries and 20th century reanalysis data during the 19th century

Abstract:

Historical daily weather records in old diaries are useful proxy data for reconstructing daily synoptic weather patterns for the pre-instrumental period (before 1872) in Japan. On the other hand, development of global atmospheric reanalysis data back to the early 19th century has been progressed in recent years. We compared winter daily weather patterns reconstructed from Historical Weather Data Base (Yoshimura,2013) in Japan and circulation field represented in 20th century reanalysis data ver.3(Slivinski et al.,2019).On the basis of Historical Weather Data Base, we defined “winter monsoon type weather day (WM-day)” by focusing on weather contrasts between Sea of Japan and Pacific Ocean side of Japanese Islands for the period from 1836 to 1868. Then, we made composite analysis of daily mean sea level pressure (SLP) field and 500hPa level field using 20th century reanalysis data ver3. As a result, we confirmed strengthening of winter monsoon circulation and development of mid-tropospheric trough over East Asia for WM-day. Although, few surface pressure data in East Asia were assimilated in the 19th century, our results suggested that wintertime circulation fields around Japan were reasonably represented by reanalysis data.

References

Yoshimura M., (2013) Making the database of weather record in old diaries and its significance. The Historical Geography (Rekishi-Chirigaku), 55-5: 39-47.

Slivinski L.C. et al., (2019) Towards a more reliable historical reanalysis: Improvements for version 3 of the Twentieth Century Reanalysis system. Q J RMeteorol Soc.145:2876–2908. https://doi.org/10.1002/qj.3598