Graphical Abstract

Shibata, K., and A. Sai, 2021: Long-term trends and variations in surface humidity and temperature in the Japanese archipelago over 100 years from 1880s. J. Meteor. Soc. Japan, 99,
https://doi.org/10.2151/jmsj.2021-019
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Plain Language Summary: The surface observation data in Japan, beginning around the 1880s, are analyzed focusing on the long–term trends and variations in humidity and temperature. It is found that the annual–mean temperature trend exhibits statistically significant warming of 1.0°C–2.5°C century¬1, while the annual–mean relative humidity shows significantly decreasing trend of −2% to −12% century-1. On the other hand, the annual–mean mixing ratio trend displays a different spatial distribution compared to the temperature or relative humidity trend. In this study, three types of trends exist: significantly positive and negative values, and virtually zero. Significantly negative trends of about −0.2 to −0.3 g kg−1 century−1 are located approximately in the Pacific side of Honshu from the middle Tohoku through Shikoku to the eastern Kyushu. Significantly positive trends of about 0.2 to 0.4 g kg−1 century−1 are observed over Hokkaido, the western Japan along Sea of Japan, the western Kyushu, and the remote islands including Okinawa.

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