[A-CG43] 北極域の科学

[ACG43-P08] 地球温暖化に対して複雑な応答を示す北半球の積雪域分布

*堀 雅裕¹、庭野 匡思^2,3、青木 輝夫^3,2、島田 利元^4,2 (1.富山大学都市デザイン学部、2.気象庁気象研究所、3.極地研究所、4.宇宙航空研究開発機構地球観測研究センター)

キーワード：積雪域、衛星光学センサ、リモートセンシング 、気候、北半球

The extent of snow cover is a key variable to be observed from space for assessing the impacts of global warming on the Earth’s climate. Satellite-derived snow cover extent (SCE) in the Northern Hemisphere (NH) exhibits decreasing trends in all seasons during the past nearly 40 years (1982-2020) (Hori et al., 2017). However, when looking into regional and seasonal trends in SCE, the signals exhibit more complicated behavior. In this study, we examine the long-term trends of NH SCE by analyzing the following three temporal metrics; 1) annual snow cover duration (SCD), 2) snow disappearance date in spring (SDD), and 3) snow appearance date in autumn (SAD) for three temporal periods of 1982-2020 (P-I: 37 years), 1982-2000 (P-II: 17 years), and 2001-2020 (P-III: 20 years). Analysis results indicate that SCD trends always exhibit shortening signals in Europe, southern Siberia, Alaska, northwestern Canada, and southern part of the United States of America (USA) in all temporal periods (P-I, P-II, and P-II). On the other hand, SCD trends in central and some parts of eastern Asia, Tibetan Plateau, northern part of the USA, northern and eastern part of Canada, and Scandinavia exhibit different signals, that is, shortening in P-II and lengthening in P-III. The lengthening of SCD trends in P-III resulted both from the delay of SDD in spring and earlier SAD in autumn in most of the regions. Therefore, the response of snow cover in NH to the global warming seems to be polarized in recent 20 years.