[A-CG42] 北極域の科学

[ACG42-P13] 主要な大陸河川を通した北極海へ流入するエネルギーフラックスの2018-2023年の季節・経年変動

*堀 雅裕¹ (1.富山大学都市デザイン学部)

キーワード：河川水温、河川流量、北極、SGLI、リモートセンシング

The continental Arctic rivers play an important role in transporting fresh water, chemicals, and heat to the Arctic Ocean. Nevertheless, the number of ground stations measuring discharge and temperature has been decreasing since the 20 Century. Recently, satellite observations enabled us to monitor river surface temperature and channel width from space on a daily basis (Hori, 2021). In this study, the satellite-derived river surface temperature and in-situ measured water discharge obtained from the ArcticGRO (McClelland et al., 2024) were used to estimate energy fluxes during open water season (OWS, from April 1^st to November 30^th) into the Arctic Ocean through the river mouths for the seven Arctic rivers of Pechora, Ob, Yenisei, Lena, Kolyma, Yukon, and Mackenzie during the period from 2018 to 2023. On a six-year average, the Lena river had the largest energy flux with 20120 PJ/OWS, followed by Yenisei (15200 PJ/OWS), Ob (14280 PJ/OWS), Mackenzie (9170 PJ/OWS), Yukon (6900 PJ/OWS) , Kolyma (3450 PJ/OWS) , Pechora (2700 PJ/OWS). By month, the Ob and Mackenzie rivers had their highest energy fluxes in July, while the other rivers had their highest energy fluxes in June. During the six years, however, the month of maximum energy fluxes has shifted. For example, the energy fluxes of the Lena river in July gradually became larger and comparable to the energy fluxes in June. Similar or opposite phenomena have occurred in other rivers, suggesting that a seasonal shift in the amount of energy fluxes entering the Arctic Ocean may have occurred in recent years.

Reference:
Hori, M., 2021: Near-daily monitoring of surface temperature and channel width of the six largest Arctic rivers from space using GCOM-C/SGLI. Remote Sens. Environ., 263, 112538.
McClelland, J.W., S.E. Tank, R.G.M. Spencer, A.I. Shiklomanov, S. Zolkos, and R.M. Holmes. 2024: Arctic Great Rivers Observatory. Discharge Dataset, Version 20240125.