Hydroclimatic Controls on the Isotopic (δ18 O, δ2 H, d-excess) Traits of Pan-Arctic Summer Rainfall Events

• Main Authors: Klein Eric S., Zarov Evgeny, Jones Samantha, Kroon Aart, Bailey Hannah, Bret-Harte M. Syndonia, Raundrup Katrine, Chupakov Artem V., Nielsen Martin, Olsen Maia, Gribanov Konstantin, Kirpotin Sergey N., Welker Jeffrey M., Pokrovsky Oleg S., Hyöky Valtteri, Divine Dmitry V., Mustonen Kaisa-Riikka, Markussen Helge Tore, Marttila Hannu, Suominen Otso, Filippov Ilya, Syvänperä Ilkka, Prokushkin Anatoly, Paavola Riku, Mellat Moein, Else Brent, Vignisson Sölvi Rúnar, Rasch Morten
• Other Authors: ympäristömuutokset, Ympäristömuutokset, 2606018
• Language: English
• Published: FRONTIERS MEDIA SA 2022
• Subjects: Arctic; Greenland; Iceland; Sea ice; Subarctic; Tundra; Alaska
• Online Access: https://www.utupub.fi/handle/10024/169207; https://www.frontiersin.org/articles/10.3389/feart.2021.651731/full

Arctic sea-ice loss is emblematic of an amplified Arctic water cycle and has critical feedback implications for global climate. Stable isotopes (delta O-18, delta H-2, d-excess) are valuable tracers for constraining water cycle and climate processes through space and time. Yet, the paucity of well-resolved Arctic isotope data preclude an empirically derived understanding of the hydrologic changes occurring today, in the deep (geologic) past, and in the future. To address this knowledge gap, the Pan-Arctic Precipitation Isotope Network (PAPIN) was established in 2018 to coordinate precipitation sampling at 19 stations across key tundra, subarctic, maritime, and continental climate zones. Here, we present a first assessment of rainfall samples collected in summer 2018 (n = 281) and combine new isotope and meteorological data with sea ice observations, reanalysis data, and model simulations. Data collectively establish a summer Arctic Meteoric Water Line where delta H-2 = 7.6.delta O-18-1.8 (r(2) = 0.96, p < 0.01). Mean amount-weighted delta O-18, delta H-2, and d-excess values were -12.3, -93.5, and 4.9 parts per thousand, respectively, with the lowest summer mean delta O-18 value observed in northwest Greenland (-19.9 parts per thousand) and the highest in Iceland (-7.3 parts per thousand). Southern Alaska recorded the lowest mean d-excess (-8.2%) and northern Russia the highest (9.9 parts per thousand). We identify a range of delta O-18-temperature coefficients from 0.31 parts per thousand/degrees C (Alaska) to 0.93 parts per thousand/degrees C (Russia). The steepest regression slopes (>0.75 parts per thousand/degrees C) were observed at continental sites, while statistically significant temperature relations were generally absent at coastal stations. Model outputs indicate that 68% of the summer precipitating air masses were transported into the Arctic from mid-latitudes and were characterized by relatively high delta O-18 values. Yet 32% of precipitation events, characterized by lower delta O-18 and high ...