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Sedimentological survey by the icebreaker Shirase during JARE-61
Full text link第61次日本南極地域観測隊（JARE-61）では，南極観測船「しらせ」（AGB-5003）による初の本格的な採泥観測が行われた．堆積物試料は，大口径グラビティーコアラー及びGSJ型木下式グラブ採泥器を用い，トッテン氷河前縁～ダルトン・ポリニア海域，リュツォ・ホルム湾，ケープダンレー・ポリニアの3海域の計28地点において採取された．本論では，今後の調査の参考としてオペレーションの詳細を記録するとともに，これらの試料を用いた今後の分析の基礎情報として，得られた堆積物の予察観察結果を報告する．The first systematic sediment survey by the icebreaker Shirase (AGB-5003) was conducted during the 61st Japanese Antarctic Research Expedition (JARE-61). Sediment samples were obtained from a total of 28 sites in 3 areas of the Totten Glacier front–Dalton polynya, Lützow-Holm Bay and Cape Darnley polynya using a large-bore gravity corer and GSJ-type K-grab sampler. In this paper, details of the survey operation are described as a reference for the future experience. In addition, preliminary results of the obtained sediments are reported as a fundamental information for future analysis using these samples.departmental bulletin pape
Biophysical effects of an old tundra fire in the Brooks Range Foothills of Northern Alaska, U.S.A
No full textOur understanding of tundra fire effects in Northern Alaska is limited because fires have been relatively rare. We sampled a 70+ year-old burn visible in a 1948 aerial photograph for vegetation composition and structure, soil attributes, terrain rugosity, and thermokarst pit density. Between 1948 and 2017 the burn initially became wetter as ice wedges melted but then drained and dried as the troughs became hydrologically connected. The reference tundra has become wetter over the last few decades and appears to be lagging through a similar sequence. The burn averaged 2.5 °C warmer than the reference tundra at 30 cm depth. Thinning of organic soil following fire appears to dramatically accelerate the background degradation of ground-ice features in response to climate change and promotes a plant community that is distinct in terms of taxa and structure, dominated by tall willows and other competitive, rather than cold-tolerant, species. The cover of sedges and mosses is low while that of willows and grass is high relative to the reference tundra. The changes in plant community composition and structure, increasing ground temperature, and thermokarst lead us to expect the observed biophysical changes to the tundra will persist centuries into the future.journal articl
Can dwarf birch (Betula nana) growth rings be used as indicators of permafrost degradation?
No full textAccelerating Arctic permafrost thaw results in increasing methane emissions affecting regional and global climates, but the rate of permafrost disappearance can be difficult to estimate with remote sensing, field surveys and modelling. Here we investigate if the annual growth rings of the shrub Betula nana (dwarf birch) may be used to detect and monitor near-surface permafrost degradation. Whole B. nana samples were collected at Latnjajávri and Corrvosjávri, northernmost Sweden, and their annual growth rings were analysed regarding their potential as permafrost indicators. Permafrost disappeared in Latnjajávri between 1993 and 2001, whereas Corrvosjávri lost its frozen ground decades earlier. Annual growth rings from more than twenty B. nana shrubs at each site were measured and crossdated by serial sectioning, and then averaged into two separate shrub-ring chronologies. Growth rates were higher at Corrvosjávri than at Latnjajávri. Analysing the 1972–2015 period disclosed a stronger climate-growth relationship at Corrvosjávri, with significant correlations with summer temperatures. In Latnjajávri the association with climate was much weaker before the permafrost disappeared, but afterwards reached similar levels as at Corrvosjávri. Our results suggest that changes in the B. nana growth-climate relationship may be used to indicate permafrost degradation. Moreover, the strong correlation between summer temperature and shrub growth after disappearance of permafrost supports previous research that B. nana ring widths are useful climate proxies.journal articl
Alkaline-rich accessory minerals in Ryugu grain and Orgueil CI chondrite
Full text linkThe 15th Symposium on Polar Science/Ordinary sessions [OA] Antarctic Meteorite, Thu. 5 Dec. / 3F Conference room, The Institute of Statistical Mathematicsconference outpu
Preliminary curation process for micrometeorites collected at Tottuki ice field, Antarctica
Full text linkThe 15th Symposium on Polar Science/Ordinary sessions [OA] Antarctic Meteorite, Thu. 5 Dec. / Entrance Hall (1st floor), National Institute of Polar Researchconference outpu
The Principles of the ISC Data Collection, Management, Protection, and Distribution
Full text linkThe 15th Symposium on Polar Science/Interdisciplinary sessions [ID] Polar data science, Thu. 5 Dec. / 3F Conference room, National Institute of Polar Researchconference outpu
Design of Antarctic Penetrator Network Observations Based on Icequake Analysis and Its Application to Planetary Seismic Observations
Full text linkThe 15th Symposium on Polar Science/Interdisciplinary sessions [ID] Polar data science, Thu. 5 Dec. / 3F Conference room, National Institute of Polar Researchconference outpu
Introduction of a New Project for Terrestrial Biological Observations Conducted from JARE 67 to JARE 69
Full text linkThe 15th Symposium on Polar Science/Ordinary sessions [OB] Polar biology, Wed. 4 Dec. / 3F Conference room, The Institute of Statistical Mathematicsconference outpu
Survival strategies of algae in the first-year ice of Saroma Ko Lagoon, Hokkaido, Japan: species distribution, shape change, and photosynthetic activity
Full text linkThe 15th Symposium on Polar Science/Ordinary sessions [OB] Polar biology, Wed. 4 Dec. / Entrance Hall (1st floor), National Institute of Polar Researchconference outpu
An M5.5 earthquake on a lamprophyre dyke crosscutting West Rand Group (3.5-7 km depth range) in Witwatersrand Supergroup (2.97-2.80 Ga)
Full text linkThe 15th Symposium on Polar Science/Ordinary sessions [OG] Polar geosciences, Wed. 4 Dec. / 3F Conference room, National Institute of Polar Researchconference outpu