scholarly journals Response of the sea‐ice diatom Fragilariopsis cylindrus to simulated polar night darkness and return to light

2019 ◽  
Vol 65 (5) ◽  
pp. 1041-1060 ◽  
Author(s):  
Philippe‐Israël Morin ◽  
Thomas Lacour ◽  
Pierre‐Luc Grondin ◽  
Flavienne Bruyant ◽  
Joannie Ferland ◽  
...  
Keyword(s):  
Sea Ice ◽  
Polar Night ◽  
Fragilariopsis Cylindrus

scholarly journals Dark metabolism: a molecular insight into how the Antarctic sea‐ice diatom Fragilariopsis cylindrus survives long‐term darkness

2019 ◽  
Vol 223 (2) ◽  
pp. 675-691 ◽  
Author(s):  
Fraser Kennedy ◽  
Andrew Martin ◽  
John P. Bowman ◽  
Richard Wilson ◽  
Andrew McMinn
Keyword(s):  
Sea Ice ◽  
Antarctic Sea Ice ◽  
Fragilariopsis Cylindrus ◽  
Dark Metabolism ◽  
The Antarctic ◽  
Insight Into

scholarly journals Identifying metabolic pathways for production of extracellular polymeric substances by the diatom Fragilariopsis cylindrus inhabiting sea ice

2018 ◽  
Vol 12 (5) ◽  
pp. 1237-1251 ◽  
Author(s):  
Shazia N. Aslam ◽  
Jan Strauss ◽  
David N. Thomas ◽  
Thomas Mock ◽  
Graham J. C. Underwood
Keyword(s):  
Sea Ice ◽  
Metabolic Pathways ◽  
Extracellular Polymeric Substances ◽  
Fragilariopsis Cylindrus

scholarly journals An assessment of diatom assemblages in the Sea of Okhotsk as a proxy for sea-ice cover

2020 ◽  
Vol 39 (1) ◽  
pp. 77-92
Author(s):  
Hiroki Nakamura ◽  
Yusuke Okazaki ◽  
Susumu Konno ◽  
Takeshi Nakatsuka
Keyword(s):  
Sea Ice ◽  
Surface Sediment ◽  
Sea Of Okhotsk ◽  
Spring Bloom ◽  
Diatom Species ◽  
Diatom Assemblages ◽  
Sea Ice Extent ◽  
Sinking Particles ◽  
Resting Spores ◽  
Fragilariopsis Cylindrus

Abstract. Knowledge of past variations in sea-ice extent is crucial for understanding the relationship between climate change and changes in sea ice. Diatom assemblages could be applied as a proxy for paleo-sea-ice extent; this requires accurate information on the modern species that are indicative of sea ice. Scanning electron microscope observations were performed on modern diatom assemblages in sea ice, sinking particles, and surface sediments in the Sea of Okhotsk. A sea-ice sample was collected in the southwestern Sea of Okhotsk near Hokkaido island in February 2013. Fragilariopsis cylindrus was the dominant diatom species in the sea-ice sample, accounting for 87 % of the total diatom assemblage. Time-series sediment traps were deployed during 1998–2000 at two stations, M4 and M6, off Sakhalin island. Total diatom fluxes ranged from 105 to 108 valves m−2 d−1 with noticeable seasonality. During the sea-ice covering period, the total diatom flux decreased by 1 or 2 orders of magnitude. The highest diatom fluxes were observed in spring and summer. The diatom species composition in sinking particles also showed pronounced seasonal changes. During summer and fall, the Shionodiscus trifultus group and Neodenticula seminae were the major diatom taxa. During the sea-ice covering period, Fragilariopsis cylindrus and Bacterosira bathyomphala resting spores were abundant. Both the sea-ice-related species showed similar flux patterns except for the spring bloom after sea-ice retreat: F. cylindrus fluxes exhibited pronounced spring bloom peaks of 108 valves m−2 d−1; in contrast, the fluxes of Bacterosira bathyomphala resting spores during the spring bloom were 1 order of magnitude lower than those of F. cylindrus. Surface-sediment core XP98-MC4 was obtained near station M6 sediment-trap site off Sakhalin island. The relative abundance of Fragilariopsis cylindrus in the surface-sediment diatom assemblage was only 6.4 %, markedly lower than that in the sediment-trap samples (43.4 %). In the surface sediment, the relative abundances of diatom taxa with heavily silicified valves such as B. bathyomphala resting spores, Shionodiscus variantius, and Thalassionema nitzschioides were greater than their relative abundances in sinking particles.

Photosynthetic carbon allocation of an Antarctic sea ice diatom (Fragilariopsis cylindrus)

2013 ◽  
Vol 446 ◽  
pp. 228-235 ◽  
Author(s):  
Sarah C. Ugalde ◽  
Klaus M. Meiners ◽  
Andrew T. Davidson ◽  
Karen J. Westwood ◽  
Andrew McMinn
Keyword(s):  
Sea Ice ◽  
Carbon Allocation ◽  
Antarctic Sea Ice ◽  
Photosynthetic Carbon ◽  
Fragilariopsis Cylindrus

scholarly journals Effect of Wind Speed and Leads on Clear-Sky Cooling over Arctic Sea Ice during Polar Night

2019 ◽  
Vol 76 (8) ◽  
pp. 2481-2503 ◽  
Author(s):  
Dmitry G. Chechin ◽  
Irina A. Makhotina ◽  
Christof Lüpkes ◽  
Alexander P. Makshtas
Keyword(s):  
Wind Speed ◽  
Sea Ice ◽  
Threshold Value ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Strong Impact ◽  
Polar Night ◽  
Sea Ice Concentration ◽  
Clear Sky ◽  
Ice Concentration

Abstract A simple analytical model of the atmospheric boundary layer (ABL) coupled to sea ice is presented. It describes clear-sky cooling over sea ice during polar night in the presence of leads. The model solutions show that the sea ice concentration and wind speed have a strong impact on the thermal regime over sea ice. Leads cause both a warming of the ABL and an increase of stability over sea ice. The model describes a sharp ABL transition from a weakly stable coupled state to a strongly stable decoupled state when wind speed is decreasing. The threshold value of the transition wind speed is a function of sea ice concentration. The decoupled state is characterized by a large air–surface temperature difference over sea ice, which is further increased by leads. In the coupled regime, air and surface temperatures increase almost linearly with wind speed due to warming by leads and also slower cooling of the ABL. The cooling time scale shows a nonmonotonic dependency on wind speed, being lowest for the threshold value of wind speed and increasing for weak and strong winds. Theoretical solutions agree well with results of a more realistic single-column model and with observations performed at the three Russian “North Pole” drifting stations (NP-35, -37, and -39) and at the Surface Heat Budget of the Arctic Ocean ice camp. Both modeling results and observations show a strong implicit dependency of the net longwave radiative flux at the surface on wind speed.

scholarly journals Parameter Identification for Salinity in a Quasilinear Thermodynamic System of Sea Ice

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Wei Lv ◽  
Xiaojiao Li ◽  
Enmin Feng
Keyword(s):  
Sea Ice ◽  
Parameter Identification ◽  
Optimal Solution ◽  
Thermodynamic System ◽  
Polar Night ◽  
Night Time ◽  
Zhongshan Station ◽  
Estimated Parameters ◽  
Salinity Data ◽  
Antarctic Research

This study is intended to provide a parameter identification method to determine salinity of sea ice by temperature and salinity observations. A quasilinear thermodynamic system of sea ice with unknown salinity is described and its property is proved. Then, a parameter identification model is established and the existence of its optimal solution is discussed. The salinity profile is calculated by the temperature and salinity data, which were measured at Nella Fjord around Zhongshan Station, Antarctica, during the polar night time by the 22nd Chinese Antarctic Research Expedition. Another simulation for temperature profiles during different measurement periods is operated. Results show that better simulations of the salinity and temperature distribution are possible with the estimated parameters than Eicken’s (Eicken 1992) and THESCI’s (Lv et al. 2009). This method will help people understand the salinity evolution of sea ice more thoroughly.

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