Effects of snow, snowmelting and refreezing processes on air–sea-ice CO2 flux

Nomura, Daïki; Yoshikawa-Inoue, Hisayuki; Toyota, Takenobu; Shirasawa, Kunio

doi:10.3189/002214310791968548

Cited by 59 publications

(92 citation statements)

References 36 publications

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“…On the contrary, decreasing z BL to 0.1 mm or less does not efficiently increase simulated CO 2 fluxes because of the rapid exhaustion of near-surface DIC by more intense ice-atmosphere fluxes (see section 4.3, for more explanations on the limitation of CO 2 fluxes by DIC stocks). [Delille et al, 2007;Geilfus et al, 2013Geilfus et al, , 2014Nomura et al, 2010aNomura et al, , 2013Nomura et al, , 2010b. The simulated CO 2 fluxes during INTERICE 4 are also lower than observations.…”

Section: Model Calibrationmentioning

confidence: 83%

Drivers of inorganic carbon dynamics in first‐year sea ice: A model study

et al. 2015

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Sea ice is an active source or a sink for carbon dioxide (CO 2 ), although to what extent is notclear. Here, we analyze CO 2 dynamics within sea ice using a one-dimensional halothermodynamic sea ice model including gas physics and carbon biogeochemistry. The ice-ocean fluxes, and vertical transport, of total dissolved inorganic carbon (DIC) and total alkalinity (TA) are represented using fluid transport equations. Carbonate chemistry, the consumption, and release of CO 2 by primary production and respiration, the precipitation and dissolution of ikaite (CaCO 3 Á6H 2 O) and ice-air CO 2 fluxes, are also included. The model is evaluated using observations from a 6 month field study at Point Barrow, Alaska, and an ice-tank experiment. At Barrow, results show that the DIC budget is mainly driven by physical processes, wheras brine-air CO 2 fluxes, ikaite formation, and net primary production, are secondary factors. In terms of ice-atmosphere CO 2 exchanges, sea ice is a net CO 2 source and sink in winter and summer, respectively. The formulation of the ice-atmosphere CO 2 flux impacts the simulated near-surface CO 2 partial pressure (pCO 2 ), but not the DIC budget. Because the simulated ice-atmosphere CO 2 fluxes are limited by DIC stocks, and therefore <2 mmol m 22 d 21 , we argue that the observed much larger CO 2 fluxes from eddy covariance retrievals cannot be explained by a sea ice direct source and must involve other processes or other sources of CO 2 . Finally, the simulations suggest that near-surface TA/DIC ratios of $2, sometimes used as an indicator of calcification, would rather suggest outgassing.

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Section: Model Calibrationmentioning

confidence: 83%

Drivers of inorganic carbon dynamics in first‐year sea ice: A model study

et al. 2015

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“…Although our estimate treated sea ice as impermeable to CO 2 exchange, recent studies have proposed that CO 2 exchange occurs through sea ice (Semiletov et al, 2004;Delille, 2006;Nomura et al, 2006Nomura et al, , 2010aNomura et al, , b, 2013aZemmelink et al, 2006;Loose et al, 2009;Miller et al, 2011;Geilfus et al, 2012). Early during the period of ice growth, pCO 2 of brine in sea ice attains supersaturation with respect to the atmosphere with decreasing temperature and increasing salinity (e.g., Papadimitriou et al, 2003).…”

Section: Discussionmentioning

confidence: 99%

Winter-to-summer evolution of pCO2 in surface water and air–sea CO2 flux in the seasonal ice zone of the Southern Ocean

et al. 2014

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Abstract. Partial pressure of CO 2 (pCO 2 ) in surface water and vertical profiles of the carbonate system parameters were measured during austral summer in the Indian sector of the Southern Ocean (64-67 • S, 32-58 • E) in January 2006 to understand the CO 2 dynamics of seawater in the seasonal ice zone. Surface-water pCO 2 ranged from 275 to 400 µatm, and longitudinal variations reflected the dominant influence of water temperature and dilution by sea ice meltwater between 32 and 40 • E and biological productivity between 40 and 58 • E. Using carbonate system data from the temperature minimum layer (−1.9 • C < T < −1.5 • C, 34.2 < S < 34.5), we examined the winter-to-summer evolution of surface-water pCO 2 and the factors affecting it. Our results indicate that pCO 2 increased by as much as 32 µatm, resulting mainly from the increase in water temperature. At the same time as changes in sea ice concentration and surface-water pCO 2 , the air-sea CO 2 flux, which consists of the exchange of CO 2 between sea ice and atmosphere, changed from −1.1 to +0.9 mmol C m −2 day −1 between winter and summer. These results suggest that, for the atmosphere, the seasonal ice zone acts as a CO 2 sink in winter and a temporary CO 2 source in summer immediately after the retreat of sea ice. Subsequent biological productivity likely decreases surface-water pCO 2 and the air-sea CO 2 flux becomes negative, such that in summer the study area is again a CO 2 sink with respect to the atmosphere.

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“…(2) As noted in the field, the site was characterized by high levels of moisture above the snowice interface. Such conditions might lead to the formation of superimposed ice within the snow, which has been found to inhibit gas exchanges (Nomura et al, 2010). This might explain the limited gas exchanges observed during the coldest part of the day (02:00-06:00 UTC).…”

Section: Site Energy Fluxesmentioning

confidence: 97%

Winter observations of CO2 exchange between sea ice and the atmosphere in a coastal fjord environment

et al. 2015

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Abstract. Eddy covariance observations of CO 2 fluxes were conducted during March-April 2012 in a temporally sequential order for 8, 4 and 30 days, respectively, at three locations on fast sea ice and on newly formed polynya ice in a coastal fjord environment in northeast Greenland. CO 2 fluxes at the sites characterized by fast sea ice (ICEI and DNB) were found to increasingly reflect periods of strong outgassing in accordance with the progression of springtime warming and the occurrence of strong wind events: F ICE1 CO 2 = 1.73 ± 5 mmol m −2 day −1 and F DNB CO 2 = 8.64 ± 39.64 mmol m −2 day −1 , while CO 2 fluxes at the polynya site (POLYI) were found to generally reflect uptake F POLY1 CO 2 = −9.97 ± 19.8 mmol m −2 day −1 . Values given are the mean and standard deviation, and negative/positive values indicate uptake/outgassing, respectively. A diurnal correlation analysis supports a significant connection between site energetics and CO 2 fluxes linked to a number of possible thermally driven processes, which are thought to change the pCO 2 gradient at the snow-ice interface. The relative influence of these processes on atmospheric exchanges likely depends on the thickness of the ice. Specifically, the study indicates a predominant influence of brine volume expansion/contraction, brine dissolution/concentration and calcium carbonate formation/dissolution at sites characterized by a thick sea-ice cover, such that surface warming leads to an uptake of CO 2 and vice versa, while convective overturning within the sea-ice brines dominate at sites characterized by comparatively thin sea-ice cover, such that nighttime surface cooling leads to an uptake of CO 2 to the extent permitted by simultaneous formation of superimposed ice in the lower snow column.

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Effects of snow, snowmelting and refreezing processes on air–sea-ice CO₂ flux

Cited by 59 publications

References 36 publications

Drivers of inorganic carbon dynamics in first‐year sea ice: A model study

Drivers of inorganic carbon dynamics in first‐year sea ice: A model study

Winter-to-summer evolution of <i>p</i>CO<sub>2</sub> in surface water and air–sea CO<sub>2</sub> flux in the seasonal ice zone of the Southern Ocean

Winter observations of CO<sub>2</sub> exchange between sea ice and the atmosphere in a coastal fjord environment

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Effects of snow, snowmelting and refreezing processes on air–sea-ice CO2 flux

Cited by 59 publications

References 36 publications

Drivers of inorganic carbon dynamics in first‐year sea ice: A model study

Drivers of inorganic carbon dynamics in first‐year sea ice: A model study

Winter-to-summer evolution of &lt;i&gt;p&lt;/i&gt;CO&lt;sub&gt;2&lt;/sub&gt; in surface water and air–sea CO&lt;sub&gt;2&lt;/sub&gt; flux in the seasonal ice zone of the Southern Ocean

Winter observations of CO&lt;sub&gt;2&lt;/sub&gt; exchange between sea ice and the atmosphere in a coastal fjord environment

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Effects of snow, snowmelting and refreezing processes on air–sea-ice CO₂ flux

Winter-to-summer evolution of <i>p</i>CO<sub>2</sub> in surface water and air–sea CO<sub>2</sub> flux in the seasonal ice zone of the Southern Ocean

Winter observations of CO<sub>2</sub> exchange between sea ice and the atmosphere in a coastal fjord environment