Near-surface water vapor over polar sea ice is always near ice saturation

Abstract. We present a high-resolution record of properties in the subsurface (250–100 m), near surface (100–30 m) and surface (30–0 m) water masses at the SW Svalbard margin in relation to climate changes during the last 2000 years. The study is based on planktic foraminiferal proxies including the distribution patterns of planktic foraminiferal faunas, δ18O and δ13C values measured on Neogloboquadrina pachyderma, Turborotalita quinqueloba, and Globigerinita uvula, Mg / Ca-, δ18O- and transfer function-based sea surface temperatures, mean shell weights and other geochemical and sedimentological data. We compared paleo-data with modern planktic foraminiferal fauna distributions and the carbonate chemistry of the surface ocean. The results showed that cold sea surface conditions prevailed at ~ 400–800 AD and ~ 1400–1950 AD are associated with the local expression of the Dark Ages Cold Period and Little Ice Age, respectively. Warm sea surface conditions occurred at ~ 21–400 AD, ~ 800–1400 AD and from ~ 1950 AD until present and are linked to the second half of the Roman Warm Period, Medieval Warm Period and recent warming, respectively. On the centennial to multi-centennial time scale, sea surface conditions seem to be governed by the inflow of Atlantic water masses (subsurface and surface) and the presence of sea-ice and the variability of sea-ice margin (near surface water masses). However, the close correlation of sea surface temperature recorded by planktic foraminifera with total solar irradiance implies that solar activity could have exerted a dominant influence on the sea surface conditions on the decadal to multidecadal time scale.

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Impact of warming shelf waters on ice mélange and terminus retreat at a large SE Greenland glacier

The Cryosphere ◽

10.5194/tc-13-2303-2019 ◽

2019 ◽

Vol 13 (9) ◽

pp. 2303-2315 ◽

Cited By ~ 6

Author(s):

Suzanne L. Bevan ◽

Adrian J. Luckman ◽

Douglas I. Benn ◽

Tom Cowton ◽

Joe Todd

Keyword(s):

Surface Water ◽

Sea Ice ◽

Continental Shelf ◽

Deep Ocean ◽

Near Surface ◽

Surface Ocean ◽

The Past ◽

Tidewater Glacier ◽

Warm Surface Water ◽

Bed Slope

Abstract. By the end of 2018 Kangerlussuaq Glacier in southeast Greenland had retreated further inland than at any time in the past 80 years and its terminus was approaching a region of retrograde bed slope from where further rapid retreat would have been inevitable. Here we show that the retreat occurred because the glacier failed to advance during the winters of 2016/17 and 2017/18 owing to a weakened proglacial mélange. This mixture of sea ice and icebergs is normally rigid enough to inhibit calving in winter, but for 2 consecutive years it repeatedly collapsed, allowing Kangerlussuaq Glacier to continue to calve all year round. The mélange break-ups followed the establishment of anomalously warm surface water on the continental shelf during 2016, which likely penetrated the fjord. As calving continued uninterrupted from summer 2016 to the end of 2018 the glacier accelerated by 35 % and thinned by 35 m. These observations demonstrate the importance of near-surface ocean temperatures in tidewater glacier stability and show that it is not only deep-ocean warming that can lead to glacier retreat. During winter 2019 a persistent mélange reformed and the glacier readvanced by 3.5 km.

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Decadal variance of summer near-surface temperature maximum in Canada Basin of Arctic Ocean

10.5194/egusphere-egu2020-6853 ◽

2020 ◽

Author(s):

Long Lin ◽

Hailun He

Keyword(s):

Surface Water ◽

Sea Ice ◽

Surface Temperature ◽

Heat Content ◽

Canada Basin ◽

Previous Theory ◽

Sea Ice Extent ◽

Sea Ice Thickness ◽

Near Surface ◽

Warm Surface Water

In the summer Arctic, bump-like vertical temperature profiles of the upper layer in the Canada Basin suggest a near-surface temperature maximum (NSTM) beneath the mixed layer. This paper concentrates on describing the decadal variance of these NSTMs. Essentially, the temporal evolution of the summer NSTM revealed three decadal phases. The first period is before 2003, when the summer NSTM could rarely be observed except around the marginal of the Canada Basin. The second period is between 2003 and 2015, when the summer NSTM nearly occurred over the whole basin as accelerated decline of summer sea ice. The third period is from 2016 to 2017, when the summer NSTM almost disappeared due to prevailing warm surface water. Furthermore, for the background behind the decadal variance of summer NSTM, linear trends of the September minimum sea ice extent and surface water heat content in the Canada Basin from 2003 to 2017 were &#8211;2.75&#177;1.08&#215;104km2yr&#8211;1 and 2.29&#177;1.36MJ m&#8211;2yr&#8211;1, respectively. According to a previous theory, if we assume that the trend of the summer surface water heat content was only contributed by NSTM, it would cause a decrease in sea ice thickness of approximately 13 cm. The analysis partially explains the reason for sea ice decline in recent years.

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The impact of shallow stratification on air-sea CO2 flux in the summer Arctic Ocean

10.5194/egusphere-egu21-715 ◽

2021 ◽

Author(s):

Yuanxu Dong ◽

Dorothee Bakker ◽

Thomas Bell ◽

Peter Liss ◽

Ian Brown ◽

...

Keyword(s):

Surface Water ◽

Wind Speed ◽

Sea Ice ◽

Surface Temperature ◽

Arctic Ocean ◽

The Arctic ◽

Near Surface ◽

Ice Melt ◽

The Arctic Ocean ◽

The Impact

Air-sea carbon dioxide (CO2) flux is often indirectly estimated by the bulk method using the in-situ air-sea difference in CO2 fugacity and a wind speed dependent parameterisation of the gas transfer velocity (K). In the summer, sea-ice melt in the Arctic Ocean generates strong shallow stratification with significant gradients in temperature, salinity, dissolved inorganic carbon (DIC) and alkalinity (TA), and thus a near-surface CO2 fugacity &#160;(fCO2w) gradient. This gradient can cause an error in bulk air-sea CO2 flux estimates when the fCO2w is measured by the ship&#8217;s underway system at ~5 m depth. Direct air-sea CO2 flux measurement by eddy covariance (EC) is free from the impact of shallow stratification because the EC CO2 flux does not rely on a fCO2w measurement. In this study, we use summertime EC flux measurements from the Arctic Ocean to back-calculate the sea surface fCO2w and temperature and compare them with the underway measurements. We show that the EC air-sea CO2 flux agrees well with the bulk flux in areas less likely to be influenced by ice melt (salinity > 32). However, in regions with salinity less than 32, the underway fCO2w is higher than the EC estimate of surface fCO2w and thus the bulk estimate of ocean CO2 uptake is underestimated. The fCO2w difference can be partly explained by the surface to sub-surface temperature difference. The EC estimate of surface temperature is lower than the sub-surface water temperature and this difference is wind speed-dependent. Upper-ocean salinity gradients from CTD profiles suggest likely difference in DIC and TA concentrations between the surface and sub-surface water. These DIC and TA gradients likely explain much of the near-surface fCO2w gradient. Accelerating summertime loss of sea ice results in additional meltwater, which enhances near-surface stratification and increases the uncertainty of bulk air-sea CO2 flux estimates in polar regions.

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An Analysis of the Processes Affecting Rapid Near-Surface Water Vapor Increases during the Afternoon to Evening Transition in Oklahoma

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-19-0062.1 ◽

2019 ◽

Vol 58 (10) ◽

pp. 2217-2234 ◽

Cited By ~ 1

Author(s):

W. G. Blumberg ◽

D. D. Turner ◽

S. M. Cavallo ◽

Jidong Gao ◽

J. Basara ◽

...

Keyword(s):

Water Vapor ◽

Surface Water ◽

Surface Cooling ◽

Near Surface ◽

Evening Transition ◽

Relative Contribution ◽

Oklahoma Mesonet ◽

Conditional Instability ◽

Water Vapor Mixing Ratio ◽

Spring Harvest

AbstractThis study used 20 years of Oklahoma Mesonet data to investigate the changes of near-surface water vapor mixing ratio qυ during the afternoon to evening transition (AET). Similar to past studies, increases in qυ are found to occur near sunset. However, the location, magnitude, and timing of the qυ maximum occurring during the AET are shown to be dependent on the seasonal growth and harvest of vegetation across Oklahoma in the spring and summer months. Particularly, the late spring harvest of winter wheat grown in Oklahoma appears to modify the relative contribution of local and nonlocal processes on qυ. By analyzing time series of qυ during the AET, it is found that the likelihood of a presunset qυ maximum is strongly dependent upon vegetation, soil moisture, wind speed, and cloud cover. Analysis also reveals that the increase in qυ during the AET can increase the parcel conditional instability despite the surface cooling produced by loss of insolation. Next to known changes in low-level wind shear, these changes in instability and moisture demonstrate new ways the AET can modify the presence of the key ingredients relevant to explaining the climatological increase in severe convective storm hazards around sunset.

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