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

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

<p>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 –2.75±1.08×10<sup>4</sup>km<sup>2</sup>yr<sup>–1</sup> and 2.29±1.36MJ m<sup>–2</sup>yr<sup>–1</sup>, 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.</p>

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

2019 ◽  
Vol 13 (9) ◽  
pp. 2303-2315 ◽  
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.

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

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

<p>Air-sea carbon dioxide (CO<sub>2</sub>) flux is often indirectly estimated by the bulk method using the i<em>n-situ</em> air-sea difference in CO<sub>2</sub> fugacity and a wind speed dependent parameterisation of the gas transfer velocity (<em>K</em>). 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 CO<sub>2</sub> fugacity  (<em>f</em>CO<sub>2w</sub>) gradient. This gradient can cause an error in bulk air-sea CO<sub>2</sub> flux estimates when the <em>f</em>CO<sub>2w</sub> is measured by the ship’s underway system at ~5 m depth. Direct air-sea CO<sub>2</sub> flux measurement by eddy covariance (EC) is free from the impact of shallow stratification because the EC CO<sub>2</sub> flux does not rely on a <em>f</em>CO<sub>2w</sub> measurement. In this study, we use summertime EC flux measurements from the Arctic Ocean to back-calculate the sea surface <em>f</em>CO<sub>2w</sub> and temperature and compare them with the underway measurements. We show that the EC air-sea CO<sub>2</sub> 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 <em>f</em>CO<sub>2w</sub> is higher than the EC estimate of surface <em>f</em>CO<sub>2w</sub> and thus the bulk estimate of ocean CO<sub>2</sub> uptake is underestimated. The <em>f</em>CO<sub>2w</sub> 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 <em>f</em>CO<sub>2w</sub> gradient. Accelerating summertime loss of sea ice results in additional meltwater, which enhances near-surface stratification and increases the uncertainty of bulk air-sea CO<sub>2</sub> flux estimates in polar regions.</p>

scholarly journals Climate Change Study via the Centennial Trend of Climate Factors

Hydrology ◽  
2020 ◽  
Vol 7 (2) ◽  
pp. 25
Author(s):  
Nezamoddin N. Kachouie ◽  
Osita E. Onyejekwe
Keyword(s):  
Climate Change ◽  
Sea Ice ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Heat Content ◽  
Sea Surface ◽  
Climate Factors ◽  
Sea Ice Extent ◽  
Inflection Points ◽  
Increasing Trend

Background: The purpose of this work is to discover underlying trends of climate factors, identify their peaks and inflection points between 1880 and 2017, and study their response to climate change. Five climate factors including Land Temperature, Sea Surface Temperature, Temperature Over Land Plus Ocean, Carbon Dioxide concentration, and Northern Hemisphere Sea Ice Extent are studied in this paper. Methods: First, the kernel regression is applied to smooth and recover underlying trends of the climate factors between 1880 and 2017. To characterize temporal changes in the global climate via climate factors, peaks and inflection points of each climate factor are located and identified. Results: Five climate factors are studied between 1880 and 2017. Despite locating multiple inflection points in the climate factors and indicating fluctuations in the weather patterns, it was observed that Land Temperature, Sea Surface Temperature, Temperature Over Land Plus Ocean, and Carbon Dioxide concentration have experienced consistent increasing trends since the mid 20 t h century. It was also observed that in response to climate change, the Northern Hemisphere Sea Ice Extent has experienced a consistent decreasing trend since the 1960s. Conclusion: An increasing trend was observed for four climate factors (all but Sea Ice Extent) since the early 1900s. Sea Ice Extent shows a consistent decreasing trend dropping to a new minimum, year after year. Among all factors, the Sea Surface Temperature shows a decreasing trend between the late 1800s and the early 1900s. It reaches its minimum in 1911 and has experienced an increasing trend since then. Our observations agree with the global heat content map during this time interval between 1880 and 2017. The heat content in the Americas, Europe, Africa, Asia, and Australia shows an increasing trend since the late 1800s. It agrees with what was observed in the Land Temperature anomalies. In contrast, the heat content of the Pacific, Atlantic, and Indian Oceans shows a decreasing trend from the late 1800s to the early 1900s when its trend turns the course to an increasing trend.

scholarly journals Interannual sea ice thickness variability in the Bay of Bothnia

2018 ◽  
Vol 12 (11) ◽  
pp. 3459-3476 ◽  
Author(s):  
Iina Ronkainen ◽  
Jonni Lehtiranta ◽  
Mikko Lensu ◽  
Eero Rinne ◽  
Jari Haapala ◽  
...  
Keyword(s):  
Sea Ice ◽  
Interannual Variability ◽  
Thickness Distribution ◽  
Ice Thickness ◽  
Data Sets ◽  
Sea Ice Extent ◽  
Sea Ice Thickness ◽  
Thickness Variability ◽  
Fast Ice ◽  
Ridged Ice

Abstract. While variations of Baltic Sea ice extent and thickness have been extensively studied, there is little information about drift ice thickness, distribution, and its variability. In our study, we quantify the interannual variability of sea ice thickness in the Bay of Bothnia during the years 2003–2016. We use various different data sets: official ice charts, drilling data from the regular monitoring stations in the coastal fast ice zone, and helicopter and shipborne electromagnetic soundings. We analyze the different data sets and compare them to each other to characterize the interannual variability, to discuss the ratio of level and deformed ice, and to derive ice thickness distributions in the drift ice zone. In the fast ice zone the average ice thickness is 0.58±0.13 m. Deformed ice increases the variability of ice conditions in the drift ice zone, where the average ice thickness is 0.92±0.33 m. On average, the fraction of deformed ice is 50 % to 70 % of the total volume. In heavily ridged ice regions near the coast, mean ice thickness is approximately half a meter thicker than that of pure thermodynamically grown fast ice. Drift ice exhibits larger interannual variability than fast ice.

Holocene variability in sea surface temperature and sea ice extent in the northern Bering Sea: A multiple biomarker study

2017 ◽  
Vol 113 ◽  
pp. 1-9 ◽  
Author(s):  
Jiaping Ruan ◽  
Yuanhui Huang ◽  
Xuefa Shi ◽  
Yanguang Liu ◽  
Wenjie Xiao ◽  
...  
Keyword(s):  
Sea Ice ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Bering Sea ◽  
Sea Surface ◽  
Sea Ice Extent ◽  
Northern Bering Sea

scholarly journals ICESat observations of seasonal and interannual variations of sea-ice freeboard and estimated thickness in the Weddell Sea, Antarctica (2003–2009)

2011 ◽  
Vol 52 (57) ◽  
pp. 43-51 ◽  
Author(s):  
Donghui Yi ◽  
H. Jay Zwally ◽  
John W. Robbins
Keyword(s):  
Sea Ice ◽  
Weddell Sea ◽  
Ice Thickness ◽  
Sea Ice Extent ◽  
Sea Ice Thickness ◽  
Earth Observing System ◽  
Pack Ice ◽  
Snow Water ◽  
The Mean ◽  
Seasonal And Interannual Variations

AbstractSea-ice freeboard heights for 17 ICESat campaign periods from 2003 to 2009 are derived from ICESat data. Freeboard is combined with snow depth from Advanced Microwave Scanning Radiometer for Earth Observing System (AMSR-E) data and nominal densities of snow, water and sea ice, to estimate sea-ice thickness. Sea-ice freeboard and thickness distributions show clear seasonal variations that reflect the yearly cycle of growth and decay of the Weddell Sea (Antarctica) pack ice. During October–November, sea ice grows to its seasonal maximum both in area and thickness; the mean freeboards are 0.33–0.41m and the mean thicknesses are 2.10–2.59 m. During February–March, thinner sea ice melts away and the sea-ice pack is mainly distributed in the west Weddell Sea; the mean freeboards are 0.35–0.46m and the mean thicknesses are 1.48–1.94 m. During May–June, the mean freeboards and thicknesses are 0.26–0.29m and 1.32–1.37 m, respectively. the 6 year trends in sea-ice extent and volume are (0.023±0.051)×106 km2 a–1 (0.45% a–1) and (0.007±0.092)×103 km3 a–1 (0.08% a–1); however, the large standard deviations indicate that these positive trends are not statistically significant.

Evaluation of regional NWP results for sea ice covered Bothnia Bay (Baltic Sea) in winter 2020.

2021 ◽  
Author(s):  
Marta Wenta ◽  
Agnieszka Herman
Keyword(s):  
Boundary Layer ◽  
Wind Speed ◽  
Sea Ice ◽  
Surface Temperature ◽  
Atmospheric Boundary Layer ◽  
Baltic Sea ◽  
Polar Regions ◽  
Near Surface ◽  
Accurate Representation ◽  
Complex Processes

<p>The ongoing development of NWP (Numerical Weather Prediction) models and their increasing horizontal resolution have significantly improved forecasting capabilities. However, in the polar regions models struggle with the representation of near-surface atmospheric properties and the vertical structure of the atmospheric boundary layer (ABL) over sea ice. Particularly difficult to resolve are near-surface temperature, wind speed, and humidity, along with diurnal changes of those properties. Many of the complex processes happening at the interface of sea ice and atmosphere, i.e. vertical fluxes, turbulence, atmosphere - surface coupling are poorly parameterized or not represented in the models at all. Limited data coverage and our poor understanding of the complex processes taking place in the polar ABL limit the development of suitable parametrizations. We try to contribute to the ongoing effort to improve the forecast skill in polar regions through the analysis of unmanned aerial vehicles (UAVs) and automatic weather station (AWS) atmospheric measurements from the coastal area of Bothnia Bay (Wenta et. al., 2021), and the application of those datasets for the analysis of regional NWP models' forecasts. </p><p>Data collected during HAOS (Hailuoto Atmospheric Observations over Sea ice) campaign (Wenta et. al., 2021) is used for the evaluation of regional NWP models results from AROME (Applications of Research to Operations at Mesoscale) - Arctic, HIRLAM (High Resolution Limited Area Model) and WRF (Weather Research and Forecasting). The presented analysis focuses on 27 Feb. 2020 - 2 Mar. 2020, the time of the HAOS campaign, shortly after the formation of new, thin sea ice off the westernmost point of Hailuoto island.  Throughout the studied period weather conditions changed from very cold (-14℃), dry and cloud-free to warmer (~ -5℃), more humid and opaquely cloudy. We evaluate models’ ability to correctly resolve near-surface temperature, humidity, and wind speed, along with vertical changes of temperature and humidity over the sea ice. It is found that generally, models struggle with an accurate representation of surface-based temperature inversions, vertical variations of humidity, and temporal wind speed changes. Furthermore, a WRF Single Columng Model (SCM) is launched to study whether specific WRF planetary boundary layer parameterizations (MYJ, YSU, MYNN, QNSE), vertical resolution, and more accurate representation of surface conditions increase the WRF model’s ability to resolve the ABL above sea ice in the Bay of Bothnia. Experiments with WRF SCM are also used to determine the possible reasons behind model’s biases. Preliminary results show that accurate representation of sea ice conditions, including thickness, surface temperature, albedo, and snow coverage is crucial for increasing the quality of NWP models forecasts. We emphasize the importance of further development of parametrizations focusing on the processes at the sea ice-atmosphere interface.</p><p> </p><p>Reference:</p><p>Wenta, M., Brus, D., Doulgeris, K., Vakkari, V., and Herman, A.: Winter atmospheric boundary layer observations over sea ice in the coastal zone of the Bay of Bothnia (Baltic Sea), Earth Syst. Sci. Data, 13, 33–42, https://doi.org/10.5194/essd-13-33-2021, 2021. </p><p><br><br><br><br><br><br></p>

scholarly journals Effects of ocean acidification, warming and melting of sea ice on aragonite saturation of the Canada Basin surface water

2011 ◽  
Vol 38 (3) ◽  
pp. n/a-n/a ◽  
Author(s):  
M. Yamamoto-Kawai ◽  
F. A. McLaughlin ◽  
E. C. Carmack
Keyword(s):  
Surface Water ◽  
Sea Ice ◽  
Ocean Acidification ◽  
Canada Basin ◽  
Aragonite Saturation ◽  
Basin Surface

scholarly journals A Pilot Climate Sensitivity Study Using the CEN Coupled Adjoint Model (CESAM)

2018 ◽  
Vol 31 (5) ◽  
pp. 2031-2056 ◽  
Author(s):  
D. Stammer ◽  
A. Köhl ◽  
A. Vlasenko ◽  
I. Matei ◽  
F. Lunkeit ◽  
...  
Keyword(s):  
Sea Ice ◽  
Surface Temperature ◽  
Climate Sensitivity ◽  
North Atlantic ◽  
Sensitivity Study ◽  
Northern Europe ◽  
Surface Salinity ◽  
Near Surface ◽  
Temperature Anomalies ◽  
Northern European

A pilot coupled climate sensitivity study is presented based on the newly developed adjoint coupled climate model, Centrum für Erdsystemforschung und Nachhaltigkeit (CEN) Earth System Assimilation Model (CESAM). To this end the components of the coupled forward model are summarized, and the generation of the adjoint code out of the model forward code through the application of the Transformation of Algorithms in FORTRAN (TAF) adjoint compiler is discussed. It is shown that simulations of the intermediate-complexity CESAM are comparable in quality to CMIP-type coupled climate models, justifying the usage of the model to compute adjoint sensitivities of the northern Europe near-surface temperature to anomalies in surface temperature, sea surface salinity, and sea ice over the North Atlantic and the Arctic on time scales of up to one month. Results confirm that on a time scale of up to a few days surface temperatures over northern Europe are influenced by Atlantic temperature anomalies just upstream of the target location. With increasingly longer time lapse, however, it is the influence of SSTs over the central and western North Atlantic on the overlying atmosphere and the associated changes in storm-track pattern that dominate the evolution of the surface European temperature. Influences of surface salinity and sea ice on the northern European temperature appear to have similar sensitivity mechanisms, invoked indirectly through their influence on near-surface temperature anomalies. The adjoint study thus confirms that the SST’s impact on the atmospheric dynamics, notably storm tracks, is the primary cause for the influence of northern European temperature changes.

scholarly journals Better constraints on the sea-ice state using global sea-ice data assimilation

2012 ◽  
Vol 5 (2) ◽  
pp. 1627-1667 ◽  
Author(s):  
P. Mathiot ◽  
C. König Beatty ◽  
T. Fichefet ◽  
H. Goosse ◽  
F. Massonnet ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Sea Ice ◽  
Ice Thickness ◽  
Initial State ◽  
Concentration Data ◽  
Sea Ice Concentration ◽  
Sea Ice Extent ◽  
Sea Ice Thickness ◽  
Ice Concentration ◽  
The Impact

Abstract. Short-term and decadal sea-ice prediction systems need a realistic initial state, generally obtained using ice-ocean model simulations with data assimilation. However, only sea-ice concentration and velocity data are currently assimilated. In this work, an Ensemble Kalman Filter system is used to assimilate observed ice concentration and freeboard (i.e. thickness of emerged sea ice) data into a global coupled ocean–sea-ice model. The impact and effectiveness of our data assimilation system is assessed in two steps: firstly, through the assimilation of synthetic data (i.e., model-generated data) and, secondly, through the assimilation of satellite data. While ice concentrations are available daily, freeboard data used in this study are only available during six one-month periods spread over 2005–2007. Our results show that the simulated Arctic and Antarctic sea-ice extents are improved by the assimilation of synthetic ice concentration data. Assimilation of synthetic ice freeboard data improves the simulated sea-ice thickness field. Using real ice concentration data enhances the model realism in both hemispheres. Assimilation of ice concentration data significantly improves the total hemispheric sea-ice extent all year long, especially in summer. Combining the assimilation of ice freeboard and concentration data leads to better ice thickness, but does not further improve the ice extent. Moreover, the improvements in sea-ice thickness due to the assimilation of ice freeboard remain visible well beyond the assimilation periods.

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