scholarly journals Warm and moist atmospheric flow caused a record minimum July sea ice extent of the Arctic in 2020

2021 ◽  
Author(s):  
Yu Liang ◽  
Haibo Bi ◽  
Haijun Huang ◽  
Ruibo Lei ◽  
Xi Liang ◽  
...  
Keyword(s):  
Sea Ice ◽  
Large Scale ◽  
Extreme Event ◽  
Longwave Radiation ◽  
Decisive Role ◽  
High Energy ◽  
The Arctic ◽  
Sea Ice Extent ◽  
Atmospheric Flow ◽  
Downward Longwave Radiation

Abstract. The satellite observations unveiled that the July sea ice extent of the Arctic shrank to the lowest value in 2020 since 1979, with a major ice retreat in the Eurasian shelf seas including Kara, Laptev, and East Siberian Seas. Based on the ERA-5 reanalysis products, we explored the impacts of warm and moist air-mass transport on this extreme event. The results reveal that anomalously high energy and moisture converged into these regions in the spring months (April to June) of 2020, leading to a burst of high moisture content and warming within the atmospheric column. The convergence is accompanied by local enhanced downward longwave radiation and turbulent fluxes, which is favorable for initiating an early melt onset in the areas with severe ice loss. Once the melt begins, solar radiation played a decisive role in leading to further sea ice depletion due to ice-albedo positive feedback. The typical trajectories of the synoptic cyclones that occurred on the Eurasian side in spring 2020 agree well with the path of atmospheric flow. Assessments suggest that variations in characteristics of the spring cyclones are conducive to the severe melt of sea ice. We argue that large-scale atmospheric circulation and synoptic cyclones act in concert to trigger the exceptional poleward transport of total energy and moisture from April to June to cause this new record minimum of sea ice extent in the following July.

scholarly journals Mechanism of Seasonal Arctic Sea Ice Evolution and Arctic Amplification

2016 ◽  
Author(s):  
Kwang-Yul Kim ◽  
Benjamin D. Hamlington ◽  
Hanna Na ◽  
Jinju Kim
Keyword(s):  
Heat Flux ◽  
Sea Ice ◽  
Air Temperature ◽  
Surface Air Temperature ◽  
Longwave Radiation ◽  
The Arctic ◽  
Turbulent Heat ◽  
Arctic Amplification ◽  
Ice Melting ◽  
Downward Longwave Radiation

Abstract. Sea ice melting is proposed as a primary reason for the Artic amplification, although physical mechanism of the Arctic amplification and its connection with sea ice melting is still in debate. In the present study, monthly ERA-interim reanalysis data are analyzed via cyclostationary empirical orthogonal function analysis to understand the seasonal mechanism of sea ice melting in the Arctic Ocean and the Arctic amplification. While sea ice melting is widespread over much of the perimeter of the Arctic Ocean in summer, sea ice remains to be thin in winter only in the Barents-Kara Seas. Excessive turbulent heat flux through the sea surface exposed to air due to sea ice melting warms the atmospheric column. Warmer air increases the downward longwave radiation and subsequently surface air temperature, which facilitates sea surface remains to be ice free. A 1 % reduction in sea ice concentration in winter leads to ~ 0.76 W m−2 increase in upward heat flux, ~ 0.07 K increase in 850 hPa air temperature, ~ 0.97 W m−2 increase in downward longwave radiation, and ~ 0.26 K increase in surface air temperature. This positive feedback mechanism is not clearly observed in the Laptev, East Siberian, Chukchi, and Beaufort Seas, since sea ice refreezes in late fall (November) before excessive turbulent heat flux is available for warming the atmospheric column in winter. A detailed seasonal heat budget is presented in order to understand specific differences between the Barents-Kara Seas and Laptev, East Siberian, Chukchi, and Beaufort Seas.

Large-scale Arctic sea ice motion from Sentinel-1 and the RADARSAT Constellation Mission

2021 ◽  
Author(s):  
Stephen Howell ◽  
Mike Brady ◽  
Alexander Komarov
Keyword(s):  
Sea Ice ◽  
Spatial Resolution ◽  
Temporal Resolution ◽  
Large Scale ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
High Temporal Resolution ◽  
Sar Images ◽  
Sea Ice Extent ◽  
Arctic Sea

<p>As the Arctic’s sea ice extent continues to decline, remote sensing observations are becoming even more vital for the monitoring and understanding of this process.  Recently, the sea ice community has entered a new era of synthetic aperture radar (SAR) satellites operating at C-band with the launch of Sentinel-1A in 2014, Sentinel-1B in 2016 and the RADARSAT Constellation Mission (RCM) in 2019. These missions represent a collection of 5 spaceborne SAR sensors that together can routinely cover Arctic sea ice with a high spatial resolution (20-90 m) but also with a high temporal resolution (1-7 days) typically associated with passive microwave sensors. Here, we used ~28,000 SAR image pairs from Sentinel-1AB together with ~15,000 SAR images pairs from RCM to generate high spatiotemporal large-scale sea ice motion products across the pan-Arctic domain for 2020. The combined Sentinel-1AB and RCM sea ice motion product provides almost complete 7-day coverage over the entire pan-Arctic domain that also includes the pole-hole. Compared to the National Snow and Ice Data Center (NSIDC) Polar Pathfinder and Ocean and Sea Ice-Satellite Application Facility (OSI-SAF) sea ice motion products, ice speed was found to be faster with the Senintel-1AB and RCM product which is attributed to the higher spatial resolution of SAR imagery. More sea ice motion vectors were detected from the Sentinel-1AB and RCM product in during the summer months and within the narrow channels and inlets compared to the NSIDC Polar Pathfinder and OSI-SAF sea ice motion products. Overall, our results demonstrate that sea ice geophysical variables across the pan-Arctic domain can now be retrieved from multi-sensor SAR images at both high spatial and temporal resolution.</p>

scholarly journals Suppression of Arctic sea ice growth by winter clouds and snowfall

2021 ◽  
Author(s):  
Won-il Lim ◽  
Hyo-Seok Park ◽  
Andrew Stewart ◽  
Kyong-Hwan Seo
Keyword(s):  
Sea Ice ◽  
Longwave Radiation ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Ice Thickness ◽  
Sea Ice Thickness ◽  
Ice Growth ◽  
Downward Longwave Radiation ◽  
Arctic Sea ◽  
The Impact

Abstract The ongoing Arctic warming has been pronounced in winter and has been associated with an increase in downward longwave radiation. While previous studies have demonstrated that poleward moisture flux into the Arctic strengthens downward longwave radiation, less attention has been given to the impact of the accompanying increase in snowfall. Here, utilizing state-of-the art sea ice models, we show that typical winter snowfall anomalies of 1.0 cm, accompanied by positive downward longwave radiation anomalies of ~5 W m-2 can decrease sea ice thickness by around 5 cm in the following spring over the Eurasian Seas. This basin-wide ice thinning is followed by a shrinking of summer ice extent in extreme cases. In the winter of 2016–17, anomalously strong warm/moist air transport combined with ~2.5 cm increase in snowfall decreased spring ice thickness by ~10 cm and decreased the following summer sea ice extent by 5–30%. Projected future reductions in the thickness of Arctic sea ice and snow will amplify the impact of anomalous winter snowfall events on winter sea ice growth and seasonal sea ice thickness.

Poleward moisture transport and its influence on precipitation in the Arctic: From case studies to long-term statistics

2020 ◽  
Author(s):  
Melanie Lauer ◽  
Annette Rinke ◽  
Irina Gorodetskaya ◽  
Susanne Crewell
Keyword(s):  
Sea Ice ◽  
Case Studies ◽  
Water Vapour ◽  
Moisture Transport ◽  
Longwave Radiation ◽  
The Arctic ◽  
Vapour Transport ◽  
Water Vapour Transport ◽  
Downward Longwave Radiation

<p>There are many factors which could contribute to the Arctic warming: feedback processes like the lapse rate and ice-albedo feedback, the increasing downward longwave radiation caused by clouds and water vapour, and the reduction of sea ice in summer that leads to absorption of solar radiation and increase in local evaporation and more clouds. But also the atmospheric moisture transport from the lower latitudes can contribute to the surface warming in high-latitudes. This poleward moisture transport is mostly accomplished by extra-tropical cyclones, with especially strong contribution by the Atmospheric Rivers (ARs). ARs are long, narrow bands of enhanced water vapour transport which are responsible for over 90% of the poleward water vapour transport in and across mid-latitudes. Furthermore, they are responsible for producing significant levels of rain and snow. In addition, the greenhouse effect of water vapour and the formation of clouds increase the downward longwave radiation which can cause a thinning and melting of Arctic sea ice and snow.</p><p>In this study, we investigate the contribution of ARs to Arctic precipitation. Firstly, we look into different case studies for which observational data from the campaigns within the Collaborative Research Center “Arctic Amplification: Climate Relevant Atmospheric and Surface Processes, and Feedback Mechanisms (AC)<sup>3</sup>” exist. The data include enhanced observations at/around Svalbard performed during the ACLOUD and the AFLUX campaigns.</p><p>Previous studies have shown that ARs reaching into the Arctic have different origins, including the Atlantic and the Pacific pathways and also Siberia. Here we examine which pathway is more common and which one transports more moisture into the Arctic for these case studies by using existing AR catalogues from global and polar-specific algorithms. Furthermore, the variability of precipitation influences the surface mass and energy balance of polar sea ice and ice sheets. Therefore, we will analyse the influence of ARs on precipitation in terms of frequency, intensity, and type of precipitation (rain or snow) for the different case studies. For this purpose, we will use reanalyses and observational data for the water vapour transport, total precipitation, rain and snow profiles.The occurrence of ARs and its influence on precipitation will be extended from case studies to the long-term statistics (for at least 10 years).</p>

Relative contributions of internal atmospheric variability and surface processes to the interannual variations in wintertime Arctic surface air temperatures

2021 ◽  
pp. 1-48
Author(s):  
Fengmin Wu ◽  
Wenkai Li ◽  
Peng Zhang ◽  
Wei Li
Keyword(s):  
Sea Ice ◽  
Large Scale ◽  
Surface Air Temperature ◽  
Surface Processes ◽  
The Arctic ◽  
Interannual Variations ◽  
Atmospheric Variability ◽  
Near Surface ◽  
Atmospheric Circulations ◽  
Downward Longwave Radiation

AbstractSuperimposed on a warming trend, Arctic winter surface air temperature (SAT) exhibits substantial interannual variability, whose underlying mechanisms are unclear, especially regarding the role of sea-ice variations and atmospheric processes. Here, atmospheric reanalysis data and idealized atmospheric model simulations are used to reveal the mechanisms by which sea-ice variations and atmospheric anomalous conditions affect interannual variations in wintertime Arctic SAT. Results show that near-surface interannual warming in the Arctic is accompanied by comparable warming throughout large parts of the Arctic troposphere and large-scale anomalous atmospheric circulation patterns. Within the Arctic, changes in large-scale atmospheric circulations due to internal atmospheric variability explain a substantial fraction of interannual variation in SAT and tropospheric temperatures, which lead to an increase in moisture and downward longwave radiation, with the rest likely coming from sea ice-related and other surface processes. Arctic winter sea-ice loss allows the ocean to release more heat and moisture, which enhances Arctic warming; however, this effect on SAT is confined to the ice-retreat area and has a limited influence on large-scale atmospheric circulations.

scholarly journals Rapid Arctic Sea Ice Loss on the Synoptic Time Scale and Related Atmospheric Circulation Anomalies

2020 ◽  
Vol 33 (5) ◽  
pp. 1597-1617 ◽  
Author(s):  
Zhuo Wang ◽  
John Walsh ◽  
Sarah Szymborski ◽  
Melinda Peng
Keyword(s):  
Water Vapor ◽  
Sea Ice ◽  
Time Scale ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Energy Propagation ◽  
Sea Ice Extent ◽  
Atmospheric Rivers ◽  
Downward Longwave Radiation ◽  
Wave Trains

AbstractLarge sea ice loss on the synoptic time scale is examined in various subregions in the Arctic as well as at the pan-Arctic scale. It is found that the frequency of large daily sea ice loss (LDSIL) days is significantly correlated with the September sea ice extent over the Beaufort–Chukchi–Siberian Seas, the Laptev–Kara Seas, the central Arctic, and the all-Arctic regions, indicating a link between the synoptic sea ice variability and the interannual variability of the annual minimum sea ice extent. A composite analysis reveals dipoles of anomalous cyclones and anticyclones associated with LDSIL days. Different from the well-known Arctic dipole pattern, the east–west dipoles are found over the corresponding regions of LDSIL in the Arctic marginal seas and are associated with the increasing occurrence of Rossby wave breaking and atmospheric rivers. The anticyclones of the dipoles are persistent and quasi-stationary, reminiscent of blocking. The anomalous poleward flow between the cyclone and the anticyclone enhances the poleward transport of heat and water vapor in the lower troposphere. Although enhanced downward shortwave radiation, associated with reduced cloud fraction, is found in some regions, it is not collocated with the regions of LDSIL. In contrast, enhanced downward longwave radiation owing to increasing column water vapor shows good spatial correspondence with LDSIL, indicating the importance of atmospheric rivers in LDSIL events. Lead/lag composites with respect to the onset of LDSIL episodes reveal precursor wave trains spanning the midlatitudes. The wave trains have predominantly zonal energy propagation in the midlatitudes and do not show a clear link to tropical or subtropical forcing.

scholarly journals Inter-annual variations observed in spring and summer Antarctic sea ice extent in recent decade

MAUSAM ◽  
2021 ◽  
Vol 62 (4) ◽  
pp. 633-640
Author(s):  
SANDIP R.OZA ◽  
R.K.K. SINGH ◽  
ABHINAV SRIVASTAVA ◽  
MIHIR K.DASH ◽  
I.M.L. DAS ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Large Scale ◽  
Ross Sea ◽  
Ice Cover ◽  
Weddell Sea ◽  
The Arctic ◽  
Sea Ice Extent ◽  
Antarctic Sea Ice ◽  
The Antarctic

The growth and decay of sea ice are complex processes and have important feedback onto the oceanic and atmospheric circulation. In the Antarctic, sea ice variability significantly affects the primary productivity in the Southern Ocean and thereby negatively influences the performance and survival of species in polar ecosystem. In present days, the awareness on the sea ice variability in the Antarctic is not as matured as it is for the Arctic region. The present paper focuses on the inter-annual trends (1999-2009) observed in the monthly fractional sea ice cover in the Antarctic at 1 × 1 degree level, for the November and February months, derived from QuikSCAT scatterometer data. OSCAT scatterometer data from India’s Oceansat-2 satellite were used to asses the sea ice extent (SIE) observed in the month of November 2009 and February 2010 and its deviation from climatic maximum (1979-2002) sea ice extent (CMSIE). Large differences were observed between SIE and CMSIE, however, trend results show that it is due to the high inter-annual variability in sea ice cover. Spatial distribution of trends show the existence of positive and negative trends in the parts of Western Pacific Ocean, Ross Sea, Amundsen and Bellingshausen Seas (ABS), Weddell Sea and Indian ocean sector of southern ocean. Sea ice trends are compared with long-term SST trends (1982-2009) observed in the austral summer month of February. Large-scale cooling trend observed around Ross Sea and warming trend in ABS sector are the distinct outcome of the study.

scholarly journals Atmospheric influences on the anomalous 2016 Antarctic sea ice decay

2017 ◽  
Author(s):  
Elisabeth Schlosser ◽  
F. Alexander Haumann ◽  
Marilyn N. Raphael
Keyword(s):  
Sea Ice ◽  
Early Onset ◽  
Meridional Flow ◽  
Reanalysis Data ◽  
Rapid Decrease ◽  
Weddell Sea ◽  
The Arctic ◽  
Sea Ice Extent ◽  
Atmospheric Flow ◽  
Antarctic Sea Ice

Abstract. In contrast to the Arctic, where total sea ice extent (SIE) has been decreasing for the last three decades, Antarctic SIE has shown a small, but significant increase during the same time period. However, in 2016, an unusually early onset of the melt season was observed; the maximum Antarctic SIE was already reached as early as August rather than end of September, and was followed by a rapid decrease. The decline of the sea ice area (SIA) started even earlier, namely in July. The decay was particularly strong in November where Antarctic SIE exhibited a negative anomaly (compared to the 1979–2015 average) of approximately 2 Mio. km2, which, combined with reduced Arctic SIE, led to a distinct minimum in global SIE. ECMWF- Interim reanalysis data were used to investigate possible atmospheric influences on the observed phenomena. The early onset of the melt and the rapid decrease in SIA and SIE were associated with atmospheric flow patterns related to a positive ZW3 index, i.e. synoptic situations leading to strong meridional flow. Particularly, in the first third of November northerly flow conditions in the Weddell Sea and the Western Pacific triggered accelerated sea ice decay, which was continued in the following weeks due to positive feed-back effects, leading to the extraordinary low November SIE. In 2016, the monthly mean SAM index reached its second lowest November value since the beginning of the satellite observations. SIE decrease was preconditioned by SIA decrease. A better spatial and temporal coverage of reliable ice thickness data is needed to assess the change in ice mass rather than ice area.

scholarly journals Strong Dependence of Wintertime Arctic Moisture and Cloud Distributions on Atmospheric Large-Scale Circulation

2019 ◽  
Vol 32 (24) ◽  
pp. 8771-8790 ◽  
Author(s):  
Tiina Nygård ◽  
Rune G. Graversen ◽  
Petteri Uotila ◽  
Tuomas Naakka ◽  
Timo Vihma
Keyword(s):  
North Atlantic ◽  
Moisture Transport ◽  
Large Scale ◽  
Strong Dependence ◽  
Longwave Radiation ◽  
The Arctic ◽  
Large Scale Circulation ◽  
The North ◽  
Downward Longwave Radiation ◽  
The Impact

Abstract This study gives a comprehensive picture of how atmospheric large-scale circulation is related to moisture transport and to distributions of moisture, clouds, and surface downward longwave radiation in the Arctic in winter. Anomaly distributions of the abovementioned variables are compared in 30 characteristic wintertime atmospheric circulation regimes, which are allocated from 15 years (2003–17) of mean sea level pressure data of ERA-Interim reanalysis applying the self-organizing map method. The characteristic circulation regimes are further related to known climate indices—the North Atlantic Oscillation (NAO), the Arctic Oscillation (AO), and Greenland blocking index—as well as to a frequent high pressure pattern across the Arctic Ocean from Siberia to North America, herein called the Arctic bridge. Effects of large-scale circulation on moisture, cloud, and longwave radiation are to a large extent occurring through the impact of horizontal moisture transport. Evaporation is typically not efficient enough to shape those distributions, and much of the moisture evaporated in the Arctic is transported southward. The positive phase of the NAO and AO increases moisture and clouds in northern Europe and the eastern North Atlantic Ocean, and a strong Greenland blocking typically increases those in the southwest of Greenland. When the Arctic bridge is lacking, the amount of moisture, clouds, and downward longwave radiation is anomalously high near the North Pole. Our results reveal a strong dependence of moisture, clouds, and longwave radiation on atmospheric pressure fields, which also appears to be important from a climate change perspective.

scholarly journals Sea Ice Concentration and Sea Ice Extent Mapping with L-Band Microwave Radiometry and GNSS-R Data from the FFSCat Mission Using Neural Networks

2021 ◽  
Vol 13 (6) ◽  
pp. 1139
Author(s):  
David Llaveria ◽  
Juan Francesc Munoz-Martin ◽  
Christoph Herbert ◽  
Miriam Pablos ◽  
Hyuk Park ◽  
...  
Keyword(s):  
Sea Ice ◽  
Microwave Radiometer ◽  
Cost Effective ◽  
The Arctic ◽  
Sea Ice Concentration ◽  
Sea Ice Extent ◽  
Neural Network Approach ◽  
Ice Concentration ◽  
L Band ◽  
Moderate Cost

CubeSat-based Earth Observation missions have emerged in recent times, achieving scientifically valuable data at a moderate cost. FSSCat is a two 6U CubeSats mission, winner of the ESA S3 challenge and overall winner of the 2017 Copernicus Masters Competition, that was launched in September 2020. The first satellite, 3Cat-5/A, carries the FMPL-2 instrument, an L-band microwave radiometer and a GNSS-Reflectometer. This work presents a neural network approach for retrieving sea ice concentration and sea ice extent maps on the Arctic and the Antarctic oceans using FMPL-2 data. The results from the first months of operations are presented and analyzed, and the quality of the retrieved maps is assessed by comparing them with other existing sea ice concentration maps. As compared to OSI SAF products, the overall accuracy for the sea ice extent maps is greater than 97% using MWR data, and up to 99% when using combined GNSS-R and MWR data. In the case of Sea ice concentration, the absolute errors are lower than 5%, with MWR and lower than 3% combining it with the GNSS-R. The total extent area computed using this methodology is close, with 2.5% difference, to those computed by other well consolidated algorithms, such as OSI SAF or NSIDC. The approach presented for estimating sea ice extent and concentration maps is a cost-effective alternative, and using a constellation of CubeSats, it can be further improved.

Sign in / Sign up

Export Citation Format

Share Document