scholarly journals Trends and spatial variation in rain-on-snow events over the Arctic Ocean during the early melt season

2021 ◽  
Vol 15 (2) ◽  
pp. 883-895
Author(s):  
Tingfeng Dou ◽  
Cunde Xiao ◽  
Jiping Liu ◽  
Qiang Wang ◽  
Shifeng Pan ◽  
...  
Keyword(s):  
Sea Ice ◽  
Phase Change ◽  
Arctic Ocean ◽  
The Arctic ◽  
Onset Date ◽  
Marginal Seas ◽  
Ice Melt ◽  
The Pacific ◽  
The Arctic Ocean ◽  
Liquid Precipitation

Abstract. Rain-on-snow (ROS) events can accelerate the surface ablation of sea ice, thus greatly influencing the ice–albedo feedback. However, the variability of ROS events over the Arctic Ocean is poorly understood due to limited historical station data in this region. In this study early melt season ROS events were investigated based on four widely used reanalysis products (ERA-Interim, JRA-55, MERRA, and ERA5) in conjunction with available observations at Arctic coastal stations. The performance of the reanalysis products in representing the timing of ROS events and the phase change of precipitation was assessed. Our results show that ERA-Interim better represents the onset date of ROS events in spring, and ERA5 better represents the phase change of precipitation associated with ROS events. All reanalyses indicate that ROS event timing has shifted to earlier dates in recent decades (with maximum trends up to −4 to −6 d per decade in some regions in ERA-Interim) and that sea ice melt onset in the Pacific sector and most of the Eurasian marginal seas is correlated with this shift. There has been a clear transition from solid to liquid precipitation, leading to more ROS events in spring, although large discrepancies were found between different reanalysis products. In ERA5, the shift from solid to liquid precipitation phase during the early melt season has directly contributed to a reduction in spring snow depth on sea ice by more than −0.5 cm per decade averaged over the Arctic Ocean since 1980, with the largest contribution (about −2.0 cm per decade) in the Kara–Barents seas and Canadian Arctic Archipelago.

scholarly journals Trends and spatial variation in rain-on-snow events over the Arctic Ocean during the early melt season

2020 ◽  
Author(s):  
Tingfeng Dou ◽  
Cunde Xiao ◽  
Jiping Liu ◽  
Qiang Wang ◽  
Shifeng Pan ◽  
...  
Keyword(s):  
Sea Ice ◽  
Phase Change ◽  
Arctic Ocean ◽  
The Arctic ◽  
Onset Date ◽  
Marginal Seas ◽  
Ice Melt ◽  
The Pacific ◽  
The Arctic Ocean ◽  
Liquid Precipitation

Abstract. Rain-on-snow (ROS) events can accelerate the surface ablation of sea ice, thus greatly influencing the ice-albedo feedback. However, the variability of ROS events over the Arctic Ocean is poorly understood due to limited historical station data in this region. In this study early melt season ROS events were investigated based on four widely-used reanalysis products (ERA-Interim, JRA-55, MERRA2 and ERA5) in conjunction with available observations at Arctic coastal stations. The performance of the reanalysis products in representing the timing of ROS events and the phase change of precipitation was assessed. Our results show that ERA-Interim better represents the onset date of ROS events in spring and ERA5 better represents the phase change of precipitation associated with ROS events. All reanalyses indicate that ROS event timing has shifted to earlier dates in recent decades (with maximum trends up to −4 to −6 days/decade in some regions in ERA-Interim), and that sea ice melt onset in the Pacific sector and most of the Eurasian marginal seas is correlated with this shift. There has been a clear transition from solid to liquid precipitation, leading to more ROS events in spring, although large discrepancies were found between different reanalysis products. In ERA5, the shift from solid to liquid precipitation phase during the early melt season has directly contributed to a reduction in spring snow depth on sea ice by more than −0.5 cm/decade averaged over the Arctic Ocean since 1980, with the largest contribution (about −2.0 cm/decade) in the Kara-Barents Seas and Canadian Arctic Archipelago.

scholarly journals Chytrid fungi distribution and co-occurrence with diatoms correlate with sea ice melt in the Arctic Ocean

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Estelle S. Kilias ◽  
Leandro Junges ◽  
Luka Šupraha ◽  
Guy Leonard ◽  
Katja Metfies ◽  
...  
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
The Arctic ◽  
Ice Melt ◽  
The Arctic Ocean

scholarly journals Time and space variability of freshwater content, heat content and seasonal ice melt in the Arctic Ocean from 1991 to 2011

2012 ◽  
Vol 9 (4) ◽  
pp. 2621-2677 ◽  
Author(s):  
M. Korhonen ◽  
B. Rudels ◽  
M. Marnela ◽  
A. Wisotzki ◽  
J. Zhao
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Mixed Layer ◽  
Heat Content ◽  
The Arctic ◽  
Upper Ocean ◽  
Heat Sources ◽  
Time And Space ◽  
Ice Melt ◽  
The Arctic Ocean

Abstract. The Arctic Ocean gains freshwater mainly through river discharge, precipitation and the inflowing low salinity waters from the Pacific Ocean. In addition the recent reduction in sea ice volume is likely to influence the surface salinity and thus contribute to the freshwater content in the upper ocean. The present day freshwater storage in the Arctic Ocean appears to be sufficient to maintain the upper ocean stratification and to protect the sea ice from the deep ocean heat content. The recent freshening has not, despite the established strong stratification, been able to restrain the accelerating ice loss and other possible heat sources besides the Atlantic Water, such as the waters advecting from the Pacific Ocean and the solar insolation warming the Polar Mixed Layer, are investigated. Since the ongoing freshening, oceanic heat sources and the sea ice melt are closely related, this study, based on hydrographic observations, attempts to examine the ongoing variability in time and space in relation to these three properties. The largest time and space variability of freshwater content occurs in the Polar Mixed Layer and the upper halocline. The freshening of the upper ocean during the 2000s is ubiquitous in the Arctic Ocean although the most substantial increase occurs in the Canada Basin where the freshwater is accumulating in the thickening upper halocline. Whereas the salinity of the upper halocline is nearly constant, the freshwater content in the Polar Mixed Layer is increasing due to decreasing salinity. The decrease in salinity is likely to result from the recent changes in ice formation and melting. In contrast, in the Eurasian Basin where the seasonal ice melt has remained rather modest, the freshening of both the Polar Mixed Layer and the upper halocline is mainly of advective origin. While the warming of the Atlantic inflow was widespread in the Arctic Ocean during the 1990s, the warm and saline inflow events in the early 2000s appear to circulate mainly in the Nansen Basin. Nevertheless, even in the Nansen Basin the seasonal ice melt appears independent of the continuously increasing heat content in the Atlantic layer. As no other oceanic heat sources can be identified in the upper layers, it is likely that increased absorption of solar energy has been causing the ice melt prior to the observations.

scholarly journals Export of Arctic freshwater components through the Fram Strait 1998–2010

2012 ◽  
Vol 9 (4) ◽  
pp. 2749-2792
Author(s):  
B. Rabe ◽  
P. Dodd ◽  
E. Hansen ◽  
E. Falck ◽  
U. Schauer ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
The Arctic ◽  
Ice Formation ◽  
Fram Strait ◽  
Pacific Water ◽  
Ice Melt ◽  
The North ◽  
Beaufort Gyre ◽  
The Pacific ◽  
The Arctic Ocean

Abstract. The East Greenland Current in the Western Fram Strait is an important pathway for liquid freshwater export from the Arctic Ocean to the Nordic Seas and the North Atlantic subpolar gyre. We analysed five hydrographic surveys and data from moored current meters around 79° N in the Western Fram Strait between 1998 and 2010. To estimate the composition of southward liquid freshwater transports, inventories of liquid freshwater and components from Dodd et al. (2012) were combined with transport estimates from an inverse model between 10.6° W and 4° E. The southward liquid freshwater transports through the section averaged to 92 mSv (2900 km3 yr−1), relative to a salinity of 34.9. The transports consisted of 123 mSv water from rivers and precipitation (meteoric water), 28 mSv freshwater from the Pacific and 60 mSv freshwater deficit due to brine from ice formation. Variability in liquid freshwater and component transports appear to have been partly due to advection of these water masses to the Fram Strait and partly due to variations in the local volume transport; an exception are Pacific Water transports, which showed little co-variability with volume transports. An increase in Pacific Water transports from 2005 to 2010 suggests a release of Pacific Water from the Beaufort Gyre, in line with an observed expansion of Pacific Water towards the Eurasian Basin. The co-variability of meteoric water and brine from ice formation suggests joint processes in the main sea ice formation regions on the Arctic Ocean shelves. In addition, enhanced levels of sea ice melt observed in 2009 likely led to reduced transports of brine from ice formation. At least part of this additional ice melt appears to have been advected from the Beaufort Gyre and from north of the Bering Strait towards the Fram Strait. The observed changes in liquid freshwater component transports are much larger than known trends in the Arctic liquid freshwater inflow from rivers and the Pacific. Instead, recent observations of an increased storage of liquid freshwater in the Arctic Ocean suggest a decreased export of liquid freshwater. This raises the question how fast the accumulated liquid freshwater will be exported from the Arctic Ocean to the deep water formation regions in the North Atlantic and if an increased export will occur through the Fram Strait.

scholarly journals Arctic freshwater fluxes: sources, tracer budgets and inconsistencies

2019 ◽  
Vol 13 (8) ◽  
pp. 2111-2131
Author(s):  
Alexander Forryan ◽  
Sheldon Bacon ◽  
Takamasa Tsubouchi ◽  
Sinhué Torres-Valdés ◽  
Alberto C. Naveira Garabato
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Inorganic Nutrients ◽  
The Arctic ◽  
Freshwater Flux ◽  
Geochemical Tracers ◽  
Ice Melt ◽  
Boundary Velocity ◽  
The Arctic Ocean ◽  
Geochemical Method

Abstract. The net rate of freshwater input to the Arctic Ocean has been calculated in the past by two methods: directly, as the sum of precipitation, evaporation and runoff, an approach hindered by sparsity of measurements, and by the ice and ocean budget method, where the net surface freshwater flux within a defined boundary is calculated from the rate of dilution of salinity, comparing ocean inflows with ice and ocean outflows. Here a third method is introduced, the geochemical method, as a modification of the budget method. A standard approach uses geochemical tracers (salinity, oxygen isotopes, inorganic nutrients) to compute “source fractions” that quantify a water parcel's constituent proportions of seawater, freshwater of meteoric origin, and either sea ice melt or brine (from the freezing-out of sea ice). The geochemical method combines the source fractions with the boundary velocity field of the budget method to quantify the net flux derived from each source. Here it is shown that the geochemical method generates an Arctic Ocean surface freshwater flux, which is also the meteoric source flux, of 200±44 mSv (1 Sv=106 m3 s−1), statistically indistinguishable from the budget method's 187±44 mSv, so that two different approaches to surface freshwater flux calculation are reconciled. The freshwater export rate of sea ice (40±14 mSv) is similar to the brine export flux, due to the “freshwater deficit” left by the freezing-out of sea ice (60±50 mSv). Inorganic nutrients are used to define Atlantic and Pacific seawater categories, and the results show significant non-conservation, whereby Atlantic seawater is effectively “converted” into Pacific seawater. This is hypothesized to be a consequence of denitrification within the Arctic Ocean, a process likely becoming more important with seasonal sea ice retreat. While inorganic nutrients may now be delivering ambiguous results on seawater origins, they may prove useful to quantify the Arctic Ocean's net denitrification rate. End point degeneracy is also discussed: multiple property definitions that lie along the same “mixing line” generate confused results.

Atmospheric and oceanic drivers of regional Arctic winter sea-ice variability in present and future climates

2021 ◽  
Author(s):  
Jakob Dörr ◽  
Marius Årthun ◽  
Tor Eldevik ◽  
Erica Madonna
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Heat Transport ◽  
Barents Sea ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Ocean Heat Transport ◽  
The Pacific ◽  
Arctic Sea ◽  
The Arctic Ocean

<p>The recent retreat of Arctic sea ice area is overlaid by strong internal variability on all timescales. In winter, sea ice retreat and variability are currently dominated by the Barents Sea, primarily driven by variable ocean heat transport from the Atlantic. Climate models from the latest intercomparison project CMIP6 project that the future loss of winter Arctic sea ice spreads throughout the Arctic Ocean and, hence, that other regions of the Arctic Ocean will see increased sea-ice variability. It is, however, not known how the influence of ocean heat transport will change, and to what extent and in which regions other drivers, such as atmospheric circulation or river runoff into the Arctic Ocean, will become important. Using a combination of observations and simulations from the Community Earth System Model Large Ensemble (CESM-LE), we analyze and contrast the present and future regional drivers of the variability of the winter Arctic sea ice cover. We find that for the recent past, both observations and CESM-LE show that sea ice variability in the Atlantic and Pacific sector of the Arctic Ocean is influenced by ocean heat transport through the Barents Sea and Bering Strait, respectively. The two dominant modes of large-scale atmospheric variability – the Arctic Oscillation and the Pacific North American pattern – are only weakly related to recent regional sea ice variability. However, atmospheric circulation anomalies associated with regional sea ice variability show distinct patterns for the Atlantic and Pacific sectors consistent with heat and humidity transport from lower latitudes. In the future, under a high emission scenario, CESM-LE projects a gradual expansion of the footprint of the Pacific and Atlantic inflows, covering the whole Arctic Ocean by 2050-2079. This study highlights the combined importance of future Atlantification and Pacification of the Arctic Ocean and improves our understanding of internal climate variability which essential in order to predict future sea ice changes under anthropogenic warming.   </p><p> </p>

scholarly journals Cyclone impact on sea ice in the central Arctic Ocean: a statistical study

2014 ◽  
Vol 8 (1) ◽  
pp. 303-317 ◽  
Author(s):  
A. Kriegsmann ◽  
B. Brümmer
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Ocean Model ◽  
The Arctic ◽  
Central Arctic Ocean ◽  
Cumulative Impact ◽  
Model Composite ◽  
Ice Melt ◽  
The Arctic Ocean ◽  
The Impact

Abstract. This study investigates the impact of cyclones on the Arctic Ocean sea ice for the first time in a statistical manner. We apply the coupled ice–ocean model NAOSIM which is forced by the ECMWF analyses for the period 2006–2008. Cyclone position and radius detected in the ECMWF data are used to extract fields of wind, ice drift, and concentration from the ice–ocean model. Composite fields around the cyclone centre are calculated for different cyclone intensities, the four seasons, and different sub-regions of the Arctic Ocean. In total about 3500 cyclone events are analyzed. In general, cyclones reduce the ice concentration in the order of a few percent increasing towards the cyclone centre. This is confirmed by independent AMSR-E satellite data. The reduction increases with cyclone intensity and is most pronounced in summer and on the Siberian side of the Arctic Ocean. For the Arctic ice cover the cumulative impact of cyclones has climatologic consequences. In winter, the cyclone-induced openings refreeze so that the ice mass is increased. In summer, the openings remain open and the ice melt is accelerated via the positive albedo feedback. Strong summer storms on the Siberian side of the Arctic Ocean may have been important contributions to the recent ice extent minima in 2007 and 2012.

scholarly journals Cyclone impact on sea ice in the central Arctic Ocean: a statistical study

2013 ◽  
Vol 7 (2) ◽  
pp. 1141-1176 ◽  
Author(s):  
A. Kriegsmann ◽  
B. Brümmer
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Ocean Model ◽  
The Arctic ◽  
Central Arctic Ocean ◽  
Model Composite ◽  
Ice Melt ◽  
The Arctic Ocean ◽  
Arctic Ice ◽  
The Impact

Abstract. This study investigates the impact of cyclones on the Arctic Ocean sea ice for the first time in a statistical manner. We apply the coupled ice–ocean model NAOSIM which is forced by the ECMWF analyses for the period 2006–2008. Cyclone position and radius detected in the ECMWF data are used to extract fields of wind, ice drift, and concentration from the ice–ocean model. Composite fields around the cyclone centre are calculated for different cyclone intensities, the four seasons, and different regions of the Arctic Ocean. In total about 3500 cyclone events are analyzed. In general, cyclones reduce the ice concentration on the order of a few percent increasing towards the cyclone centre. This is confirmed by independent AMSR-E satellite data. The reduction increases with cyclone intensity and is most pronounced in summer and on the Siberian side of the Arctic Ocean. For the Arctic ice cover the impact of cyclones has climatologic consequences. In winter, the cyclone-induced openings refreeze so that the ice mass is increased. In summer, the openings remain open and the ice melt is accelerated via the positive albedo feedback. Strong summer storms on the Siberian side of the Arctic Ocean may have been important reasons for the recent ice extent minima in 2007 and 2012.

scholarly journals Liquid export of Arctic freshwater components through the Fram Strait 1998–2011

Ocean Science ◽  
2013 ◽  
Vol 9 (1) ◽  
pp. 91-109 ◽  
Author(s):  
B. Rabe ◽  
P. A. Dodd ◽  
E. Hansen ◽  
E. Falck ◽  
U. Schauer ◽  
...  
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Meteoric Water ◽  
The Arctic ◽  
Ice Formation ◽  
Fram Strait ◽  
Pacific Water ◽  
Ice Melt ◽  
The North ◽  
The Arctic Ocean

Abstract. We estimated the magnitude and composition of southward liquid freshwater transports in the East Greenland Current near 79° N in the Western Fram Strait between 1998 and 2011. Previous studies have found this region to be an important pathway for liquid freshwater export from the Arctic Ocean to the Nordic Seas and the North Atlantic subpolar gyre. Our transport estimates are based on six hydrographic surveys between June and September and concurrent data from moored current meters. We combined concentrations of liquid freshwater, meteoric water (river water and precipitation), sea ice melt and brine from sea ice formation, and Pacific Water, presented in Dodd et al. (2012), with volume transport estimates from an inverse model. The average of the monthly snapshots of southward liquid freshwater transports between 10.6° W and 4° E is 100 ± 23 mSv (3160 ± 730 km3 yr−1), relative to a salinity of 34.9. This liquid freshwater transport consists of about 130% water from rivers and precipitation (meteoric water), 30% freshwater from the Pacific, and −60% (freshwater deficit) due to a mixture of sea ice melt and brine from sea ice formation. Pacific Water transports showed the highest variation in time, effectively vanishing in some of the surveys. Comparison of our results to the literature indicates that this was due to atmospherically driven variability in the advection of Pacific Water along different pathways through the Arctic Ocean. Variations in most liquid freshwater component transports appear to have been most strongly influenced by changes in the advection of these water masses to the Fram Strait. However, the local dynamics represented by the volume transports influenced the liquid freshwater component transports in individual years, in particular those of sea ice melt and brine from sea ice formation. Our results show a similar ratio of the transports of meteoric water and net sea ice melt as previous studies. However, we observed a significant increase in this ratio between the surveys in 1998 and in 2009. This can be attributed to higher concentrations of sea ice melt in 2009 that may have been due to enhanced advection of freshwater from the Beaufort Gyre to the Fram Strait. Known trends and variability in the Arctic liquid freshwater inflow from rivers are not likely to have had a significant influence on the variation of liquid freshwater component transports between our surveys. On the other hand, known freshwater inflow variability from the Pacific could have caused some of the variation we observed in the Fram Strait. The apparent absence of a trend in southward liquid freshwater transports through the Fram Strait and recent evidence of an increase in liquid freshwater storage in the Arctic Ocean raise the question: how fast will the accumulated liquid freshwater be exported from the Arctic Ocean to the deep water formation regions in the North Atlantic and will an increased export occur through the Fram Strait.

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