Trends and variability in polar sea ice, global atmospheric circulations, and baroclinicity

Revisiting the Linkages between the Variability of Atmospheric Circulations and Arctic Melt-Season Sea Ice Cover at Multiple Time Scales

10.5194/egusphere-egu2020-373 ◽

2020 ◽

Author(s):

Lejiang Yu ◽

Sharon Zhong

Keyword(s):

Sea Ice ◽

Arctic Ocean ◽

Time Scales ◽

Arctic Sea Ice ◽

The Arctic ◽

Multiple Time Scales ◽

Multiple Time ◽

Atmospheric Circulations ◽

The Pacific ◽

Arctic Sea

The sharp decline of Arctic sea ice in recent decades has captured the attention of the climate science community. A majority of climate analyses performed to date have used monthly or seasonal data. Here, however, we analyze daily sea ice data for 1979&#8211;2016 using the self-organizing map (SOM) method to further examine and quantify the contributions of atmospheric circulation changes to the melt-season Arctic sea ice variability. Our results reveal two main variability modes: the Pacific sector mode and the Barents and Kara Seas mode, which together explain about two-thirds of the melt-season Arctic sea ice variability and more than 40% of its trend for the study period. The change in the frequencies of the two modes appears to be associated with the phase shift of the Pacific decadal oscillation (PDO) and the Atlantic multidecadal oscillation (AMO). The PDO and AMO trigger anomalous atmospheric circulations, in particular, the Greenland high and the North Atlantic Oscillation and anomalous warm and cold air advections into the Arctic Ocean. The changes in surface air temperature, lower-atmosphere moisture, and downwelling longwave radiation associated with the advection are consistent with the melt-season sea ice anomalies observed in various regions of the Arctic Ocean. These results help better understand the predictability of Arctic sea ice on multiple (synoptic, intraseasonal, and interannual) time scales.

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

Journal of Climate ◽

10.1175/jcli-d-20-0779.1 ◽

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.

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Revisiting the Linkages between the Variability of Atmospheric Circulations and Arctic Melt-Season Sea Ice Cover at Multiple Time Scales

Journal of Climate ◽

10.1175/jcli-d-18-0301.1 ◽

2019 ◽

Vol 32 (5) ◽

pp. 1461-1482 ◽

Cited By ~ 5

Author(s):

Lejiang Yu ◽

Shiyuan Zhong ◽

Mingyu Zhou ◽

Donald H. Lenschow ◽

Bo Sun

Keyword(s):

Sea Ice ◽

Arctic Ocean ◽

Time Scales ◽

Arctic Sea Ice ◽

The Arctic ◽

Multiple Time Scales ◽

Atmospheric Circulations ◽

The Pacific ◽

Arctic Sea ◽

The Arctic Ocean

Abstract The sharp decline of Arctic sea ice in recent decades has captured the attention of the climate science community. A majority of climate analyses performed to date have used monthly or seasonal data. Here, however, we analyze daily sea ice data for 1979–2016 using the self-organizing map (SOM) method to further examine and quantify the contributions of atmospheric circulation changes to the melt-season Arctic sea ice variability. Our results reveal two main variability modes: the Pacific sector mode and the Barents and Kara Seas mode, which together explain about two-thirds of the melt-season Arctic sea ice variability and more than 40% of its trend for the study period. The change in the frequencies of the two modes appears to be associated with the phase shift of the Pacific decadal oscillation (PDO) and the Atlantic multidecadal oscillation (AMO). The PDO and AMO trigger anomalous atmospheric circulations, in particular, the Greenland high and the North Atlantic Oscillation and anomalous warm and cold air advections into the Arctic Ocean. The changes in surface air temperature, lower-atmosphere moisture, and downwelling longwave radiation associated with the advection are consistent with the melt-season sea ice anomalies observed in various regions of the Arctic Ocean. These results help better understand the predictability of Arctic sea ice on multiple (synoptic, intraseasonal, and interannual) time scales.

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Attribution of late summer early autumn Arctic sea ice decline in recent decades

npj Climate and Atmospheric Science ◽

10.1038/s41612-020-00157-4 ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Lejiang Yu ◽

Shiyuan Zhong ◽

Timo Vihma ◽

Bo Sun

Keyword(s):

Sea Ice ◽

Arctic Sea Ice ◽

The Arctic ◽

Atmospheric Circulations ◽

Sea Ice Decline ◽

Decadal Scale ◽

Downward Longwave Radiation ◽

Arctic Sea ◽

Circulation Changes ◽

Thermodynamic Processes

AbstractThe underlying mechanisms for Arctic sea ice decline can be categories as those directly related to changes in atmospheric circulations (often referred to as dynamic mechanisms) and the rest (broadly characterized as thermodynamic processes). An attribution analysis based on the self-organizing maps (SOM) method is performed to determine the relative contributions from these two types of mechanisms to the Arctic sea ice decline in August–October during 1979–2016. The daily atmospheric circulations represented by daily 500-hPa geopotential height anomalies are classified into 12 SOM patterns, which portray the spatial structures of the Arctic Oscillation and Arctic Dipole, and their transitions. Due to the counterbalance between the opposite trends among the circulation patterns, the net effect of circulation changes is small, explaining only 1.6% of the declining trend in the number of August–October sea ice days in the Arctic during 1979–2016. The majority of the trend (95.8%) is accounted for by changes in thermodynamic processes not directly related to changes in circulations, whereas for the remaining trend (2.6%) the contributions of circulation and non-circulation changes cannot be distinguished. The sea ice decline is closely associated with surface air temperature increase, which is related to increasing trends in atmospheric water vapor content, downward longwave radiation, and sea surface temperatures over the open ocean, as well as to decreasing trends in surface albedo. An analogous SOM analysis extending seasonal coverage to spring (April–October) for the same period supports the dominating role of thermodynamic forcing in decadal-scale Arctic sea ice loss.

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Possible Relationship between the Chukchi Sea Ice in the Early Winter and the February Haze Pollution in the North China Plain

Journal of Climate ◽

10.1175/jcli-d-18-0634.1 ◽

2019 ◽

Vol 32 (16) ◽

pp. 5179-5190 ◽

Cited By ~ 7

Author(s):

Zhicong Yin ◽

Huijun Wang ◽

Xiaohui Ma

Keyword(s):

Sea Ice ◽

Large Scale ◽

North China Plain ◽

North China ◽

Chukchi Sea ◽

Early Winter ◽

Atmospheric Circulations ◽

The North ◽

The North China Plain ◽

Haze Pollution

AbstractHaze pollution is among the most serious disasters in the North China Plain, dramatically damaging human health and the social economy. The frequency of haze events in February typically varies from the number of haze days in the winter. To improve the understanding of haze pollution in February, this study not only showed the large-scale atmospheric circulations associated with the variation in the haze, but also analyzed its connection with Arctic sea ice. The observational and large ensemble model results both illustrated that the preceding increase in the early-winter Chukchi Sea ice might intensify the February haze pollution. The accumulated sea ice over the Chukchi Sea resulted in a steeper meridional sea surface temperature gradient and a significant and persistent westerly thermal wind. In February, the responsive pattern in the atmosphere developed into a Rossby wave–like pattern, linking the Chukchi Sea ice and the February haze pollution. Modulating by the induced large-scale atmospheric circulations, the horizontal and vertical atmospheric ventilation conditions and the hygroscopic growth conditions enhanced the frequency of haze pollution events.

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