the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Simultaneous Bering Sea and Labrador Sea ice melt extremes in March 2023: A confluence of meteorological events aligned with stratosphere-troposphere interactions
Abstract. Today’s Arctic is characterized by a lengthening of the sea ice melt season, but also by fast and at times unseasonal melt events. Such anomalous melt cases have been identified in Pacific and Atlantic Arctic sector sea ice studies. Through observational analyses, we document an unprecedented, simultaneous marginal ice zone melt event in the Bering Sea and Labrador Sea in March of 2023. Taken independently, variability in the cold season ice edge at synoptic time scales is common. However, such anomalous, short-term ice loss over either region during the climatological sea ice maxima is uncommon, and the tandem ice loss that occurred qualifies this as a rare event. The atmospheric setting that supported the unseasonal melt events was preceded by a sudden stratospheric warming event that, along with ongoing La Niña teleconnections, led to positive tropospheric height anomalies across much of the Arctic and the development of anomalous mid-troposphere ridges over the ice loss regions. These large-scale anticyclonic centers funneled extremely warm and moist airstreams onto the ice causing melt. Further analysis identified the presence of atmospheric rivers within these warm airstreams whose characteristics likely contributed to this bi-regional ice melt event. Whether such a confluence of anomalous wintertime events associated with troposphere-stratosphere coupling may occur more often in a warming Arctic remains a research area ripe for further exploration.
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CC1: 'Comment on egusphere-2024-925', Ruonan Zhang, 18 Jun 2024
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The authors investigated the effects of the SSW and La Nina teleconnections on the unseasonal melt events of the tandem ice loss over the Bring and Labrador Seas in March 2023. Associated large-scale anticyclonic anomalies funneled warm and atmospheric rivers to the bi-regional ice melt events. These results are generally interesting, focusing on the combination of stratospheric and La Nina-related tropospheric effects on Arctic surface thermal conditions. However, the atmospheric circulation features and characteristics associated with La Nina are rather unclear. I would like to propose further research into the effects of La Nina on the Arctic.
1. It is quite clear that the SSW occurred around 15 Feb and then propagated downward to the surface around 6 Mar, and the Greenland and Alaska blocking intensified. The first question is, how can we link the SSW to the increased mid-tropospheric blocking? Could the authors provide more evidence of the evolution and pattern of the polar vortex?
2. The La Nina teleconnections are highlighted in the abstract and the main paper, but the associated atmospheric circulation and physical mechanisms are missing. I do not think the present evidence is sufficient to guarantee such a causal link between La Nina and Arctic sea ice melt.
3. Surface air temperature anomalies reach up to 15K over the Labrador and Bering Seas, but the extent and area of sea ice melt is quite small. Could the authors quantify the relative changes in area, extent and concentration?
4. The atmospheric river plays an important role in Arctic warming in March. I am curious about the atmospheric water vapour transports associated with the blockings and the role of water vapour on surface temperature. Is the water vapour converted into snow or rain to lower the temperature, or is the surface warmed by increased longwave radiation?
5. Figure 5: I would suggest that the authors show the climatological daily evolution to facilitate contrasts between the extreme event and the climatology, so that the magnitude of the anomalies is more apparent. I am also curious about the magnitude of the geopotential height and 2m temperature, which reach 500m and 16k respectively. Is this correct?
Citation: https://doi.org/10.5194/egusphere-2024-925-CC1 -
RC1: 'Comment on egusphere-2024-925', Anonymous Referee #1, 19 Jun 2024
reply
The authors investigated the effects of the SSW and La Nina teleconnections on the unseasonal melt events of the tandem ice loss over the Bring and Labrador Seas in March 2023. Associated large-scale anticyclonic anomalies funneled warm and atmospheric rivers to the bi-regional ice melt events. These results are generally interesting, focusing on the combination of stratospheric and La Nina-related tropospheric effects on Arctic surface thermal conditions. However, the atmospheric circulation features and characteristics associated with La Nina are rather unclear. I would like to propose further research into the effects of La Nina on the Arctic.
1. It is quite clear that the SSW occurred around 15 Feb and then propagated downward to the surface around 6 Mar, and the Greenland and Alaska blocking intensified. The first question is, how can we link the SSW to the increased mid-tropospheric blocking? Could the authors provide more evidence of the evolution and pattern of the polar vortex?
2. The La Nina teleconnections are highlighted in the abstract and the main paper, but the associated atmospheric circulation and physical mechanisms are missing. I do not think the present evidence is sufficient to guarantee such a causal link between La Nina and Arctic sea ice melt.
3. Surface air temperature anomalies reach up to 15K over the Labrador and Bering Seas, but the extent and area of sea ice melt is quite small. Could the authors quantify the relative changes in area, extent and concentration?
4. The atmospheric river plays an important role in Arctic warming in March. I am curious about the atmospheric water vapour transports associated with the blockings and the role of water vapour on surface temperature. Is the water vapour converted into snow or rain to lower the temperature, or is the surface warmed by increased longwave radiation?
5. Figure 5: I would suggest that the authors show the climatological daily evolution to facilitate contrasts between the extreme event and the climatology, so that the magnitude of the anomalies is more apparent. I am also curious about the magnitude of the geopotential height and 2m temperature, which reach 500m and 16k respectively. Is this correct?
Citation: https://doi.org/10.5194/egusphere-2024-925-RC1
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