Interaction between Atlantic cyclones and Eurasian atmospheric blocking drives wintertime warm extremes in the high Arctic

Abstract. Atmospheric blocking can influence Arctic weather by diverting the mean westerly flow and steering cyclones polewards, bringing warm, moist air to high latitudes. Recent studies have shown that diabatic heating processes in the ascending warm conveyor belt branch of extratropical cyclones are relevant to blocking dynamics. This leads to the question of the extent to which diabatic heating associated with mid-latitude cyclones may influence high-latitude blocking and drive Arctic warm events. In this study we investigate the dynamics behind 50 extreme warm events of wintertime high-Arctic temperature anomalies during 1979–2016. Classifying the warm events based on blocking occurrence within three selected sectors, we find that 30 of these events are associated with a block over the Urals, featuring negative upper-level potential vorticity (PV) anomalies over central Siberia north of the Ural Mountains. Lagrangian back-trajectory calculations show that almost 60 % of the air parcels making up these negative PV anomalies experience lifting and diabatic heating (median 11 K) in the 6 d prior to the block. Further, almost 70 % of the heated trajectories undergo maximum heating in a compact region of the mid-latitude North Atlantic, temporally taking place between 6 and 1 d before arriving in the blocking region. We also find anomalously high cyclone activity (on average five cyclones within this 5 d heating window) within a sector northwest of the main heating domain. In addition, 10 of the 50 warm events are associated with blocking over Scandinavia. Around 60 % of the 6 d back trajectories started from these blocks experience diabatic heating, of which 60 % undergo maximum heating over the North Atlantic but generally closer to the time of arrival in the block and further upstream relative to heated trajectories associated with Ural blocking. This study suggests that, in addition to the ability of blocks to guide cyclones northwards, Atlantic cyclones play a significant role in the dynamics of high-latitude blocking by providing low-PV air via moist-diabatic processes. This emphasizes the importance of the mutual interactions between mid-latitude cyclones and Eurasian blocking for wintertime Arctic warm extremes.

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Interaction between Atlantic cyclones and Eurasian atmospheric blocking drives warm extremes in the high Arctic

10.5194/wcd-2021-23 ◽

2021 ◽

Author(s):

Sonja Murto ◽

Rodrigo Caballero ◽

Gunilla Svensson ◽

Lukas Papritz

Keyword(s):

North Atlantic ◽

High Latitude ◽

Diabatic Heating ◽

High Arctic ◽

Back Trajectory ◽

Time Of Arrival ◽

Atmospheric Blocking ◽

Ural Mountains ◽

Maximum Heating ◽

Midlatitude Cyclones

Abstract. Atmospheric blocking can influence Arctic weather by diverting the mean westerly flow polewards, bringing warm, moist air to high latitudes. Recent studies have shown that diabatic heating processes in the ascending warm conveyor belt branch of extratropical cyclones are relevant to blocking dynamics. This leads to the question of the extent to which diabatic heating associated with midlatitude cyclones may influence high-latitude blocking and drive Arctic warm events. In this study we investigate the dynamics behind 50 extreme warm events of wintertime high Arctic temperature anomalies. Classifying the warm events based on blocking occurrence within three selected sectors, we find that 30 of these events are associated with a block over the Urals, featuring negative upper-level PV anomalies over central Siberia north of the Ural Mountains. Lagrangian back-trajectory calculations show that almost 60 % of the air parcels making up these negative PV anomalies experience lifting and diabatic heating (median 11 K) in the six days prior to the block. Further, almost 70 % of the heated trajectories undergo maximum heating in a compact region of the midlatitude North Atlantic, temporally taking place between six and one days before arriving in the blocking region. We also find anomalously high cyclone activity (on average five cyclones within this five-day heating window) within a sector northwest of the main heating domain. In addition, 10 of the 50 warm events are associated with blocking over Scandinavia; the contribution of diabatic heating to these blocks is again around 60 % for six-day back-trajectories, of which 60 % undergo maximum heating over the North Atlantic but generally closer to the time of arrival in the block and further upstream relative to heated trajectories associated with Ural blocking. This study highlights the role of diabatic heating in high-latitude blocking dynamics and the importance of the interaction between midlatitude cyclones and Eurasian blocking as driver for Arctic warm extremes.

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Interaction between Atlantic cyclones and Eurasian atmospheric blocking drives warm extremes in the high Arctic

10.5194/egusphere-egu21-8719 ◽

2021 ◽

Author(s):

Sonja Murto ◽

Rodrigo Caballero ◽

Gunilla Svensson ◽

Lukas Papritz

Keyword(s):

Diabatic Heating ◽

High Arctic ◽

Conveyor Belt ◽

Back Trajectory ◽

Atmospheric Blocking ◽

Ural Mountains ◽

Compact Region ◽

Westerly Flow ◽

Upper Level ◽

Maximum Heating

<p>Atmospheric blocking can influence Arctic weather by diverting the mean westerly flow polewards, bringing warm, moist air to high latitudes. Recent studies have shown that diabatic heating processes in the ascending warm conveyor belt branch of extratropical cyclones are relevant to blocking dynamics. This leads to the question of the extent to which diabatic heating associated with mid-latitude cyclones may influence high-latitude blocking and drive Arctic warm events. In this study we investigate the dynamics behind 50 extreme warm events of wintertime high Arctic surface temperature anomalies. We find that 30 of these events are associated with &#8220;Ural&#8221; blocking, featuring negative upper-level PV anomalies over central Siberia north of the Ural Mountains. Lagrangian back-trajectory calculations show that almost 70% of the air parcels making up these negative PV anomalies experience lifting and diabatic heating (average 14,7 K) in the 9-days prior to blocking. Further, 43,4 % of the heated trajectories undergo maximum heating and lifting in a compact region of the midlatitude North Atlantic, temporally taking place between 6 and 2.5 days before arriving in the blocking region. These trajectories mainly reside in the subtropics before being advected into the lifting region. We also find anomalously high cyclonic activity (on average 3,9 cyclones within a 3,5-day window around the time of maximum lifting) within a sector northwest of the main lifting domain. This study highlights the importance of the interaction between mid-latitude cyclones and Eurasian blocking as driver for Arctic warm extremes.</p>

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Two Types of Mid-High-Latitude Low-Frequency Intraseasonal Oscillations Near the Ural Mountains During Boreal Summer

Journal of Climate ◽

10.1175/jcli-d-20-0589.1 ◽

2021 ◽

pp. 1-56

Author(s):

Tao Zhu ◽

Jing Yang

Keyword(s):

North America ◽

North Atlantic ◽

High Latitude ◽

Eastern China ◽

Low Frequency ◽

Boreal Summer ◽

Decadal Change ◽

Mean Flow ◽

Ural Mountains ◽

Intraseasonal Oscillations

AbstractTwo types of mid-high-latitude low-frequency intraseasonal oscillations (LF ISOs), featuring eastward and westward propagation, have been identified over the Eurasian continent in the past 37 summers (1982–2018). The eastward and westward propagating modes commonly have a dominant periodicity of 30–50 days near the Ural Mountains (UM) but have different origins and evolutions. The eastward propagating LF-ISO initiates over the eastern North America, migrates northeastward across the northeastern North America-Western North Atlantic, central North Atlantic, Western Europe and the UM, then propagates southeastward to northwestern and eastern China, which is the Atlantic-Eurasian continental mode. In contrast, the westward propagating mode is quasi-circumpolar, initiating over the East Siberian Sea and moving southwestward across the UM, northern Europe and eventually reaching Greenland and Canadian Arctic Archipelago. These two mid-high-latitude LF-ISOs are accompanied by significant tropical intraseasonal variations with evident tropical-extratropical interactions. Meanwhile, these two LF-ISOs have different decadal preferences before and after 2000, which are ascribed to the decadal change of both intraseasonal efficient kinetic energy obtained from the mean flow over their genesis region and their background flow associated with the North Atlantic Oscillation/Arctic Oscillation decadal change. This study deepens the understanding of subseasonal variations for mid-high-latitudes and subseasonal prediction sources for low-latitude regions.

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Simulation and Projection of Northern Hemisphere Blockings In CMIP5 Models

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.962-965.1308 ◽

2014 ◽

Vol 962-965 ◽

pp. 1308-1313 ◽

Cited By ~ 1

Author(s):

Pei Long Ye ◽

Yan Li

Keyword(s):

North Atlantic ◽

High Latitude ◽

Coupled Model ◽

Cold Season ◽

Reanalysis Data ◽

Cmip5 Models ◽

Atmospheric Blocking ◽

Increasing Trend ◽

Intercomparison Project ◽

Blocking Index

The frequencies of atmospheric blocking are analyzed as simulated in 16 models from phase 5 of the Coupled Model Intercomparison Project (CMIP5) over North Hemisphere especially over key regions where blocking highs influencing China (the Ural, Baikal and Okhotsk), and the Representative Concentration Pathway 4.5 (RCP4.5) integrations are used to examine projected future changes in a warmer climate. Comparison with reanalysis data reveals that the frequencies of North Atlantic-Eurasia blocking are significantly underestimated throughout the year, however, multi-model mean generally overestimates the blocking frequency over high-latitude of Pacific. Ural blocking, Lake Baikal and Okhotsk Sea blocking frequencies are found to be mainly underestimated especially during the cold season. The RCP4.5 integrations show a heavily reduced for blocking frequency over North Atlantic and higher latitude of Eurasia in 2044-2099, but high-latitude blocking over Atlantic and Pacific presents a small increase. A significant increase of the Ural blocking is found. In contrast to the trend of blocking index for RCP4.5 path in the second half of the 21st, the increasing trend from 2006 to 2050 is distinct, the blocking increasing trend is more significant in summer than in winter over the three regions.

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Trends in cyclones in the high‐latitude North Atlantic during 1979–2016

Quarterly Journal of the Royal Meteorological Society ◽

10.1002/qj.3707 ◽

2019 ◽

Vol 146 (727) ◽

pp. 762-779 ◽

Cited By ~ 5

Author(s):

S. Wickström ◽

M. O. Jonassen ◽

T. Vihma ◽

P. Uotila

Keyword(s):

North Atlantic ◽

High Latitude

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Potential Source Areas for Atmospheric Lead Reaching Ny-Ålesund from 2010 to 2018

Atmosphere ◽

10.3390/atmos12030388 ◽

2021 ◽

Vol 12 (3) ◽

pp. 388

Author(s):

Andrea Bazzano ◽

Stefano Bertinetti ◽

Francisco Ardini ◽

David Cappelletti ◽

Marco Grotti

Keyword(s):

North American ◽

Enrichment Factors ◽

Atmospheric Particulate Matter ◽

Back Trajectory ◽

Pb Isotope ◽

Back Trajectories ◽

Source Areas ◽

The North ◽

Central Asian ◽

Pb Concentration

Lead content, enrichment factors, and isotopic composition (208Pb/206Pb and 207Pb/206Pb) measured in atmospheric particulate matter (PM10) samples collected for nine years at Ny-Ålesund (Svalbard islands, Norwegian Arctic) during spring and summer are presented and discussed. The possible source areas (PSA) for particulate inferred from Pb isotope ratio values were compared to cluster analysis of back-trajectories. Results show that anthropogenic Pb dominates over natural crustal Pb, with a recurring higher influence in spring, compared to summer. Crustal Pb accounted for 5–16% of the measured Pb concentration. Anthropogenic Pb was affected by (i) a Central Asian PSA with Pb isotope signature compatible with ores smelted in the Rudny Altai region, at the Russian and Kazakhstan border, which accounted for 85% of the anthropogenic Pb concentration, and (ii) a weaker North American PSA, contributing for the remaining 15%. Central Asian PSA exerted an influence on 71–86% of spring samples, without any significant interannual variation. On the contrary, 59–87% of summer samples were influenced by the North American PSA, with higher contributions during 2015 and 2018. Back-trajectory analysis agreed on the seasonal difference in PSA and highlighted a possible increased influence for North American air masses during summer 2010 and 2018, but not for summer 2015.

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Distributions of Arctic and Northwest Atlantic killer whales inferred from oxygen isotopes

Scientific Reports ◽

10.1038/s41598-021-86272-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Cory J. D. Matthews ◽

Fred J. Longstaffe ◽

Jack W. Lawson ◽

Steven H. Ferguson

Keyword(s):

Oxygen Isotopes ◽

North Atlantic ◽

High Latitude ◽

Newfoundland And Labrador ◽

Killer Whales ◽

Low Latitude ◽

Northwest Atlantic ◽

Oxygen And Carbon Isotope ◽

Stable Oxygen ◽

Morphological Differences

AbstractKiller whales (Orcinus orca) are distributed widely in all oceans, although they are most common in coastal waters of temperate and high-latitude regions. The species’ distribution has not been fully described in the northwest Atlantic (NWA), where killer whales move into seasonally ice-free waters of the eastern Canadian Arctic (ECA) and occur year-round off the coast of Newfoundland and Labrador farther south. We measured stable oxygen and carbon isotope ratios in dentine phosphate (δ18OP) and structural carbonate (δ18OSC, δ13CSC) of whole teeth and annual growth layers from killer whales that stranded in the ECA (n = 11) and NWA (n = 7). Source δ18O of marine water (δ18Omarine) at location of origin was estimated from dentine δ18OPvalues, and then compared with predicted isoscape values to assign individual distributions. Dentine δ18OPvalues were also assessed against those of other known-origin North Atlantic odontocetes for spatial reference. Most ECA and NWA killer whales had mean δ18OPand estimated δ18Omarinevalues consistent with18O-depleted, high-latitude waters north of the Gulf Stream, above which a marked decrease in baseline δ18O values occurs. Several individuals, however, had relatively high values that reflected origins in18O-enriched, low-latitude waters below this boundary. Within-tooth δ18OSCranges on the order of 1–2‰ indicated interannual variation in distribution. Different distributions inferred from oxygen isotopes suggest there is not a single killer whale population distributed across the northwest Atlantic, and corroborate dietary and morphological differences of purported ecotypes in the region.

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