Impact of Ural Blocking on Early Winter Climate Variability Under Different Barents‐Kara Sea Ice Conditions

Journal of Geophysical Research Atmospheres, Год журнала: 2023, Номер 128(6)

Опубликована: Март 8, 2023

Abstract Ural blocking (UB) is a prominent mode of variability the Northern Hemisphere atmospheric circulation, particularly in fall. It can persist for several days and exert lagged influence on wintertime NH providing predictability at subseasonal time scale. Using two models, we explore how early winter circulation responds to 2‐week persistent UB anomaly imposed November. Experiments are carried out with different configurations Barents‐Kara (BK) sea‐ice concentration examine whether it plays role impacts variability. In both followed by weakening stratospheric polar vortex negative phase North Atlantic Oscillation (NAO), which lasts up 2 months after forcing released. Interestingly, response more under low BK conditions, that is, sea ice modulates UB. Additional experiments prescribed anomalies alone suggest exerts limited The involves persists longer ice, explains configuration. Our study highlights November robust precursor NAO/polar stratosphere anomalies, this may be relevant context declining Arctic extent. Provided climate models accurately capture teleconnection, has potential improve predictions climate.

Язык: Английский

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Reconciling conflicting evidence for the cause of the observed early 21st century Eurasian cooling

Weather and Climate Dynamics, Год журнала: 2023, Номер 4(1), С. 95 - 114

Опубликована: Янв. 18, 2023

Abstract. It is now well established that the Arctic warming at a faster rate than global average. This warming, which has been accompanied by dramatic decline in sea ice, linked to cooling over Eurasian subcontinent recent decades, most dramatically during period 1998–2012. counter-intuitive impact under given land regions should warm more ocean (and average). Some studies have proposed causal teleconnection from sea-ice retreat wintertime cooling; other argue mainly driven internal variability. Overall, there an impression of strong disagreement between those holding “ice-driven” versus “internal variability” viewpoints. Here, we offer alternative framing showing ice and variability views can be compatible. Key this viewing through lens dynamics (linked primarily with some potential contribution ice; cools Eurasia) thermodynamics retreat; warms Eurasia). approach, combined recognition uncertainty hypothesized mechanisms themselves, allows both viewpoints others) co-exist contribute our understanding cooling. A simple autoregressive model shows magnitude consistent variability, periods exhibiting stronger others, either chance or forced changes. Rather posit “yes-or-no” relationship cooling, constructive way forward consider whether trend was likely observed loss, as sources low-frequency Taken are factors affect likelihood regional presence ongoing warming.

Язык: Английский

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Improved teleconnection between Arctic sea ice and the North Atlantic Oscillation through stochastic process representation

Weather and Climate Dynamics, Год журнала: 2022, Номер 3(3), С. 951 - 975

Опубликована: Авг. 17, 2022

Abstract. The extent to which interannual variability in Arctic sea ice influences the mid-latitude circulation has been extensively debated. While observational data support existence of a teleconnection between November Barents–Kara region and subsequent winter North Atlantic Oscillation, climate models do not consistently reproduce such link, with only very weak inter-model consensus. We show, using EC-Earth3 model, that while an ensemble coupled simulations shows no evidence teleconnection, inclusion stochastic parameterizations ocean component results emergence robust comparable magnitude observed. exact mechanisms causing this remain unclear, we argue it can be accounted for by improved ice–ocean–atmosphere coupling due perturbations, aim represent effect unresolved variability. In particular, consensus may large model biases surface coupling, being one possible remedy.

Язык: Английский

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Significant contribution of internal variability to recent Barents–Kara sea ice loss in winter

Communications Earth & Environment, Год журнала: 2024, Номер 5(1)

Опубликована: Авг. 2, 2024

The Arctic has experienced a rapid sea ice loss in the Barents and Kara Seas winter over satellite era. Such been modulated by anthropogenic forcing internal variability, but precise estimate of their relative contribution remains unclear. Here, using large ensemble simulations machine-learning techniques, we successfully reproduce wintertime Barents-Kara trends as joint impact variability components. Over whole period, contributes about 70% to loss, with contributing remainder. However, is more important explaining varying shorter periods (~20 years), including accelerated up 2017, consistent an extreme, unforced atmospheric circulation dipole trend Euro-Atlantic sector. Overall, this study highlights that plays role shaping recent than previously thought, implications for projections use machine learning methods future attribution studies. Internal period though primary influence, according analyzed machine-learning.

Язык: Английский

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Evaluating Causal Arctic‐Midlatitude Teleconnections in CMIP6

Journal of Geophysical Research Atmospheres, Год журнала: 2023, Номер 128(17)

Опубликована: Сен. 2, 2023

Abstract To analyze links among key processes that contribute to Arctic‐midlatitude teleconnections we apply causal discovery based on graphical models known as graphs. First, calculate the dependencies from observations during 1980–2021. Observations show several robust connections early late winter, such atmospheric blocking within central Asia via Ural and Siberian High, North Atlantic Oscillation phase polar vortex (PV). The PV is affected by poleward eddy heat flux at 100 hPa, which also directly connected with Aleutian Low. We then evaluate climate participating in Coupled Model Intercomparison Project Phase 6 (CMIP6) comparing their graphs those derived observations. Compared observations, CMIP6 historical future simulations do not robustly capture arising Arctic sea ice variability. This highlights role of internal variability modulating teleconnections. However, find distinct patterns are simulated most analyzed models. For example, both model observed Asia. But contrary a link between temperature cover over Barents Kara seas. analysis changes reveals connection Low hPa expected become more toward end 21st century than past.

Язык: Английский

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Reconciling conflicting evidence for the cause of the observed early 21st century Eurasian cooling

Опубликована: Июнь 20, 2022

Abstract. It is now well established that the Arctic warming at a faster rate than global average. This warming, which has been accompanied by dramatic decline in sea ice, linked to cooling over Eurasian subcontinent recent decades, most dramatically during period 1998–2012. counterintuitive impact under given land regions should warm more ocean (and average). Some studies have proposed causal teleconnection from ice retreat wintertime cooling; other argue mainly driven internal variability and relationship coincidental. Overall, there an impression of strong disagreement between those holding “ice-driven” versus “internal variability” viewpoints. Here, we offer alternative framing showing views can be compatible. Key this viewing through lens dynamics (linked primarily with small contribution ice; cools Eurasia) thermodynamics retreat; warms Eurasia). approach, combined recognition uncertainty hypothesized mechanisms themselves, allow both viewpoints others) co-exist contribute our understanding cooling. A simple autoregressive model shows magnitude consistent variability, some periods being susceptible others. Rather posit “yes-or-no” cooling, constructive way forward consider whether trend was likely observed loss, as sources low-frequency variability. Taken are factors affect likelihood regional presence ongoing warming.

Язык: Английский

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Climatic variability of the ice extent of the Barents Sea and its individual areas

Arctic and Antarctic Research, Год журнала: 2022, Номер 68(3), С. 234 - 247

Опубликована: Сен. 27, 2022

The ongoing decrease in the ice coveren is one of main consequences global climate change. Barents Sea, as part North European basin, an area that first to react these changes. According AARI database, before start current century extent winter season varied from 600·10 3 km 2 900·10 different years, while over past 20 years lower border has dropped 350·10 . At same time, summer decreased more than times. aim article study statistical structure longterm variability on basis latest data, order identify patterns change characteristic individual areas Sea decades. research methods include basic statistics, linear trend, stationary assessment, autocorrelation and correlation coefficient. work contains numerical estimates trend component for all parts water area. maximum contribution due northeastern region comprises 63 %. seasonal fluctuations are southeastern region, with almost complete freezing (up 99 %, northeast) clearing absence old ice. least connection other (R less 0.25) its characteristics depends a greater not only circulation cold Arctic waters entry warm Atlantic water, but also river runoff. north-eastern characterized by capacity retaining “memory” previous state 5 which indicates highest inertia factors making extent. speed reducing because melting estimated at 1.76·10 /month, rate increase result growth 1.26·10 /month. Accordingly, melts faster it time grow, leads

Язык: Английский

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Tropical Forcing of Barents‐Kara Sea Ice During Autumn

Geophysical Research Letters, Год журнала: 2023, Номер 50(8)

Опубликована: Апрель 23, 2023

Abstract The causality of the link between Autumn Barents‐Kara (BK) sea ice and winter North Atlantic Oscillation (NAO) is uncertain, given teleconnections stemming from tropics may influence both extra‐tropics Arctic. We explore relationship tropical rainfall BK in autumn, by nudging to follow observed variability otherwise free running ensemble simulations. Tropical forcing alone can skillfully reproduce a significant fraction interannual NAO late autumn. also show that strongly related simulated ice. As result, we are able some autumn However, only during strong 1997 El Niño clear influences at high latitudes found. Large ensembles required detect forced models latitudes.

Язык: Английский

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The Influence of Arctic Sea Ice Concentration Perturbations on Subseasonal Predictions of North Atlantic Oscillation Events

Advances in Atmospheric Sciences, Год журнала: 2023, Номер 40(12), С. 2242 - 2261

Опубликована: Сен. 8, 2023

Язык: Английский

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Circulation responses to surface heating and implications for polar amplification

Опубликована: Янв. 4, 2024

Abstract. A seminal study by Hoskins and Karoly (1981) explored the atmospheric circulation response to tropospheric heating perturbations at low mid latitudes. Here we revisit extend their investigating temperature low, high latitude surface using an idealised moist, gray radiation model. Our results corroborate previous findings showing that latitudes are balanced different mean responses - upward motion horizontal advection, respectively. Transient eddy heat flux divergence plays increasingly important role with latitude, becoming main However, this mechanism is less efficient balancing than leading greater reliance on additional contribution from radiative cooling. These dynamical adjustments promote stronger lower warming for compared latitudes, suggesting a which sea ice loss promotes polar-amplified signal of climate change.

Язык: Английский

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