Predictors and prediction skill for marine cold‐air outbreaks over the Barents Sea

Polkova, Iuliia; Afargan‐Gerstman, Hilla; Domeisen, Daniela I.V.; King, Martin P.; Ruggieri, Paolo; Athanasiadis, Panos; Dobrynin, Mikhail; Aarnes, Øivin; Kretschmer, Marlene; Baehr, Johanna

doi:10.1002/qj.4038

Cited by 10 publications

(14 citation statements)

References 60 publications

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“…The choice of the characteristic pressure level used for computing the conventional MCAO index varies substantially amongst previous studies -from 500 hPa (Landgren et al, 2019), to 700 hPa (Kolstad et al, 2009), 800 hPa (Fletcher et al, 2016), 850 hPa (Papritz et al, 2015;Kolstad, 2017;Polkova et al, 2019Polkova et al, , 2021, and 900 hPa (Papritz and Sodemann, 2018). Consequently, the magnitude of the MCAO index values, as well as the geographical extent of areas with positive MCAO index values, differs between studies, and a classification into weak, moderate, and strong MCAO events requires adjustment accordingly.…”

Section: Introductionmentioning

confidence: 99%

Interactive 3-D visual analysis of ERA5 data: improving diagnostic indices for marine cold air outbreaks and polar lows

Meyer

Polkova

Modali³

et al. 2021

Weather Clim. Dynam.

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Abstract. Recent advances in visual data analysis are well suited to gain insights into dynamical processes in the atmosphere. We apply novel methods for three-dimensional (3-D) interactive visual data analysis to investigate marine cold air outbreaks (MCAOs) and polar lows (PLs) in the recently released ERA5 reanalysis data. Our study aims at revealing 3-D perspectives on MCAOs and PLs in ERA5 and at improving the diagnostic indices to capture these weather events in long-term assessments on seasonal and climatological timescales. Using an extended version of the open-source visualization framework Met.3D, we explore 3-D perspectives on the structure and dynamics of MCAOs and PLs and relate these to previously used diagnostic indices. Motivated by the 3-D visual analysis of selected MCAO and PL cases, we conceptualize alternative index variants that capture the vertical extent of MCAOs and their distance to the dynamical tropopause. The new index variants are evaluated, along with previously used indices, with a focus on their skill as a proxy for the occurrence of PLs. Testing the association of diagnostic indices with observed PLs in the Barents and the Nordic seas for the years 2002–2011 shows that the new index variants based on the vertical structure of cold air masses are more skilful in distinguishing the times and locations of PLs, compared with conventional indices based on sea–air temperature difference only. We thus propose using the new diagnostics for further analyses in climate predictions and climatological studies. The methods for visual data analysis applied here are available as an open-source tool and can be used generically for interactive 3-D visual analysis of atmospheric processes in ERA5 and other gridded meteorological data.

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Section: Introductionmentioning

confidence: 99%

Interactive 3-D visual analysis of ERA5 data: improving diagnostic indices for marine cold air outbreaks and polar lows

Meyer

Polkova

Modali³

et al. 2021

Weather Clim. Dynam.

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“…To address this challenge, we suggest a simple method that results in a computationally cheaper, region-specific variant of the conventional MCAO index, which maintains the same quantitative link to observed PLs as the new MCAO index. Instead of using a subjectively chosen characteristic pressure level for calculating the conventional MCAO index (Kolstad et al, 2009;Papritz et al, 2015;Fletcher et al, 2016;Kolstad, 2017;Papritz and Sodemann, 2018;Landgren et al, 2019;Polkova et al, 2019Polkova et al, , 2021, we introduce a region-specific MCAO index,…”

Section: Methods For Determining a Region-specific Characteristic Pressure Level For The Conventional Mcao Index From Data About Observedmentioning

confidence: 99%

“…The term "conventional MCAO index" summarizes previously-used diagnostics that are based on the difference in potential temperature between the ocean surface and a fixed characteristic pressure level aloft, as e.g. 850 hPa (Papritz et al, 2015;Kolstad, 2017;Polkova et al, 2019Polkova et al, , 2021, or others (Kolstad et al, 2009;Fletcher et al, 2016;Papritz and Sodemann, 2018;Landgren et al, 2019). The variants of the conventional MCAO index and the new indices are introduced and evaluated here for avoiding the subjective element in the choice of the characteristic pressure level and for capturing the vertical structure of MCAOs.…”

Section: Characterizing Mcao and Pls With New Diagnostic Indicesmentioning

confidence: 99%

“…Marine Cold Air Outbreaks (MCAOs) are transport events of cold air from sea-ice or snow-covered regions towards relatively warmer oceans (Rasmussen, 1983;Kolstad and Bracegirdle, 2008;Gryschka, 2018;Polkova et al, 2021). Understanding MCAOs is relevant because they represent conditions favourable for extreme weather phenomena known as Polar Lows (PLs) (Rasmussen, 1983;Ese et al, 1988;Kolstad, 2011;Michel et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

“…The temperature gradient is termed MCAO index, where positive potential temperature difference between the ocean surface and the air aloft indicates vertical instability. Conventional MCAO indices (Papritz et al, 2015;Kolstad, 2017;Polkova et al, 2019Polkova et al, , 2021 have the form…”

Section: Introductionmentioning

confidence: 99%

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Comment on wcd-2021-20

Meyer

2021

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Causal model evaluation of Arctic-midlatitude teleconnections in CMIP6

Galytska

Weigel

Handorf

et al. 2022

Preprint

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In this study, we apply causal discovery to analyse causal links among key processes that contribute to Arctic-midlatitude teleconnections. First, we calculate the causal dependencies from observations. We then evaluate climate models participating in the Coupled Model Intercomparison Project Phase 6 (CMIP6) via a comparison of their causal graphs for the period of 1979-2019 with those derived from observations. Based on observations, we show that the increase (decline) of near-surface Arctic temperature is associated not only with the reduction (increase) of sea ice over the Barents and Kara seas, but also with the strengthening (weakening) of atmospheric blocking over central Asia. We show that the near-surface westerly winds are strongly associated with the phase of the North Atlantic Oscillation (NAO). Observations show that the phase of NAO is connected with the polar vortex (PV), which is affected by the strengthening of the poleward eddy heat flux at 100 hPa. The analysis of CMIP6 historical simulations is in good agreement with the observations but reveals a negative connection between near-surface Arctic temperature and sea ice over Barents and Kara seas, which was not found in observations during December-January-February 1979-2019. Moreover, climate models simulate a more robust link between Arctic temperature and Barents and Kara sea ice towards the end of the century. The analysis of future changes in the Arctic-midlatitude teleconnections during cold seasons 2059-2099 also reveals that the connection between the Aleutian Low and the poleward eddy heat flux is expected to become more robust than in the analysed past.

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Predictors and prediction skill for marine cold‐air outbreaks over the Barents Sea

Cited by 10 publications

References 60 publications

Interactive 3-D visual analysis of ERA5 data: improving diagnostic indices for marine cold air outbreaks and polar lows

Interactive 3-D visual analysis of ERA5 data: improving diagnostic indices for marine cold air outbreaks and polar lows

Comment on wcd-2021-20

Causal model evaluation of Arctic-midlatitude teleconnections in CMIP6

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