scholarly journals Stratospheric influence on marine cold air outbreaks in the Barents Sea

2020 ◽  
Author(s):  
Hilla Afargan-Gerstman ◽  
Iuliia Polkova ◽  
Lukas Papritz ◽  
Paolo Ruggieri ◽  
Martin P. King ◽  
...  
Keyword(s):  
Barents Sea ◽  
Polar Vortex ◽  
The Arctic ◽  
Stratospheric Polar Vortex ◽  
Cold Air ◽  
Norwegian Sea ◽  
The Barents Sea ◽  
Strong Surface ◽  
Dipole Pattern ◽  
Cold Air Outbreaks

Abstract. Marine cold air outbreaks (MCAOs) in the Arctic are associated with a range of severe weather phenomena, such as polar lows, strong surface winds and intense cooling of the ocean surface. While MCAO frequency has been linked to the strength of the stratospheric polar vortex, a connection to the occurrence of extreme stratospheric events, known as sudden stratospheric warmings (SSWs), has dominantly been investigated with respect to cold extremes over land. Here, the influence of SSW events on MCAOs in the Barents Sea is studied using observational and reanalysis datasets. Overall, more than a half of SSW events lead to more frequent MCAOs in the Barents Sea. SSW events with an enhanced MCAO response in the Barents Sea are associated with a ridge over Greenland and a trough over Scandinavia, leading to an anomalous dipole pattern of 500-hPa geopotential height and strong northerly flow over the Norwegian Sea. As SSW events tend to have a long-term influence on surface weather, these results can shed light on the predictability of MCAOs in the Arctic for winters with SSW events.

scholarly journals Northern hemisphere cold air outbreaks are more likely to be severe during weak polar vortex conditions

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Jinlong Huang ◽  
Peter Hitchcock ◽  
Amanda C. Maycock ◽  
Christine M. McKenna ◽  
Wenshou Tian
Keyword(s):  
Northern Hemisphere ◽  
Energy Use ◽  
Climate Model ◽  
Polar Vortex ◽  
Anomalous Behavior ◽  
The Arctic ◽  
Stratospheric Polar Vortex ◽  
Air Mass ◽  
Cold Air ◽  
Cold Air Outbreaks

AbstractSevere cold air outbreaks have significant impacts on human health, energy use, agriculture, and transportation. Anomalous behavior of the Arctic stratospheric polar vortex provides an important source of subseasonal-to-seasonal predictability of Northern Hemisphere cold air outbreaks. Here, through reanalysis data for the period 1958–2019 and climate model simulations for preindustrial conditions, we show that weak stratospheric polar vortex conditions increase the risk of severe cold air outbreaks in mid-latitude East Asia by 100%, in contrast to only 40% for moderate cold air outbreaks. Such a disproportionate increase is also found in Europe, with an elevated risk persisting more than three weeks. By analysing the stream of polar cold air mass, we show that the polar vortex affects severe cold air outbreaks by modifying the inter-hemispheric transport of cold air mass. Using a novel method to assess Granger causality, we show that the polar vortex provides predictive information regarding severe cold air outbreaks over multiple regions in the Northern Hemisphere, which may help with mitigating their impact.

Stratospheric modulation of cold air outbreaks and winter storms in the North Atlantic region and impacts on predictability

2021 ◽  
Author(s):  
Hilla Afargan-Gerstman ◽  
Iuliia Polkova ◽  
Lukas Papritz ◽  
Paolo Ruggieri ◽  
Martin P. King ◽  
...  
Keyword(s):  
North Atlantic ◽  
Storm Track ◽  
Polar Vortex ◽  
The Arctic ◽  
Damage Potential ◽  
Stratospheric Polar Vortex ◽  
Winter Storms ◽  
Cold Air ◽  
The North ◽  
Cold Air Outbreaks

<div> <p>Variability of the stratospheric polar vortex has the potential to influence surface weather by imposing negative North Atlantic Oscillation (NAO) conditions, associated with cold air outbreaks in the Arctic and a southward shift of the extratropical storm track. In particular, the likelihood of cold temperature extremes over the ocean, known as marine cold air outbreaks (MCAOs), have been associated with a range of hazardous conditions, including strong surface winds and the occurrence of extreme cyclones known as Polar Lows (PLs), posing risks for Arctic marine activity and infrastructure. Likewise, winter storms can lead to high damage potential in the extratropics due to their associated extreme winds.</p> </div><div> <p>Skillful predictions of MCAOs and extratropical winter storms on subseasonal timescales have been linked to the strength of the stratospheric polar vortex. Using ERA-Interim reanalysis (1979-2019) and ECMWF forecasts from the S2S Prediction Project database we investigate the stratospheric influence on surface extremes such as MCAOs and high-impact winter storms. Following weak stratospheric vortex extremes, anomalous circulation patterns accompanied by increased storminess over the eastern North Atlantic are found to be strong indicators for enhanced MCAOs in high- and mid-latitudes. Understanding the role of the stratosphere in subseasonal variability and predictability of cold air outbreaks and storm tracks during winter can provide a key for a reliable forecast of severe impacts.</p> </div>

scholarly journals Eurasian Cold Air Outbreaks under Different Arctic Stratospheric Polar Vortex Strengths

2019 ◽  
Vol 76 (5) ◽  
pp. 1245-1264 ◽  
Author(s):  
Jinlong Huang ◽  
Wenshou Tian
Keyword(s):  
Climate Models ◽  
Sensible Heat Flux ◽  
Coupled Model ◽  
Surface Air Temperature ◽  
Polar Vortex ◽  
Northern Eurasia ◽  
Reanalysis Dataset ◽  
Stratospheric Polar Vortex ◽  
Cold Air ◽  
Cold Air Outbreaks

Abstract This study analyzes the differences and similarities of Eurasian cold air outbreaks (CAOs) under the weak (CAOW), strong (CAOS), and neutral (CAON) stratospheric polar vortex states and examines the potential links between the polar vortex and Eurasian CAOs. The results indicate that the colder surface air temperature (SAT) over Europe in the earlier stages of CAOW events is likely because the amplitude of the preexisting negative North Atlantic Oscillation pattern is larger in CAOW events than in CAON and CAOS events. Marked by the considerably negative stratospheric Arctic Oscillation signals entering the troposphere, the SAT at midlatitudes over eastern Eurasia in CAOW events is colder than in CAON events. A larger diabatic heating rate related to a positive sensible heat flux anomaly in CAOW events likely offsets, to some degree, the cooling effect caused by the stronger cold advection and makes the differences in area-averaged SAT anomalies over northern Eurasia between the CAOW and CAON events look insignificant in most stages. Massive anomalous waves from the low-latitude western Pacific merge over northeastern Eurasia, then weaken the westerly wind over this region to create favorable conditions for southward advection of cold air masses in the earlier stages of all three types of CAOs. This study further analyzes the interannual relationship between the stratospheric polar vortex strength and the intensity of Eurasian CAOs and finds that climate models participating in phase 5 of the Coupled Model Intercomparison Project (CMIP5) relative to the reanalysis dataset tend to underestimate the correlation between them. The relationship between them is strengthening under representative concentration pathway 4.5 (RCP4.5) and 8.5 (RCP8.5) scenarios over the period 2006–60. In addition, the intensity of Eurasian CAOs exhibits a decreasing trend in the past and in the future.

scholarly journals Unusual Late-Season Cold Surges during the 2005 Asian Winter Monsoon: Roles of Atlantic Blocking and the Central Asian Anticyclone

2009 ◽  
Vol 22 (19) ◽  
pp. 5205-5217 ◽  
Author(s):  
Mong-Ming Lu ◽  
Chih-Pei Chang
Keyword(s):  
Barents Sea ◽  
Winter Monsoon ◽  
The Arctic ◽  
Late Winter ◽  
Cold Air ◽  
Asian Winter Monsoon ◽  
Central Asian ◽  
East And Southeast Asia ◽  
Cold Surges ◽  
Cold Air Outbreaks

Abstract The highest frequency of late-winter cold-air outbreaks in East and Southeast Asia over 50 years was recorded in 2005, when three strong successive cold surges occurred in the South China Sea within a span of 30 days from mid-February to mid-March. These events also coincided with the first break of 18 consecutive warm winters over China. The strong pulsation of the surface Siberian Mongolia high (SMH) that triggered these events was found to result from the confluence of several events. To the east, a strong Pacific blocking with three pulses of westward extension intensified the stationary East Asian major trough to create a favorable condition for cold-air outbreaks. To the west, the dominance of the Atlantic blocking and an anomalous deepened trough in the Scandinavian/Barents Sea region provided the source of a succession of Rossby wave activity fluxes for the downstream development. An upper-level central Asian anticyclone that is often associated with a stronger SMH was anomalously strong and provided additional forcing. In terms of the persistence and strength, this central Asian anticyclone was correlated with the Arctic Oscillation (AO) and North Atlantic Oscillation (NAO) only when SMH is weak (warm winters). During strong SMH seasons (cold winters) the correlation vanishes. However, during late winter 2005 the central Asian anticyclone was strengthened by the Atlantic blocking through both the downstream wave activities and a circulation change that affected the Atlantic and west Asian jets. As a result, the period from mid-February to mid-March of 2005 stands out as a record-breaking period in the Asian winter monsoon.

scholarly journals Sea waves impact on turbulent heat fluxes in the Barents Sea according to numerical modeling

2020 ◽  
Author(s):  
Stanislav Myslenkov ◽  
Anna Shestakova ◽  
Dmitry Chechin
Keyword(s):  
Roughness Length ◽  
Barents Sea ◽  
Heat Fluxes ◽  
Turbulent Heat ◽  
Sea Waves ◽  
Cold Air ◽  
Mean Values ◽  
The Barents Sea ◽  
Turbulent Heat Fluxes ◽  
Cold Air Outbreaks

Abstract. This paper investigates the impact of sea waves on turbulent heat fluxes in the Barents Sea. The COARE algorithm, meteorological data from reanalysis and wave data from the WW3 wave model results were used. The turbulent heat fluxes were calculated using the modified Charnock parameterization for the roughness length and several parameterizations, which explicitly account for the sea waves parameters. A catalog of storm wave events and a catalog of extreme cold-air outbreaks over the Barents Sea were created and used to calculate heat fluxes during extreme events. The important role of cold-air outbreaks in the energy exchange of the Barents Sea and the atmosphere is demonstrated. A high correlation was found between the number of cold-air outbreaks days and turbulent fluxes of sensible and latent heat, as well as with the net flux of long-wave radiation averaged over the ice-free surface of the Barents Sea during a cold season. The differences in the long-term mean values of heat fluxes calculated using different parameterizations for the roughness length are small and are on average 1–3 % of the flux magnitude. Parameterizations of Taylor and Yelland and Oost et al. on average lead to an increase of the magnitude of the fluxes, and the parameterization of Drennan et al. leads to a decrease of the magnitude of the fluxes over the entire sea compared to the Charnock parameterization. The magnitude of heat fluxes and their differences during the storm wave events exceed the mean values by a factor of 2. However, the effect of explicit accounting for the wave parameters is, on average, small and multidirectional, depending on the used parameterization for the roughness length. In the climatic aspect, it can be argued that the explicit accounting for sea waves in the calculations of heat fluxes can be neglected. However, during the simultaneously observed storm waves and cold-air outbreaks, the sensitivity of the calculated values of fluxes to the used parameterizations increase along with the turbulent heat transfer increase. In some extreme cases, during storms and cold-air outbreaks, the difference reaches 700 W m−2.

scholarly journals The impact of sea waves on turbulent heat fluxes in the Barents Sea according to numerical modeling

2021 ◽  
Vol 21 (7) ◽  
pp. 5575-5595
Author(s):  
Stanislav Myslenkov ◽  
Anna Shestakova ◽  
Dmitry Chechin
Keyword(s):  
Roughness Length ◽  
Barents Sea ◽  
Heat Fluxes ◽  
Turbulent Heat ◽  
Sea Waves ◽  
Cold Air ◽  
The Barents Sea ◽  
Turbulent Heat Fluxes ◽  
Storm Wave ◽  
Cold Air Outbreaks

Abstract. This paper investigates the impact of sea waves on turbulent heat fluxes in the Barents Sea. The Coupled Ocean–Atmosphere Response Experiment (COARE) algorithm, meteorological data from reanalysis and wave data from the WAVEWATCH III wave model results were used. The turbulent heat fluxes were calculated using the modified Charnock parameterization for the roughness length and several parameterizations that explicitly account for the sea wave parameters. A catalog of storm wave events and a catalog of extreme cold-air outbreaks over the Barents Sea were created and used to calculate heat fluxes during extreme events. The important role of cold-air outbreaks in the energy exchange between the Barents Sea and the atmosphere is demonstrated. A high correlation was found between the number of cold-air outbreak days and turbulent fluxes of sensible and latent heat, as well as with the net flux of longwave radiation averaged over the ice-free surface of the Barents Sea during a cold season. The differences in the long-term mean values of heat fluxes calculated using different parameterizations for the roughness length are small and are on average 1 %–3 % of the flux magnitude. The parameterizations of Taylor and Yelland (2001) and Oost et al. (2002) lead to an increase in the magnitude of the fluxes on average, and the parameterization of Drennan et al. (2003) leads to a decrease in the magnitude of the fluxes over the entire sea compared with the Charnock parameterization. The magnitude of heat fluxes and their differences during the storm wave events exceed the mean values by a factor of 2. However, the effect of explicitly accounting for the wave parameters is, on average, small and multidirectional, depending on the parameterization used for the roughness length. With respect to the climatic aspect, it can be argued that explicitly accounting for sea waves in the calculations of heat fluxes can be neglected. However, during the simultaneously observed storm wave events and cold-air outbreaks, the sensitivity of the calculated values of fluxes to the parameterizations used increases along with the turbulent heat transfer increase. In some extreme cases, during storms and cold-air outbreaks, the difference exceeds 700 W m−2.

scholarly journals Stratospheric influence on North Atlantic marine cold air outbreaks following sudden stratospheric warming events

2020 ◽  
Vol 1 (2) ◽  
pp. 541-553
Author(s):  
Hilla Afargan-Gerstman ◽  
Iuliia Polkova ◽  
Lukas Papritz ◽  
Paolo Ruggieri ◽  
Martin P. King ◽  
...  
Keyword(s):  
North Atlantic ◽  
Geopotential Height ◽  
Barents Sea ◽  
Height Anomaly ◽  
Labrador Sea ◽  
Stratospheric Polar Vortex ◽  
Cold Air ◽  
The North ◽  
The North Atlantic ◽  
Cold Air Outbreaks

Abstract. Marine cold air outbreaks (MCAOs) in the northeastern North Atlantic occur due to the advection of extremely cold air over an ice-free ocean. MCAOs are associated with a range of severe weather phenomena, such as polar lows, strong surface winds and intense cooling of the ocean surface. Given these extreme impacts, the identification of precursors of MCAOs is crucial for improved long-range prediction of associated impacts on Arctic infrastructure and human lives. MCAO frequency has been linked to the strength of the stratospheric polar vortex, but the study of connections to the occurrence of extreme stratospheric events, known as sudden stratospheric warmings (SSWs), has been limited to cold extremes over land. Here, the influence of SSW events on MCAOs over the North Atlantic ocean is studied using reanalysis datasets. Overall, SSW events are found to be associated with more frequent MCAOs in the Barents Sea and the Norwegian Sea compared to climatology and less frequent MCAOs in the Labrador Sea. In particular, SSW events project onto an anomalous dipole pattern of geopotential height 500 hPa, which consists of a ridge anomaly over Greenland and a trough anomaly over Scandinavia. By affecting the variability of the large-scale circulation patterns in the North Atlantic, SSW events contribute to the strong northerly flow over the Barents and Norwegian seas and thereby increase the likelihood of MCAOs in these regions. In contrast, the positive geopotential height anomaly over Greenland reduces the probability of MCAOs in the Labrador Sea after SSW events. As SSW events tend to have a long-term influence on surface weather, these results are expected to benefit the predictability of MCAOs in the Nordic Seas for winters with SSW events.

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