scholarly journals Feeling the Pulse of the Stratosphere: An Emerging Opportunity for Predicting Continental-Scale Cold-Air Outbreaks 1 Month in Advance

2016 ◽  
Vol 97 (8) ◽  
pp. 1475-1489 ◽  
Author(s):  
Ming Cai ◽  
Yueyue Yu ◽  
Yi Deng ◽  
Huug M. van den Dool ◽  
Rongcai Ren ◽  
...  
Keyword(s):  
North America ◽  
Human Life ◽  
Well Being ◽  
Extreme Weather Events ◽  
Cold Air ◽  
Operational Forecast ◽  
Continental Scale ◽  
Forecast Models ◽  
Polar Stratosphere ◽  
Cold Air Outbreaks

Abstract Extreme weather events such as cold-air outbreaks (CAOs) pose great threats to human life and the socioeconomic well-being of modern society. In the past, our capability to predict their occurrences has been constrained by the 2-week predictability limit for weather. We demonstrate here for the first time that a rapid increase of air mass transported into the polar stratosphere, referred to as the pulse of the stratosphere (PULSE), can often be predicted with a useful degree of skill 4–6 weeks in advance by operational forecast models. We further show that the probability of the occurrence of continental-scale CAOs in midlatitudes increases substantially above normal conditions within a short time period from 1 week before to 1–2 weeks after the peak day of a PULSE event. In particular, we reveal that the three massive CAOs over North America in January and February of 2014 were preceded by three episodes of extreme mass transport into the polar stratosphere with peak intensities reaching a trillion tons per day, twice that on an average winter day. Therefore, our capability to predict the PULSEs with operational forecast models, in conjunction with its linkage to continental-scale CAOs, opens up a new opportunity for 30-day forecasts of continental-scale CAOs, such as those occurring over North America during the 2013/14 winter. A real-time forecast experiment inaugurated in the winter of 2014/15 has given support to the idea that it is feasible to forecast CAOs 1 month in advance.

scholarly journals Dynamic Linkage between Cold Air Outbreaks and Intensity Variations of the Meridional Mass Circulation

2015 ◽  
Vol 72 (8) ◽  
pp. 3214-3232 ◽  
Author(s):  
Yueyue Yu ◽  
Rongcai Ren ◽  
Ming Cai
Keyword(s):  
Mass Transport ◽  
Western Europe ◽  
Peak Time ◽  
Cold Air ◽  
Continental Scale ◽  
Icelandic Low ◽  
Meridional Mass Circulation ◽  
Azores High ◽  
Mass Circulation ◽  
Cold Air Outbreaks

Abstract This study investigates the dynamical linkage between the meridional mass circulation and cold air outbreaks using the ERA-Interim data covering the period 1979–2011. It is found that the onset date of continental-scale cold air outbreaks coincides well with the peak time of stronger meridional mass circulation events, when the net mass transport across 60°N in the warm or cold air branch exceeds ~88 × 109 kg s−1. During weaker mass circulation events when the net mass transport across 60°N is below ~71.6 × 109 kg s−1, most areas of the midlatitudes are generally in mild conditions except the northern part of western Europe. Composite patterns of circulation anomalies during stronger mass circulation events greatly resemble that of the winter mean, with the two main routes of anomalous cold air outbreaks being along the climatological routes of polar cold air: namely, via East Asia and North America. The Siberian high shifts westward during stronger mass circulation events, opening up a third route of cold air outbreaks through eastern Europe, where lies the poleward warm air route in the winter-mean condition. The strengthening of the Icelandic low and Azores high during stronger mass circulation events acts to close off the climatological-mean cold air route via western Europe; this is responsible for the comparatively normal temperature there. The composite pattern for weaker mass circulation events is generally reversed, where the weakening of the Icelandic low and Azores high, corresponding to the negative phase of the North Atlantic Oscillation (NAO), leads to the reopening and strengthening of the equatorward cold air route through western Europe, which is responsible for the cold anomalies there.

scholarly journals Persistent cold air outbreaks over North America in a warming climate

2015 ◽  
Vol 10 (4) ◽  
pp. 044001 ◽  
Author(s):  
Yang Gao ◽  
L Ruby Leung ◽  
Jian Lu ◽  
Giacomo Masato
Keyword(s):  
North America ◽  
Cold Air ◽  
Warming Climate ◽  
Cold Air Outbreaks

scholarly journals Occurrence and mechanisms of extreme winter air temperatures in the Arctic and surrounding continents

2020 ◽  
Author(s):  
Timo Vihma ◽  
Petteri Uotila ◽  
Tuomas Naakka ◽  
Tiina Nygård
Keyword(s):  
High Pressure ◽  
North America ◽  
Sea Ice ◽  
Central Europe ◽  
Northern China ◽  
The Arctic ◽  
Extreme Weather Events ◽  
Jet Stream ◽  
Cold Air ◽  
Weather Events

<p>The recent rapid warming of the Arctic atmosphere and ocean and related sea ice decline have been associated with increasing occurrence of extreme weather events in the Arctic. Applying ERA-Interim reanalysis, we identify 100 days with largest positive and negative anomalies (compared to local climatology) in 2-m air temperature (T2m) in the Northern Hemisphere in winter during 2005-2019, and address various physical mechanisms contributing to these events. The mechanisms responsible for warm extremes in the Arctic are often associated with a meandering Polar front jet stream, favouring cases of large transports of heat and moisture from mid-latitudes to the Arctic. In addition, subsidence heating often contributes to warm extremes in the Arctic, allowing them to occur also under high-pressure conditions. The coldest T2m anomalies north of 30<sup>o</sup>N mostly occur in regions that are also climatologically cold, i.e., cannot be strongly affected by cold-air advection. This suggests a dominating role local surface energy budget and boundary-layer processes.</p><p>Extreme weather events often interact with anomalies in sea ice concentration. Cases of strong winds transporting warm, moist air masses to the Arctic provide both dynamic and thermodynamic forcing for large sea ice anomalies, and during winter the openings in sea ice field contribute to air temperature extremes via large heat fluxes from the ocean to atmosphere.</p><p>Coldest winter extremes in mid-latitudes are typically associated with meandering jet stream and high-pressure blockings, but show differences between Central Europe, North America and northern China. In Central Europe the coldest events are typically associated with cold-air advection from the East or Northeast, whereas during the coldest events in North American East Coast the cold air is transported from the North. In northern China, the coldest events often occur under high-pressure conditions with weak winds. Accordingly, the role of cold-air advection is much smaller than in the case of the coldest events in North America.</p>

scholarly journals What Is the Polar Vortex and How Does It Influence Weather?

2017 ◽  
Vol 98 (1) ◽  
pp. 37-44 ◽  
Author(s):  
Darryn W. Waugh ◽  
Adam H. Sobel ◽  
Lorenzo M. Polvani
Keyword(s):  
Polar Vortex ◽  
Extreme Weather ◽  
Extreme Weather Events ◽  
Science Literature ◽  
Stratospheric Polar Vortex ◽  
Cold Air ◽  
Weather Events ◽  
Science Community ◽  
The Media ◽  
Cold Air Outbreaks

Abstract The term polar vortex has become part of the everyday vocabulary, but there is some confusion in the media, general public, and science community regarding what polar vortices are and how they are related to various weather events. Here, we clarify what is meant by polar vortices in the atmospheric science literature. It is important to recognize the existence of two separate planetary-scale circumpolar vortices: one in the stratosphere and the other in the troposphere. These vortices have different structures, seasonality, dynamics, and impacts on extreme weather. The tropospheric vortex is much larger than its stratospheric counterpart and exists year-round, whereas the stratospheric polar vortex forms in fall but disappears in the spring of each year. Both vortices can, in some circumstances, play a role in extreme weather events at the surface, such as cold-air outbreaks, but these events are not the consequence of either the existence or gross properties of these two vortices. Rather, cold-air outbreaks are most directly related to transient, localized displacements of the edge of the tropospheric polar vortex that may, in some circumstances, be related to the stratospheric polar vortex, but there is no known one-to-one connection between these phenomena.

A climatology of cold air outbreaks over North America: WACCM and ERA-40 comparison and analysis

2011 ◽  
Vol 116 (D12) ◽  
Author(s):  
D. D. Wheeler ◽  
V. L. Harvey ◽  
D. E. Atkinson ◽  
R. L. Collins ◽  
M. J. Mills
Keyword(s):  
North America ◽  
Cold Air ◽  
Comparison And Analysis ◽  
Cold Air Outbreaks

scholarly journals Economic Complexity and Human Development: Moderated by Logistics and International Migration

2021 ◽  
Vol 13 (4) ◽  
pp. 1867
Author(s):  
Emilie Sophie Le Caous ◽  
Fenghueih Huarng
Keyword(s):  
Human Development ◽  
International Migration ◽  
Hierarchical Linear Modeling ◽  
Human Life ◽  
Well Being ◽  
Linear Modeling ◽  
Statistical Tool ◽  
Economic Wealth ◽  
Economic Complexity ◽  
The Relationship

Living in a world where we can expand our economic wealth and the richness of human life is the core of the human development concept. Greater well-being for all can be achieved by improving people’s capabilities and more importantly, by giving individuals the ability to use their knowledge and skills. The economic complexity index (i.e., ECI) is a new indicator that defines a country’s complexity. Through a vast network, citizens can transfer an enormous quantity of relevant knowledge, leading to the creation of diversified and complex products. However, the relationship between economic complexity and human development is not that simple. Thus, this paper aimed to understand it deeper—international migration and logistics performance are used as moderators. Hierarchical linear modeling was the statistical tool used to analyze two groups of countries from 1990 to 2017. For robustness and to deal with possible endogeneity issues, different year lags were also included. The results show that international migration and logistics performance are decisive moderators as they change the relationship between economic complexity and human development.

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