New paper submitted

I just submitted a paper that I co-authored with T. Breiteig and A. A. Scaife to the Quarterly Journal of the Royal Meteorological Society. The title of the paper is: The association between stratospheric weak polar vortex events and cold air outbreaks and here is the abstract:

Previous studies have identified an association between near-surface temperature anomalies in the Northern Hemisphere and weak stratospheric polar westerlies. Large regions in northern Asia, Europe and North America have been found to cool in the mature and late stages of stratospheric weak vortex events. A substantial part of the temperature changes are associated with changes to the tropospheric Northern Annular Mode and North Atlantic Oscillation pressure patterns. The apparent coupling between the stratosphere and the troposphere may be of relevance for weather forecasting, but only if the temporal and spatial nature of the coupling is known. Here we show, using 51 winters of re-analysis data, that the tropospheric temperature development relative to stratospheric weak polar vortex events goes through a series of well-defined stages, including geographically distinct cold air outbreaks. At the inception of weak vortex events, a precursor signal in the form of a strong high-pressure anomaly is found over Northwest Europe. At the same time, long-lived and robust cold anomalies appear over Asia and Western Europe. A few weeks later, near the mature stage of weak vortex events, a shorter-lived cold anomaly emerges off the east coast of North America.The probability of cold air outbreaks in different phases of the weak vortex life cycle increases by 40–70 % in four key regions. This shows that the stratospheric polar vortex contains information that can be used to enhance forecasts of cold air outbreaks. 300-year pre-industrial control runs of 11 state-of-the-art coupled climate models corroborate our results.

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One Comment Add yours

  1. erlhapp says:

    Hi Eric,
    Nice blog with excellent photos. Scandinavian flair.

    I am Australian so a long way away on the south west corner of Western Australia.

    I skimmed your recent paper on cold outbreaks and the association with weak vortex events.I am an amateur researcher on climate. I have done a lot of work with the NCAR reanalysis data set looking at atmsopheric characterisitics and associations. My particular interest is the association between the aao (and the ao) and the incidence of warming events in the tropics. I see long term cycles of warming and now cooling that are linked to changes in the distribution of the atmsophere between high, mid and low latitudes and between the southern and the northern hemsiphere that impinge on the differential pressure driving the trades and the westerlies. As the trades intensify the tropical ocean cools. As the trades relax it warms. Result of changing evaporation levels and degree of upwelling.

    There is an external influence driving change in the distribution of the atmsophere that varies on 80+ year time scales.

    The polar vortex weakens when atmsopheric pressure falls. When it weakens at the north pole it frequently weakens in the south at the same time. The ao and the aao move together when you deseaonalise the data. But they also compete. When 10hpa temperature rises over the poles it falls at the equator. The zone of ionization plainly moves outwards as atmsopheric pressure rises in the tropics. I can not see planetary waves impacting both poles simultaneously, but I can imagine that the distribution of the atmsophere is driven by plasmasphere dynamics.

    Is any of this making sense to you? If it is and you are interested to exchange ideas please email me at erlathapps.com.au

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