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Baffin Bay exports Arctic Water to the North Atlantic while receiving northward flowing Atlantic Water. Warm Atlantic Water has impacted the retreat of tidewater glaciers draining the Greenland Ice Sheet. Periods of enhanced Atlantic Water transport into Baffin Bay have been observed, but the oceanic processes are still not fully explained. At the end of 2010 the net transport at Davis Strait, the southern gateway to Baffin Bay, reversed from southward to northward for a month, leading to significant northward oceanic heat transport into Baffin Bay. This was associated with an extreme high in the Greenland Blocking Index and a stormtrack path that shifted away from Baffin Bay. Thus fewer cyclones in the Irminger Sea resulted in less frequent northerly winds along the western coast of Greenland, allowing anomalous northward penetration of warm waters, reversing the volume and heat transport at Davis Strait.
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Summertime midlatitude weather and climate extremes induced by moisture intrusions to the west of Greenland
Abstract The summer of 2010 was characterized by weather and climate extremes such as the western Russia heatwave and the Pakistan floods. A recent study found that summer was dominated by a particular 200 hPa geopotential height pattern featuring an anomalous Rossby wave train with ridges centred over Greenland, Europe and Russia. The daily frequency of this pattern has dramatically increased recently and closely resembles the mean‐state difference in 200 hPa geopotential height fields between 1998–2014 (P2) and 1979–1997 (P1). Because anomalous wave trains are often driven by localized diabatic heating, it is tested in this study whether the P2 minus P1 pattern is caused by diabatic heating anomalies near Greenland. While it is found that sea ice concentrations declined and sea‐surface temperatures rose over Baffin Bay to the west of Greenland during P2, surface latent heat fluxes actually increased downward, indicating that surface processes were likely not the source of diabatic heating. Rather, an increase in vertically integrated horizontal latent‐heat flux convergence over Baffin Bay was observed in P2, which led to the condensation of water vapour and latent heating. Thus, the mid‐tropospheric circulation established the diabatic heating. A set of initial‐value calculations with idealized heating over Baffin Bay show solutions that remarkably resemble the P2 minus P1 pattern and provide a plausible explanation as to why the pattern has been occurring more frequently. This study demonstrates that changes in the Arctic can arise from moisture transport from the midlatitudes, and, in turn, these changes can induce weather and climate extremes in distant midlatitude regions.
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- PAR ID:
- 10453801
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Quarterly Journal of the Royal Meteorological Society
- Volume:
- 145
- Issue:
- 724
- ISSN:
- 0035-9009
- Page Range / eLocation ID:
- p. 3148-3160
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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