Tropical Cyclone Track Convergence Patterns, Arctic Sea-Ice Loss, and Superstorm Sandy: Is There a Connection?
Abstract
The potential for disruption to populations and food production due to global climate change will be catastrophic in some regions. Among the most vulnerable regions are those impacted by intensifying or changing tropical cyclones (TC). The objective of this research is to identify historical trends in TC tracks and regional circulation patterns that may forecast increasing risks due to TC intensification under global climate warming. We carry out spatial and temporal analysis of the 1979 - 2011 International Best Track Archive for Climate Stewardship (IBTrACS) historical hurricane database. The data were divided into several subsets to allow analysis of trend in: (i) early (JJAS) and late (OND) seasonal trends; and (ii) multi-year intervals (1979-95 and 1996-2011) to differentiate possible long term trends, if any. Geographical Information Systems (GIS) overlay analysis of the IBTrACS 64 knot hurricane wind radii data identified varying levels of historical tropical cyclone track convergence in the North Atlantic (NA) basin. Results of the track convergence analysis provide a first order analysis regarding changing potential population vulnerabilities due to changing seasonal or long-term tropical cyclone activity. During the summer of 2012, the amount of sea ice on the Arctic Ocean was diminished to about half of its normal extent and 25% of its normal volume relative to the nearly steady conditions that existed before the 1980s. This record loss continues an inexorable decline observed during recent decades. The dramatic increase in open water allows much more solar energy absorption at high latitude. Most of this extra heat returns to the atmosphere in autumn, contributing to the Arctic's rate of warming; exceeding that of mid-latitudes by a factor of two to three, a phenomenon called Arctic Amplification (AA). During October 2012, prior to the arrival of Superstorm Sandy along the eastern seaboard, AA was particularly strong, resulting in a substantial weakening of the poleward temperature gradient in the northern hemisphere. Evidence will be presented suggesting that the anomalous Arctic warming following record sea-ice losses in summer 2012 contributed to the formation of the strong and persistent high-pressure blocking pattern that set up a steep pressure gradient from the mid-Atlantic to Nova Scotia. The result was the diversion of Sandy from the typical NE AB path to an unprecedented westward collision with the coast of New Jersey. The critical question now is whether the storm track intensification trend in recent years will combine with a consistent NA blocking high in fall to increase TC threats to the US northeast and Canadian maritime provinces?
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFMGC11C1012B
- Keywords:
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- 1630 GLOBAL CHANGE Impacts of global change;
- 4313 NATURAL HAZARDS Extreme events;
- 3372 ATMOSPHERIC PROCESSES Tropical cyclones;
- 3305 ATMOSPHERIC PROCESSES Climate change and variability