Is the Modern Arctic Marginal Ice Zone More Susceptible to Summer Cyclones?

Abstract

Abstract As Arctic sea ice melts, cyclones potentially enhance the mechanical and thermodynamic forces that influence the vulnerable ice edge. However, examples can be found in satellite observations and reanalyses where cyclones either locally increase or decrease ice within the marginal ice zone (MIZ). Two case studies with these opposing ice responses are presented. Guided by the tendencies during these events, 264 strong (minimum surface pressure below 984 mb) summer cyclones were sorted by prevailing wind direction and SST changes within the MIZ to quantify the net ice impacts in the present-day Arctic (2010–2019) and early satellite era (1982–1991). By tracking MIZ ice area from one week before the cyclone’s formation through two weeks after, we find cyclones that enhance southerly winds mostly decrease ice area, whereas enhanced northerlies generally increase ice area within the MIZ later in the season. Furthermore, early-summer storms tend to decrease MIZ ice area more than late-summer storms. A shift towards more frequent early-summer storms is observed from the 1980s to 2010s, resulting in almost two-thirds of recent storms decreasing area. Consequently, recent summer cyclones have more negative impacts, resulting in a decline of more than 40,000 km2 of MIZ ice area on average, whereas 1980s cyclones had little aggregate impact. Wind direction and SST trends partially reconcile the wide range of MIZ ice area changes due to cyclone passage, yet considerable variations in individual cyclones’ impacts remain even when controlling for these factors. These bulk diagnostics therefore only explain part of the complex ice-cyclone relationship.