Sea ice and snow phenology in the Canadian Arctic Archipelago from 1997 to 2018

Abstract

The multiple islands and narrow channels that form the Canadian Arctic Archipelago (CAA) complicate snow/ice monitoring, as coarse resolution satellite observations are unable to resolve smaller-scale changes in snow/ice cover. We present the first study showing the utility of the Interactive Multisensor Snow and Ice Mapping System (IMS) 24 km (1997–2018) and 4 km (2004–2018) products to investigate changes in sea ice and snow phenology together in the CAA. While ice break-up and snow retreat are shifting earlier (p>0.05), on par with other Arctic regions, the final summer clearing of ice is shifting later. This, combined with trends towards earlier ice freeze and snow fall (p<0.05), result in shorter open water and snow free seasons in the CAA. Spatial links between sea ice and snow are evident as significant clusters of trends were identified for all phenology parameters. The western regions were dominated by shifts toward shorter snow/ice seasons, while eastern regions tended to exhibit longer cover. Our research highlights the considerable regional and interannual variability in the timing of sea ice and snow advance/retreat within the CAA and emphasizes how the ice and snow dynamics in this complex region are responding to ongoing changing climate conditions.

Comment on tc-2021-52

“…Examining snow and ice cover at the pan-Arctic scale provides important information on how the cryosphere is responding to climate change as a whole, however the large degree of spatial variability warrants further investigation into snow and ice conditions at regional scales. For example, Dauginis and Brown (2020) demonstrate that the CAA is responding differently to warming compared to other regions of the Arctic; their findings show later summer clearing of ice and earlier sea ice freeze and snow onset since 2004, in line with findings from previous studies that showed no significant trends toward earlier sea ice melt onset dates in the CAA (e.g. Mahmud et al 2016;Marshall et al 2019).…”

“…). Regions of later WCIS are also evident, for example the Eastern Parry Channel (Dauginis andBrown, 2020). The surrounding area(Cornwallis Island, Bathurst Island, and Northern Somerset Island) shows significant clustering between the sea ice and snow trends (no lakes are large enough to be detected at 4 km resolution in this region) (Figure6c, d), further highlighting this local region of later ice/snow-off.…”

“…The 24 km and 4 km IMS products were used to examine changes in snow and ice phenology dates across the pan-Arctic following the methodology of Brown et al (2014) and Dauginis and Brown (2020). For each pixel, consecutive days of IMS imagery were compared to determine the first and last changes between snow/ice and land/water to determine the timing of the snow/ice-on and off parameters examined.…”

“…The final result is the Sen's slope (amount of increase or decrease) at each location over the given time period, as well as the significance of each trend (Bronaugh and Werner 2019). Interannual and regional variability in snow and ice conditions will inherently affect phenology parameters, particularly for sea ice, which may not entirely clear out of some regions in a particular season leading to no iceoff or -on phenology detected for that year (Dauginis and Brown, 2020). Pixels with less than 14 years of phenology data (e.g.…”

Recent changes in Pan-Arctic sea ice, lake ice, and snow on/off timing

“…The Canadian Arctic Archipelago (CAA), however, has been shown to exhibit earlier freeze trends during recent years (e.g. Dauginis and Brown, 2020) and weaker trends toward earlier melt onset compared to other Arctic regions (e.g. Mahmud et al 2016;Marshall et al 2019).…”