Open Water Adds to Winter Chill - Part 2

Observation by John Henry:

Yesterday, I noticed conditions similar to last year's "Morning Winter Fog" and this year, "Open Water Adds to Winter Chill."

Unalakleet has had "open water" throughout the winter season. The snow that has left the coast may have embedded temporarily in the water (slush), but the weather has not been cold enough to form solid ice. While taking photos this afternoon of the snow ice on various objects near the Native Village of Unalakleet, which was on the approximate order of 4 minutes and with very little wind (playground, grass, powerlines), my hands were cold due to the "wetness" in the air and the ambient air temperature.

Hajo Eicken, from the International Arctic Research Center, writes:

Thanks to John Henry for these observations and photos. They highlight some connections between unseasonably warm weather, lack of sea ice, and different forms of water, snow and ice deposited from the air. The photos likely show ice that has been deposited on power lines, towers and other structures through either rime ice (when small water droplets that are part of fog freeze directly onto an exposed surface) or through hoar frost (when the water vapor in the air directly deposits ice onto a surface without first forming water droplets). Hoar frost often forms large, beautiful crystals that can look similar to snow crystals. As John Henry writes, the presence of open water late into the season and the “wetness in the air” are directly linked to these types of ice deposits. Technically, they are not snow because they did not fall out of the sky like snow crystals, but froze directly onto a surface.

Part of the unseasonable conditions in the area are due to the very late freeze-up of the Chukchi and northern Bering Sea, one of the latest, if not the latest on record. The satellite ice map shown below for December 28 shows that “normally” the ice edge at this point should be well south of Norton Sound whereas you still see some open water north of Bering Strait. This late freeze-up is in part due to more heat trapped in the upper ocean in recent years. One outcome of this late freeze-up is the greater moisture content of the air compared to conditions when the ocean is covered by ice. Another outcome is the persistence of slush ice late into the season. Typically slush ice is the first stage of new sea ice formed under windy conditions, quickly overtaken by the growth of thicker ice floes. Slush ice can form from snow falling or blowing into coastal waters and it seems that’s what is shown in one of John Henry’s photos. It is interesting to note that in the satellite ice map, Norton Sound is shown as part ice-covered. Observations and photos such as those from John Henry’s observation help provide important detail on the actual process of freeze-up.

Comments from LEO Network Editors:

This observation has been added to two projects, one for observation of Extreme or Unseasonbable Weather, and another collecting observations of change in Sea Ice. A decline in sea ice has been a serious consequence of warming arctic temperatures. Many communities in this region of Alaska have documented warmer winter temperatures, leading to dangerously icy roads, sudden weather changes, and open water. Pictured below is a graphic showing a 6-9 degree change in average temperature for this region during November of 2017.

According to the 2017 Arctic Report Card, "observations in 2017 continue to indicate that the Arctic environmental system has reached a 'new normal', characterized by long-term losses in the extent and thickness of the sea ice cover, the extent and duration of the winter snow cover and the mass of ice in the Greenland Ice Sheet and Arctic glaciers, and warming sea surface and permafrost temperatures." Read more on sea ice extent from the Arctic Report Card.

Resources:

The National Snow and Ice Data Center maintains an information portal for Arctic Sea Ice News and Analysis. Information sections provide an overview of conditions, conditions in context, comparisons to previous years, as well as information on ice extent and open water areas. Read more here.