National Aeronautics and Space Administration

Wallops Flight Facility

Matusevich-Cook IS-2

OIB completed the “Matusevich-Cook IS-2” mission today in smooth clear conditions. The low level science flight tracks consisted of two long ICESat 2 ground tracks with a short excursion on the second track to overfly a firn core (GV7)* in two directions which will be interesting to compare to the CReSIS snow radar data. All OIB instruments reported good data collection.

OIB will attempt another mission tomorrow, weather permitting.

Wiki notes: https://en.wikipedia.org/wiki/Ice_core 

*An ice core is a vertical column through a glacier, sampling the layers that formed through an annual cycle of snowfall and melt.[1] As snow accumulates, each layer presses on lower layers, making them denser until they turn into firn. Firn is not dense enough to prevent air from escaping; but at a density of about 830 kg/m3 it turns to ice, and the air within is sealed into bubbles that capture the composition of the atmosphere at the time the ice formed.[2]

Wiki notes: https://en.wikipedia.org/wiki/Firn

Firn (/fɪərn/; from Swiss German firn “last year’s”, cognate with before) is partially compacted névé, a type of snow that has been left over from past seasons and has been recrystallized into a substance denser than névé. It is ice that is at an intermediate stage between snow and glacial ice. Firn has the appearance of wet sugar, but has a hardness that makes it extremely resistant to shovelling. Its density generally ranges from 0.4 g/cm³ to 0.83 g/cm³,[1] and it can often be found underneath the snow that accumulates at the head of a glacier.

Snowflakes are compressed under the weight of the overlying snowpack. Individual crystals near the melting point are semiliquid and slick, allowing them to glide along other crystal planes and to fill in the spaces between them, increasing the ice’s density. Where the crystals touch they bond together, squeezing the air between them to the surface or into bubbles.

In the summer months, the crystal metamorphosis can occur more rapidly because of water percolation between the crystals. By summer’s end, the result is firn.

Wide view of today’s flight path

Detail of today’s flight path

NASA 5 in the morning sun

ATMer Matt Linkswiler preparing the ATM instrument suite this morning.

Lower McLeod Glacier (John Sonntag / NASA)

Outback Nunataks (John Sonntag / NASA)

The snow surface today was flat and featureless, so below are some ATM plots of sea ice as the GV flew south to the IS2 line:

ATM T6 wide scan elevation plot over sea ice southbound (ATM Linkswiler)

ATM T6 wide scan elevation plot over sea ice southbound (ATM Linkswiler)

ATM T6 wide scan elevation plot over sea ice southbound (ATM Linkswiler)