28 May 2001
Snow structure at 0m on the Chukchi albedo line. There
was a layer of fresh snow not more than a few days old 4 cm thick. The
density is estimated to be between 0.1 and 0.15 g/cm3. The
crystal dimensions were ¼ to 3 mm consisting of needles and some
platelets. The next layer was 6 cm
thick consisting of windpack. The crystals were about 0.5 to 2 mm across
and the density was an estimated 0.33. Below
that the ice had a 4-5 cm thick layer of milky, perhaps superposed –
ice. The layer was solid with an apparent granular structure with a size
of about 1 mm. The thickness of the superposed layer ranged from 5 cm to 0
cm over the 4 areas I looked at.
Snow cover on the Tundra albedo line.
The snow cover was 100% and still dry with
little sign of melting. There was a 5 cm thick layer of fresh snow
(probably 5 days or so old). The crystals were fine grained with
dimensions of 0.1 to 0.2 mm by 0.5 to 1 mm. Below 5 cm was windpack and
depth hoar. The depth hoar thickness was considerable – perhaps 10-20
cm. The snow thickness along the line was quite variable, in contrast with
the snow at the Chukchi site.
29 May 2001
Imikpuk Lake. The snow was still
dry today with a 5 cm layer of the recent snow over the windpack and depth
hoar. We’ll do a more thorough jop of characterization tomorrow, but the
upper layer is similar to the snow at the Chukchi site – ¼ to 2 mm
crystal dimensions. The density appears to have increased a bit, but I can’t
find the snow density kit. My best estimate is about 0.2 g/cm3
at the moment.
30 May 2001
Imikpuk Lake and Elson Lagoon. The
snow is of packing consistency today with grain metamorphism.
31 May 2001
Chukchi Site. The snow thickness is
about half of what it was on the 27th, and the grains have
metamorphosed probably to about 1 mm characteristic size. The albedo took
a corresponding dive.
1-5 June 2001
The snow grains have increased to 1-3 mm in diameter at the surface
increasing at the base in a fashion characteristic of spring snow.
6 June 2001
Imikpuk Lake – the melt ponds have formed and drained leaving areas
of polar bear fur and some snow. The weather is a bit cooler and the snow
has frozen up at the surface. The passive microwave should be seeing some
apparent multiyear ice. The snow grains have not decreased but they are
frozen together to a greater extent.
7 June and following
We are into summer snow conditions now except for one or two brief new
deposition episodes whose crystals quickly metamorphosed. By the 14th
the snow was gone at almost all sites. Elson Lagoon and the Beaufort Sea
were the last.
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