Sunday, April 26, 2009

Sea Ice blips

Stoat links to this IJIS plot of Arctic sea ice extent for the last several years. My question is, why is there a weird upward blip in the data every year about June 1st?

UPDATE: I asked JAXA, and here's what they told me (it's along the lines of what we all expected):
Current version of data processing makes an erroneous bias of
sea ice extent on June 1st and October 15th which are seen
in the graph of sea ice extent as a small blip on these dates.
The apparent bias arises due to a switching of some parameters
in the processing on both dates. The parameter switching is
needed because the surface of the Arctic sea-ice becomes
wet in summer due to the melting of ice which changes
satellite-observed signatures of sea-ice drastically.

We are planning to improve the processing to make the gap
much smoother soon.


3 comments:

Belette said...

That is a good question. I don't know. Mail the source?

Hank Roberts said...

Or email Remote Sensing:
http://www.remss.com/papers/amsr/on-orbit_calibration_amsre_and_ocean_products.pdf

I recall noticing and asking about that some previous year; I think they recalibrate annually.

Dano said...

I'm disappointed Wm didn't know. What is the world coming to? ;o)

Best,

D