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Saturday, April 24, 2010

Polar Science Center: Arctic Sea Ice Volume Anomaly, continuously updated

Arctic Sea Ice Volume Anomaly

Sea Ice Volume is calculated using the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) developed at APL/PSC by Dr. J. Zhang and collaborators.  Anomalies for each day are calculated relative to the average over the 1979-2009 period for that day to remove the annual cycle. The model mean seasonal cycle of sea ice volume ranges from 28,600 km³ in April to 14,400 km³ in September.  The blue line represents the trend calculated from January 1 1979 to the most recent date indicated on the figure.  Total Arctic Ice Volume for March 2010 is 20,300 km³, the lowest over the 1979-2009 period and 38% below the 1979 maximum. September Ice Volume was lowest in 2009 at 5,800 km³ or 67% below its 1979 maximum. Shaded areas represent one and two standard deviations of the anomaly from the trend. Updates will be generated at 3-5 day intervals.

Continuously updated Arctic Sea Ice Volume Anomaly from PIOMAS. Daily Sea Ice volume anomalies for each day are computed relative to the 1979 to 2009 average for that day. The trend for the 1979- present period is shown in blue. Shaded areas show one and two standard deviations from the trend. Click on image for a larger version of the figure

The purpose of this page is to visualize recent variations of total Arctic Sea Ice Volume in the context of longer term variability.  Arctic Sea Ice Volume is an important indicator of climate change because it accounts for variations in sea ice thickness as well as sea ice extent.  Total Arctic sea ice volume cannot currently be observed continuously.  Observations from satellites, Navy submarines, moorings, and field measurements are limited in space or time.  The assimilation of observations into numerical models, currently provides one way of estimating sea ice volume changes on a continuing basis. Volume estimates using age of sea ice as a proxy for ice thickness are another useful method (see here and here).  Comparisons with observations help test our understanding of sea ice conditions in the Arctic.

Model and Assimilation Procedure
PIOMAS is a numerical model with components for sea ice and ocean and the capacity for assimilating observations. For the Ice Volume simulations shown here, sea ice concentration information from the NSIDC near-real time product are assimilated into the model to improve ice thickness estimates. Atmospheric information to drive the model, specifically wind, surface air temperature, and cloud cover to compute solar and long wave radiation are specified from the NCEP/NCAR reanalysis. The Pan-Arctic ocean model is forced with input from a global ocean model at its open boundaries.

Model Validation

Arctic Sea Ice Volume Anomaly from PIOMAS and the NASA ICESat satellite in November for each year relative to the 2003-2007 mean ice volume.
ICEsat Ice volume is from Kwok et al. 2009. Click on image for a larger version of the figure

PIOMAS has been extensively validated through comparisons with observations from US-Navy submarines, moorings, and satellites. The example on the left shows a comparison of PIOMAS-derived ice volume anomalies with anomalies measured by the NASA ICEsat Satellite. More details on the model, assimilation procedures and validation results can be found here



FredT said...

Won't we ever see a Good News ???

Tenney, thanks for all these posts, you're awesome.

Tenney Naumer said...

Thanks for the encouragement, Fred, I appreciate it.

I'm not so sure I'm awesome, though.