Wednesday, August 31, 2011

JAXA Ice extent and JS

Everyone's eyes seem to be on the progress of the Acrtic ice melt. I've been posting daily data and plots here from the IJIS Site. I include an expanded section of the current region. However, there are different time regions that peoiple might like to look at more closely (eg September), and rather than a lot of different plots, I thought a JS-enhanced interactive plot might help. I'll use it on the daily site, but you can try it here.

There is an extra legend, top middle, describing four different time periods. Just click on the one you want to see.


6 comments:

  1. I heard and enjoyed your talk at CMIS.

    To my mind the real story on Arctic Ice is not about extent, but about volume, as I posted on RealClimate:
    http://www.realclimate.org/index.php/archives/2011/09/the-unnoticed-melt/

    To summarise what I said there - we've already broken the record minimum ice volume in August 2011, 1 month before the minimum extent. The 2nd lowest ice volume was September 2010. September 2007 comes in third place.
    See here:
    http://neven1.typepad.com/blog/2011/09/piomas-august-2011.html

    It strikes me that the GCMs used to predict sea-ice extent are still woefully wrong. This linear trend is self-evident non-sense.
    http://psc.apl.washington.edu/wordpress/wp-content/uploads/schweiger/ice_volume/BPIOMASIceVolumeAnomalyCurrentV2.png?%3C?php%20echo%20time%28%29%20?

    The trend is either accelerating or autocorrelated, and not just for the minimum but for every month of the year. This appears to be an amateur effort but I'd give it higher marks than the PIOMAS plot:
    http://psc.apl.washington.edu/wordpress/wp-content/uploads/schweiger/ice_volume/BPIOMASIceVolumeAnomalyCurrentV2.png?%3C?php%20echo%20time%28%29%20?

    Cheers,

    Bruce

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  2. Thanks, Bruce.

    I agree volume is the measure of heat needed for melting, so it is very important. Extent has its place in the physics because of feedback. An early extent loss means more sunlight absorbed in the Arctic over the summer, which means more extent (and volume) loss, etc.

    I'm not sure the line in the Piomass plot you linked to is meant as a prediction. They may be making the same point as you - the loss is accelerating.

    I think your last link is a repeat.

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  3. Whoops,

    The last link should have been to here:
    http://neven1.typepad.com/.a/6a0133f03a1e37970b015435378c39970c-pi

    From a discussion here:
    http://neven1.typepad.com/blog/2011/09/piomas-august-2011.html

    If I had time I'd try an ARIMA model with lags of 1 and 12 months. The data is apparently available here:
    http://psc.apl.washington.edu/wordpress/research/projects/arctic-sea-ice-volume-anomaly/

    Using an exponential trend and 95% CIs, Wipneus' approach predicts a seasonally ice-free Actic between 2013 and 2019 with a mean of 2015. I suspect an ARIMA model would stretch the CI's somewhat.

    That is a long way ahead of Figure 3 here, which is the story from climate scientists:
    http://www.realclimate.org/index.php/archives/2011/09/the-unnoticed-melt/

    Clearly accurate physical modeling should trump statistical extrapolation, but climate scientists seem to consistently underestimate the response of the cryosphere.

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  4. Sorry about the aggressive spam filter here, Bruce. I thought it had been getting better. Tamino has done quite a lot on the ice time series, including volume - I can't remember him using ARIMA.

    ReplyDelete