jump to navigation

NSIDC: satellite sea ice sensor has “catastrophic failure” – data faulty for the last 45 or more days February 19, 2009

Posted by honestclimate in sea ice.
Tags: , , ,
add a comment

NSIDC: satellite sea ice sensor has “catastrophic failure” – data faulty for the last 45 or more days

From Watts Up With That, February 19, 2009

https://i2.wp.com/gbailey.staff.shef.ac.uk/researchoverview_images/dmsp.jpg
The DMSP satellite is still operating, but the  SSM/I sensor is not

Regular readers will recall that on Feb 16th I blogged about this graph of arctic sea ice posted on the National Snow and Ice Data Center sea ice news page. The downward jump in the blue line was abrupt and puzzling.

nsidc_extent_timeseries_021509

Click for larger image

Today NSIDC announced they had discovered the reason why. The sensor on the  Defense Meteorological Satellite Program (DMSP) satellite they use had degraded and now apparently failed to the point of being unusable. Compounding the bad news they discovered it had been in slow decline for almost two months, which caused a bias in the arctic sea ice data that underestimated the total sea ice by 500,000 square kilometers. This will likely affect the January NSIDC sea ice totals.

Read the rest here

Advertisements

NSIDC issues documentation corrections – WUWT guest post a catalyst December 24, 2008

Posted by honestclimate in Discussions.
Tags: , , , ,
add a comment

NSIDC issues documentation corrections – WUWT guest post a catalyst

From Watts Up with That?, December 24, 2008

– WUWT guest post a catalyst

24 12 2008

You may recall the guest post from Jeff Id of the Air Vent I carried about a week ago called Global Sea Ice Trend Since 1979 – surprising

In that post, a note of correction was issued because that we were led to believe (by Tamino) that the entire post was “invalidated” due to an error in accounting for ice area very near the pole. Both Jeff and I were roundly criticized for “not reading the documentation”, which was one of the more civil criticisms over there at Tamino’s site.

After further investigation It turns out that the error was in NSIDC’s public documentation, and they have issued a correction to it. Even more importantly the correction now affects NSIDC’s own trend graph, and they are considering how to handle it.

This episode illustrates how citizen science can be useful. Sometimes people too close to the science they publish can make mistakes, (we’ve all been there) which is why peer review of papers is important.  But “web review” in this day and age of instant publication is equally important.  It also illustrates how mistakes, however embarrassing initially, can be useful if you learn from them and study the cause.  There is no shame in mistakes if they are corrected and you learn from them.  But, the blogospheric noise of angry and sometimes juvenile criticism (on both sides) really isn’t useful as it often masks the real issue. The key is to put that aside and find the truth behind the error. Jeff has done that. His update follows below.

Merry Christmas to everyone!  – Anthony


Based on The Air Vent post carried by Watts Up With That, the National Snow Ice Data Center has issued several corrections to the documentation of their sea ice area time series.Guest post by Jeff ID

Most will remember my earlier post which plotted global sea ice trends. After initially concluding that the global ice level wasn’t decreasing measurably Tamino pointed out a problem in my analysis. After issuing my corrections, thanks and apologies to Tamino and the um…..thousands of readers of Watts Up With That, I went back to work investigating what was really happening to the ice area time series.

It was actually quite lucky that Tamino mentioned the step in the data and criticized me for not reading carefully (something which was mentioned in several comments on the various threads). When I first learned of it, I found the criticism was based on an entirely different set of ice area data with different source documentation. Still, I checked closely and found the tiny step in the time series and was convinced that I had missed something. I had spent a huge amount of time learning the data before I made my post so it was frustrating to say the least. Understand, I used several resources to check my work; not the least of which was the National Snow Ice Data Center (NSIDC) anomaly graph which has the same shape as the one I generated.

The first graph below is from the NSIDC website, the second is my calc. Differences in the noise between the two are explained by the daily resolution used in my graph compared to what my eyes tell me must be monthly data for their plot. They also seem to have an additional year (2007) in their data plot which is not available in the bootstrap time series I used.

Read the rest click link below

http://wattsupwiththat.com/2008/12/24/nsidc-issues-documentation-corrections

Arctic Ice Extent Now Likely Highest Level Since 2002 November 10, 2008

Posted by honestclimate in Global Cooling.
Tags: , , , , ,
1 comment so far
Joseph D’Aleo

Joseph D’Aleo

Arctic Ice Extent Now Likely Highest Level Since 2002

From ICECAP, November 8, 2008

By Joseph D’Aleo

The latest daily arctic sea ice extent chart from IJIS shows the current year ice extent at the highest level in the record back to 2002. (2003 was missing).

image
See larger image here

The daily extents on November 7 look like this:

image
See larger image here

This represents an increase of 655,781 square kilometers over last November 7 or 7.4%. Side-by-side images from the Cryosphere show there is more ice on both the Pacific and Atlantic side this year. This is 44 days before the start of the Northern Hemisphere winter and 5 months before it will peak.

image
See larger image here
See pdf here.