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We've just passed the maximum for the year, which, for the 2nd consecutive year, set a new record low. Current sea ice extent is the lowest on record, sea ice area is lowest on record and volume (according to PIOMAS) is the 2nd lowest on record after 2011. Here are the daily minima since 2000, and the 80s and 90s averages. 80s 6.963 90s 6.423 2000 5.943 2001 6.567 2002 5.625 2003 5.969 2004 5.770 2005 5.314 2006 5.746 2007 4.147 2008 4.548 2009 5.047 2010 4.590 2011 4.333 2012 3.340 2013 5.040 2014 4.988 2015 4.341 Votes are set to private and the we'll use the daily NSIDC data to determine the minimum. I'll update this a few times during the melt season.
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Seeing as nobody has started this topic... The melt season is here, generally lasting from March/April to September each year. After previous slight improvements in the minima in both 2013 and 2014 after the record low of 2012, many AGW "sceptics" see this as a sign of an Arctic sea ice recovery, while others see it as short term variation on a long term trend. Most extent and area measures have this years max as the lowest on record, while volume sits about 6th lowest and highest since 2010. So, how will this season pan out? A continued reversion to the mean or return to the long term downward trend?
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We're at the end of June and things are looking mixed in the Arctic. After a large May melt phase, including about 3 weeks up to the first week of June as the lowest extent on record, declines began to slow just as previous years declines accelerated. This means we've gone from lowest on record to about 6th or 7th lowest over the last 3 weeks or so, and we're now about 600k above 2012. PIOMAS volume is still down around 6th lowest up to the end of May, while the DMI's new volume measures have us closer to the bottom 3 on record. At the moment it appears all to play for, but if we don't see a serious acceleration in the melt rate this month, the chances of a bottom 3 finish will be very slim. Below are the September daily lows up to 2014 As always, votes are set to private EDIT: The poll didn't seem to save? Can a mod add one in (it's exactly the same as last months poll) or do I need to start a new thread?
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- sea icearctic
- melt season
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Now that we're entering the full swing of the melt season, I thought it would be time for the first sea ice minimum poll of 2015. (Most ice info used here is based on the daily NSIDC daily sea ice extent data, unless otherwise stated). We've just come out of a very mild, though not exceptionally so, winter which saw the lowest sea ice maximum on record by most area and extent measures. 925hPa temps north of 70N ......... ............. .............. Maximum Sea Ice Extent The early part of the melt season has seen temperatures well above average across most of the Arctic, with sea ice extent generally in the bottom 3 on record, with the daily value of 12,531,000km2 being the 2nd lowest for May 16th (most recent). On the other hand, sea ice volume has continued to slowly grow from the minimum in 2012, with April 2015 the 7th smallest volume on record. There is a long way to go this melt season, but the forecast for the near term shows things warming up across much of the Arctic with temperatures climbing well above freezing, especially across the Pacific side, around the Beaufort/Chukchi regions, so a good chance of an accelerated melt period over the next 7 days. After that, who knows? (Votes are set to private, for anyone concerned about that)
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The sea ice growth appears to be accelerating now, with NSIDC extent up over 300k on the minimum. including an increase of almost 60k yesterday, while the 5 day trailing average is up 165k on the minimum and 36k up on yesterday. Below is the extent increase (with the 5 day trailing average), between the minimum and September 30th for each year. The same, but for the minimum to October 31st each year is below it. Extent increases over the last week have been well above recent and long term averages, but temperatures look like warming up relative to average across much of the Arctic during the weekend and early next week, so closer to average sea ice coverage increases may occur next week.
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Here is my understanding of the PV: As we head towards Winter the differences in temperatures at lower and higher latitudes create a vortex in the stratosphere and troposphere around the Arctic regions. Differences in temperatures in the stratosphere over the Arctic due to several factors (eg Rossby waves) can cause changes in the Stratospheric Polar Vortex which then feed down to the Tropospheric Polar Vortex. These changes can affect weather patterns at sea level. Dramatic changes caused by events such as SSW's can cause the PV to split or displace, which will have massive effects on weather patterns. But how? For example, does a PV that is displaced over Greenland cause high pressure to build here? Or does it do the complete opposite? Basically, my question is; in what way does the positioning of a split/ displaced PV affect weather patterns such as pressure systems, zonal/ meridonial winds, etc? I appreciate this may get a bit technical (for me at least!), but I will try my best to understand. Any answers would be much appreciated. Many thanks.
