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Weather Preferences

Found 11 results

  1. With the Arctic sea ice extent by some measures reaching close to or event setting record lows today and area doing the same, it feels like it's about time the melt season thread got underway for 2019. There's been a phenomenal crash in the past week with the extent moving from 9th to 1st lowest position. In the GEFS mean 850 hPa and 500 hPA GPH anomaly plots for the next 5 days averaged, we can still see a large and strong footprint from the events that brought this crash about: There's essentially a 'warm Arctic, cold continents' (WACC) event going on. The impact on ice from this has been mostly via the unusual wind patterns moving unusually thin, fragile ice around, as opposed to melting it directly. It's still too cold near and at the surface for the most part even with such large anomalies aloft. The pattern shows strong persistence during the next 10 days or so. Ice declines may continue at above normal rates during this time, which could take 2019 well below any previously observed years, depending on the surface wind patterns and how much more ice is still in a position from which it may be driven into a melting environment. The pattern also served to decelerate the mid-latitude westerlies faster than usual. Once the displaced from Arctic cold air disperses or warms out, it's possible that this will facilitate an unusually rapid warm-up in regions without snow cover. Meanwhile, late snow gains across the likes of Scandinavia and E. Canada may manage to restrain the rate of advance of heat onto the Arctic, depending on how much the weather patterns de-amplify as the WAAC event subsides. I'm concerned that they may not do so very much given the El Nino event currently underway. That aside, this big loss of sea ice cover opens the door to the open water feedbacks that, before this event came into view, I had been wondering if would be negated for this melting season. Will anomalous atmospheric moisture content yet again (as was particularly evident each season 2016-2018) bring about more cloud and LP formation than usual to diminish the solar-driven melt April through July? Science really is built on questions! p.s. If for whatever reason this new topic is to be deleted, may I please request that this leading post is placed into the topic being used instead, TIA.
  2. Poll number 4 of the summer. The average guess from the last poll was 3.54 million, up from 3.03 million in May, but with a lot less votes. After a slow melt in June, most extent and area measures are mixed, with 2016 somewhere between lowest and 3rd lowest on record. With volume, 2012 now has a clear lead, while 2016 now sits in 3rd, quite close to 2010, 2011 and 2013. With the weather looking highly favourable for melt over the next 10 days, lowest on record is still very much a possibility. 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 As always, voting is set to private.
  3. This is the 3rd sea ice minimum poll of the summer. The previous poll, posted on May 5th, had an average of 3.03 million km2 after 21 votes, while the April poll average 3.48 million from 16 votes. At the moment, we are still lowest on record by about half a million km2 going by most area and extent calculations, and lowest or 2nd lowest by volume. The sensor calibration is underway at the NSIDC and we should hopefully have the full official extent data back again soon. For now, we are going by the uncalibrated data provided by Wipneus. 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 As always, voting is set to private.
  4. This is the 2nd sea ice minimum poll of the summer. The previous poll, posted on April 5th, had an average of 3.48 million km2 after 16 votes. At the moment, we appear to still be lowest on record going by most area and extent calculations, and lowest or 2nd lowest by volume. Unfortunately, there was an issue with on the sensors used for calculating the NSIDC extent values used here, so we may not have NSIDC extent data for a few months. 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 As always, voting is set to private.
  5. 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.
  6. I am enrolled at UNIS,Svalbard, studying Arctic glaciers till September. I am hoping to keep this blog updated with details of what I am up to and pictures. So far I am limited to Longyearbyen, having not received gun training, but next week will start with fieldwork. The weather has so far been sunny, and rather warm, reaching a high of 15c yesterday. The constant light is taking some getting use too! I'll be visiting a local glacier on Thursday, where I hope to update!
  7. 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?
  8. It seems that we've likely passed the maximum this year going by most sea ice spatial coverage measures (area/extent). So with the refreeze over, it's time to start looking toward the melt season. The two polls above are based on the NSIDC data, with the first being the daily minimum, and the second being the September mean. Voting is set to private. I might create a new poll every month or so to see how opinions change during the inevitable ups and downs of the melt season. Going by the NSIDC extent data the daily maximum extent this year looks like it was 14,960,300km2 on the 20th, making it the 5th lowest maximum on record (since 1979), with the monthly average likely to be the 4th or 5th lowest. The volume according to PIOMAS was the 3rd lowest on record at the end of February. While this winter looks as though it was around the 2nd mildest on record (though changing the latitude bands may give slightly different values) Here are the daily minima from the past 10 years, with the monthly average in brackets. 2004: 5,776,080km2(5,989,560) 2005: 5,318,320km2(5,510,020) 2006: 5,748,770km2(5,868,890) 2007: 4,166,740km2(4,280,470) 2008: 4,554,690km2(4,695,040) 2009: 5,054,880km2(5,269,370) 2010: 4,599,180km2(4,872,050) 2011: 4,330,280km2(4,568,180) 2012: 3,369,730km2(3,580,150) 2013: 5,079,390km2(5,235,700)
  9. Hi folks. It's time for the first ARCUS sea ice extent prediction poll of the summer. ARCUS basically gather the prediction for the mean September Arctic sea ice extent from different scientists, organisations and public contributions, and make short reports based on them. More information can be found here http://www.arcus.org/search/seaiceoutlook The poll is for the MEAN September sea ice extent, which is always slightly higher than the daily minimum. Below is a graph of the September mean since 1979 The values from the last 10 years are 2003: 6.15 millionkm2 2004: 6.05 millionkm2 2005: 5.57 millionkm2 2006: 5.92 millionkm2 2007: 4.3 millionkm2 2008: 4.73 millionkm2 2009: 5.39 millionkm2 2010: 4.93 millionkm2 2011: 4.63 millionkm2 2012: 3.61 millionkm2 Monthly data is here ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/Sep/N_09_area.txt The current extent is at about 12.25 millionkm2. This is 11th lowest on record and almost the same as last year. The latest volume estimate from the PIOMAS model has us on lowest on record (end of April). The results of the prediction polls will be compared to the NSIDC data The results of this poll will be submitted on the evening of JUNE 7th, so any votes made after that time will not count.
  10. Hi I’ve extended the work that I’ve been doing into the downloading the Arctic sea ice data made freely available from the National Snow and Ice Data Center in Boulder and which I blogged about earlier this week. MethodWith the data that I had already obtained by parsing the files I had downloaded from the NSIDC, I calculated the following statistics: [*]Average extent of sea ice by meaning every available day of the year. [*]The percentage of the 1979 annual average. [*]The date and extent for the maximum extent of sea ice for that year. [*]The date and extent for the minimum extent of sea ice for that year. [*]The number of days between the spring maximum and the autumn minimum (melt days). [*]The total ice gain and loss from the previous season and the balance of the two. I inserted the statistics into a data grid and then plotted them into four separate graphs. [*]A line chart (1979-2069) of the mean and annual extremes, along with a linear regression trend for each series. [*]An area chart (1979-2012) of the length of the Summer melt season in days a long with an average of the entire series. [*]A bar chart (1979-2012) of each years gains and losses. [*]Another area (1979-2012) chart of the changes compared to the 1979 annual average. I purposely didn’t plot either the first and last years because they are incomplete years and screw the charts up! I did add forecast values to the first chart from the values I obtained from calculating trends for the maximum, mean and minimum ice extents. I added them till the Autumn minimum fell to below zero which it does by the year 2069. Before I get blitzed with complaints (that’ll be the day) about why I did this, I will freely admit that the logic behind doing this is more than a little bit dodgy. I know nature doesn’t like straight lines and that’s what linear regression give you, but the I thought what the heck and just did it anyway. I’ll also add that my calculations don’t take into account the year 2013 so they may be slightly out when I do make a calculation when this year is finally in. I also added a couple of image controls to compare the Arctic sea ice at its Winter maximum and it’s Autumn minimum. I did this by picking up the images directly from the NSIDC before archiving them so I could use them next time I ran my BioGraph application without having to access the internet again. ResultsThe decline in maximum, average and minimum sea ice is pretty uniform. We are already at just over 15% lower in 2012 than we were in 1979 using the annual average. If you look at the forecast trends for the year 2069 will mean that the annual average will be a third of what it was in 1979, and the autumn minimum will be 0%, meaning an Arctic clear of late summer sea ice in just 56 years time. The Summer melt season was interesting and varied enormously year to year. I don’t know if I’ve got these figures right but in 1997 the melt days were 168, the next year 1998 they shot up to 205, before falling again to 167 in 1999. I did read on the Met Office that storms in the the Summer can have a pretty dramatic effect on sea ice either one way or another. The third graph shows the gains and losses over the last 35 years or so. This year (if you look at the table we have a net gain of 1.7 million square kilometres in sea ice which reverses the losses of the last 3 years. As always please let me know if any of my calculation look a bit dodgy and I’ll put the right. The fourth and final chart just shows the difference in the annual average since 1979. This may look at odds to the last graph but this is due to the fact that I’m calculating a unique value for an entire year rather that just looking at extreme values. ConclusionApologies to the NSIDC for me fiddling with one of their images! I think the point of this blog is that anyone can make an educated guess at the future of the Arctic sea ice in the summer with a little bit of work, it may be unscientific but I did it without the help of a super Cray computer (or whatever they use nowadays) and came to the same conclusion that the IPCC have come to in their latest assessment – but cleverly I don’t think they specified a year! Bruce. PS Extra Image as always on my blog.
  11. Hi I have graphed just about every kind of data related to climate and meteorology over the last eighteen months, but for some reason I’ve never got round to looking for a data set of sea ice extent, and with all the hoo-ha at the moment concerning that and climate change, I thought I would investigate what was going on by downloading the sea ice data made freely available from the National Snow and Ice Data Center in Boulder (thank God for America and its attitude to free data). MethodQuite a simple parsing of CSV text file, made slightly tricky because the data for the first year or so was not daily but every other day, and the data for the the latest year was in a separate file. I combined both the Arctic data and the Antarctic data into one class to keep everything tidy. The nearly 11,000 lines of data in each file were parsed in less than 0.1 of a second. I plotted two graphs one showing an area chart with the daily values of sea ice extent in 10^6 square kilometres along with a trend line using all the data points. The second graph, a bar chart, displays the change in extent of sea ice in the last 365 days, red indicates less ice (warmer), blue indicates more ice (colder). ResultsThe Arctic graphs were how I expected them to look, with a steady decline in sea ice from around 12.5^6 to 10.5^6 square kilometres in the last 35 years a reduction of approximately 16%. I knew that this year Arctic sea ice had been more stubborn to shift by watching the SYNOP observations from northern Canada and Greenland (see this blog). What did surprise me is even though they has been a steady decline in sea ice how volatile the change from season to season is. The Antarctic graphs were a little surprising too, I did know that there had been a slight increase in sea ice there, and this was borne out by the area chart and the trend line showing a change from around 11.3^6 to 12.0^6 square kilometres, an increase of Antarctic sea ice of approximately 6% in 35 years. The other surprising thing was that for some reason I thought the Antarctic had a great deal more sea ice than the Arctic! To doI’ll try and link in this sea ice data set with global surface temperatures and maybe try and find an overlay the projections for future sea ice extent. Let me know if you spot any errors Bruce. PS More images on my blog.
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