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Interitus

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  1. The simple fact is that solar forcing during the varying solar cycles is now overwhelmed by other factors - primarily greenhouse gases, aided currently by AMO phase. Since solar cycle (SC) 20 global temperatures have been rising counter to solar activity and SC 22 and 23 (1986-95 and 1996-2007) the solar/temperature correlation has broken down completely (see "On the Relationship Between Global Land-Ocean Temperature and Various Descriptors of Solar-Geomagnetic Activity and Climate" https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20140006389.pdf). Remember according to Solheim et al in this current cycle 24, Svalbard was supposed to be 6°C colder in winter than the last cycle - complete fail, it is warmer and they ignored other influences such as the ice retreat through Arctic amplification and the favourable AMO.
  2. Curious to where that Tackley reading has come from. There is an amateur site in Tackley which recorded 1.6°C https://www.themcintyres.dnsalias.net/weather/tables.html while the official UK min was 1.3°C at South Newington about 8.5 miles away
  3. The z500 geopotential anomaly charts are distorted by the fact that geopotential heights are proportional to temperature - with a warmer arctic there is a positive anomaly. Better to use sea level pressure - probably shows what many people want to see with regards near surface flow but the anomalies are not particularly dramatic - With regard to the stratosphere, it may have potential for wave 1 propagation from the eurasian side to the stratospheric Aleutian high giving strat vortex displacement. Just to add, looking at the earlier charts in the past year this completely missed the SSW influenced cold early spring and the warm summer.
  4. As interesting as how Helene itself progresses, this feature appears that it may be an example of downstream cyclogenesis excited by Helene.
  5. Strong sense of deja vu here as the POL was brought up in the discussion on the OPI back in 2014. At almost the same time the concept of the Taymyr Circulation Anomaly came to the fore in the paper October circulation precursors of the wintertime Arctic Oscillation (Kryjov 2014). This highlighted the correlation between Taymyr October geopotential anomalies and the following winter AO, but it seems the paper is still paywalled. At the time an arbitrary point was used to investigate this correlation (74.5°N 104°E) using 500hPa geopotential. However, the author co-wrote a follow-up paper Predictability of the wintertime Arctic Oscillation based on autumn circulation (Kryjov & Min 2016) which gives an insight to the earlier work and its application to forecasting (they use 700hPa geop. anom averaged and area weighted over 80-70°N 100-120°E). This paper is available - https://www.researchgate.net/profile/Vladimir_Kryjov/publication/292075140_Predictability_of_the_wintertime_Arctic_Oscillation_based_on_autumn_circulation/links/56c3f03708ae8a6fab5a3396/Predictability-of-the-wintertime-Arctic-Oscillation-based-on-autumn-circulation.pdf As illustrated in 2014, the homebrew Taymyr index proved superior to the POL in correlations with the AO, below are the correlations from 1950 up to last winter - Winter AO Dec AO Jan AO Feb AO Taymyr index 0.390 0.265 0.342 0.258 POL index 0.182 0.090 0.145 0.167 In particular it supports the link between October circulation and winter AO suggested by Kryjov. This doesn't tell the whole story however as shown in this chart of running 20-year correlations between the indices and winter AO. Also included are a Mongolian z500 anomaly (50°N 120°E) which has been used to create an estimated POL - The first few years are poor for all, this may be due to issues with data quality in the early reanalysis - the authors above use from 1958 onwards. After this though, the Taymyr index is better than the POL except for the 3 year period 2005-2007 (interestingly the artificial POL also beat the Taymyr), but more than this it proves to be relatively stable providing consistently good correlations over time. The same can't be said of the POL however which is poor in the early years even anticorrelated to winter AO and this is more strongly the case for the Mongolian anomaly - it would suggest that the value of the POL is given by the node in the area of the Taymyr circulation and it is dragged down by its dipole in Mongolia. In the second half of the period the Mongolian anomaly correlation improves which leads to better performance from the POL and there is also quite a marked sudden improvement for all including the Taymyr index. Couple of possibilities spring to mind - the timescales of Mongolian and POL correlations with winter AO are similar to the AMO. The 30 year correlation between the Mongolian anomaly and October AMO exceeds -0.7 when AMO leads by 29 years - but is >0.8 when AMO lags by 9 years (with over 0.95 for 10 year averaged AMO) - because of the timescales involved more data would be required to investigate this link further. The apparent sudden improvement in all indices may coincide with improved reanalysis with satellite data maybe. Finally with regards to changes since 2007, it is worth noting that all the correlations have fallen since the 2007-12 period.
  6. Crazy, on the GFS Helene still has a residual warm core as she approaches Cornwall -
  7. Gusts to 103 mph in the southwest approaches beforehand, then over 80 mph in the Bristol channel and north Wales. 60-70 mph widespread inland, then 70-80 in the lee of the pennines, according to weather.us
  8. Well of course if you're including the vessel's ice class then for the highest ratings the NSR is open all year round for independent navigation but this is not the same as ice-free. The ice-class and access to the various regions of the NSR under varying ice conditions can be seen here - http://www.arctic-lio.com/nsr_iceclasscriteria - vessels without ice reinforcement are only allowed in open water between July-November 15th without icebreaker support. This is in theory anyway, assuming they have a permit from the Russian Northern Sea Route Administration - http://nsra.ru/en/home.html Their opening dates of the ports along the route this year were in July - Summer navigation started in the NSR From 00 h 00 min July 05, 2018 summer navigation will start in the Dikson port. Order dated July 05, 2018 № 2/2018. From 00 h 00 min July 30, 2018 abolition of restrictions on the mode of navigationin the Dudinka port. Order dated May 15, 2018 № № 07/18. From 00 h 00 min July 15, 2018 summer navigation will start in the Khatanga port. Order dated July 15, 2018 № 01/18. From 00 h 00 min July 10, 2018 summer navigation will start in the Tiksi port. Order dated July 19, 2018 № 1/2018 From 00 h 00 min July 02, 2018 summer navigation will start in the Pevek port. Order dated July 02, 2018 № 1/18. As of 07/09/18 there were 84 vessels officially along various parts of the NSR - http://nsra.ru/en/grafik_dvijeniya_po_smp.html?date=2018-09-07 - only a few traverse the whole route of course. Worth bearing in mind though that the narrow ~20 mile open water in the East Siberian Sea is the width of the English Channel. If you have a decent icebreaker though you can bypass the NSR - at the moment the Swedish icebreaker Oden is near the north pole at 88°42'N
  9. The northern sea route is narrower than last year but is still wide open The ice in that area is just scattered floes, tens of kilometres offshore shown clearly in today's visible satellite images https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor,MODIS_Terra_CorrectedReflectance_TrueColor(hidden),Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2018-09-08-T00%3A00%3A00Z&z=3&v=-1466812.8553492154,1681641.1034302178,-767420.8553492154,1979625.1034302178
  10. That's +/- 2 standard deviations - assuming that there was no long term melting trend and the ice extent had a normal distribution (i.e. the range of values) then statistically there would be only around a little more than 2% chance of the extent being lower than it is the moment. The ice is still in a very poor way albeit not as bad as the end of summer in some recent years. Worth bearing in mind that the lowest summer extents don't always have the lowest values by late autumn, never mind winter - this summer's levels are similar to last year and last winter had the lowest extent on record for much of the time.
  11. Their 3rd air frost of the season already. More interesting as can be seen was that it came after a max of 24.3°C for a range of 24.5°C within 24 hrs.
  12. And tracking maps - http://www.atmos.albany.edu/facstaff/abrammer/maps/tracks/ (In fact explore his site, some good stuff there such as the GFS/ECWMF comparison maps)
  13. Interesting feature, GFS/GEFS fairly certain that it will develop. Mid-Atlantic system the ensembles have it possibly affecting the Azores or Canadian Maritimes later on but op runs have had it variously heading our way. Either aiding ridging or stormy weather mid-September, something to watch. Appropriate moment to link to Alan Brammer's experimental GEFS storm genesis tracker - http://www.atmos.albany.edu/facstaff/abrammer/maps/genesis/
  14. Well, the mode vs the mean - the GEOS analysis gave westerlies returning on 24/08 which is exactly the average date for the mean zonal wind to become positive in the MERRA reanalysis Date Data Minimum 10% 30% Mean 70% 90% Maximum Fcst 2018-08-23 -0.18 -2.70 -1.46 -0.72 -0.21 -0.01 0.23 0.55 0 2018-08-24 0.64 -2.91 -1.01 -0.32 0.12 0.30 0.71 1.58 0 https://ozonewatch.gsfc.nasa.gov/meteorology/figures/merra2/wind/u60n_10_2018_merra2.txt
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