Wednesday, March 21, 2018

The case for Invisible Arctic clouds

~Following a long series of particularly unexplainable refraction variations,  one culprit was no less  clear air water vapor and lower altitude ice crystals (specific from various geometric species).  They may not be seen,  but rival long wave feedbacks similar to  clouds physics.

~We give here some recent examples to be found amongst many others

    The first thing in identifying the effects of invisible clear air moisture is to describe what happens when the High Arctic is cloudy:

  March 5, 2018.  We observe the sea ice horizon fading by the arrival of Stratocumulus clouds 4300 feet high eventually covering the sky.   On this day with overcast conditions, precipitable water of the entire air column was a mere 1.44 mm.  In the Arctic,  cloudy conditions may occur with very little precipitable water (pw) .  During winter,  precipitable water  in the High Arctic seldom exceeds 3 mm,  more often  between 1.0 and 2.0 mm during clear sky conditions or not.   Hinting the great possibility of invisible clouds,  with moisture formations giving surface based long wave radiation variations similar to when cloudy.   In the photo above,  the sea ice horizon was 2.3 arc minutes above astronomical horizon before overcast conditions occurred.   It is common to loose the visual sea horizon when the sky is overcast with low clouds,  at times it is measurable.  When able to do so ,  the horizon can be very near the Astronomical Horizon altitude.

       Further examples abound:   January 26 2018 had very low overcast conditions,  pw was 2.10 mm,  on the 24th same month 300 feet stratus near overcast skies had a pw column of 1.18 mm,  on the 12th of January various altitude clouds were part of 1.48 mm pw. On Feb 12, 2018 0.85 mm with alto cumulus dominating overcast.  When mid air winds are not so strong, spontaneous cloud formations can also be seen throughout winter,  sometimes appearing and disappearing within a few hours,   this is not an often quoted meteorological process,  but it can be said that the cloud may revert to invisible or visible mode.

     On many observed occasions,  horizon heights defied logic,  sometimes higher or lower  than would be expected given nearly identical meteorological conditions from one day to the next.  But First Melt 2018 might have exposed  one secret player for all of us to consider.  First Melt is a horizon event marking the return of sea horizon elevation to Astronomical Horizon.  Implying
T*** = Ts,  top of snow (ice) temperature is equal to surface air temperature:

Note the March 14 horizon sky,  it is whitish by local smog,  but the sea ice is at astronomical horizon height.  First Melt came early with surface temperatures below -40 C,   otherwise suggesting dry air, but that may be a bit misleading. It was the coldest day of winter with tropopause height below 500 mb!  Of course the stratosphere above the troposphere is almost always devoid of moisture, as happening here,   the entire 0.66 mm precipitable column was found compressed between surface and 590 mb:
     Mixing Ratio (gr/kg) vs altitude in meters.  March 15 00 UTC  Radiosonde from station 71924, South Cornwallis Island Nunavut Canada.    An extraordinary moisture profile.

    First Melt is an event caused by top of sea ice temperature equal to surface air,  for March 14 event to have happened,  it was necessary for thin sea ice to be present,  because thin sea ice has more potential  heat to compensate for extreme cold air,   very frozen air  cooling top of sea ice tends to be cancelled by the heat of the ocean,  but on this afternoon,   the sun's short wave radiation stopped sea ice top from cooling,  in fact was warming it along with the air at its interface.

    With much thicker sea ice the equation of winter would be more often: T*** < Ts,  causing  strong inversions since thicker sea ice insulates the warming from -1.8 C sea water. 

      If it was only thin ice causing  First Melt to be early,   identical sun rays at equal or coming from higher point in the sky would continue giving a daily drop to Astronomical Horizon after local apparent noon for days to come,   that was not so,  next  clear days had it slightly or much higher horizons:
March 16 2918,  with 11.5 degrees sun elevation as opposed to 11.4 for the same spot 2 days ago,  gave a dramatically higher horizon elevation,  nearly 1 arc minutes higher.  Same sun elevation,  same sea ice with identical snow with no major weather event in between,  however  different horizon height??  You have noticed correctly a bluer sky  captured with identical equipment as for March 14 picture, there was a lesser local upper inversion preventing smoke from scattering,    it was also 6 degrees C warmer.    March 14 picture had highly compacted moisture but very little  as opposed to March 16:

   March 16 2018 tropopause was much higher than March 14,  with moisture more scattered throughout its upper air profile till the tropopause.  This suggests  double the precipitable water  has had an effect on the altitude of the sea ice horizon,  which it possibly had,  the air on First Melt day was very dry,  this allowed more Short Wave through,  called solar forcing . 

   The over all impact of clear air moisture ,  its contribution to long wave radiation deflections may be small to important,   however it can be measured even while not observing refraction effects. Top of snow temperature layer minus surface temperatures may dramatically vary day to day without any clouds.  While precluding windy days,  there are several examples of unexplainable variations of refraction and snow temperatures during clear air conditions,  only plausible with the presence of clouds.

     Invisible clouds were first suspected by strange refraction observation variations eventually confirmed by correct top of snow and surface air observations.  An overcast with low clouds day can have top of snow temperatures always very close or equal to surface air temperatures.  When not cloudy,  with dominant  clear skies,  top snow layer may be persistently equal to Ts  as well,  even during the presence of the sun going up and down.   Refraction observations obtained similar horizon heights  as with extensive cloud coverage or with clear skies,  in both instances an indication of a long wave feedback system,  sometimes with bounce back points easily conclusive,  sometimes not.  If all air moisture wasn't invisible I would write about their geometry.  At any rate,  we do have many examples of observed days with T***=Ts with very few clouds or none at all,

       Jan 13  2018 a clear day in darkness,  following a cloudy one,  similar T*** and Ts on all readings , pw was 3.26 mm.    Jan 17,  2.70 mm .    Apparent clear air moisture preceding coming of a cyclone system was detected March 11 with a 2.51 mm pw.  February 20,   1.79 mm.

      Some observations were rather confusing to analyze:  March 12 1.43 mm.   Jan 15 in darkness 1.37  and March 15  with 1.18 mm .....  All these observations suggest not seen moisture likely  affecting the climate in the longer term.  wd March 21,2018

Saturday, March 17, 2018

High Arctic sea ice First Melt 2018 earliest in short monitoring history

~First melt 2018 predicts a coming great sea ice melt with a high degree of confidence..  
~Very latest discoveries unveils largely invisible moisture capable of bouncing back Long Wave Radiation much like clouds.  
~This affects sea ice horizon readings without affecting the theory behind "First Melts" observations. 

When the sea ice horizon comes back down to astronomical horizon elevation after always being above that altitude throughout the entire High Arctic winter, this event is called "First Melt". When accretion stops, bottom sea ice may be fragile and or melt. This happens when the temperature top of sea ice/snow is equal to surface air. During the dark season , ice accretes when interface sea water looses heat towards space, this heat loss stops when temperature of top sea ice/snow is same as surface air some weeks after long night sunrise with sun high enough to warm up the top of ice sheet. Astronomical horizon is reached as long as the sun warms the top of ice, and then when daily sun lowers towards setting, sea ice horizon rises. The degree of horizon elevation fluctuations depends on sea ice thickness and how porous the Arctic atmosphere to short and long wave radiation. Overcast skies can theoretically create first melt conditions, but this was hardly observed. First Melts usually occur a few hours after local apparent noon when sunny with rays well above 5 degrees elevation. With thinner sea ice, the core minima temperature of sea ice column is not as strong and expansive as with very thick multiyear sea ice, the sun can warm top of sea ice quicker, likewise, and this is a very latest discovery, if the atmosphere is very porous to long and short wave radiation, the First Melt would tend to arrive later than usual, if the atmosphere blocks and bounces back all radiations, First Melts may come earlier, because it is not really a matter of temperature, but a matter of no temperature difference between surface air and top of sea ice. In simpler terms, a long Arctic night with a long term persistent more saturated or moist atmosphere is not good for sea ice accretion, sea ice would become thinner under these conditions with less radiation having escaped towards space.

First Melts in brief history:

2017 April 25,   In earliest Chronology:   2012  ~ 2012 PIOMAS peak to peak max. volume loss  
2016 March 18,                                           2016      2010                                                 
2015 March 26,                                           2010      2016
2014 April 10,                                             2013       2011           
2013 March 23,                                           2015       2015
2012 March 17,                                           2014       2013
2011 April 15,                                              2011       2017
2010 March 19.                                           2017       2014

        March 2016 was corrected upon verification of data, was off by 0.2 arc minutes. 2011 was the only outlier on otherwise largely predictive powers of First Melt data with respect to conditions of not only sea ice, currently near or at record thinness, but also atmospheric conditions, in particular how persistently moist or how dry the Arctic long night atmosphere was. This explains 2011 as it was very likely a drier long night, this has something to do with circulation patterns, unlike 2018 where we have had a continuous onslaught of Cyclonic intrusions from both the North Pacific and Atlantic. Furthermore 2011 Arctic winter occurred during a very deep La-Nina which was ideal for lesser clouds. 2011 equally had record number of very damaging tornadoes further South, along with very cold stratosphere, on "steroids" as I wrote.

     2018 First Melt happened March 14, the earliest on record since monitoring has started. Throughout the long night the sea ice horizon of the Central North West passage tended to be low. Not always, but more often low than higher. This was an indication of a largely pervasive moist atmosphere, which is an anti-accretion process during the dark season. The two geophysical processes go hand and hand, thinner sea ice is the product of a warmer more moist atmosphere during winter, snow adds on to this process, more snowfall replaces ice thickness, because a thick snow layer is fairly good insulation. The current over all sea ice thickness of the Arctic may be much thinner for a very large area of the Arctic Ocean given that South Cornwallis Island is a representative area of sea ice conditions extending well beyond the Canadian Arctic Archipelago, mainly because the stated prolonged moist atmosphere came mainly from the North Atlantic by way of the North Pole. WD March 17,2018

Friday, March 2, 2018

Back towards El-Nino; no post 1998 La-Nina rebound yet...

~High Arctic skies are recently strangely cloudier.
~A few days ago a clearer evening had telltale ominous high black cloud streaks up to 10 degrees above the horizon,  they only appear when trending El-Nino or at extreme El-Nino peak temperatures. 
~It seems not believable because we never went deep La-Nina like post 1998 immediate years

      BOM Australia demonstrates a clear ENSO trend towards El-Nino:
As we recall 2 years after 1998 super El-Nino the world SST's looked like :
Deep cold La-Nina was well in place 2 years following 1998 super El-Nino , very unlike  2016's post SST action:

    NOAA depiction of preceding 2 weeks SST's  reveal a significant warming about the Galapagos Islands.  Which if continuing would preclude a High Arctic big blue sky spring event.  Increasing cloudiness should happen if trending towards El-Nino continues.  
This has significant impact for the summer sea ice melt season which would delay earlier spring onset of melt ponds.  WD March 2, 2018