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Messages - JayW

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101
Arctic sea ice / Re: The Rammb Slider Thread
« on: June 01, 2019, 10:27:48 PM »

I remember seeing little cyclonic features like that in 2013...14?

There was some discussion but no conclusions.

I suspect they are fairly common, but exist in the lowest part of the atmosphere along frontal boundaries.  Since they are so low, higher clouds likely obscure them normally.

Speaking of swirls, some neat, fractal-like ones in the Greenland sea today.

http://rammb-slider.cira.colostate.edu/?sat=jpss&z=5&im=18&ts=1&st=0&et=0&speed=130&motion=loop&map=1&lat=1&opacity%5B0%5D=1&hidden%5B0%5D=0&pause=0&slider=-1&hide_controls=0&mouse_draw=0&follow_feature=0&follow_hide=0&s=rammb-slider&sec=northern_hemisphere&p%5B0%5D=band_i01&x=17694.875&y=13175.0419921875

Needs click, band I2, because it's the highest resolution.

102
Arctic sea ice / Re: The 2019 melting season
« on: June 01, 2019, 07:48:47 PM »
These large floes don't seem to have the strength like 2016 in the Beaufort.  I hope this isn't the thicker, multi year ice that's been discussed.

http://rammb-slider.cira.colostate.edu/?sat=jpss&z=5&im=18&ts=1&st=0&et=0&speed=130&motion=loop&map=1&lat=1&opacity%5B0%5D=1&hidden%5B0%5D=0&pause=0&slider=-1&hide_controls=1&mouse_draw=0&follow_feature=0&follow_hide=0&s=rammb-slider&sec=northern_hemisphere&p%5B0%5D=band_i01&x=16862&y=20466

This was the largest chunk. (Requires a click)

104
14 hour loop, ending on June 1, 01 UTC

105
Arctic sea ice / Re: The Rammb Slider Thread
« on: June 01, 2019, 12:03:45 AM »
Plenty of streaks showing NE of Utqiagvik.
Band 8, needs click.

106
12 hour loop.

107
 most recent VIIRS image.

Edit: I am in the June 1-7 camp.

108
Arctic sea ice / Re: The Rammb Slider Thread
« on: May 30, 2019, 01:23:24 PM »
Here's the area in the Kara Sea where more darkening in band M8 is evident.  I hypothesize that the thin, low clouds produced drizzle (liquid), wetting the snow, where the thicker clouds were able to generate higher precipitation rates, and thus snow, leaving behind the white streaks.

http://rammb-slider.cira.colostate.edu/?sat=jpss&z=4&im=18&ts=1&st=0&et=0&speed=130&motion=loop&map=1&lat=1&opacity%5B0%5D=1&hidden%5B0%5D=0&pause=20190530074202&slider=-1&hide_controls=0&mouse_draw=0&follow_feature=0&follow_hide=0&s=rammb-slider&sec=northern_hemisphere&p%5B0%5D=band_m08&x=13081.361328125&y=13241.1669921875

Click to run

110
Arctic sea ice / Re: The Rammb Slider Thread
« on: May 30, 2019, 10:32:51 AM »
worldview terra modis corrective reflectance 367 picks up the same striations on may26-28. I'm thinking peak sunlight through different layers of cloud combined with warm air temperature for a shortish time period. (click to run)
Melt ponds between pressure ridges, my 2 cents worth.
That's kinda my thinking as well, although I think that the dark is wet snow, not quite liquid water. 

The pressure from the Beaufort ice getting shoved westward by the winds must've piled the ice up somewhere.  As the pressure ridges rose up, the extra weight then lowered the troughs between ridges, allowing see water to saturate the snow.



I noticed the same with the other dark spots too.

Could it caused by rain?

I'm coming around to the idea that the dark areas in band M8 are representing wet snow, and whiter areas are drier/colder snow.  I think in many of these cases, we are seeing the snowpack "ripen", meaning that it has softened to the piont it's melting so that it's surface is wet, but it's still very white, as the water can't pool on the surface yet.  That's why everything looks white in the visible bands, but picked up by the near infrared bands and displays as darker.

Today's interesting area of darkening is SE of Wrangel Island.  Here we see a storm passing through, but offering is a window through the dry slot.  A close look reveals some white bands that follow the cyclonic curvature of the storm. My interpretation is that the majority of precipitation that fell was a mixture of rain and snow, this wet down the snow (dark patches).  The whiter arcs are areas where the the precipitation came down hard enough that it was able to stay snow.  This is very common for storms where the temperatures are neat 0°C, the heavier stuff creates more cooling in the column and can drag down enough cold to keep it snow.

There's some similar patterns emerging in the Kara Sea this morning, but waiting for a few more images to load for that area.

http://rammb-slider.cira.colostate.edu/?sat=jpss&z=4&im=18&ts=1&st=0&et=0&speed=130&motion=loop&map=1&lat=1&opacity%5B0%5D=1&hidden%5B0%5D=0&pause=0&slider=-1&hide_controls=1&mouse_draw=0&follow_feature=0&follow_hide=0&s=rammb-slider&sec=northern_hemisphere&p%5B0%5D=band_m08&x=13818.2783203125&y=21136.111328125

Edit: added the Bremen cause color, as it picked up on the "torching" in the Chukchi where I feel the rain/snow mixture fell.

Requires a click

112
Getting closer

113
Arctic sea ice / Re: The Rammb Slider Thread
« on: May 28, 2019, 12:36:44 PM »

115
Arctic sea ice / Re: The Rammb Slider Thread
« on: May 27, 2019, 11:48:57 PM »
Okay, instead of clogging up the melting thread with my speculative post, this fits well here.  I was perusing the arctic using band M8 ("snow/cloud"), and was struck by some features on the Pacific side, these also show up in the two "snow/ice" bands. As an aside, the "I" bands are 375m resulting, "M" bands are 750m.  They are clearly features of the ice, not atmospheric, but I'm not willing to go as far as saying it is wetness, as much as I'm tempted.  The satellite definitely "sees" something, but I can't discern if it's a roughness thing, a temperature thing, or a wetness thing, or even a combination.  I've reattached the NPP satellites a bit, but haven't gained clarity.  Incidentally, the area that uniquorn referenced at 85.3N, 96.5E shows as a dark spot. (Third attachment, still image)

First attachment is north of the Chukchi. (Click it)
Link to are area http://rammb-slider.cira.colostate.edu/?sat=jpss&z=5&im=42&ts=1&st=0&et=0&speed=130&motion=loop&map=1&lat=1&opacity%5B0%5D=1&hidden%5B0%5D=0&pause=0&slider=-1&hide_controls=1&mouse_draw=0&follow_feature=0&follow_hide=0&s=rammb-slider&sec=northern_hemisphere&p%5B0%5D=band_m08&x=14903.9169921875&y=19530.083984375

Second is further north. (Click it)
Link http://rammb-slider.cira.colostate.edu/?sat=jpss&z=5&im=42&ts=1&st=0&et=0&speed=130&motion=loop&map=1&lat=1&opacity%5B0%5D=1&hidden%5B0%5D=0&pause=0&slider=-1&hide_controls=1&mouse_draw=0&follow_feature=0&follow_hide=0&s=rammb-slider&sec=northern_hemisphere&p%5B0%5D=band_m08&x=14903.9169921875&y=19530.083984375

116
Arctic sea ice / Re: The 2019 melting season
« on: May 27, 2019, 04:36:52 PM »
Plotted the average skin surface temp from May 1-25 for the last 8 years. Sorry about the resolution, I was trying to save space.  2012 is upper left, 2019 lower right.

117
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: May 26, 2019, 04:03:17 PM »
"Compactness" running on the low side.

118
Arctic sea ice / Re: The 2019 melting season
« on: May 26, 2019, 02:27:23 PM »
Dove-tailing with the melt pond and snow cover discussion, here's a couple of screen grabs of the snow cover model from Climate Reanalyzer; the first is today, the second is for June 1st.

The takeaway is, GFS predicts snow cover over the next 6 days will be hammered, seriously.

A lot of that melt - 6-10CM worth - will be on the snowpack in the CAB.


I'm wary of the *raw* GFS data and its handling of snowmelt, especially on the ice.  The GFS is not coupled to sea ice, and also has issues dealing with boundary layer (the part that interacts with earth's surface) temperatures.

First attachment
The plots provided by the NOAA/ESRL Physical Sciences Division, Boulder, CO from their Web site at https://www.esrl.noaa.gov/psd/ , which are forced by the GFS forecast, but with a markedly different result. Note that the upper right panel, "GFS ice area", remains unchanged through the 7 day forecast, as its un-coupled"

Second attachment (Requires a click) is the 10 day sea ice forecast from the ECMWF, available at https://weather.us/model-charts/euro/north-pole-zoom1/ice-ocean-lake/20190605-0000z.html , this is a coupled model.

119
Arctic sea ice / Re: The 2019 melting season
« on: May 26, 2019, 01:23:02 PM »
May 21-25.
On top of other comments, it seems like the Beaufort expanded and solidified, almost as if a refreeze was going on. I would say it's probably a removal of the effect of clouds on the sensor, or a freezing of surface meltwater on the ice, but would like to hear more expert opinions.
Not an expert here, but I'd say it's a result of the cyclone that moved through the region.  It finally reversed the persistent easterlies that dominated the Beaufort for a week or so, and pushed sea ice back to the southeast.  I'm sure that the storm brought precipitation, and some wet snow can't be totally ruled out, in my humble opinion.

http://rammb-slider.cira.colostate.edu/?sat=jpss&z=2&im=42&ts=1&st=0&et=0&speed=130&motion=loop&map=1&lat=0&opacity%5B0%5D=1&hidden%5B0%5D=0&pause=0&slider=-1&hide_controls=1&mouse_draw=0&follow_feature=0&follow_hide=0&s=rammb-slider&sec=northern_hemisphere&p%5B0%5D=band_m07&x=16668&y=18760

120
Arctic sea ice / Re: The 2019 melting season
« on: May 24, 2019, 12:38:27 PM »
7 day Melt pond fraction forecast from ESRL, Physical science division.

https://www.esrl.noaa.gov/psd/forecasts/seaice/

122
Consequences / Re: Wildfires
« on: May 20, 2019, 01:48:10 AM »
GOES west today, northern Alberta.

123
Arctic sea ice / Re: The 2019 melting season
« on: May 19, 2019, 08:06:47 PM »
I'd wager that it rained in that yellow area near the center.


124
Arctic sea ice / Re: The 2019 melting season
« on: May 19, 2019, 03:32:52 PM »
 60s hour loop of the Kara Sea. May 16, 22Z - May 19, 9Z.  The winds appear to be shifting in the most recent frames, likely leading to less sea ice loss in the coming days for this area, just the slush getting moved around.

http://rammb-slider.cira.colostate.edu/?sat=jpss&z=3&im=12&ts=1&st=0&et=0&speed=130&motion=loop&map=1&lat=0&opacity%5B0%5D=1&hidden%5B0%5D=0&pause=0&slider=-1&hide_controls=1&mouse_draw=0&follow_feature=0&follow_hide=0&s=rammb-slider&sec=northern_hemisphere&p%5B0%5D=band_i02&x=13555.5&y=12655.5556640625

Second attachment is Kara Sea ice area.

125
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: May 18, 2019, 12:07:12 AM »
 I figure this is the best place for this.
Slater sea ice anomaly persistence model predicting 8.47 million km2 on July 6.

I believe the Charctic graph (third attachment) is the proper comparison, apologies if I'm mistaken.
Lowest for that date is 2012, with 8.796 million km2

I'm not saying it'll be correct, but I found it interesting.

126
Arctic sea ice / Re: The 2019 melting season
« on: May 17, 2019, 11:47:49 AM »
60 hour loop of the Beaufort. May 14 12Z  - May 17 0Z.
 (Requires a click)

Second attachment is the ECMWF forecast. The tight pressure gradient north of Alaska is progged to persist another 5 days or so, resulting in 20-30 knot easterly winds.

127
Arctic sea ice / Re: The Rammb Slider Thread
« on: May 15, 2019, 12:14:10 PM »
49 hour loop - Kara Sea - ending at 722Z, May 15, 2019 - contrast enhanced
(Requires a click)


128
Arctic sea ice / Re: The 2019 melting season
« on: May 12, 2019, 09:15:29 PM »
ECMWF suggests some southerly winds over the Kara Sea over the next couple days, might see meaningful losses three over the next couple days.  At day three, a period of strong easterly winds should begin north of Alaska, this'll could really open up the Beaufort (beginning in 3 days) I'm well aware of the pitfalls of trusting the models, but this has been consistent in several models.


129
Arctic sea ice / Re: The 2019 melting season
« on: May 01, 2019, 12:28:51 PM »
One week (~174 hours) movie, Pacific side.

130
Arctic sea ice / Re: The Rammb Slider Thread
« on: April 29, 2019, 12:19:06 PM »
Effects of southerly winds over the Bering and Chukchi are evident.
Last 3 days.

131
Arctic sea ice / Re: The Rammb Slider Thread
« on: April 23, 2019, 12:50:35 PM »
Laptev sea April 18-23. Band M7.

132
Arctic sea ice / Re: The 2019 melting season
« on: April 05, 2019, 10:09:59 AM »
The nice folks over at the RAMMB CIRA site from Colorado State University have added Suomi and N20 imagery to their slider at 51 minute intervals.  Perhaps some will find this of interest.
Here's the last 2 days focused on the Kara Sea.  There are additional bands available, along with the ability to overlay and zoom.  Unfortunately, it can't be rotated in the slider.

http://rammb-slider.cira.colostate.edu/?sat=jpss&z=2&im=54&ts=1&st=0&et=0&speed=130&motion=loop&map=1&lat=1&opacity%5B0%5D=1&hidden%5B0%5D=0&pause=0&slider=-1&hide_controls=1&mouse_draw=0&follow_feature=0&follow_hide=0&s=rammb-slider&sec=northern_hemisphere&p%5B0%5D=band_m07&x=13379&y=12292

133
Arctic sea ice / Re: The 2018/2019 freezing season
« on: October 14, 2018, 04:26:13 PM »
The RAMMB/CIRA slider now has some VIIRS imagery from the Suomi and JPSS-1 satellites. It's not resolution isn't on offer with worldview, but it does allows for sub-daily imagery, as it uploads a new image roughly every 51 minutes.  It should prrpe fun in boreal summer, but for now, it's useful for tracking storms.  In clear conditions, the ice surface can also be picked up.

I chose a water vapor band.
http://rammb-slider.cira.colostate.edu/?sat=jpss&z=1&im=24&ts=1&st=0&et=0&speed=130&motion=loop&map=1&lat=1&opacity%5B0%5D=1&hidden%5B0%5D=0&pause=0&slider=-1&hide_controls=1&mouse_draw=0&follow_feature=0&follow_hide=0&s=rammb-slider&sec=northern_hemisphere&p%5B0%5D=15&x=16432&y=15824

135
Arctic sea ice / Re: The 2018 melting season
« on: June 11, 2018, 11:44:23 AM »
According to WindyTv's ECMWF temperature map air below 100m altitude is immediately losing 15-20C as it enters the Laptev Sea - I made the crude calculation that the ~110kg of air in a 1m2 area below 100m altitude  loses enough energy  to melt 6mm of ice over 1m2. Not a lot if the air stayed still maybe but with 19kt winds off the land the coastal ice will be getting hammered.

  And there is plenty of warmth further aloft , with temperatures peaking at 925hPa at 19C, way out near the CAB, and above freezing almost to 3000m across the Laptev and a swathe of the CAB. It would be interesting to know what proportion of the energy in the air will ultimately be transferred to the ice, - I don't know enough about atmospheric physics to even make a guess - but eg if all the warmth to 925hPa were transtered to the ice, that would melt several cm over the region, adding to insolation losses and bottom melt. And warm wind continues to blow in, with clear skies under a high



Most of the time, air near the surface is warmer than aloft, but often when there is snow and ice on the surface, an inversion develops.  Low clouds and fog can prevent this warm air from mixing down, forcing the warmer air to ride up over the cold air.  I can't find any model that shows the mixing depth.  It's not always easy to scour out that surface cold.

https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2018-06-11-T00%3A00%3A00Z&z=3&v=-33594.171304008225,-362428.14196693257,2264558.0330386385,2342688.515228058

136
Arctic sea ice / Re: The 2018 melting season
« on: June 03, 2018, 12:23:01 PM »
What am i missing ? The first 2 pics are from yesterday. The 3th is for 22 July. There shoud be a 4,5 million square km gap.

It's a purely statistical "forecast".  Areas that have a positive extent anomaly currently will be "assumed" by the model to persist. 

Perhaps the late Dr. Slater's post explains it.  I couldn't quote the original post. Linked here https://forum.arctic-sea-ice.net/index.php/topic,778.msg28212.html#msg28212

Quote
Persistence (light blue line) in the time series plot is an anomaly persistence. At the issue date (d), compute the difference of the observation from the long term mean for that day of year; this is the anomaly. At the forecast date (d+lead_time), find the long term mean and add the previously computed anomaly i.e. you have persisted the anomaly.
The "Forecast" is the method based on regression and integrating the probability of ice survival etc.
Persistence is on the plot in response to a comment that the Forecast provides no added value compared to persistence, but this can't be judged from just one year. My brief bits of work suggest it is non-trivial to beat persistence at sub-seasonal timescales.

The plots on the page should update every day - it's only a 50-day forecast (though I have run longer cases).  I haven't got around to adding conf. intervals ...

137
Arctic sea ice / Re: The 2018 melting season
« on: June 02, 2018, 11:21:29 AM »
106 hour loop of Chukchi and Beaufort.  Some larger pieces in the Beaufort can be seen breaking up.  Open water in the Chukchi is slowly expanding.  It makes me wonder about the time of wind stress on the currents in the Chukchi, due to its late freeze up the last couple years combined with early breakup.


http://feeder.gina.alaska.edu/npp-gina-alaska-truecolor-images

139
Arctic sea ice / Re: The 2018 melting season
« on: May 21, 2018, 12:03:52 PM »
Pacific side, 105 hours, May 16-20.  I went with an mp4 to preserve detail.  Low clouds are clearing out as a "cleaner" high pressure appears to be taking over.  If the ECMWF is to be believed, it will have some staying power.

"Little darling, it's been a long cold lonely winter
Little darling, it feels like years since it's been here
Here comes the sun, here comes the sun
And I say it's all right…"

  - George Harrison


http://feeder.gina.alaska.edu/npp-gina-alaska-landcover-images?search%5Bfeeds%5D%5B6%5D=1&search%5Bsensors%5D%5B3%5D=1

140
Arctic sea ice / Re: The 2018 melting season
« on: May 17, 2018, 12:04:10 PM »
925mb reanalysis temp anomaly from April 14-May 14, 2018.

https://www.esrl.noaa.gov/psd/data/composites/day/

141
Arctic sea ice / Re: What the Buoys are telling
« on: May 17, 2018, 11:14:23 AM »

142
Arctic sea ice / Re: The 2018 melting season
« on: May 16, 2018, 02:52:13 AM »
Is that clouds or is there a little bit of refreeze in the Beaufort as the ice fractures and separates?

There's certainly low clouds, especially today.  I wouldn't rule out some freezing over of leads locally, but it's my opinion that it's mostly clouds, perhaps entirely.

Here's the "landcover" band from VIIRS.  May 12-15, ~81 hours

http://feeder.gina.alaska.edu/npp-gina-alaska-landcover-images?search%5Bfeeds%5D%5B6%5D=1&search%5Bsensors%5D%5B3%5D=1

143
Arctic sea ice / Re: The 2018 melting season
« on: May 15, 2018, 03:00:49 AM »
Beaufort Sea May 9-13, 102 hours. Contrast boosted for detail, I also find it makes it easier to distinguish the clouds from the surface.

http://feeder.gina.alaska.edu/npp-gina-alaska-truecolor-images?search%5Bfeeds%5D%5B5%5D=1&search%5Bsensors%5D%5B3%5D=1

144
Arctic sea ice / Re: Arctic Image of the Day
« on: May 12, 2018, 04:15:46 PM »
I haven't tried to upload an mp4 yet, but I'll try.   

Barrow webcam, neat to see the sun riding the horizon.

http://feeder.gina.alaska.edu/feeds/webcam-uaf-barrow-seaice-images/movies/10018_webcam-uaf-barrow-seaice-images_2018-5-11_1-day-animation

145
Arctic sea ice / Re: The 2018 melting season
« on: May 10, 2018, 12:02:26 AM »
May 5-9 Beaufort and some Chukchi, 101 hour loop.  Easterly winds north of Alaska are beginning to ramp up, and are progged to increase over the next 24 hours, persistenting for several days.  We'll see soon if anything freezes.

Contrast slightly increased for detail.  Imagery courtesy of the University of Alaska at Fairbanks.
.
http://feeder.gina.alaska.edu/npp-gina-alaska-truecolor-images?search%5Bfeeds%5D%5B5%5D=1&search%5Bsensors%5D%5B3%5D=1

146
Arctic sea ice / Re: The 2018 melting season
« on: May 08, 2018, 12:25:18 PM »
Looking at the tightly packed isobars, there should be some strong easterly winds over the Beaufort beginning in a couple days, if the ECMWF is to be believed.  Unlike last week, the winds are progged to be warmer, so I wouldn't expect the leads to freeze over this time.  While there appears to be some thicker multi year ice in the Beaufort Sea, there is also a fair amount of ice that is only weeks old that formed in leads opened by previous wind events. Could be an interesting week.

https://www.tropicaltidbits.com/analysis/models/?model=ecmwf&region=ak&pkg=z500_mslp&runtime=2018050800&fh=72

147
Arctic sea ice / Re: The 2018 melting season
« on: May 02, 2018, 12:01:15 PM »
102 hours loop April 27- May 1, Beaufort and some Chukchi.  Looks like most of the fast ice NE of Alaska has sheared away.  The Chukchi isn't freezing over anymore, at least the southern part, but low clouds ( likely due to the open water) are obscuring things.  The Beaufort is freezing over the leads opened up by the winds.

Contrast slightly increased for detail

http://feeder.gina.alaska.edu/npp-gina-alaska-truecolor-images?page=4&search%5Bfeeds%5D%5B5%5D=1&search%5Bsensors%5D%5B3%5D=1

148
Arctic sea ice / Re: The 2018 melting season
« on: April 27, 2018, 12:24:34 PM »
April 23-26, 2018, 78 hour loop of the Beaufort Sea.  Doubt there is much melting, but certainly a fair amount of wind driven displacement.

<snip>
It's a non-trivial decrease in Albedo is what it is... aside from the fragmentation of the ice that is taking place.

I agree. According to the ECMWF (and largely agreed upon by other models), the easterly winds north of Alaska are progged to pick up over the next 24-36 hours and persist for the next four days.  Forecast skill decreases rapidly, so I won't speculate beyond that, but it suggests the "rifting" in the Beaufort should continue in the near future.

https://weather.us/model-charts/euro/north-pole/wind-mean-direction/20180503-0000z.html

149
Arctic sea ice / Re: The 2018 melting season
« on: April 27, 2018, 12:44:16 AM »
April 23-26, 2018, 78 hour loop of the Beaufort Sea.  Doubt there is much melting, but certainly a fair amount of wind driven displacement.

Contrast slightly increased for detail.

http://feeder.gina.alaska.edu/npp-gina-alaska-truecolor-images?page=3&search%5Bfeeds%5D%5B5%5D=1&search%5Bsensors%5D%5B3%5D=1

150
Arctic sea ice / Re: The 2018 melting season
« on: April 24, 2018, 12:11:50 AM »

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