Support the Arctic Sea Ice Forum and Blog

Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.


Messages - Greenbelt

Pages: [1]
1
Arctic sea ice / Re: The 2019 melting season
« on: September 16, 2019, 03:31:20 PM »
Hey folks, sorry I've been away for a bit. Unfortunately, discussing the CAA ice here is necessarily low on my list of obligations. There's been some question about how the current ice regime will interact with the traditional "garlic press" process of the CAA. Short story: there's not much garlic left to press.

The way the garlic press is supposed to work, thick MYI at the southern boundary of the CAB gets forced into the steep channels of the CAA resulting in additional ridging and compaction. Over a number of years, that ice is eventually delivered south into melt-accessible areas. All of this works because the average prevailing wind pattern in the region forces that ice into the archipelago and then south (and, to some extent, southeast). This process is the primary reason why the ice in the CAA has traditionally behaved very differently from fast ice elsewhere (although the channel size and bathymetry of the archipelago would otherwise suggest that CAA ice is comparatively uninteresting fast ice).

This melting season did a lot of damage to these assumptions. Most of the season was spent with an atypical wind pattern that forced ice from the CAA/CAB boundary north against the CAB and west into the Beaufort. Thus, the Crack was born. Additionally, while this wasn't a record-setting year for CAA melt, it was pretty devastating nevertheless. Massey Sound was a killing field for ice. The Peary and Sverdrup Channels have some ice only by dint of latitude. In the Perry Channel, the surviving ice (primarily associated with the Viscount Melville Sound) has been forced by late storms to the southwest into areas that are frequent melt-out traps. The region that has been the temperature "cold core" of the archipelago in historical data wasn't actually very cold; ice in the PGAS is badly fragmented and exceptionally mobile, and even the sheltered ice in Wilkins Strait looks more than a little roughed up.

More importantly, what remains of the MYI -- the tiny, thin line of red on the age maps -- has been displaced north into the CAB, away from the CAA boundary. The Crack has filled as the wind patterns return to their expected directions, but the ice that filled the Crack is not that MYI stopgap, but an assemblage of broken bits transported in from elsewhere, including no small part of relatively young ice from the Lincoln Sea area. This is not robust garlic for the press. It's reasonable -- one hopes -- to assume that wind flow will indeed push ice south into the CAA. But this ice has demonstrated considerable structural weakness. So I expect floe disintegration rather than ridging as the disparate floes are forced together. Winter's cold will mitigate some of this, and the whole mess will freeze into a matrix of FYI (effectively fast) ice.

The overall trend for the Arctic is, of course, hotter with more melt. But as we've seen this year and the past couple, that melt is not always distributed in the same pattern year over year. If we get a year or two where the melt focus turns away from the CAA, and we don't see Crack 2 in 2020, the garlic press will likely crank back up for awhile anyway. Otherwise, within a couple of years, we may very well see what happens when the CAA explores a new modality (as we're already seeing with Bering/Chucki mechanics).

2
Arctic sea ice / Re: The 2019 melting season
« on: August 13, 2019, 09:02:44 PM »
They are both wrong.

And back to the point, we are in some control of where the climate heads although we cannot control the details and we are struggling to understand the complex interactions between the ocean, ice and atmosphere. It's shocking to me that the Arctic ocean is so thinly observed given its key role in earth's climate. The few buoys we have making observations of the upper ocean show heat at about 50m that the Mercator model is missing.

Careful observation of individual floes shows that A-Team is correct that the ice does not directly follow wind streamlines, sea surface height gradients or ocean currents. It is affected by all of them, plus it compresses and forms ridges. Below the surface, we have sparse measurements of the movements of water masses. We're still trying to untangle the effects of the GAC in 2012 on the sea ice because we have don't have dense enough data on Arctic ocean heat content changes through the melting season. And "we" includes the sea ice experts who don't do significantly better at predicting September extent than this ragged group of interested observers. For a variety of reasons, but mainly because we can't predict seasonal weather well, the expert's models don't work very well.

Ironic, isn't it that the one thing we do know pretty well, the effects of CO2 on paleoclimate, has been so poorly explained in this melting thread. Geothermal heat has an inconsequential effect on climate. https://skepticalscience.com/heatflow.html

Solar heat and all the factors that affect the earth's radiation balance control the climate. Greenhouse gases are among the most important controls and CO2 is the key gas over the past billion years. The modern climate is paradoxical because the sun was cooler in the precambrian than it is now. Of course, we know that declining CO2 levels over the past 25 million years led to the onset of the Pleistocene and the ice ages. Those declining CO2 levels we mostly caused by increased rock weathering rates associated with the continental collision of the Indian plate with the Eurasian plate.

So while we watch the impacts of unprecedented ocean temperatures in the far north Pacific and Atlantic oceans, and shockingly warm Arctic seas, on Arctic weather and sea ice, two proudly ignorant fools are clogging this thread with arguments that ignore the effects of CO2 on climate. Siberia is literally on fire, thunderstorms are approaching the north pole and the Arctic oscillation has been stuck in hot subsidence mode almost all summer and yet some folks here don't seem to get that rapidly increasing CO2 levels are the primary cause of all of it.

Click image to animate. The heat keeps on coming into the Eurasian side of the Arctic.

3
Arctic sea ice / Re: The 2019 melting season
« on: July 29, 2019, 01:59:41 PM »
..

4
Arctic sea ice / Re: The 2019 melting season
« on: July 25, 2019, 04:38:16 PM »
First time this month we have 2012 ASI Image for the date. Here is 2007/2012/2016/2019 comparison. I shifted the day since 12 and 16 are leap years.


5
Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: April 22, 2019, 03:42:48 PM »
Large area drop in Greenland Sea Region today:

torching in Fram Strait and above.

6
Arctic sea ice / Re: The 2018/2019 freezing season
« on: October 28, 2018, 07:09:31 AM »
October 23-27.

8
Arctic sea ice / Re: The 2018 melting season
« on: August 07, 2018, 06:51:57 PM »
Doing a 'reality check', I'm zooming in on an area of thick ice.

Arctic ice thickness (CICE), via yesterday's Navy website [I ignore certificate issues.] shows lots of 2 to 4 meter ice in the Lincoln Sea.  (Color scale pasted into image).  WorldView shows the Lincoln Sea to be filled with a loose mélange with some larger floes that I presume are thick (probably 3 meters or more thick). [Scale moved to be within view.] An arrow points to a floe that, in the Sentinel Hub image (note 3 km scale),  is in the lower right corner.  This shows much of the mélange to be floes, some 5 km across or more, but many on the order of 50-500 meters across.  (Arrow points to corner of floe that is in the lower left corner of 200m scaled enlargement.)  These are plenty big enough to be 2 or more meters thick. [Sentinel-hub doesn't go north of this location.]  See the melt ponds on the enlargement.

Even if it is mostly thick floes, there are a lot of floe edges that can chip away (wind-induced bumper-car style destruction) or melt (wave assisted).

9
Arctic sea ice / Re: 2018 sea ice area and extent data
« on: August 05, 2018, 10:55:39 PM »
Time to break out 2018's Arctic minimum running back chart (named after the way it will wiggle through a crowd of dots in a few weeks' time).

10
Arctic sea ice / Re: Latest PIOMAS update (July)
« on: July 03, 2018, 04:26:30 PM »
PIOMAS gridded thickness data has updated, the official volume data not yet.
Calculated from thickness I get 13.8 [1000 km3] for 30th June, fifth sixth lowest place.

Here is the animation. As PIOMAS uses NSIDC sea ice concentration, I watched for some visual disturbance on the 27th. I don't see much there, perhaps you do.

11
Arctic sea ice / Re: 2018 sea ice area and extent data
« on: June 29, 2018, 03:36:47 PM »
Yesterday's data (ice date 2018-06-27) has not been corrected. Today's data (ice date 2018-06-28) looks much better with a jump in area of +471k.

Is the data good or bad? I am not sure, attached is a delta of two days skipping the obvious faulty 27th.

12
Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: June 21, 2018, 06:45:07 PM »
Update of the Jaxa AMSR2 sea ice thickness/melt animation. During the melting season thickness is rather without meaning, but the melting area should be interesting.

Here I combine the Ascending and Descending data: in melting if detected in either, else average thicknesses.

13
Arctic sea ice / Re: The 2018 melting season
« on: June 16, 2018, 08:31:15 AM »
Watch that fast ice crumble! This is three days' worth of imagery of the Laptev Sea, 14, 15 and 16th June.

(Click image to see animation).

14
Here are updated Healy links, conveniently posted in post #200:
As this is a new season, some repeated info:
ship position:  http://www.sailwx.info/shiptrack/shipposition.phtml?call=NEPP
ship webcam:  http://icefloe.net/Aloftcon_Photos/index.php?album=2018 [images start May 31, 2018]
Healy Track Map: http://icefloe.net/uscgc-healy-track-map [currently showing end of recent sea trials]
current mission http://icefloe.net/healy-current-mission [showing three 2018 missions, but
only the Sept/Oct mission link has info at this time.]
current deployment info:  https://www.pacificarea.uscg.mil/Our-Organization/Cutters/cgcHealy/ [current as of July 26.]
Healy background, tour and specs, etc.:  http://icefloe.net/healy-main
Press releases and selected published articles:  https://www.pacificarea.uscg.mil/Our-Organization/Area-Cutters/CGC-Healy/Updates/AWS18/ [no 2018 data, but some 2017 stuff at this time]
Wikipedia page

15
Arctic sea ice / Re: The 2018 melting season
« on: June 05, 2018, 08:53:17 AM »
I've been looking for a quick way to validate temperatures from models across the Arctic. VIIRS Brightness Temperature (Band I5, Day) and Night overlays seem to work pretty well. In tandem with using Terra / MODIS Bands 7-2-1 to locate clouds, one can look at the surface temperatures where there are no clouds.

Here is June 4th with the day band overlayed. The lowest shaded bucket is 270.9-271.6K (-2.25C - -1.55C). Above freezing temps occur at the transition to purple and max out at 4.05C.


(https://i.imgur.com/Ai5kMi8.jpg)

Here is a link to Worldview which has this overlay specified for VIIRS day and night bands: https://worldview.earthdata.nasa.gov/?p=arctic&l=MODIS_Terra_CorrectedReflectance_Bands721,VIIRS_SNPP_CorrectedReflectance_TrueColor,MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor(hidden),Coastlines,VIIRS_SNPP_Brightness_Temp_BandI5_Day(opacity=0.67,palette=rainbow_1,min=270.9,271.6,max=276.6,277.2,squash),VIIRS_SNPP_Brightness_Temp_BandI5_Night(hidden,opacity=0.67,palette=rainbow_1,min=270.9,271.6,max=276.6,277.2,squash)&t=2018-06-04-T00%3A00%3A00Z&z=3&v=-2860023.1037379596,-1120673.8055663547,3038216.8962620404,2700894.1944336453

My biggest takeaway is that the open water on the Pacific side is a kill zone for ice that gets transported into it.

16
Arctic sea ice / Re: The 2018 melting season
« on: May 31, 2018, 12:17:16 PM »
The Lena River is certainly a big beast, with a huge maximum discharge when the snow melts. June is the big month - but apparently snow-melting is also happening in May now. Presumably large amounts (200gt ?) of fresh water entering the Laptev in just one month must impact how ice loss happens in the Laptev.   See data below and images attached.


A nice video about Lena and the nature of Yakutia. The video was shot near the Lena delta at this time of year several years ago. In this video, Lena breaks ice and the ice flow begins.

In 2018, front edge of the ice flow will reach Lena delta in 3-4 days.

17
Arctic sea ice / Re: The 2018 melting season
« on: May 29, 2018, 03:01:37 PM »
The Canadian model has been desperately trying to get Iqaluit above freezing, but seems powerless to make it happen. The forecast keeps getting closer but yesterday again it only hit -1.1 C when the forecast was 0 C.

I’m curious what it is that’s making the models run so warm (ECMWF seems to not be having this problem).
You of course have seen Rick Mercer's take on the Environment Canada forecasts? ( )

18
Arctic sea ice / Re: 2018 sea ice area and extent data
« on: May 21, 2018, 06:44:14 AM »
[ADS-NIPR-JAXA] ASI Extent.

May 20th, 2018: 11,374,694 km2, a drop of 60,049 km2.
2018 is the second lowest on record.
2018 has 384,740 km2 more than 2016 and 138,836 km2 less than 2015.

19
Arctic sea ice / Re: The 2018 melting season
« on: May 18, 2018, 10:40:06 AM »
The ECMWF SLP forecast is looking a bit worse again now, with high pressure remaining relatively high and quite extensive. D7-10 has the high pressure moving over to the Siberian side of the Arctic, but forecasts that far out tend to be volatile, and so there's no use in posting them. Here's D1-6:

Pages: [1]