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Messages - uniquorn

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1
Antarctica / Re: Pine Island Glacier (PIG) Calving and Discussion
« on: January 13, 2021, 10:51:38 AM »
A larger version of Ice Velocity from Images Pairs for an overview. Apologies for the fast speed, it's the only way I know how to compress a slow 53MB gif down to 2.1MB. For analysis, best to download it and view frame by frame. (or better, download the original .png files, the ani is half size, cropped)
jul2018-dec2020
The images differ in size by a few pixels so the ani jumps around a bit

I'm quite new to panoply so the third image should be treated with some caution. It focuses on a smaller area from 0-160m. Some of the settings are included in the capture.
x,y coordinate scaling may not be quite right
STD x,y velocity probably not so interesting.

2
Antarctica / Re: Pine Island Glacier (PIG) Calving and Discussion
« on: January 12, 2021, 03:44:14 PM »
PIG Along-Flow, Across-Flow ice speed and Ice Velocity from Images Pairs since may2018
http://www.cpom.ucl.ac.uk/csopr/iv/index.php?glacier_number=3
Quote
Hogg, A., A. Shepherd, N. Gourmelen (2015) A first look at the performance of Sentinel-1 over the West Antarctic Ice Sheet, FRINGE 2015, Frascati, Italy, 23-27 March 2015.

All best viewed at half speed.

3
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: January 10, 2021, 05:04:39 PM »
A look at CMEMS mixed layer depth model from Mercator
Quote
The Operational Mercator global ocean analysis and forecast system at 1/12 degree is providing 10 days of 3D global ocean forecasts updated daily. The time series start on January 1st, 2016 and is aggregated in time in order to reach a two full year’s time series sliding window. This product includes daily and monthly mean files of temperature, salinity, currents, sea level, mixed layer depth and ice parameters from the top to the bottom over the global ocean. It also includes hourly mean surface fields for sea level height, temperature and currents. The global ocean output files are displayed with a 1/12 degree horizontal resolution with regular longitude/latitude equirectangular projection. 50 vertical levels are ranging from 0 to 5500 meters. This product also delivers a special dataset for surface current which also includes wave and tidal drift called SMOC (Surface merged Ocean Current).


https://en.wikipedia.org/wiki/Mixed_layer
Quote
Oceanic mixed layer

Importance of the mixed layer
The mixed layer plays an important role in the physical climate. Because the specific heat of ocean water is much larger than that of air, the top 2.5 m of the ocean holds as much heat as the entire atmosphere above it. Thus the heat required to change a mixed layer of 2.5 m by 1 °C would be sufficient to raise the temperature of the atmosphere by 10 °C. The depth of the mixed layer is thus very important for determining the temperature range in oceanic and coastal regions. In addition, the heat stored within the oceanic mixed layer provides a source for heat that drives global variability such as El Niño.

The mixed layer is also important as its depth determines the average level of light seen by marine organisms. In very deep mixed layers, the tiny marine plants known as phytoplankton are unable to get enough light to maintain their metabolism. The deepening of the mixed layer in the wintertime in the North Atlantic is therefore associated with a strong decrease in surface chlorophyll a. However, this deep mixing also replenishes near-surface nutrient stocks. Thus when the mixed layer becomes shallow in the spring, and light levels increase, there is often a concomitant increase of phytoplankton biomass, known as the "spring bloom".

Oceanic mixed layer formation
There are three primary sources of energy for driving turbulent mixing within the open-ocean mixed layer. The first is the ocean waves, which act in two ways. The first is the generation of turbulence near the ocean surface, which acts to stir light water downwards.[1] Although this process injects a great deal of energy into the upper few meters, most of it dissipates relatively rapidly.[2] If ocean currents vary with depth, waves can interact with them to drive the process known as Langmuir circulation, large eddies that stir down to depths of tens of meters.[3][4] The second is wind-driven currents, which create layers in which there are velocity shears. When these shears reach sufficient magnitude, they can eat into stratified fluid. This process is often described and modelled as an example of Kelvin-Helmholtz instability, though other processes may play a role as well. Finally, if cooling, addition of brine from freezing sea ice, or evaporation at the surface causes the surface density to increase, convection will occur. The deepest mixed layers (exceeding 2000 m in regions such as the Labrador Sea) are formed through this final process, which is a form of Rayleigh–Taylor instability. Early models of the mixed layer such as those of Mellor and Durbin included the final two processes. In coastal zones, large velocities due to tides may also play an important role in establishing the mixed layer.

The mixed layer is characterized by being nearly uniform in properties such as temperature and salinity throughout the layer. Velocities, however, may exhibit significant shears within the mixed layer. The bottom of the mixed layer is characterized by a gradient, where the water properties change. Oceanographers use various definitions of the number to use as the mixed layer depth at any given time, based on making measurements of physical properties of the water. Often, an abrupt temperature change called a thermocline occurs to mark the bottom of the mixed layer; sometimes there may be an abrupt salinity change called a halocline that occurs as well. The combined influence of temperature and salinity changes results in an abrupt density change, or pycnocline. Additionally, sharp gradients in nutrients (nutricline) and oxygen (oxycline) and a maximum in chlorophyll concentration are often co-located with the base of the seasonal mixed layer.

Oceanic mixed layer depth determination
The depth of the mixed layer is often determined by hydrography—making measurements of water properties. Two criteria often used to determine the mixed layer depth are temperature and sigma-t (density) change from a reference value (usually the surface measurement). The temperature criterion used in Levitus[5] (1982) defines the mixed layer as the depth at which the temperature change from the surface temperature is 0.5 °C. The sigma-t (density) criterion used in Levitus[5] uses the depth at which a change from the surface sigma-t of 0.125 has occurred. Neither criterion implies that active mixing is occurring to the mixed layer depth at all times. Rather, the mixed layer depth estimated from hydrography is a measure of the depth to which mixing occurs over the course of a few weeks.

The mixed layer depth is in fact greater in winter than summer in each hemisphere. During the summer increased solar heating of the surface water leads to more stable density stratification, reducing the penetration of wind-driven mixing. Because seawater is most dense just before it freezes, wintertime cooling over the ocean always reduces stable stratification, allowing a deeper penetration of wind-driven turbulence but also generating turbulence that can penetrate to great depths.

Palette colours chosen to highlight 10m-190m. West Spitzbergen current and other areas are deeper at times.

4
Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: January 09, 2021, 05:21:19 PM »
Kara Sea.
Compilation of AWI v103, SMOS and Mercator salinity at 34m, oct28-jan8.
Some interference in the Barents on SMOS. Some small colour changes in compilation so the scales are a rough guide

AMSR2 3.125 data from Wipneus. Kara not quite reaching the dip of 2017 yet.

5
The forum / Re: Forum Decorum
« on: January 06, 2021, 01:15:23 AM »
ASIF info centre Jan6

6
Arctic sea ice / Re: What the Buoys are telling
« on: January 05, 2021, 12:46:37 PM »
drift track and ~6m-200m temperature and salinity profile contours for selected whoi itp's. The criteria for selection was that the buoys should drift close to or within the BGOS buoy moorings (white circles) and have a reasonably long profile. Some fail quickly. Note that there are a couple of scale changes early on and that often the drift track is longer than the profiler battery life (or other reason for failure). So, as nearly always, this is just a very rough historical guide over a small area in the Beaufort from 2006-2021
White can often be interpreted as warmer than top of the scale (off the chart) but may also be due to missing data. For itp121 white means off the chart. Found a newer version of itp5 temp.

7
Arctic sea ice / Re: The 2020/2021 freezing season
« on: January 03, 2021, 06:16:41 PM »
A possible candidate is upwelling.
http://oceanmotion.org/html/background/upwelling-and-downwelling.htm

Meanwhile in the Beaufort the warm layer is even thicker below whoi itp120

8
Arctic sea ice / Re: What the Buoys are telling
« on: January 02, 2021, 08:52:38 PM »
IABP buoys 2012-2014.

9
Arctic sea ice / Re: The 2020/2021 freezing season
« on: January 02, 2021, 12:10:16 PM »
A comparison of 2017, 2018 and 2020 freezing seasons using amsr2-uhh

10
Arctic sea ice / Re: The 2020/2021 freezing season
« on: December 30, 2020, 01:17:46 PM »
-- Was this ice retreat wind-driven?  If so, then it indicates to me the ice front in that area was really fragmentary and weak in its nature in mid December. <>
Yes. There are similarities with 2016. Note the refreeze south of the wind driven ice front (see #953 above)
Is it melting? In my view ice is always melting along much of the West Spitzbergen current. During most winters drift speed and thickness is enough that it is not visible from above except (imo) occasionally along the shelf break north of FJL.

amsr2-uhh comparison of 2020 and 2016, dec20-29

11
Arctic sea ice / Re: What the Buoys are telling
« on: December 28, 2020, 09:29:11 PM »
1994 dir. Contains 92-95
check 11252

12
Arctic sea ice / Re: The 2020/2021 freezing season
« on: December 26, 2020, 08:19:10 PM »
An attempt to identify the white band in worldview by overlaying S1B onto a very enlarged ascat and suomi npp viirs brightness temperature band15 night. All from dec14, the nearest clear(ish) day.

Also an overlay of dec26 S1B onto dec14 at 50% transparent.

On a different note, the Atlantic front is still very sensitive to wind direction.
amsr2 awi v103 dec18-26(early)

Mosaic floe2 at ~87N also reacting to yesterday's 50km/h southerlies.

13
Arctic sea ice / Re: The 2020/2021 freezing season
« on: December 24, 2020, 01:53:48 PM »
CS2SMOS merged SIT oct16-22 to dec14-20. An attempt at measurement rather than modelling.

14
Arctic sea ice / Re: What the Buoys are telling
« on: December 22, 2020, 05:54:58 PM »

//////////////// PS, would welcome criticism of my Arctic-donut approach to defining region (will also be bugged before 1986):

lon=(df.Lon.values.tolist())
lat=(df.Lat.values.tolist())
locations=[]
for lon_i,lat_i in zip(lon,lat):
    if lat_i > 80:
        location='Central Arctic Basin'
    else:
        if lon_i > -161 and lon_i < -125:
            location= 'Beaufort'
        elif lon_i > 148 and lon_i < 178:
            location= 'ESS'
        elif lon_i > 95 and lon_i < 148:
            location= 'Laptev'
        elif lon_i > 56 and lon_i < 95:
            location= 'Kara'
        elif lon_i > 16 and lon_i < 56:
            location= 'Barents'
        elif lon_i > -15 and lon_i < 16:
            location= 'Greenland'
        else:
            location= 'Chukchi'     
    locations.append(location)   
df['location']= locations
A couple of suggestions to align a bit closer to wipneus and nsidc. I think 80N is a good compromise.
if lon_i > -157 and lon_i < -125:     ## utqiagvic as marker
            location= 'Beaufort'
        elif lon_i > 145.5 and lon_i < 178:
            location= 'ESS'
        elif lon_i > 97 and lon_i < 145.5:  ##mid NSI
            location= 'Laptev'
        elif lon_i > 64 and lon_i < 97:
            location= 'North Kara'  ##not many buoys in Kara anyway?
        elif lon_i > 16 and lon_i < 64:
            location= 'Barents'
        elif lon_i > -45 and lon_i < 16:  ##coastal drift might be interesting
            location= 'Greenland'
        else:                   ## 157 to 178 though this will include bering, cutoff at 66.5N?
            location= 'Chukchi' ##probably best to define chukchi or it may pick up CAA/baffin outliers

15
Arctic sea ice / Re: The 2020/2021 freezing season
« on: December 21, 2020, 09:44:47 PM »
The last of the thick MYI has now completely moved into the beaufort, and the wind pattern for the coming week will surely speed that up...
Ascat tending to confirm that hycom forecast, day297-355.
crf 27 compression, 1.2MB

16
Arctic sea ice / Re: MOSAiC news
« on: December 17, 2020, 10:37:25 PM »
Will probably try an overlay comparison of buoys on to (modelled) sea ice age once I've worked through all the data.
A comparison of Eulerian and Lagrangian methods for dating in numerical ice-sheet models

A new tracking algorithm for sea ice age distribution estimation
Quote
The new algorithm is driven by the new sea ice drift products from OSI SAF, which is void of potential artifacts due to inclusion of autonomous ice drifter buoys. This leads to a more homogeneous distribution of ice age fractions over the Arctic Ocean. The algorithm is also constrained by the observed sea ice concentration from OSI SAF, which reduces fractions of old ice and, consequently, ice age by 20–30 %. It  was  applied  to  generate  time  series  of  daily  sea  ice  age fraction product from October 2012 to October 2017. Comparisons with the NSIDC SIA time series indicate that the fractions of MYI in the new product melt faster during the year and after a spin-up time of 3 years the area of older ice in the SICCI product is almost 20 % lower than in the NSIDC product.Data availability.The   data   generated   with   the   algorithm   are openly  available  at  FTP  (for  bulk  download;  ftp://ftp.nersc.no/ArcticData/esa_cci_sea_ice_age/)  and  at  THREDDS  (subsetting and online visualization; http://thredds.nersc.no/thredds/arcticData/esa-cci-sea-ice-age.html) in netCDF format following CF conventions containing values of sea ice age fractions concentrations, MYI concentration,  and  sea  ice  age  computed  using  weighted  average(Korosov  amd  Rampal,  2018).  Detailed  information  on  datasets used in this paper can be found in Sect. 2
my bold
bulk  download;  ftp://ftp.nersc.no/ArcticData/esa_cci_sea_ice_age/

Is there a Beaufort Gyre thread? I think there should also be some distinction between an ocean gyre and an ice drift gyre.

colour version of ice age 2000-2020 here. It tends to support the case for a small gyre  in the Beaufort, but not so much the large one that extends to the Lomonosov ridge. Similarly for ice age 84-99(not shown) imho.

17
Arctic sea ice / Re: What the Buoys are telling
« on: December 17, 2020, 09:43:16 PM »
old iabp buoys drift 1987-89

18
Arctic sea ice / Re: What the Buoys are telling
« on: December 15, 2020, 12:57:10 AM »
What some old buoys said. iabp 1979-81
edit: https://iabp.apl.uw.edu/Data_Products/BUOY_DATA/
BuoyID,Year,Hour,DOY,Lat,Lon,BP,Ts

19
Arctic sea ice / Re: The 2020/2021 freezing season
« on: December 14, 2020, 03:35:19 PM »
CS2SMOS merged thickness from AWI netcdf via panoply. click for ani(5.7MB)

Cryosat SAR click for 14day and 2day


20
Arctic sea ice / Re: The 2020/2021 freezing season
« on: December 14, 2020, 12:31:52 AM »
A closer look (750m resolution) at the Chukchi ice edge. Wind blown ice drifting over warm(ish) water. Smaller floes disappearing as they cool the ocean. 1000hPa winds translating to roughly 80km surface winds forecast again for much of tomorrow.
rammb https://col.st/b7feS
stationary frames have been left in to maintain the flow of time,  72% scale to reduce to 6.3MB
further coverage to Wrangel island here


edit: surface winds were a bit lower today than forecast ~70km/h (~90km/h at 1000hPa)

21
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: December 06, 2020, 03:10:27 PM »
A precarious grip on the eastern side
rammb slider, https://col.st/9gapL  dec4-6

Focus is a bit dodgy on rammb, here is suomi-npp and noaa-20, dec6. Roughly 160km of almost stationary ice.
https://go.nasa.gov/3opH4KL

22
Very interesting, had no idea about "flushing"
Could be that many of our assumptions about ice melting and refreeze need confirming.
Quote
For the time being, instead of having a set value of -1.8 I just set ice bottom as the thermistor below which the temp is 0.2degC less than whatever the ocean temp is at that measurement time.
''
ice_thermistors=ice_or_water_thermistors.where(ice_or_water_thermistors<mean_ocean_heat-0.2)
''
Looks good if my ice temperature doubts turn out to be wrong.

17 older tbuoys deployment report update

23
Arctic sea ice / Re: MOSAiC news
« on: December 03, 2020, 11:07:00 PM »
Well we have another chance to develop our thickness estimate algorithm soon. Core ice temperature is dropping to levels where we thought we had some reasonable estimates last year. I have doubts though.
Looking at T78 data the deployment report (1) states the ice was 1.52m thick with 2cm of fresh snow on aug23. Thermistor buoy sensors are 2cm apart so we can't really detect snow at that point but we are also given the sensor id of the air/snow interface as 33. Great. So the bottom of the ice on that day was at sensor 110.
The temperature profile then was almost flat by winter standards but a more detailed look shows the ice thickness quite well. (2)
Thermistors 33 and 110 have been marked roughly at the beginning of the animation(3) and again on nov22 when the temperature profile shows them clearly (with a short pause both times). There is not much additional thickening since then.
So my doubt is this. Did the ice melt quickly during end of august/september or has it been 1.5m thick and possibly porous all the time but took 3 months to cool down again?

added T78 drift path(4)

24
Arctic sea ice / Re: MOSAiC news
« on: December 02, 2020, 09:51:42 PM »
First impression of nextSIM is that new ice looks a lot thinner than the representation by both ascat and amsr2. It all depends on the scale though.

Two first hand accounts of the mosaic expedition. Basic, but includes a lot of photos not seen on this thread before.

Quote
Antonia Immerz of the Alfred Wegener Institute is a data scientist for the MOSAiC expedition. Join her for a live video call on December 2nd where she'll talk about her experience working in the Arctic and what's going to happen to all of the data collected during MOSAiC.




Quote
Jackson Osborn is a scientist at the Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder who served as an engineer for Team Atmosphere during MOSAiC. Join Jackson for a live video call to learn what it's like to troubleshoot scientific instruments in the Arctic.




25
Developers Corner / Re: Test space
« on: December 01, 2020, 05:59:52 PM »
iabp drift oct26-nov30
stop start in the mclure strait.

26
Developers Corner / Re: Test space
« on: November 29, 2020, 02:18:41 PM »
added clahe 2.1 to bring out the thin ice movement in the laptev. file size is a bit bigger

27
Arctic sea ice / Re: The Rammb Slider Thread
« on: November 29, 2020, 11:47:43 AM »
tidal movement in the nares Band I4  https://col.st/x9U76

28
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: November 29, 2020, 10:51:10 AM »
Correction.The top arch not really firming up. https://go.nasa.gov/3mkTliL nov26-29
Full moon coming up.

29
Arctic sea ice / Re: The 2020/2021 freezing season
« on: November 28, 2020, 01:13:27 PM »
cs2smos merged sea ice thickness, oct22-nov25. The thicker short wrangel arm area north of ESS appears to have dispersed. smos also picking up the lower concentration area north west of Mackenzie Bay (see post #855 up thread)
click for animation

Reasonably cloudless over the Beaufort since nov21   https://go.nasa.gov/37hZwxQ

30
Arctic sea ice / Re: The 2020/2021 freezing season
« on: November 27, 2020, 10:40:18 PM »
amsr2 awi v103 hudson, nov1-27(early) click for animation
noaa sea ice concentration, hudson nov27, 1981-2019 animation and compressed static (might be useful for the atmospheric connections thread) No data for 82 and 85.
The static image is compressed 1/10 width for easier visual comparison see more detail for other areas on the mosaic thread here
amap hudson bay currents.

31
Arctic sea ice / Re: The 2020/2021 freezing season
« on: November 23, 2020, 12:23:12 PM »
Not only the Laptev. The Alaskan coast in the Beaufort is also looking unsettled. Southerly winds, then persistent easterlies drawing ice out to sea. (ice to the right of wind) Possible there is also upwelling there.
http://bulletin.mercator-ocean.fr/en/permalink/PSY4/animation/3/20201101/20201123/2/2

amsr2 awi v103, nov14-22
the swaths on this dev version not quite overlapping on nov15

The low concentration area verifies on viirs brightness temperature https://go.nasa.gov/3pTbTsN
Nullschool has ~-16C there today so the leads will be refreezing except those close to the chukchi.

edit: added laptev while it's all set up

32
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: November 19, 2020, 07:04:41 PM »
A quick look at itp116 drift path for old times sake.

33
Arctic sea ice / Re: The caa-greenland mega crack
« on: November 18, 2020, 08:24:58 PM »
The restless sea. Similar view as above, https://go.nasa.gov/3kJcJEz nov5-18. There's a lot going on down there. click for movement
edit: better with clahe 1.7

added CS2SMOS merged thickness (note nov1-15)
found a better panoply map

34
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: November 17, 2020, 01:59:03 PM »
A small visual analysis of possible years for state change using Wipneus' piomas modeled ice thickness (Zhang and Rothrock 2003). I think there are data and charts that show roughly the same thing though limiting the observed area to that of the thickest remaining ice near the september minimum may be instructive.

35
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: November 15, 2020, 07:55:50 PM »
some doubts about atlantic water affecting ice concentration in the Laptev above the SE Nansen shelf. Here is an overlay of amsr2uhh onto gmrt bathymetry, oct20-29, 2013-2020.
accepted that correlation (if it can be seen) is not causation.
I don't have some older days or they have poor data

36
Arctic sea ice / Re: The 2020/2021 freezing season
« on: November 15, 2020, 02:49:46 PM »
amsr2 awi v103, nov14 overlaid onto gmrt bathymetry. (click)
While the ice is still thin it is possible to discern some ocean activity.

Leads north of the chukchi align with the shelf break and chukchi plateau topography where sinking Pacific water causes turbulence and possible mixing.
The remaining open water in the Laptev sits over the shear zone at the eastern edge of the Nansen basin. This is where incoming atlantic water is forced to turn back towards the Fram or attempt to rise up the shelf. Note also the low concentration ice along the shelf break north of SZ.

Some incoming Atlantic water from the Barents limits refreeze in the Kara to the fresher surface layer in the shallower coastal area but most continues north, sinking into the St Anna trough between SZ and FJL.

Most Atlantic water enters via the Fram strait, passing to the north of Svalbard and FJL, sinking along the shelf as it moves east.

https://www.nature.com/scitable/knowledge/library/arctic-ocean-circulation-going-around-at-the-102811553/

37
Arctic sea ice / Re: MOSAiC news
« on: November 14, 2020, 08:47:00 PM »
A look at relative drift in the mosaic buoy cluster. This presentation centres on one of the buoys in the cluster by subtracting its coordinates from all of the others, allowing us to study their relative drift.
oct11-nov13
edit: made it a bit smaller
the next few days should be interesting

38
Arctic sea ice / Re: The 2020/2021 freezing season
« on: November 14, 2020, 12:54:52 AM »
Atlantification of the Beaufort or the Western CAB sounds very.... improbable? (I was going to say impossible)
I suspect that you know that Atlantic water and Atlantification are different things but just in case.


 

39
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: November 13, 2020, 11:09:24 PM »
mercator (model) salinity at 34m, sep2018-nov2020

40
Arctic sea ice / Re: The 2020/2021 freezing season
« on: November 13, 2020, 11:05:58 PM »
Following up on whoi itp121 up thread, here are the charts and drift path for itp120 which is a little further north. The warm layer here at ~50m is not so pronounced and salinity is not high enough to be atlantic water which would probably be deeper in the basin anyway.
It's likely that itp120 and itp121 may have been deployed in those locations hoping to monitor pacific incoming from the chukchi plateau, in which case someone has done their homework very well.

whoi itp120 profile and location.
mercator (model) salinity at 34m, pacific side, sep2018-nov2020
full arctic animation here


41
Arctic sea ice / Re: The 2020/2021 freezing season
« on: November 13, 2020, 12:41:24 AM »
Is it normal?                   Recently it seems that it is.
Does it affect surface?   It seems not much at the moment

Beaufort 50m temperatures from whoi itp buoys, 2006-oct2020

previously discussed here

42
Arctic sea ice / Re: The 2020/2021 freezing season
« on: November 12, 2020, 08:51:07 PM »
~7days raw buoy data from iabp
drift and surface temperature (some sea, some ice, some faulty, NA don't report temp) 9MB. Click twice for full res.

Still some movement in the Mclure Strait. Drift direction changing along the Alaskan coast.

adding 7m-250m temperature and salinity from whoi itp121. 50m temperature remains high along that drift path in the Beaufort. The white areas on the temperature profile are over 1.8C. Click the chart for daily detail.

43
Arctic sea ice / Re: Latest PIOMAS update (November)
« on: November 12, 2020, 03:44:24 PM »
Piomas 2006/7 every 5th day from the 40yr mp4 here.

added sep22, 1980-2020.

44
Arctic sea ice / Re: MOSAiC news
« on: November 11, 2020, 07:45:29 PM »
Any volunteers to keep an eye on a new snow buoy, 2020S98, close the the pole?

Also 2020S106, 2020S107 and Also 2020S108
The ever improving meereisportal makes it visually simple.
update, a large range in snow depth, increasing by 20-60cm since deployment. (click)

45
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: November 05, 2020, 11:41:46 AM »
Nares still moving, https://go.nasa.gov/2I6D7e9   nov2-5
amsr2 awi v103, oct26-nov4

46
Arctic sea ice / Re: The 2020/2021 freezing season
« on: November 04, 2020, 08:07:39 PM »
amsr2-uhh comparison of 2016 and 2020, sep21-nov3.
bad data on 20160924
click for movement (10MB)

47
Arctic sea ice / Re: The 2020/2021 freezing season
« on: November 04, 2020, 11:12:11 AM »
I made a different daily change graph to get a better view of this year's late refreeze and to compare it with previous years when extent minimum was very low. I also used 7 day trailing averages which seems to help.
Thanks, much clearer.


gmrt bathymetry with amsr2-awi-v103 overlay at 90% with heavy contrast to help view lower concentration ice, oct25-nov3

Siberian coastal ice is shown drifting out to sea. That may fasten up with more northerly winds forecast.

Some discussion upthread about ice movement close to Severnaya Zemlya. It appears that the ice that formed and drifted to the south west did melt or disperse to the point where it became undetectable to amsr2. Too cloudy for viirs brightness temperature to verify, those interested could check if there are any Sentinel images. Coastal Kara ice is spreading from the south east with favourable winds to replace it.

My interest in this presentation is the area north of NSI previously looked at here.
Not much to see but there may be a further weakness over the Lomonosov Ridge. Looking for evidence to identify if there is persistent turbulence causing vertical mixing there.

It's easy to see the more well known turbulent area north east of Chukchi as the warmer Pacific waters sink into the basin.
Recent extent gains have been impressive. There's still a long way to go.
click for movement

48
Arctic sea ice / Re: The 2020/2021 freezing season
« on: November 03, 2020, 04:17:58 PM »
A couple of IABP buoys in the right place in the ESS to track sea temperature during refreeze.
SVP-B, UPTEMPO and one undocumented.
Quote
UPTEMPO   Upper Temperature of the Polar Oceans
Data attached as txt file.
Over 50hrs at -0.16C suggests there may be a problem with 174639

49
The forum / Re: Forum Decorum
« on: November 03, 2020, 12:39:22 AM »
any chance of removing politics from the info centre?

50
Arctic sea ice / Re: The 2020/2021 freezing season
« on: November 02, 2020, 11:54:29 PM »
It looks like peak daily ice gains are happening now. Which means that in terms of extent the advantage of 2020 has peaked for this year. It was 942k a few days ago.

Recent extent gain does stand out this year. Difficult to quantify any advantage.
edit: y scale was incorrect
Thinking about it more, Gerontocrat and BFTV do a great job of making the data more pleasant to look at, but at the moment we only get one daily data point and one full amsr2 image per day. The curves and transitions are approximations.
Thank you for your wonderful plots. They basically show an unprecedented very late refreeze finally ensuing.
Thank you for your basic interpretation.

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