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Niall Dollard

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Null School Sea Surface Temperature Anomalies
« on: November 11, 2017, 06:57:36 PM »
I could not find a thread already open specifically for null school output. I have seen this discussed before though but I am wondering can anyone shed some light on why there is always very high SSTs displayed west of Svalbard and also to the SE of Svalbard.

I know the West Spitzbergen Current is a renowned warm,salty current but the temps shown by null school are well out of line. Today for example it shows SSTs of 16 C. There are also SSTs of 13 C to the south east of Svalbard and it is also picking up very warm lake temps from Finland.

Any thoughts why it (Null School) is picking up these high values at these locations. It is very persistent also?

In contrast SSTs from the Norwegian met here

Forest Dweller

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Re: Null School Sea Surface Temperature Anomalies
« Reply #1 on: November 22, 2017, 06:33:55 PM »
Hey Niall,

Don't know if this helps but i had asked Carana the same question already a year or more ago.
I was wondering about shallow waters as a factor and he/she did seem to think the sea floor topography plays a part.
Sent me a nice image of it but in the meantime i no longer do the wretched Facebook thing so can't give it to you now.
That would only refer to the western Svalbard anomaly however.
Maybe the combined effects of that, the current conditions you mentioned as well come together and different monitoring tools may indeed be at play as well...
I forget the correct term for seafloor topography but you get what i mean i'm sure and may wanna check that, good luck.

Brigantine

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Re: Null School Sea Surface Temperature Anomalies
« Reply #2 on: November 22, 2017, 08:51:32 PM »
I'll just leave this bathymetry map here.

(Note in the right hand sidebar the arctic map option, and the top right options drop menu the regional bathymetric contours. Also turn multibeam bathymetric surveys off.)

Niall Dollard

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Re: Null School Sea Surface Temperature Anomalies
« Reply #3 on: November 22, 2017, 11:59:43 PM »
Thanks folks.

I've attached an image of bathymetry and circulation and circled the two "nullschool hot spots". Spot to the SE of Svalbard is much more shallow compared to spot west of Svalbard. So two very different sea depths (330m vs 2500m). However they are both in areas of Atlantic water.
« Last Edit: November 23, 2017, 12:06:21 AM by Niall Dollard »

Brigantine

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Re: Null School Sea Surface Temperature Anomalies
« Reply #4 on: November 23, 2017, 01:42:04 AM »
ARGO float #6902042 profiled the area of the western hotspot through most of 2015. Nothing unusual to see, temperatures around 4.3C in the top 200m in November. About 8C in August in the top 50m.

The only recent profiles have been two this October by float #3901633 - About 7.5C in the top 50m. - but that's off to the SE edge of the hotspot where Nullschool is reporting about 6C.

There's nothing with high temps (>8C) at any depth either.

In short, ARGO agrees with the Norweigian Met and HYCOM. Though with no smoking gun recent profile in the core of the hotspot.

OTOH, NOAA agrees with Nullschool. I guess they both use the output of the same model??
Yes. Nullschool use MMABs RTGSST product - the same one.

kullboys

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Null School Sea Surface Temperature Anomalies
« Reply #5 on: March 12, 2019, 05:54:17 AM »
I could not find a thread already open specifically for null school output. I have seen this discussed before though but I am wondering can anyone shed some light on why there is always very high SSTs displayed west of Svalbard and also to the SE of Svalbard.

I know the West Spitzbergen Current is a renowned warm,salty current but the temps shown by null school are well out of line. Today for example it shows SSTs of 16 C. There are also SSTs of 13 C to the south east of Svalbard and it is also picking up very warm lake temps from Finland.

Any thoughts why it (Null School) is picking up these high values at these locations. It is very persistent also?
Thanks.

b_lumenkraft

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Re: Null School Sea Surface Temperature Anomalies
« Reply #6 on: March 12, 2019, 08:51:38 AM »
That's a good thing to open a thread about kullboys!

I'm looking forward to hearing the opinions of meteorologists and everyone knowing things about climate system models.

Juan C. García

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Re: Null School Sea Surface Temperature Anomalies
« Reply #7 on: March 12, 2019, 06:39:57 PM »
« Last Edit: March 12, 2019, 06:47:22 PM by Juan C. García »
Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost.

Ken Feldman

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Re: Null School Sea Surface Temperature Anomalies
« Reply #8 on: March 12, 2019, 07:33:03 PM »
I could not find a thread already open specifically for null school output. I have seen this discussed before though but I am wondering can anyone shed some light on why there is always very high SSTs displayed west of Svalbard and also to the SE of Svalbard.

I know the West Spitzbergen Current is a renowned warm,salty current but the temps shown by null school are well out of line. Today for example it shows SSTs of 16 C. There are also SSTs of 13 C to the south east of Svalbard and it is also picking up very warm lake temps from Finland.

Any thoughts why it (Null School) is picking up these high values at these locations. It is very persistent also?
Thanks.

Someone asked this on Reddit:

https://www.reddit.com/r/askscience/comments/7nwovt/why_are_there_two_spots_with_higher_sea_surface/

Here is the answer they got:

Quote
I've sent an email to the Robert Grumbine, he goes over the sea surface temperature data of NOAA, the data in question.


Dear Mr. Grumbine,

Recently, I have come across a curiosity while exploring a visualisation tool for, among others, Sea Surface Temperatures. The tool, accessible online via the link https://earth.nullschool.net/, showed two spots near Svalbard where the SST was considerably higher than its surroundings, at 78°N 7°E and at 76°N 30°E. This visualisation tool cites NOAA as its source for Real Time Global Sea Surface Temperature, and linked to the website http://polar.ncep.noaa.gov/. These warmer spots are also visible on the website’s own charts: http://polar.ncep.noaa.gov/sst/ophi/archive/20180103/color_newdisp_sst_north_pole_stereo_ophi0.png These spots also seem to be present every winter.

Out of personal curiosity, I would like to know if there is an explanation for this phenomenon. Without much expertise in this field, it seems unlikely to me that these spots exist because of ocean currents. Volcanic activity also seems to fall short as an explanation for the roughly 10°C warmer water.

So I would like to ask you if it would be possible that some kind of error has occurred in the data, either during measurement takings or during data analysis, that would explain these warmer spots?

This inquiry is not for academic purposes, merely out of personal interests, but I would appreciate it if you could help me.

Thank you in advance. Yours sincerely,

His response:


Hello Mr. Reusens,

Those two areas always challenging. Both areas tend to be cloudy, so the satellites we use can't see the ocean surface. Only a microwave instrument can do so. And neither is close to much shipping, so we get no observations that way either. We're left with drifting buoys and the occasional clear day for our data. That means we're also occasionally rejecting good data because it disagrees by too much with our last good observation.

But these two spots have some pecularities that make those warm temperatures not as exceptional as you might think. In particular, the 78 N, 7 E. There are two currents between Greenland and Svalbard. One carries near-freezing water out of the Arctic down the east coast of Greenland. The other brings some of the warm North Atlantic current water from Norway in to the Arctic west and east of Svalbard. Warm being relative, of course; 6-8 is still pretty cold for swimming.

In looking at the anomaly (deviation) from climatology (which is 1961-1990), these are showing > +8 C. But you'll notice that there are other substantial areas of such extremely warmer than usual water. This is happening a lot in areas where there is historically a sharp temperature gradient (see also the Gulf Stream) in temperatures, and the transition zone has moved northward (in the Atlantic or Arctic). http://polar.ncep.noaa.gov/sst/ophi/archive/20180103/color_newdisp_anomaly_north_pole_stereo_ophi0.png

The many tight contours do look suspicious, so I'll be investigating the locations specifically for what observations we have to support them being this warm and do an update if needed.

Regards, Robert Grumbine

b_lumenkraft

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Re: Null School Sea Surface Temperature Anomalies
« Reply #9 on: March 12, 2019, 07:43:51 PM »
Great find Ken! Thank you.

Niall Dollard

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Re: Null School Sea Surface Temperature Anomalies
« Reply #10 on: March 12, 2019, 10:00:25 PM »
I could not find a thread already open specifically for null school output. .

Here is the link to the old thread on this same topic : (Maybe mods could merge them ? )

https://forum.arctic-sea-ice.net/index.php/topic,2194.0.html

Neven

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Re: Null School Sea Surface Temperature Anomalies
« Reply #11 on: March 13, 2019, 09:53:53 AM »
Thanks for this, Niall. It seems a spambot has copied that comment of yours and opened a new thread. Had me fooled. I'll try and merge the treads now.

edit: done
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Juan C. García

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Re: Null School Sea Surface Temperature Anomalies
« Reply #12 on: March 22, 2019, 07:51:08 PM »
Just to include today's image and link for future follow-up:
https://earth.nullschool.net/#current/ocean/primary/waves/overlay=sea_surface_temp/orthographic=18.09,75.85,1914/loc=5.573,77.895
It is interesting that after 10 days, the hot spot continues at the same place.
It doesn't seem to move.
The other hot spot is still there, but with only 5.2°C.
Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost.

Freegrass

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Re: Null School Sea Surface Temperature Anomalies
« Reply #13 on: August 07, 2019, 12:46:38 AM »
Let's continue this here.

that anomaly map has been considered unreliable for years
Thanks for that information!

Can also just use the actual temps rather than anomalies. A big problem with SST anomalies around sea ice is that as soon as a location melts out relative to the baseline, the anomaly skyrockets. But that's not telling you much, other than that it melted, which we already know from other sources.

Yes, I've read the Nullschool thread, so I understand the problem a little better now. But not fully...

Quote
as a location melts out relative to the baseline, the anomaly skyrockets.
Isn't the baseline calculated on a long term basis? And that anomaly has been there for years. I would think that the models would have compensated this by now.
« Last Edit: August 07, 2019, 12:51:44 AM by Freegrass »
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petm

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Re: Null School Sea Surface Temperature Anomalies
« Reply #14 on: August 07, 2019, 01:01:36 AM »
Let's continue this here.

Sounds good. I'm not sure exactly. It would depend on the map you're using. I meant just generally that's what an anomaly is defined as: the difference between the current value and a baseline. Presumably some baselines might work better than others, hence some anomaly maps may be more reliable.

Myself, I use the DMI for SSTs. According to their website, this is their method:

Quote
The SST anomalies have been calculated with respect to a mean, which has been derived from observations from 1985 to 2001. They are SST climatology monthly values from the Pathfinder project and temporal interpolation is used between the two nearest months to obtain this days SST climatology. For more information on the monthly climatology, see: www.nodc.noaa.gov/sog/pathfinder4km/

-- http://ocean.dmi.dk/satellite/index.uk.php (click "data/method")

But as I said, I usually look only at the actual SSTs, not the anomalies. I find I get more information that way, as the useful temperature range gets saturated (at least on most maps I've seen) as near-maximum anomaly. E.g., One "red" anomaly might be 2 C and another 5 C, whereas 2 C vs 5 C typically show as much different colors on the non-anomaly map.
« Last Edit: August 07, 2019, 01:09:57 AM by petm »

petm

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Re: Null School Sea Surface Temperature Anomalies
« Reply #15 on: August 07, 2019, 01:07:07 AM »
I would think that the models would have compensated this by now.

I think maybe for SSTs it's not something that can be easily compensated for because of the variable location of sea ice in different years. Sea ice is always at or below freezing (except for melt ponds). I suppose you could only include in your baseline years when each particular grid square (pixel) is ice-free, but I don't think that's how it's done. I don't even think the baseline is updated regularly in many cases (e.g. see the DMI method, posted above, which only uses 1985-2001), which means that positive anomalies increase continually.

Grubbegrabben

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Re: Null School Sea Surface Temperature Anomalies
« Reply #16 on: August 07, 2019, 01:27:48 AM »
One "red" anomaly might be 2 C and another 5 C, whereas 2 C vs 5 C typically show as much different colors on the non-anomaly map.

The anomalies do not even match the numbers (hourly forecast europe). I think the reanalyzer needs some fixing.

Edit: Sorry this was maybe the wrong thread.

Freegrass

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Re: Null School Sea Surface Temperature Anomalies
« Reply #17 on: August 07, 2019, 02:18:52 AM »
Thank you so much for your help Petm! Like I said before, I'm a complete amateur who's trying to understand what's happening with the climate. I have much to learn!

That Danish website is awesome! I saw it before, but never really used it. I like the ice thickness tool. How reliable is this model? If this is right, that would mean that a whole lot of ice could melt out from Laptev to svalbard, because it's only 50 cm thick over a quarter of the pack. A little wind, and poof?
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petm

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Re: Null School Sea Surface Temperature Anomalies
« Reply #18 on: August 07, 2019, 02:35:19 AM »
Thank you so much for your help Petm! Like I said before, I'm a complete amateur who's trying to understand what's happening with the climate. I have much to learn!

That Danish website is awesome! I saw it before, but never really used it. I like the ice thickness tool. How reliable is this model? If this is right, that would mean that a whole lot of ice could melt out from Laptev to svalbard, because it's only 50 cm thick over a quarter of the pack. A little wind, and poof?

My pleasure. I'm sure the same could be said for virtually everyone here.

The SST data on DMI is from satellite measurements (infrared), interpolated for areas/days that are cloudy. But I'm not sure how well it compares with other models in terms of accuracy. Perhaps someone with more knowledge could comment. (I generally just trust the Danes ;) .) Yeah, the website features are excellent, e.g. jump back/forward by day/week/month and play/loop.

Not sure about the thickness or other models, so far I've just used this site for SSTs.

Juan C. García

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Re: Null School Sea Surface Temperature Anomalies
« Reply #19 on: August 07, 2019, 03:07:31 AM »
Just to include today's image and link for future follow-up:
https://earth.nullschool.net/#current/ocean/primary/waves/overlay=sea_surface_temp/orthographic=18.09,75.85,1914/loc=5.573,77.895
I posted the link to the point with the heat, just to be able to check if it change the place or if it disappears.
It is in the same place that we had it on March 12th and it is not an anomaly (not SSTA, just SST): the 16.2 °C is the actual temperature, while the near regions are below 8 °C.
Just click on the link...

[I don't know what generates it]
« Last Edit: August 07, 2019, 03:14:43 AM by Juan C. García »
Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost.

petm

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Re: Null School Sea Surface Temperature Anomalies
« Reply #20 on: August 07, 2019, 03:55:29 AM »
DMI also shows a hot spot west of Svalbard, but more like 10 C, in line with other Atlantic hotspots. However, Nullschool seems to display higher resolution in the center of that blob where the 16 C point is confined. Presumably this is due to the West Spitsbergen Current (WSC), bringing warm surface waters from the Atlantic:

Quote
The WSC is the northernmost extension of the Norwegian Atlantic Current. It flows poleward through eastern Fram Strait along the western coast of Spitsbergen. A mainly barotropic current, the WSC appears to be predominantly steered by the bathymetry (Bourke et al. 1988). It is about 100 km wide and is confined over the continental slope, where it reaches its maximum current speed of 24 to 35 cm s-1 at the surface (Boyd and D'Asaro 1994; Fahrbach et al. 2001; Saloranta and Svendsen 2001). Because it transports relatively warm (6 to 8°C) and salty (35.1 to 35.3) Atlantic Water, the WSC keeps this area free of ice (Aagaard et al. 1987; Maslowski 1994; Piechura et al. 2001).
https://oceancurrents.rsmas.miami.edu/atlantic/spitsbergen.html
« Last Edit: August 07, 2019, 04:03:14 AM by petm »

stjuuv

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Re: Null School Sea Surface Temperature Anomalies
« Reply #21 on: August 07, 2019, 08:53:21 AM »
Thank you so much for your help Petm! Like I said before, I'm a complete amateur who's trying to understand what's happening with the climate. I have much to learn!

That Danish website is awesome! I saw it before, but never really used it. I like the ice thickness tool. How reliable is this model? If this is right, that would mean that a whole lot of ice could melt out from Laptev to svalbard, because it's only 50 cm thick over a quarter of the pack. A little wind, and poof?
Comparing this thickness map with the unihamburg amsr2-uhh concentration map, there are a few areas where there are significant discrepancies between the maps. Of course thickness and concentration are different things, but in the two marked areas there seems to be very little ice concentration left, even though the thickness indicates quite a thick ice there, especially in the red circles.

However in the low thickness area extending almost to the pole, the concentrations seem to be quite high. If nothing else, this should show that different models and different metrics paint a completely different picture of the ice at the moment.