2011-02-15 20:09:19New paper to blog about: sea level budget balanced by deep ocean heat
John Cook

john@skepticalscience...
124.186.217.214

Here's an important new paper that was published today  - would be very worthy writing a simple blog post about it. General gist of the paper - sea level rise is a combination of thermal expansion and ice melt. The amount of upper ocean heat warming doesn't add up to close the sea level budget, so that observed sea level rise = expansion + melt. This paper closes the budget by working out deep ocean warming:

  • Deep ocean warming assessed from altimeters, Gravity Recovery and Climate Experiment, in situ measurements, and a non-Boussinesq ocean general circulation model

    Observational surveys have shown significant oceanic bottom water warming, but they are too spatially and temporally sporadic to quantify the deep ocean contribution to the present-day sea level rise (SLR). In this study, altimetry sea surface height (SSH), Gravity Recovery and Climate Experiment (GRACE) ocean mass, and in situ upper ocean (0–700 m) steric height have been assessed for their seasonal variability and trend maps. It is shown that neither the global mean nor the regional trends of altimetry SLR can be explained by the upper ocean steric height plus the GRACE ocean mass. A non-Boussinesq ocean general circulation model (OGCM), allowing the sea level to rise as a direct response to the heat added into the ocean, is then used to diagnose the deep ocean steric height. Constrained by sea surface temperature data and the top of atmosphere (TOA) radiation measurements, the model reproduces the observed upper ocean heat content well. Combining the modeled deep ocean steric height with observational upper ocean data gives the full depth steric height. Adding a GRACE-estimated mass trend, the data-model combination explains not only the altimetry global mean SLR but also its regional trends fairly well. The deep ocean warming is mostly prevalent in the Atlantic and Indian oceans, and along the Antarctic Circumpolar Current, suggesting a strong relation to the oceanic circulation and dynamics. Its comparison with available bottom water measurements shows reasonably good agreement, indicating that deep ocean warming below 700 m might have contributed 1.1 mm/yr to the global mean SLR or one-third of the altimeter-observed rate of 3.11 ± 0.6 mm/yr over 1993–2008. 

Anyone keen to blog about it, stake your claim here...

2011-02-16 09:33:51
Riccardo

riccardoreitano@tiscali...
93.147.82.111
John, if you or someone else could send me the paper I'll give it a read and let you know if I'll be able to write something.
2011-02-16 10:39:01Emailed
John Cook

john@skepticalscience...
144.131.205.143

Thanks, Riccardo! Just emailed you the paper. Sorry, it's 5Mb in size and only the pre-press version. I could probably rustle up the final version if that doesn't suffice.

2011-02-16 19:42:39
Ari Jokimäki

arijmaki@yahoo...
192.100.112.211

Deja vu:

http://www.skepticalscience.com/thread.php?t=629&r=5

Edited to add: By the way, I have written a Finnish news article on this:

http://ilmastotieto.wordpress.com/2011/02/04/syvan-meren-lampolaajeneminen-puuttuva-palapelin-osa-merenpinnan-nousussa/

2011-02-16 19:50:03
Riccardo

riccardoreitano@tiscali...
192.84.150.209
Ari if you have the post ready let's go with your version, I'd save the work and it can be publishes sooner.
2011-02-17 01:06:14
Ari Jokimäki

arijmaki@yahoo...
91.154.108.124

Ok, I'll make it into an English article. That probably takes me a couple of days to finish.

2011-02-17 02:27:48
Ari Jokimäki

arijmaki@yahoo...
91.154.108.124

Well, that didn't take as long as I thought:

http://www.skepticalscience.com/deep_ocean_thermal_expansion.html

I had trouble with formatting (because I copy/pasted from Word) but I try to dig around, there probably is a style guide here somewhere.

2011-02-17 10:01:14
Riccardo

riccardoreitano@tiscali...
93.147.82.141
It's probably worth showing fig. 9a, the comparison between satellite and model.
2011-02-17 14:22:08Thanks Ari
John Cook

john@skepticalscience...
144.131.205.143

This is great Ari. I fixed the formatting, that's just a quirk of the WYSIWYG system, when you copy and paste from elsewhere, it can bring in its own HTML code.

I hope you don't mind, I added a green box at the bottom linking to your original post. I figure why not send you some link kudos for your google rankings and a bit of traffic.

Let me know if you'd like to go live with this as is or if you want to add fig 9a - your call, whatever you think best.

2011-02-17 17:52:25
Ari Jokimäki

arijmaki@yahoo...
192.100.112.211
I added some links (references and couple of links to Purkey & Johnson) to the end. I think I'll also add some links to the text (for example to Argo website). First paragraph is an abstract, should it be in different formatting (bolded for example)? I'll come back later to check and add the Fig. 9a.
2011-02-17 20:04:09
MarkR
Mark Richardson
m.t.richardson2@gmail...
134.225.187.80
I find that pasting from word to notepad (or whatever) then into SkS seemed to fix my formatting problems. At least, they've stopped since then!
2011-02-17 20:13:54
MarkR
Mark Richardson
m.t.richardson2@gmail...
134.225.187.80

Ari, another graph or picture would be nice to break up the text. If you can find one of the missing heat graphs or missing sea level budget graphs that would be nice. Also, there was a paper on ground water extraction on sea level rise that's worth looking at, it helps close the budget iirc.

 

Also, I think the English could be simplified and it would shorten the text so you'd get more readers finishing with it! e.g.:

Recent sea level rise has so far been difficult to fully explain: satellites measure global sea level rise since 1993 to be about 3.1 mm/year. The warming and expanding 'upper ocean', or the top 700 metres measured by ships and buoys can explain 1.2 mm/year whilst the water added by melting snow and ice can be estimated from satellite gravity measurements (GRACE) for ice sheets and other methods for smaller glaciers, and is about 0.85 mm/year. They don't add up!

 

 

Gets across all of the points from the first 2 paragraphs and cuts the length a fair bit.

2011-02-17 21:12:23
Ari Jokimäki

arijmaki@yahoo...
192.100.112.211

I added couple of links to the text. I tried to upload the Figure 9a from the paper but it wouldn't upload. I tried both GIF and PNG format without result. Perhaps the uploader is down or something.

I have to think about what to do with Mark's suggestion. It's a good suggestion but on the other hand the first paragraph is an abstract of the rest of the text and as such not part of the introduction that starts from the second paragraph. But I'll probably do as Mark suggested. If there's more suggestions to improve the language, they are welcome - English is not my native language so I could use help there.

2011-02-17 22:49:12
MarkR
Mark Richardson
m.t.richardson2@gmail...
134.225.187.80

Oh yeah:

"The most of the previous studies and the analysis above are missing one thing "

 

 

No article for 'most', it's not referring to one object out of a choice of many, there is only one group of papers you're looking out... So "Most of the previous..."

 

"which can now occur in decadal timescales"

 -> I think that's 'on decadal...' but I only use it colloquially. More google hits for 'on decadal...' and the links are to scientific papers.

 

"However, the temperature measurements of the deep ocean"

-> You don't need an article for temperature: 'temperature measurements' would work too.

 "Therefore the ocean models have been an important tool for estimating the"

-> 'Therefore ocean models', again, I wouldn't use an article. It sounds a bit weird to me. Same with before 'ocean heat content' and 'sea level rise'.

 

Otherwise my skim read doesn't find any other major hints that it's not an English writer. You're a better author than most of our newspapers! ;)

 

 You use a lot of jargon (XBT, Argo) which you can help explain as 'ship based' and 'buoy' meaurements (I think most people sort of understand how these might work), and some of the middle explanation left me scratching my head... the description of the Boussinesq correction slipped past me on first reading. Perhaps:

"Therefore the ocean models have been an important tool for estimating the sea level rise and the ocean heat content. Most models conserve volume (which makes thermal expansion to have no effect) so they require so-called Boussinesq correction in order to estimate the sea level rise from the thermal expansion of the sea water. The correction is globally uniform so the regional estimates might not be correct even if the global estimate would be good."

 

Should be:

 

"Ocean models have been important for estimating sea level rise and ocean heat content, as they use physics to 'fill in' the data between observations. However, many of these don't allow the volume to change so they use a so called 'Boussinesq approximation' to turn the heat content into a sea level rise. This approximation is applied to the total heat content so it should give a good estimate of the total, but it might be overshoot in some areas and undershoot in others."

 

That is how I'd explain it, but I think I misunderstood the original one and I don't have time to read up on Boussinesq corrections now!

2011-02-17 23:06:30
Ari Jokimäki

arijmaki@yahoo...
192.100.112.211

Thanks for the comments! I'll try to do the corrections this evening.

Our language doesn't have equivalent for "the", so that's sometimes difficult for me to se when to use it and when not. I usually try to remember to use it so perhaps that's why I insert it too much. :)

2011-02-18 05:56:08
Ari Jokimäki

arijmaki@yahoo...
91.154.108.124

I have made the corrections and were finally able to add the figure 9a:

http://www.skepticalscience.com/deep_ocean_thermal_expansion.html

Mark, I didn't make the boussinesq correction (but I adopted a small part of the paragraph you suggested) change because from the paper it seems that my explanation is closer to truth. Boussinesq approximation is something that models have that creates the need for the Boussinesq correction (i.e. the Boussinesq correction is something that corrects for the Boussinesq approximation).

John, it seems that while editing the text I managed to mess up the green box and I don't know how to add it back.

2011-02-18 06:48:08green box
dana1981
Dana Nuccitelli
dana1981@yahoo...
38.223.231.252
I put a green box around the last line - let me know if you wanted it around more of the text.  I also made a few other very minor edits while I was in there (like deleting extra spaces).  It looks good - personally I like to define acronyms before I use them, but since this is more of a technical post, the audience should probably know their meanings already.  Good summary and an interesting paper.
2011-02-18 09:56:00
Riccardo

riccardoreitano@tiscali...
93.147.82.174
The Boussinesq aproximation conserve volume via the neglect of the change in density everywhere but when it is multiplied by g (acceleration of gravity). In other words, it's like considering a wierd incompressible fluid which still have buoyancy due to a density difference. This aproximation simplify the calculations of the fluid motion a lot. As Ari correctly says, the Boussinesq correction is a correction to the Boussinesq aproximation.
2011-02-18 11:55:35
Daniel Bailey
Daniel Bailey
yooper49855@hotmail...
97.83.150.102

Suggestion in last paragraph:

 

From:

Therefore even slight warming in the deep ocean causes large rise to the sea level. Observations show that the upper parts of oceans have warmed for decades, which is sufficiently long time for the warming to show up in the deep ocean as well.

 

To:

Therefore even slight warming in the deep ocean causes a large rise in sea level. Observations show that the upper parts of oceans have warmed for decades, which is sufficiently long time for the warming to show up in the deep ocean as well.

2011-02-18 17:12:45
Ari Jokimäki

arijmaki@yahoo...
192.100.112.211
John published this already. Thanks for the help to all. I just made the correction Daniel suggested.
2011-02-18 17:38:57Nice
Daniel Bailey
Daniel Bailey
yooper49855@hotmail...
97.83.150.102
But Ken Lambert's not going to like having his favorite meme toy taken away.
2011-02-18 17:48:14
Ari Jokimäki

arijmaki@yahoo...
192.100.112.211

I published this also in my own blog:

http://agwobserver.wordpress.com/2011/02/18/deep-ocean-warming-solves-the-sea-level-puzzle/