Ocean Heat Content: Dropping again

I found Bob’s Arctic Ocean Heat Content graph quite interesting as it may explain why we are seeing a recovery in sea ice for the last two years. It also reminds me a lot of the graph seen of the Barents Sea water temperature plotted against the AMO which WUWT recently covered here.

Update of NODC (Levitus et al 2009) OHC Data Through June 2009

Guest post by Bob Tisdale

INTRODUCTION

On October 1, KNMI updated the NODC Ocean Heat Content (Levitus et al 2009) data that’s available on Climate Explorer.

http://climexp.knmi.nl/selectfield_obs.cgi?someone@somewhere

These updates are not shown on the NODC’s Global Ocean Heat Content webpage:

http://www.nodc.noaa.gov/OC5/3M_HEAT_CONTENT/index.html

The updates also aren’t shown in the table of Global Analyzed Fields (ASCII files):

http://www.nodc.noaa.gov/cgi-bin/OC5/3M_HEAT/heatdata.pl?time_type=yearly700

But the single 22.4 MB dataset at the top of the table does contain the January through March and the April through June data, which were updated (added) on September 14, 2009:

ftp://ftp.nodc.noaa.gov/pub/data.nodc/woa/DATA_ANALYSIS/3M_HEAT_CONTENT/DATA/heat_3month/HC_0-700-3month.tar.gz

GLOBAL, HEMISPERIC, AND OCEAN BASIN GRAPHS

Global OHC has dropped back to its 2003 levels.

http://i34.tinypic.com/dev5ld.png

Global OHC

North Atlantic OHC is continuing to decline from its 2004 peak.

http://i36.tinypic.com/ddkeas.png

North Atlantic OHC

The recent drop in the South Atlantic OHC was sizeable, but not outside of the range of its normal variability.

http://i36.tinypic.com/2m5fais.png

South Atlantic OHC

And of the remaining OHC datasets, the only two that showed increases over the past six months are the South Pacific and Southern Ocean OHC

http://i35.tinypic.com/1ys415.png

South Pacific

############

http://i38.tinypic.com/34f19p2.png

Southern Ocean

Here are the remaining OHC subsets without commentary.

http://i38.tinypic.com/j79h1i.png

Northern Hemisphere

############

http://i35.tinypic.com/cqr13.png

Southern Hemisphere

############

http://i37.tinypic.com/2wlxz09.png

North Pacific

############

http://i38.tinypic.com/6e0oax.png

Indian Ocean

############

http://i38.tinypic.com/9u417d.png

Arctic Ocean

CLOSING

Two earlier posts illustrated the impacts of natural variables on OHC. These included the ENSO-induced step changes in the OHC of numerous oceans and the effects of the NAO on high-latitude North Atlantic OHC:

1. ENSO Dominates NODC Ocean Heat Content (0-700 Meters) Data

2. North Atlantic Ocean Heat Content (0-700 Meters) Is Governed By Natural Variables

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Paul Vaughan
October 11, 2009 4:45 pm

Pamela Gray (16:23:36) “It is a dog eat dog system geared towards preditorial carnage.”
Charming Pamela – thanks for the delightful warning.

October 11, 2009 6:07 pm

rbateman (10:01:30) :
What Leif suggests is that C02 reflects 1/2 of what IR is incoming, and that’s a qualitative assessment. Need one of those for H20 molecules airborne. What is missing is a quantitative assessment.
For both of them it is exactly 50%. The incoming is from a definite direction, but the outgoing is radiated in a random direction, thus half goes out and half continues in. so it is very quantitative. This is AFAIK. And it is not ‘reflected’, but absorbed and re-emitted.

Richard Sharpe
October 11, 2009 6:26 pm

Leif Svalgaard (18:07:17) said:

rbateman (10:01:30) :
What Leif suggests is that C02 reflects 1/2 of what IR is incoming, and that’s a qualitative assessment. Need one of those for H20 molecules airborne. What is missing is a quantitative assessment.

For both of them it is exactly 50%. The incoming is from a definite direction, but the outgoing is radiated in a random direction, thus half goes out and half continues in. so it is very quantitative. This is AFAIK. And it is not ‘reflected’, but absorbed and re-emitted.

Although, at some point, the mean-free-path is small enough that they would have a higher probability of transferring that energy to another molecule in the atmosphere, wouldn’t they?

October 11, 2009 6:58 pm

Richard Sharpe (18:26:35) :
Although, at some point, the mean-free-path is small enough that they would have a higher probability of transferring that energy to another molecule in the atmosphere, wouldn’t they?
True, but that other molecule would eventually radiate away that energy, wouldn’t it, and in a random direction, half up, half down.

DR
October 11, 2009 7:27 pm

Is it not true that the upper 700m of ocean contains 85% of the heat?

Richard
October 11, 2009 8:42 pm

“What happened to global warming?” The BBC, of all people, asks
http://news.bbc.co.uk/2/hi/science/nature/8299079.stm

Richard
October 11, 2009 8:47 pm

The BBC says “One thing is for sure. It seems the debate about what is causing global warming is far from over.”
What next? The science is NOT settled?

Tim
October 11, 2009 9:46 pm

Bob T. wrote (regarding my comment about Schruckman 2009):
“There are no two OHC reconstructions that are exactly the same:
http://bobtisdale.blogspot.com/2009/07/ohc-trends-presented-by-levitus-et-al.html
Schuckmann et al (2009) limits the data to the period of 2003 to 2008. If we look at the NODC data for same period, it also shows an upward trend:
http://i33.tinypic.com/2ynq7v8.png
But when you include the past six months, the trend flattens considerably:
http://i38.tinypic.com/300d3dl.png
Schuckmann et al (2009) also studies the depths to 2000 meters, where the long-term reconstructions focus on 0 to 700 meters.”
Thanks for the follow-up Bob. I guess it is true that there is an upward trend from 2003 – 2008, although not if one picks mid-2003 as the starting point (http://i33.tinypic.com/2ynq7v8.png). Hard to know what it all means, isn’t it!?

tallbloke
October 12, 2009 12:07 am

Leif Svalgaard (12:34:44) :
tallbloke (11:30:31) :
I would like to think as you do that we can rely on climate scientists to get it right. Unfortunately there seem to be some sloppy, some secretive, and some downright bad apple practitioners out there. I’ll check this one out.</i?
They usually monkey with the data [or their proxies] rather than with the radiative properties of gases, which are well-known from fundamental theory and direct laboratory experiments.

True. It’s more a question of whether the ‘offset’ would slip through the net because it’s subject to the same radiative calculations but works in the opposite direction if you see what I mean. So if it’s calculated that co2 has a radiative forcing of 1.7W/m^2 it may be that when that figure is applied to the real world, account needs to be taken of the fact the co2 is preventing some solar energy arriving as well as preventing some earth radiated energy leaving.
Looking at the famous diagram by Trenberth
http://1.2.3.11/bmi/lasp.colorado.edu/sorce/images/instruments/tim/Kiehl_Trenberth_revised.gif
It talks about 77W/m^2 being reflected by the atmosphere and clouds.
In view of your observation to Rob Bateman above about re-emission not reflection, it seems possible Trenberth missed it, unless it’s just sloppy terminology.
If incoming solar IR in the waveband in question is 80W/m^2 at TOA, and a 1/4 of TSI makes it to the surface, we are looking at maybe 10-40W of incoming TSI which is going straight back out. This is not insignificant. Maybe you could help me tighten that estimate with your greater knowledge of the way Trenberth arrived at his figures.

October 12, 2009 1:20 am

Jerry: You asked, “If we are talking about heat content in the oceans, shouldn’t it be energy/volume?”
It appears I forgot to list the depth (0-700m) on the graphs…again.

Espen
October 12, 2009 1:46 am

The only evidence for AGW that still seems rather convincing to me, is sea level rise. Is there any evidence that global sea levels are starting to drop now that OHC drops?

October 12, 2009 2:14 am

tallbloke (00:07:10) :
I’ll be off the air for a couple of days. Perhaps somebody else can take up the thread….

tallbloke
October 12, 2009 3:55 am

Leif Svalgaard (07:01:11) :
tallbloke (02:13:35) :
Hi Leif, how much of TSI is in the infrared compared to visible please?
UV 100 W/m2, visible 660 W/m2, IR 600 W/m2. But the atmosphere is also mostly transparent to near IR. The absorption [mostly by CO2] really begins at 2000 nm, and the part above 2000 nm is 80 W/m2.

http://www.atmos-chem-phys-discuss.net/3/2027/2003/acpd-3-2027-2003.pdf
Page 25 fig 1 seems to show quite a big absorption band for co2 around the 6000-7500nm band. Could you comment on that please, and give figures for the part of TSI in that part of the spectrum.

tallbloke
October 12, 2009 4:08 am

lgl (09:05:04) :
Stephen,
I fail to see how your incomplete summary of the global energy budget has any bearing on that issue.
No bearing on your strawman, no, but the real issue is what’s keeping the ocean at 16 C. My energy budget is almost complete regarding the surface, only missing 340 W/m2 downwelling. Where does it come from and why?

I think Stephen is correct to point out that the SB law deals with temperature differential between black body and space.
You say a body at 16C radiates at 350W/m^2 but ask yourself this:
If you stood in a 3m^2 pool of 16C water, would you feel the heat of a 1kw electric bar fire coming off it?
I don’t think so, but maybe you disagree.
http://1.2.3.11/bmi/lasp.colorado.edu/sorce/images/instruments/tim/Kiehl_Trenberth_revised.gif

lgl
October 12, 2009 11:09 am

tallbloke,
I think Stephen is correct to point out that the SB law deals with temperature differential between black body and space.
No, SB law deal with radiation emitted from a black body. It doesn’t matter what’s ‘above’. (and I said 396, not 350 but that’s a detail)
Your experiment is a bit troublesome. Firstly you should not stand in the water because that introduces heat transfer by conduction in addition to transfer by radiation. Secondly it’s i bit difficult to direct all the radiation from the water to the surface of your body and visa versa. Suppose that was possible and you were not in direct contact with the water, then you would receive 1200 W from the water and the water would receive 1000 W from you, if your surface area is about 2 m2 and your skin temperature 33 C, i.e. a net transfer of 200 W to you. If the water was 2 m2 too, then there would be 200 W net from you to the water.

SteveSadlov
October 12, 2009 1:24 pm

Dropping like a rock.

Stephen Wilde
October 12, 2009 1:37 pm

“lgl (11:09:38) :
tallbloke,
I think Stephen is correct to point out that the SB law deals with temperature differential between black body and space.
No, SB law deal with radiation emitted from a black body. It doesn’t matter what’s ‘above’.”
If we are considering Earth and Space my comment is correct.
If we were considering Earth and another body then you would be correct and I would have used different wording.
Anyway that quibble distracts from my main point. The SB law does not deal with internal variability resulting from movements of the circulations in ocean and air.

Paul Vaughan
October 12, 2009 1:45 pm
lgl
October 12, 2009 1:59 pm

Stephen
If we are considering Earth and Space my comment is correct.
But we are not. We are considering the Earth’s surface.
Your point (or one of them) is that IR does not heat the ocean, and your problem is that it is impossible to explain the high temperature of the ocean without the energy from IR. For the third time, what else is there? Your internal variability does not create energy.

Stephen Wilde
October 12, 2009 2:08 pm

lgl (13:59:43)
You were considering energy radiated from the Earth’s surface to space when you mentioned the SB Law. I referred to internal variability within the Earth system in relation to which the SB Law is irrelevant.
The temperature of the ocean is adequately explained by the length of time it takes for solar energy input to be absorbed and then released again to the air.
That solar input gets past the evaporative barrier (unlike IR) and remains in the oceans for variable periods of time as it is moved around within the oceans.

tallbloke
October 12, 2009 3:15 pm

Thanks Paul, I keep forgetting my mobile provider does daft things like munging URL’s.
lgl, it’s a good puzzle. 🙂

lgl
October 12, 2009 3:31 pm

Stephen,
You were considering energy radiated from the Earth’s surface to space when you mentioned the SB Law
No, I said “Stefan-Boltzmann law states that a body of 16 C will radiate 396 W/m2” and 16 C is obviously at the surface and not at top of atmosphere.
Delay is no issue here. The temp has remained fairly constant (a few deg) for several thousand years. Yes or No and your suggestion if No please:
1. Is the SST 16-17 deg C?
2. Does the ocean surface radiate 390-400 W/m2 IR?
3. Is the emissivity of the surface close to 1?
4. Is the surface absorbing 160-170 W/m2 sunlight?

Philip_B
October 12, 2009 6:38 pm

lgl (08:46:48) :
The data is all over. Here is Bob’s OHC together with NCDC ocean temp from Junkscience: http://virakkraft.com/OHC-SST.jpg
and it’s of course physical that most variations start at the surface and is delayed at 700 meters.

Posting a link of a graph with no labeled x or y axis isn’t a convincing argument.
I don’t know what ‘most variations’ means.
Anyway, the oceans absorb huge amounts of solar radiation. In the tropical and subtropical oceans it’s in excess of 90% of all incoming solar insolation. If this energy input were not transported upward to the surface and then into the atmosphere, the world’s oceans would boil away within a matter of years.
IMO your error is to think that a temperature gradient of warmer to cooler downwards in the ocean is evidence of heat transport downwards. It isn’t. It results from the absorbtion gradient of sunlight in the ocean.

Invariant
October 13, 2009 12:11 am

Philip_B (06:57:23) : A bald assertion with no data to support it and unphysical as ocean heat transport is overwhelmingly upward toward the surface.
Sure. Please see my calculations of thermal time constant of oceans being ~55 years with a Nusselt number of ~1000. We all know that buoyancy forces are upward toward the surface.

Stephen Wilde
October 13, 2009 3:03 am

lgl (15:31:46)
As regards 1), 2), 3) and 4) the answer is no because of internal variations in the system caused by varying rates of energy release from the ocean to the air geographically and more importantly over at least 2 and probably 3 time scales which are clearly linked to global air temperature variability.
Those internal variations are not accommodated by the models or taken into account in the standard energy budget calculations yet they are what causes climate changes to cycle as per our observations over the past couple of thousand years and they would probably cover most climate changes right back to the last ice age.

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