Archive for the ‘Ocean dynamics’ Category

Over on realclimate, (remember them?), Stefan ‘there is no pause’ Rahmsdorf has posted an article about why OHC makes a lousy climate policy target. I’ve left a comment concerning a sentence further down in the post, but here’s the intro:

donkey-cartThe New York Times, 12 December 2027: After 12 years of debate and negotiation, kicked off in Paris in 2015, world leaders have finally agreed to ditch the goal of limiting global warming to below 2 °C. Instead, they have agreed to the new goal of limiting global ocean heat content to 1024 Joules. The decision was widely welcomed by the science and policy communities as a great step forward. “In the past, the 2 °C goal has allowed some governments to pretend that they are taking serious action to mitigate global warming, when in reality they have achieved almost nothing. I’m sure that this can’t happen again with the new 1024 Joules goal”, said David Victor, a professor of international relations who originally proposed this change back in 2014. And an unnamed senior EU negotiator commented: “Perhaps I shouldn’t say this, but some heads of state had trouble understanding the implications of the 2 °C target; sometimes they even accidentally talked of limiting global warming to 2%. I’m glad that we now have those 1024 Joules which are much easier to grasp for policy makers and the public.”

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GRL publishes letter on 18.6 year and SST

Posted: October 15, 2014 by tchannon in Cycles, ENSO, Ocean dynamics

A number of Talkshop regulars will raise eyebrows over this paper highlighted at Hockeyschtick  and perhaps like to learn about the references in a paywalled paper.

Role of the oceanic bridge in linking the 18.6-year modulation of tidal mixing and long-term SST change in the North Pacific

S. Osafune, S. Masuda and N. Sugiura
http://dx.doi.org/10.1002/2014GL061737

Abstract

The impact of the 18.6-year modulation of tidal mixing on sea surface temperature (SST) in the North Pacific is investigated in a comparative study using an ocean data synthesis system. We show that remote impact through a slow ocean response can make a significant contribution to the observed bidecadal variation in wintertime SST near the center of action of the Pacific Decadal Oscillation in the eastern Pacific. A comparative data synthesis experiment showed that the modified SST variation is amplified by bidecadal variation in the westerly wind. This relationship between SST and wind variations is consistent with an observed air–sea coupled mode in the extratropics, which suggests that a midlatitude air–sea interaction plays an important role in enhancing the climate signal of the 18.6-year modulation. This result supports the hypothesis that the 18.6-year tidal cycle influences long-term variability in climate; thus, knowledge of this cycle could contribute towards improving decadal predictions of climate.

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Guest post from Ben Wouters

Geothermal flux and the deep oceans.

To appreciate how the small geothermal flux of ~100 mW/m2 can play a significant role in our climate we’ll take a look at a cross-section of the Pacific in Fig 1.

fig1

Fig 1

A typical temperature profile is given in Fig 2 below

Fig 2

Fig 2

First the profile below ~1000 m. Slowly decreasing temperature with depth, more or less the same for all latitudes. The dark blue layer (~30 C) can be regarded as the top of the cold deep oceans. From 1000 m. upward the temperature increases rapidly, warmest water at the surface in the (sub) tropics. The dark blue layer only reaches the surface at high latitudes (red arrows). All water above this dark blue layer is warmed from above by the sun, either directly or indirectly. This layer also loses its energy again at the surface to the atmosphere, and eventually to space. Solar energy only warms the upper ~1000 m. between ~50N and 55S. How high the surface temperatures will be, depends on the temperature of the deep oceans and how much the sun can warm the upper layer above the deep ocean temperature.

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Emperor penguins, Antarctica [image credit: USAF / Wikipedia]

Emperor penguins, Antarctica [image credit: USAF / Wikipedia]

We’ll highlight some points from the official reaction later but first the opening details from a press report. Note the eagerness to talk down the relevance of Antarctic sea ice.

‘Sea ice surrounding Antarctica reached a new record high extent this year, covering more of the southern oceans than it has since scientists began a long-term satellite record to map sea ice extent in the late 1970s. The upward trend in the Antarctic, however, is only about a third of the magnitude of the rapid loss of sea ice in the Arctic Ocean.’

‘The new Antarctic sea ice record reflects the diversity and complexity of Earth’s environments, said NASA researchers. Claire Parkinson, a senior scientist at NASA’s Goddard Space Flight Center, has referred to changes in sea ice coverage as a microcosm of global climate change.’

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Hot off the press release press, NASA tells us what I’ve been telling everyone who will listen for the last four years – large amounts of heat cannot magically descend through a marginally warming (or cooling) upper ocean to lurk in the abyss… The second law of thermodynamics doesn’t like that sort of thing.

image shows heat radiating from the Pacific Ocean as imaged by the NASA’s Clouds and the Earth's Radiant Energy System

While the upper part of the world’s oceans continue to absorb heat from global warming, ocean depths have not warmed measurably in the last decade. This image shows heat radiating from the Pacific Ocean as imaged by the NASA’s Clouds and the Earth’s Radiant Energy System instrument on the Terra satellite. (Blue regions indicate thick cloud cover.) Image Credit:  NASA

The cold waters of Earth’s deep ocean have not warmed measurably since 2005, according to a new NASA study, leaving unsolved the mystery of why global warming appears to have slowed in recent years.

Scientists at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, analyzed satellite and direct ocean temperature data from 2005 to 2013 and found the ocean abyss below 1.24 miles (1,995 meters) has not warmed measurably. Study coauthor Josh Willis of JPL said these findings do not throw suspicion on climate change itself.

“The sea level is still rising,” Willis noted. “We’re just trying to understand the nitty-gritty details.”

In the 21st century, greenhouse gases have continued to accumulate in the atmosphere, just as they did in the 20th century, but global average surface air temperatures have stopped rising in tandem with the gases. The temperature of the top half of the world’s oceans — above the 1.24-mile mark — is still climbing, but not fast enough to account for the stalled air temperatures.

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bare-arsed2No reply from the eminent atmospheric physics professor… any takers?

Dear Professor xxxxxxx,

I am trying to better understand the physics underlying atmospheric science and wondered if you could answer a question for me.

The Modtran model successfully predicts the local temperature throughout the troposphere, but how do we determine the extent to which the level of radiative activity at a particular altitude is the effect of the local temperature at that altitude rather than the cause of it?

I ask because it appears from my limited reading and understanding that the theoretical underpinning of radiative-convective models neglects the effect of sea level pressure on the rate of evaporation, which must surely have a significant effect on the rate at which the ocean is able to shed the energy input to it by solar radiation.

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Paul Vaughan has suggested we hold a discussion on bi-decadal climatic variation, which exhibits quasi-cyclic patterns in various datasets. To get the ball rolling, Paul has kindly given some time to producing some very interesting plots which he has introduced across a few recent threads. This posts puts these in one place and acts as an invitation to those interested in a focussed discussion on the topic.

The Bidecadal Oscillation

Is it caused by the solar Hale Cycle as suggested by Tim Channon or is it caused by the velocity of the sun with respect to the solar system barycenter as suggested by Nicola Scafetta?

http://s18.postimg.org/74uty1eix/Bidecadal_SST_Sun_Velocity_Hale_Cycle.png

Bidecadal_SST_Sun_Velocity_Hale_Cycle
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Clams [credit: Wikipedia]

Clams [credit: Wikipedia]

El Niño and its twin La Niña are under the spotlight this year as climate-watchers hunt for signs of expected activity that seems to have gone largely missing in recent years if compared to, say, the 1990s.

Has the strength of these phenomena changed in modern times? Apparently not.

‘The charts created by the research team suggest that the ENSO cycle does not have a predictable cycle and also that it has not been increasing in strength over the course of the Holocene as others have suggested.’

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Paul’Vaughan posted a link to this plot on the tail end of a long running thread which has dropped off the front page now, so I thought I’s give it prominence today. It’s a ‘food for thought’ starter – the main course will be served as and when Paul has time.

Sun_Wind

It’s all coming together. Both Paul and I have been working on the sunspot integral over the last several years. Back in 2009 I found that by subtracting the average sunspot number at which the ocean neither gains nor loses energy from the monthly value and summing the running total, I could make use of the sunspot integral as a proxy for ocean heat content (OHC).

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From Physorg, news of a new paper  which may shed light on the rapid warming at the end of the last ice age. The young scientists don’t mention Milankovitch cycles in this presser, but these are slow to change in comparison to the rapid deglaciation, so maybe their theory lends something to the story. It does lead me to wonder if the precession cycle might be involved with bringing the oceanic oscillations into synch though.

From SoundonSound.com: Here you can see the original waveforms of the two different kick-drum samples. It's clear that they are drifting in and out of phase with each other. The resulting phase cancellation made it impossible to arrive at a consistent sound, so Mike had to edit them back into phase before processing.

From SoundonSound.com:
Here you can see the original waveforms of the two different kick-drum samples. It’s clear that they are drifting in and out of phase with each other. The resulting phase cancellation made it impossible to arrive at a consistent sound, so Mike had to edit them back into phase before processing.

Synchronization of North Atlantic, North Pacific preceded abrupt warming, end of ice age

A newly published study by researchers at Oregon State University probed the geologic past to understand mechanisms of abrupt climate change. The study pinpoints the emergence of synchronized climate variability in the North Pacific Ocean and the North Atlantic Ocean a few hundred years before the rapid warming that took place at the end of the last ice age about 15,000 years ago.

The study suggests that the combined warming of the two oceans may have provided the tipping point for abrupt warming and rapid melting of the northern ice sheets.

“If we really do cross such a boundary in the future, we should probably take a long-term perspective and realize that change will become the new normal. It may be a wild ride.”

Results of the study, which was funded by the National Science Foundation, appear this week in Science.

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There has been some progress in the greenhouse. On the ‘toy planet’ thread, physicist Tim Folkerts now agrees with me that longwave infra-red radiated from the air towards the surface doesn’t directly heat the ocean but makes it harder for the ocean to cool. In my view this is due to IR radiation from the ocean making the air warm, reducing the temperature differential between ocean and air, slowing the rate of the Sun warmed ocean’s heat loss. Tim says:

LWIR is indeed incapable of “heating” the oceans in the strict sense of the word (net transfer of thermal energy). The best it can do is aid in making it “a far more difficult task escaping” for the energy.

But it’s hard for him to let go of ingrained notions, so his next comment is full of ambiguities, which I have tried to deal with in my followup comment:

Tim Folkerts: The DWIR DOES amount to ~ 330 W/m^2.

Fine, no problem.

This energy DOES get absorbed by the ocean.

In the top few microns, and is soon re-emitted along with an additional ~60W/m^2 IR, upwards.

The ocean IS warmer than it would be without this DWIR from the atmosphere.

But not because it is absorbed and re-emitted from the top few microns of ocean. The thermalisation of IR in the bulk air helps keep the air warm and that warm air slows the sun warmed ocean’s heat loss.

But the reason the air is warm is because the ocean warms it with the energy it emits into it which is absorbed and re-emitted, or conducted to the O2 and N2 in the air, by water vapour (from the ocean) and co2 (mostly from the ocean). Air has very little heat capacity of its own, and is nearly transparent to incoming solar short wave radiation. And this ocean warmed air is usually convecting upwards.

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teacup-stormReuters news  geophysics-data agency:

(Reuters) – Coastal flooding along the densely populated Eastern Seaboard of the United States has surged in recent years, a Reuters analysis has found.

The analysis was undertaken as part of a broader examination of rising sea levels Reuters plans to publish later this year.

For its analysis, Reuters collected more than 25 million hourly tide-gauge readings from nearly 70 sites on the Atlantic, Gulf and Pacific coasts and compared them to NOAA flood thresholds.

As many Americans question the causes and even the reality of climate change, increased flooding is already posing a major challenge for local governments in much of the United States.
[sure will in landlocked States!]

And goes on about climate change and sea level rise and probably being wound up by vested interests.

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Greenhouse effectsFollowing on from our recent debate on the likely extent of the greenhouse effect on Earth, this post will broaden the scope of discussion by allowing consideration of planetary surface temperatures on imaginary worlds. Tim Folkerts proposes a world at the distance from the Sun of our moon (i.e. the same average distance as Earth), with a twist on surface composition:

Konrad,

Just out of curiosity, if I put a ball of water — say a few km in diameter — in some sort of clear plastic baggie to keep it together and prevent evaporation in orbit around the sun @ 1 AU, are you claiming the water inside the baggie will be at least 80 C everywhere?

Or if I put a series of such plastic baggies on the moon to cover the entire surface with water 1 km deep that cannot evaporate, that the surface of the moon would be at or above 80 C everywhere (lets even limit the question to the “tropics” out to ~ 30 degrees N & S to avoid question about what happens at the poles)?

(We could even make the baggie slightly elastic to apply 1 Atm of pressure inward on the ball of water).

____________________________

Tim appears to have misunderstood what Konrad and I are telling him about the atmosphere being a cooling agent rather than a warming agent, and how pressure acts to slow the loss of energy from the oceans via the atmospheric suppression of evaporation and the increased density of a near surface atmosphere, which is not present on his toy planet.

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H/T to talkshop contributor Wayne for this short piece from the physics of sailing blog which tells us that near surface windspeeds have fallen over the last 30 years. However, the evidence in a presentation by Hartwig Volz on seawater emissivity I came across yesterday apparently contradicts this. I’ve becalmed-yachtadded a couple of the relevant plot’s from that below the short article, but do take a look at the whole pdf slideshow. The discussion of wind speed is highly relevant to the whole climate debate, including the fundamentals of ocean-atmosphere interaction, energy balance and surface warming. Recall that Hans Jelbring’s thesis was entitled ‘Wind Controlled Climate‘ . 

The Wind is Dying

Wind speed has significantly decreased in the 29 years from 1979 to 2008. In extreme cases, the wind decrease was a significant 15%. More specifically, the wind decreased at 73% of measuring stations which were 10 meters above the surface (about mast height for many smaller sailboats). The measurements were mostly from Europe, but also from the United States, China and Russia.

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I came across this paper today while searching for the heat capacity of Venus near surface atmosphere, which is actually an ocean-like (in thermodynamic terms) supercritical fluid. It presages Harry Dale Huffman’s ‘rediscovery’ of the lapse rate calculation by four decades. Another paper, much more recent, (Bolmatov et al 2013) contains some theory which raises yet more questions about the reasons for Venus’ high surface temperature. So, greenhouse due to radiative proerties of co2 as Sagan claimed, lapse rate due to gravity and pressure as Nikolov and Zeller maintain, or the thermal properties of supercritical fluids and geothermal energy having a hard time escaping the lower atmosphere? Let the debate recommence!

venustemp1

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finnish2

David Archibald’s prediction for global average temperature 2014-2025

David Archibald’s post at Quadrant.org.au has stirred some interesting debate here at the talkshop. David predicts an imminent and steep drop in regional temperatures as a result of the slowdown in solar activity seen since the descent of solar cycle 23 in 2003. It’s not the first time he has made such predictions. As Nick Stokes pointed out in discussion, Archibald told the Australian senate committee in 2009 that temperature was about to go down at a scary 0.2C per annum. It didn’t happen. But David says it’s different this time, because a decade has passed since solar cycle 23 dropped towards a long minimum, followed by the weak cycle 24 we are currently in. The decadal lag is implied by David Evan’s new hypothesis which identifies a ‘notch filter’ which points to a cycle-long lag between changes in solar activity and the effect becoming visible in the terrestrial response. David goes on to predict that due to Penn and Livingstone’s prediction of a very low sunspot number in cycle 25, we are headed for drastic cooling.

There are several points on which I disagree with David’s analysis, and I’ll cover them below the break.

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While browsing Ian Wilson’s excellent Astro-Climate Connection blog, I found a graphic showing the coincidence of El Nino with the alignment of the Lunar line of nodes (declination cycle) and line of apse (orbital precession), with the Sun. I’ve taken the liberty of adding my Solar – El Nino hypothesis to it: the proposal is that El Nino tends to be initiated as the cycle starts to decline steeply and initiated again at solar minimum as it ‘bottom’s out’. I’ll reproduce Ian’s accompanying text below the break but to get to the point, here’s  the result:

enso-lunisolar

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I’m of the opinion that before getting into the complexity of numerical modelling, it’s wise to put considerable effort into trying to understand the physical processes at work in the climate system, and the origins of the energy flows that drive them. David Evans’ recent series of posts over at Jo Nova’s site have generated a lot of interesting discussion (despite being roundly ignored by Anthony Watts at WUWT), and I think we can shed some light on the ‘mysterious 11yr lag’ between solar input and climate response.

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An interesting series of posts has appeared at Jo Nova’s site. Jo’s husband, David Evans has done some competent analysis work to unravel the observed ~11 yr ‘delay’ in terrestrial climatic response to solar input. Of interest is the obervation that the solar polar magnetic fields are in the process of weakeneing and changing sign near solar maximum. It is suspected that this is connected with the delay. Head on over to read the posts and comment there as well as here.

Figure 6: The amplitudes of the empirical transfer function when the data is restricted in the ways marked (that is, using a subset of the data used to find Figure 5). The black line and the gray zone are as in Figure 5.

BIG NEWS Part I: Historic development — New Solar climate model coming
BIG NEWS Part II: For the first time – a mysterious notch filter found in the climate
BIG NEWS Part III: The notch means a delay
BIG NEWS part IV: A huge leap understanding the mysterious 11 year solar delay

I have made a comment, reproduced below the break.

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oldbrew:

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A very important topic indeed, thanks to Judith Curry for raising it.

Originally posted on Climate Etc.:

by Judith Curry

 . . . suggesting that Dansgaard-Oeschger events resulted from a combination of the effects of sea ice and ice shelves—structures that help define the margins of ice sheets—to account for both the rapid and the slower parts of the cycle.

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