"Carsten Troelsgaard" wrote in message
. ..


http://www.atmos.umd.edu/~owen/CHPI/IMAGES/emisss.html

shows the central position of CO2 and H2O-vapour in the
temperature-dependant emission-maximum.

That link only shows half of the spectrum. it makes me suspicious that
it has a hidden agenda for not showing the full spectrum from 4 microns
upwards.

In my consept I've boiled the problem down to an increase in the
temperature-gradient from the Earth's surface to the top of the troposphere,
but I'm not very well brought up to date on factual measurements of Earth's
irradiation from here.

The gradient does not increase. See;

It's obvious, that irradiation off a water-surface could be strongly
attenuated due to the eqvivalence between the surface-emitted and the
troposphere-absorbed spectrum.

No, no, no! A water surface emits blackbody radiation, i.e. pure LW
radiation
(and it reflects SW (solar) radiation.) Water vapour absorbs selected LW
frequencies, as does CO2.

But what about emittance off a soil-surface.

Soil surfaces emit blackbody LW radiation, and they reflect SW sunlight
depending on their albedo. Moreover, they heat the air by conduction and
add latent heat in the form of water vapour, depending on how wet the soil
is. In other words it is not that simple!

Cheers, Alastair.

Carsten Troelsgaard wrote:
"Robert Grumbine" skrev i en meddelelse

SNIP....

I recently engulfed 'Remote sensing and image interpretation' by Thomas M.
Lillesand and Ralph W. Kiefer, with great appetite. The point of di- and
tri-atomic influences escaped me though,

Triatomic and heteronuclear (the two atoms are different) diatomics
absorb and emit in the infrared. Homonucluear diatomics (N2, O2, etc.)
do not absorb or emit in the IR. For why you have to do quantum mechanics.

josh halpern

December 17, 2004

Joshua Halpern wrote:

Carsten Troelsgaard wrote:

I recently engulfed 'Remote sensing and image interpretation' by Thomas M.
Lillesand and Ralph W. Kiefer, with great appetite. The point of di- and
tri-atomic influences escaped me though,

Triatomic and heteronuclear (the two atoms are different) diatomics
absorb and emit in the infrared. Homonucluear diatomics (N2, O2, etc.)
do not absorb or emit in the IR. For why you have to do quantum mechanics.

Quantum Mechanics? Carsten? That'll be a cold day in hell.

http://hyperphysics.phy-astr.gsu.edu...on.html#quacon

Thomas Lee Elifritz
http://elifritz.members.atlantic.net

"Eric Swanson" wrote in message
...

Thanks, but I was hoping that Jim would reply with more detail.
The cold sea-surface conditions to the northeast of Greenland do not explain
the sinking in the Labrador Sea.

If you use the new Scholar goggle http://scholar.google.com with the spelling
'cabelling' then you get this link, which may answer that question;

Structure and mixing across an Arctic/Atlantic front in northern Baffin Bay
Lobb, Julie; Carmack, Eddy C.; Ingram, R. Grant; Weaver, Andrew J.
Geophysical Research Letters, Volume 30, Issue 16, pp. OCE 1-1, CiteID 1833,
DOI 10.1029/2003GL017755 (GeoRL Homepage) 08/2003
Abstract
A front forms in northern Baffin Bay (~75.25°N) between Atlantic-derived water
carried by the West Greenland Current and Arctic-derived waters exiting
southward through Nares Strait and Jones Sound via the Baffin Current.
Subsurface waters (e.g. below 100 m) of the West Greenland Current are as much
as 2°C warmer than those of the Baffin Current. Confluence of these waters
leads to a frontal transition between 100-500 m wherein cross-frontal
gradients of potential temperature (Delta?/DeltaL ~ 0.06-0.07 °C.km-1) and
salinity (DeltaS/DeltaL ~ 0.005-0.007 PSU.km-1) are largely density
compensating (Deltasigma?/DeltaL ~ 0.001 km-1). Subsequent thermohaline
interleaving establishes conditions conducive to mixing via cabelling and
double-diffusion. The front's location would allow it to play a contributing
role in the formation of Baffin Current water structure and eventual export of
freshwater to the North Atlantic.

http://adsabs.harvard.edu/cgi-bin/np...p;db_key=A ST

Cheers, Alastair.

SwimJim wrote:
Eric Swanson wrote:
In article ,
says...

"Eric Swanson" wrote
In article LN5wd.4403$Zn6.2494@trnddc08,
says...

SwimJim wrote:
Eric Swanson wrote:


Sorry, we can't shut up as long as fools like you are out
there
but spreading lies. First off, the CO2 increase won't stay
around
forever, will be removed by slow geological processes over
about 1
thousand years.If the next natural shift in the glacial
cycle
happens
later, there won'tbe much that could be done about it.
Second, there is
the very realpossibility that increasing CO2 will shutdown
the

ThermohalineCirculation (THC), which would produce near Ice
Age
conditions in Northern Europe.

Such a change might even trigger a full bore Ice Age...


Based on my extensive reading on the subject, I don't think
that full
THC shutdown should be characterized as a "very real"
possibility. I
think that it would be better characterized as an improbable
possibility. That doesn't mean that there won't be any
effects
on the
THC.

Unlikely but possible.

Thanks Josh, your efforts are appreciated, but not the way you
might expect.
My news service did not pick up Jim's post.

Jim's expertise and access to the literature is certainly better
than mine.
I suppose he disagrees with Wally Broecker at some point. It
would be
interesting in knowing his thoughts on the possibility of THC
Shutdown.
For example, I would like to know his ideas about exactly how
the
THC occurs
in the North Atlantic Sub Polar Gyre. I understand that there
is
a
difference in the actual process there, compared with that
around
the
Antarctic, where the sea-ice cycle causes the rejection of
brine,
which then
leads to sinking of denser waters. In the North Atlantic, the
process is
said to be more dependant on the temperature, as sinking occurs
in
locations
without sea-ice cover. I've seen some data which indicates that
the surface
water there is less saline than the water farther south,such as
that of the
Gulf Stream. It's that process in these locations that I am
particularly
interested in.

There is a process known as 'cabelling', (although other variation
of that
spelling are used,) which may be the way the sinking happens in
the
North Atlantic. AFAIK the exact site where the sinking occurs is
not
known, but the following map of SST for the GIN Seas, which is
updated daily, suggests that an area north and west of Iceland is
where
there is mixing of waters which could produce that process . See;
http://129.13.102.67/wz/pics/Reursst.gif

http://www.wetterzentrale.de/pics/brack5.html also shows similar
features.

Thanks, but I was hoping that Jim would reply with more detail.
The cold sea-surface conditions to the northeast of Greenland do
not
explain
the sinking in the Labrador Sea.

Eric,

In order to compose a full-bore response (ha), I'll need a little
more
time. Busy day today (AGU press release) and next week (have to
finish
a GRL response to reviewers). Add to that the possibility of snow on
Monday complicating the schedule.

Put broadly, it appears that the THC shutdown is density-driven. The
change in density due to surface warming is less than the change in
density due to freshwater dilution, i.e., lower salinity, and it
doesn't appear that there's enough freshwater supply, even with
accelerated melting, to induce a complete THC shutdown. However,
localized changes could definitely still happen.

More next week as time allows -- maybe even today, we'll see.

Jim

Thanks for the reply. Again, my news server didn't pick it up.

Since this is the busy season and you are also involved in other
activities,
let us know what yu think when you have the time.

There is another ship report that documented a cruise to the same area
in 2002.


http://www.damtp.cam.ac.uk/user/ak283/convection-www/Public/files/L2002.pdf

It appears that the convective "chimney" found in 2001 persisted for
almost a year???

--
Eric Swanson --- E-mail address: e_swanson(at)skybest.com :-)
--------------------------------------------------------------

"Robert Grumbine" wrote in message
...
In article ,
Alastair McDonald k wrote:

Thanks Josh, your efforts are appreciated, but not the way you might
expect.


Murky business, that NADW formation. AABW is much easier, in a
sense, but then again, perhaps only because we don't have as many
observations.

I was at a meeting a couple of years ago when I was told by Prof.
Marakotze, then at Southampton Oceanography Centre, that the
no one yet knew exactly where the NA deep water was formed.

Once you enter the NADW story, you have quite a few players, and
awfully fine balances to be found. Of course that's what makes it
interesting to study.

That was why I raised the subject of cabbeling. I suspect that there are
at least three processes happening in the NA. Salt fingering, cabbeling,
and convection cells.

On this map http://129.13.102.67/wz/pics/Reursst.gif I think I can see
a convection cell (warm cored eddy) forming north north east of Iceland.
It appears and disappears on a daily timescale. That area also seems
to generate a flow of cold fresh water which floats over the North
Atlantic Drift, down from Iceland towards Scotland.

That flow is also obvious in the second map I referenced.
http://www.wetterzentrale.de/pics/brack5.html which also shows a strong
front to the west of Iceland where I suspect cabbeling is happening.


Cabbeling (preferred spelling) is not a potential element for the north
atlantic water mass formation, from my now ancient recollection of the
hydrography.

The Glossary of Physical Oceanography and Related Disciplines appears
to agree with your first point but not your second!
http://ioc.unesco.org/Oceanteacher/r...ean/ocean.html

It has two entries;

- caballing
- See cabbeling.
-
- cabbeling
- In physical oceanography, a phenomenon that occurs when two water
- masses with identical densities but different temperatures and salinities
- mix to form a third water mass with a greater density than either of its
- constituents. This is hypothesized to be a major cause of sinking in
- high northern latitudes. See McDougall (1987b).

I suspect that at the front where temperature is changing rapidly with
distance, that the two masses are altering their densities by change
of temperature until they match, whereupon the water descends (cabbels)
to be replaced by new waters from the two masses in a self perpetuating
process.

There is a paper here about modelling cabbeling by Bob Marsh of
the SOC.
http://citebase.eprints.org/cgi-bin/...ton.ac.uk:8695

As you wrote , Bob,
Once you enter the NADW story, you have quite a few players, and
awfully fine balances to be found. Of course that's what makes it
interesting to study.

Cheers, Alastair.