Northern tropical dry trend may just be normal variation

Intertropical Convergence Zone [image credit: University of New Mexico]

A key finding of this research concerns the Intertropical Convergence Zone (ITCZ). The researchers report ‘southward mean positions of ITCZ during the early Medieval Warm Period and the Current Warm Period in the central Indo-Pacific.’ This seems to contradict claims, repeated recently, that the MWP was confined to northern parts of the European and American continents, or at least was not global. But the ITCZ is a global phenomenon, which in turn suggests any recent warming (CWP) could have similar origins to the MWP – surely a somewhat inconvenient proposition for man-made greenhouse gas theorists. Remember this Climategate story – ‘We have to get rid of the Medieval Warm Period’?

Rainfall variations in the tropics not only potentially influence 40% of the world’s population and the stability of the global ecosystem, but also the global hydrologic cycle and energy balance, says Phys.org.

Beginning in the 20th century, a decline in northern tropical rainfall has been observed, with researchers unsure whether the decline stems from natural or anthropogenic causes.

New rainfall research has shed some light on this question, but left the final answer up in the air.

Tropical Pacific is major player in global ocean heat transport

The Great Ocean Conveyor Belt – blue = deep cold and saltier water current, red = shallower and warmer current
[credit: NWS / NOAA]

Researchers put forward the idea that the role of the global ocean conveyor belt may be overrated in the grand scheme of ocean dynamics, and offer alternative ideas.

Far from the vast, fixed bodies of water oceanographers thought they were a century ago, oceans today are known to be interconnected, highly influential agents in Earth’s climate system, says Phys.org.

A major turning point in our understanding of ocean circulation came in the early 1980s, when research began to indicate that water flowed between remote regions, a concept later termed the “great ocean conveyor belt.”

The theory holds that warm, shallow water from the South Pacific flows to the Indian and Atlantic oceans, where, upon encountering frigid Arctic water, it cools and sinks to great depth.

This cold water then cycles back to the Pacific, where it reheats and rises to the surface, beginning the cycle again.

Science Says: Get used to polar vortex outbreaks

Polar vortex [image credit: NASA]

H/T Phys.org
Changing polar vortex patterns and wavy jetstreams – do they suggest solar magnetic changes as sunspots decline, or another 0.01% of trace gases in the atmosphere, or something else? Much scientific head-scratching, although research has been going on for a while.

It might seem counterintuitive, but the dreaded polar vortex is bringing its icy grip to parts of the U.S. thanks to a sudden blast of warm air in the Arctic, writes Seth Borenstein.

Get used to it. The polar vortex has been wandering more often in recent years.

Met Office fakes the Foehn effect

Descending air in the atmosphere rises in temperature as it is adiabatically compressed in the pressure gradient created by gravity acting on atmospheric mass. This has been known for centuries. However, the MET Office has decided to do away with this fundamental fact of physics in a short video it has produced.

Here is some more information on what we mean by the Foehn Effect pic.twitter.com/h8Zr9XJ2Y2

— Met Office (@metoffice) October 23, 2018

Even their own website page on the Foehn effect (now safely screenshotted and web-cited) tells us:

“ foehn air… becomes warmer and drier on the leeside after it is compressed with descent due to the increase in pressure towards the surface.”

Thermodynamics 101: Compression increases temperature.

Question: If I had a container, full with air, and I suddenly decreased the volume of the container, forcing the air into a smaller volume, will it be considered as compression, will it result in an increase in temperature, and why?

Answer on Stack Exchange by Luboš Motl: Yes, it is compression and yes, it will heat up the gas.

If there’s no heat exchange between the gas and the container (or the environment), we call it an adiabatic process. For an adiabatic process involving an ideal gas (which is a very good approximation for most common gases), pV^γ is constant where γ is an exponent such as 5/3. Because the temperature is equal to T=pV/nR and pV/pV^γ=V^1−γ is a decreasing function of V, the temperature will increase when the volume decreases.

Macroscopically, the heating is inevitable because one needs to perform work p|dV| to do the compression, the energy has to be preserved, and the only place where it can go is the interior of the gas given by a formula similar to (3/2)nRT.

Scientists reveal drivers of prolonged spring-summer drought over North China

Drought conditions in Northern China

But what is driving the drivers – that bright thing in the sky perhaps?

A recent study reveals the large-scale dynamic drivers of the prolonged spring-summer drought over North China, where prolonged drought tends to begin in spring and persists to summer with severe societal impacts, says EurekAlert!.

North China, where almost half China’s population lives and most wheat and corn are grown, is facing serious water crisis. Since the late 1990s severe and extreme droughts have frequently dropped by and drought affected area has been increasing by 3.72% decade-1 in the past five decades, posing great challenges for regional sustainable development.

Scientists have been concerned that if climate continues to warm in the future, there is a high confidence level that drought over North China will continue to increase. Thus, it is of great importance to identify the drivers and dynamic mechanisms of North China drought in order to improve drought prediction and better water management.

Research finds link between rainfall and ocean circulation in past and present

The lead author found it ‘remarkable’ that ‘The results indicate that in present and past the Atlantic Ocean surface currents correlate with rainfall patterns in the Western Hemisphere.’
It turns out that ‘If we go back in increments of 30 [years], we’re well positioned to understand things on the order of centuries.’ Could we call it natural variation perhaps…?

Research conducted at The University of Texas at Austin has found that changes in ocean currents in the Atlantic Ocean influence rainfall in the Western Hemisphere, and that these two systems have been linked for thousands of years, reports Phys.org.

The findings, published on Jan. 26 in Nature Communications, are important because the detailed look into Earth’s past climate and the factors that influenced it could help scientists understand how these same factors may influence our climate today and in the future.

Stephen Wilde: How conduction and convection cause a greenhouse effect arising from atmospheric mass.

This guest post from Stephen Wilde offers a descriptive theoretical and qualitative perspective on the ‘gravito-thermal’ theory. It covers the vertical profile of the atmosphere as well as the surface temperature comprehensively quantified by Nikolov and Zeller’s latest paper.

How conduction and convection cause a greenhouse effect arising from atmospheric mass.
Stephen Wilde

Introduction

The current scientific consensus is that Earth’s so called ‘greenhouse effect’ is caused by the presence of radiating gases in the atmosphere but many years ago, I learned what  I then understood to be the consensus view that it is actually a result of atmospheric mass such that the radiative characteristics of the atmosphere are either wholly or largely irrelevant.

The ‘greenhouse effect’ is an apt description for the mass based phenomenon because warming, descending air (which is occurring over half the planet at any given moment) will inhibit convection in the same way as does a greenhouse roof and by dissipating clouds it increases incoming sunlight through that barrier to convection just like the transparency of a greenhouse roof.

If the greenhouse effect is attributable to atmospheric mass rather than radiative characteristics then the fact that the vast bulk of Earth’s atmosphere is comprised of mass that is non-radiative is likely to mean that human emissions of radiative gases are not important as a regulator of surface temperature.

NOAA & The Oroville Dam

.
.
Over forty years ago ‘climate scientists understood that global cooling causes extreme weather, and global warming causes mild weather.’ – Tony Heller.
http://www.thegwpf.com/1975-global-cooling-extreme-weather/

Nowadays many of them seem to have ‘forgotten’ about that.

NOT A LOT OF PEOPLE KNOW THAT

By Paul Homewood

h/t Oldbrew

https://www.climate.gov/news-features/event-tracker/flooding-concerns-oroville-dam-water-levels-reach-capacity

NOAA have a good account of what has been going on with the Oroville Dam:

As mentioned previously in the Event Tracker, California is going through one of its wettest water years (October – September) on record. In particular, precipitation so far in 2017 is on a record pace for northern and central California. While the water has been a godsend in reducing and relieving drought conditions, it also has been too much of a good thing as flooding has resulted. One case in particular is the ongoing emergency at the Oroville Dam north of Sacramento. Tremendous amounts of precipitation have led to the Lake Oroville reservoir—the second largest reservoir in the state—to fill past capacity. The need to funnel water out of the reservoir and accompanying complications has led to flooding concerns and evacuations below the dam.

(top) Aerial view of the…

View original post 181 more words

A retrospective, Climate Audit and the late Prof. Kreiss

Tim writes,

Published 27th February 2016 Climate Audit published a small article in honour of Kreiss to do with atmospheric modelling, the hydrostatic balance… or not.

Comments follow from Names. I think the comments are worthy of a read and decode by Talkshop readers who have an interest in this kind of topic.

Gerry Browning: In Memory of Professor Heinz Kreiss

Gerry Browning writes:

The Correct System of Equations for Climate and Weather Models

How Northern European waters soak up carbon dioxide

Carbon cycle [image credit: NASA Earth Observatory]

Somebody seems to have re-discovered the carbon cycle, and true to form the BBC is keen to spread the word by trying to relate it to buses and jumbo jets.

The seas around the UK and the rest of northern Europe take up a staggering 24 million tonnes of carbon each year. It is a mass equivalent to two million double-decker buses or 72,000 747 jets. The number was produced by scientists studying the movement of carbon dioxide into and out of the oceans.

New insights into the dynamics of past climate change

Arctic ocean near Barrow, Alaska [image credit: Beth Ipsen/Associated Press]

A new study by the University of Cambridge ‘finds’ (their word) that changing climate in the polar regions can affect conditions in the rest of the world far quicker than previously thought. The full paper has paywalled access only, but by their own admission they say they are ‘only beginning to understand’ the processes they believe they have found.

A new study of the relationship between ocean currents and climate change has found that they are tightly linked, and that changes in the polar regions can affect the ocean and climate on the opposite side of the world within one to two hundred years, far quicker than previously thought.

Beginner’s guide to convection cells

Global circulation of Earth’s atmosphere displaying Hadley cell, Ferrell cell and polar cell [credit: NASA]

Introducing by popular demand (?) [click to view]:
‘Convection Cells Move Air Around’ (short video) – Windows to the Universe.

When you warm air, it rises. Cool air will sink. This process of convection can lead to flows in the atmosphere, in a manner that we can illustrate [see video] on a small scale. Warm and cool air in a fish tank rise and fall; this motion is made visible by adding fog. Ultimately, the motion leads to a convection cell, with air rising, moving to the side, falling, and moving back. This heat-driven motion of air moves heat around in the atmosphere. It is also responsible for making the wind blow.

***
Cue discussion by Talkshop commenters 🙂

This post arose from a discussion on another thread that seems to have started somewhere around here.

Larger version of the NASA graphic here.
————————————————————————————————
Update – a newer post (2015/06/11) can now be viewed here:
Atmospheric convection – what does it mean?
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[comments are now closed on this thread – see ‘Update’ above]

Jarl Ahlbeck: A link between Low solar activity, Easterly QBO, negative AO and cold NH winters

Future low solar activity periods may cause cold winters in North America, Europe and Russia.
Jarl Ahlbeck – Abo Akademi University, Finland

Historically, low solar activity periods like the Dalton and Maunder Minima have been connected to cold winters in Europe. It seems very possible that the low solar activity forced areas of low pressures into a southern route or caused a negative Arctic Oscillation, AO, which in turn allowed cold air from the North Pole to flow across Europe. But can we obtain from real measurements that low solar activity really is able to do that?

Donohoe et al: The missing piece of the climate puzzle

This article caught my eye because Isaac Held stuck his oar in. Talkshop readers will have a field day with this I think.

Researchers show that a canonical view of global warming tells only half the story.
Genevieve Wanucha | Program in Atmospheres Oceans and Climate
November 10, 2014

In classrooms and everyday conversation, explanations of global warming hinge on the greenhouse gas effect. In short, climate depends on the balance between two different kinds of radiation: The Earth absorbs incoming visible light from the sun, called “shortwave radiation,” and emits infrared light, or “longwave radiation,” into space.

Upsetting that energy balance are rising levels of greenhouse gases, such as carbon dioxide (CO₂), that increasingly absorb some of the outgoing longwave radiation and trap it in the atmosphere. Energy accumulates in the climate system, and warming occurs. But in a paper out this week in the Proceedings of the National Academy of Sciences, MIT researchers show that this canonical view of global warming is only half the story.

Thor Heyerdahl: Retrospective on an adventurous anthropologist

Talkshop contributor Cheremon emailed me earlier to say that today is the centenary of the birth of Adventurer and anthropologist Thor Heyerdahl. Here’s a short Biography of this remarkable man. I visited the museum and ‘ethnological park he built on Teneriffe (with Fred Olson’s money) some years ago, and marvelled at the similarity of the ancient artifacts from both sides of the Atlantic on display next to the pyramids he excavated from a pile of rubble. This from Biography.com:

 

Thor Heyerdahl Biography

Writer, Academic, Archaeologist, Explorer (1914–2002)

OCCUPATION

Writer, Academic, Archaeologist,Explorer

BIRTH DATE

October 6, 1914

DEATH DATE

April 18, 2002

EDUCATION

Oslo University

PLACE OF BIRTH

Larvik, Norway

PLACE OF DEATH

Colla Micheri, Italy

Born in 1914, Thor Heyerdahl grew up in Norway. He attended Oslo University, where he studied zoology. In 1936, Heyerdahl went to live on the Pacific island of Fatu Hiva. He made his world-famous voyage from Peru to French Polynesia aboard the Kon-Tiki in 1947. His book about this adventure became an international hit. In 1953, Heyerdahl led an archaelogical expedition to the Galapagos Islands. Two years later, he traveled to Easter Island. In his later years, Heyerdahl excavated pyramids in Peru and the Canary Islands. He died in 2002.

Study linking polar vortex chills to melting sea ice rejected by leading IPCC author

Spot the polar vortex
[image credit: BBC]

Before the usual media suspects get too worked up at yet another ‘study’ proclaiming something or other about humans and climate effects, let’s note what this well-known IPCC author thinks of it:

‘Kevin Trenberth, climate analysis chief at the National Center for Atmospheric Research in Boulder, … said he doesn’t agree with Yoon’s study.’

Paul Vaughan: Wind and Sun – correlation since 1880

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.

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).

Boris’ Bigger Burden Causes Congestion Charge Consternation

From 2020 drivers of all but the most efficient diesel cars and older petrol cars will be charged an additional £10 a day to use the London roads they already pay road tax and a ‘congestion charge’ to travel on. Boris Johnson is bringing in the new levy in response to EU pressure to further reduce emissions. The unelected EU commission launched legal proceedings against Britain in February.

Elsewhere, Labour is planning a network of low-emission zones that would force older diesel vehicles out of many cities. Sheffield, Leicester, Bradford, Leeds, Birmingham, Bristol and 14 other cities are considering bringing in the zones to cope with poor air quality.

What ‘back radiation’ does and doesn’t do

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.