Skip to content

WHY IS THE STRATOSPHERE WARM?

March 31, 2016
tags:

By Paul Homewood

 

This is a guest post by Erl Happ.

It is the second in a series on the role of ozone in the Earth’s climate.

 

 

 

WHY IS THE STRATOSPHERE WARM?

 

image

 

Energy arrives from the sun in the full gamut of wave lengths documented above. It is emitted by the Earth in a relatively narrow range in the infra-red between 1-125 um.

Ozone is made possible by the splitting of the oxygen atom by short wave radiation in the ultraviolet spectrum at wave lengths shorter than 250 nanometres, equivalent to  0.250 um. Once formed ozone can be broken down by wave lengths between 0.3 and 0.4 um in the ultraviolet.

Ozone is a greenhouse gas absorbing some of the very considerable sum of energy emitted by the Earth in the infra-red spectrum instantaneously transmitting that energy to adjacent molecules. But does this absorption in the infra-red contribute to the warmth of the stratosphere? You can survey the literature and find nary a reference to this phenomenon. The literature is dominated by the environmental concerns as to whether ozone is a significant pollutant in the troposphere and secondly, the degree to which its presence in the stratosphere enables the screening out of short wave energy that is harmful to plants and animals. The ‘ozone hole scare’ gave rise to the Montreal Protocol for the elimination of the use of certain gases including the commonly used ‘Freon’. Apart from that, the stratosphere is seen as largely irrelevant to the concerns of man, a place where the atmosphere is relatively static because ‘stratified’ with warmer air above colder air.

Now let’s get to grips with the question posed in the heading:

 

WHY IS THE STRATOSPHERE WARM?

On a website prepared by the US Earth Sciences National Teachers association with the support of NASA we have this statement:

Temperatures rise with increasing altitude in the stratosphere. Ozone molecules in the stratosphere absorb ultraviolet radiation coming from the Sun. The energy from the UV radiation is transformed into heat. The heating is most intense near the top of the stratosphere, so that is where the stratosphere is warmest.

 

From Wikipedia we have:

Within this layer, temperature increases as altitude increases (see temperature inversion); the top of the stratosphere has a temperature of about 270 K (−3°C or 26.6°F), just slightly below the freezing point of water.[3] The stratosphere is layered in temperature because ozone (O3) here absorbs high energy ultraviolet (UVB and UVC) radiation from the Sun and is broken down into the allotropes of atomic oxygen (O1) and common molecular oxygen (O2). The mid stratosphere has less UV light passing through it; O and O2 are able to combine, and this is where the majority of natural ozone is produced. It is when these two forms of oxygen recombine to form ozone that they release the heat found in the stratosphere. The lower stratosphere receives very low amounts of UVC; thus atomic oxygen is not found here and ozone is not formed (with heat as the by product).

 

So, the question arises: Is the energy absorbed at short wave lengths that is involved in both the creation and destruction of ozone sufficient to explain the warmth of the stratosphere? Well, for a start we can note that the stratosphere is warmest at 1 hPa and not at 30 hPa where the Wikipedia article suggests that the heat is released in the creation of the ozone molecule. Secondly, we can note that the reversal of the lapse rate (rate of temperature change with elevation) at the tropopause requires heating at and below that elevation to produce the reversal of the lapse rate.  It’s obvious therefore that the notion that the heat of the stratosphere is due to interception of short wave radiation is deficient.

The profile of Earth emitted outgoing long wave radiation as measured by satellites reveals a deficit at 9-10 um reflecting infra-red energy lost to ozone in heating the stratosphere.  The deficit in outgoing radiation at 9-10 um represents a hole in the energy emitted that is close to the peak of the spectrum carrying the bulk of the energy emitted by the Earth. The energy at these wave lengths is abundant. That energy is absorbed by ozone in the troposphere (contains about 10% of total ozone) and the stratosphere. There is no shortage of energy in the infra-red wavelengths to enable atmospheric warming whereas the energy available in the ultraviolet spectrum is but a tiny portion of the entirety of incoming radiation.

The effort to map the distribution of ozone in the atmosphere by satellites can utilize the attenuation of radiation in the ultraviolet spectrum OR the infra-red spectrum to infer the presence and concentration of ozone. The Toms satellite utilized the former while more recently the availability of Japanese developed instruments abroad the Gomes satellite enables the measurement of ozone utilizing the attenuation of the infra-red spectrum by ozone. The Japanese maintain a healthy interest in the ozone content of the air and matters stratospheric.

The source of that information is the following expert review:

 

image

Accessed here

 

 

The attenuation by ozone, water vapour and CO2 in the region of 9-10um is graphed:

 

image

 

 

We see that the attenuation of the energy available in certain wave lengths between 975 um and 1100 um rises to as much as 50% of the total with considerable energy imparted to the atmosphere measured in terms of watts per square centimetre.

There is another consideration that is very important. It is conveyed in the following statement that can be accessed in the original here

 

image

 

 

 

This is a very important dynamic that influences how and where the stratosphere absorbs outgoing infra-red. Consider this:

  1. The amount of radiation absorbed by ozone is pressure dependent. The lower ozone is present in the atmospheric column the greater its heating capacity. This is of particular interest given the fact that ozone is ubiquitous throughout the atmospheric column in high latitudes and richly so in winter. The closer the poles are approached, the greater is its heating power, helping to explain the velocity of the jet stream that develops at the conjunction of dense ozone deficient air of mesospheric origin and warmer air that is ozone rich on the equatorial side of the polar vortex.

  2. The greater opacity of ozone in the troposphere, to the point that the troposphere absorbs as much energy as the entire stratosphere goes a long way to explaining the attenuation of the lapse rate at very low altitudes as we approach the poles. See here for lapse rates.

  3. This phenomenon helps to explain the origin of the energy behind the generation of so called ‘cold core’ cyclones that are in reality cold core only below 500 hPa , the origin of the uplift being an extensive warm core in the atmosphere manifesting strongly above 400 hPa.

In fact the bulk of short wave radiation from the sun is fully absorbed by nitrogen and oxygen above 1 hPa while only a relatively small portion remains to directly energise oxygen and ozone in the stratosphere.  The following table from here details the particular spectra absorbed at various elevations.

 

image

According to this table, it is the Herzberg continuum between 200 and 242 nm (0.200 um to 0.242 um) that impacts oxygen in the stratosphere whereas longer wave lengths up to 0.850 um impact ozone.

The question must be posed again: How much of the heating of the atmosphere by short wave radiation at between 0.200 um and 0.850 um is due to the absorption of short wave energy from the sun? How much is the result of heating by long wave energy at 9.6-11 um that is emitted by both the sun and the Earth but overwhelmingly the latter? Fortunately, observation can inform us as to the source of the warmth in the stratosphere.

 

OBSERVATION

image

 

Above we have a hovmoller diagram showing us the evolution of surface temperature from 2005 through till 2011 at 20-40° south latitude. On the right there is another hovmoller showing the evolution of temperature at 10hPa over the same time interval.  At 10 hPa the partial pressure of ozone in the air in relation to the other gases peaks. It peaks there in part because it is gathered together in the lower atmosphere in low pressure cells of its own creation and lifted to the top of the atmospheric column. Only 1% of the atmosphere lies above the 10 hPa pressure level. The maths is (10/1000)*100/1 = 1%

10 hPa represents an elevation of 30 km. For surface dwellers that’s just a five hour walk.  Fifteen minutes on the free-way. In terms of radiation from the Earth the transit from surface to 10 hPa takes no time at all.

The surface at 20-40° south latitude emits long wave radiation according to the season of the year and the distribution of land and sea. At this latitude there is a relatively invariable level of radiation from the sun all year round.

At 10 hPa the signature of surface temperature in winter and summer is plainly evident. There is a obvious warming above the very cold waters up-welling from the deep near Chile in South America where there is very little moisture in the atmospheric column to deplete outgoing infra-red radiation.  It is obvious that the temperature of the stratosphere at 10 hPa responds very strongly to variations in the emissions of long wave radiation from the Earth. In fact the differences in temperature at 10 hPa relate to the pattern of long wave radiation from the surface of the Earth.

It is plain that the temperature of the stratosphere is in large part due to the emission of infra-red radiation from the Earth, an entirely different story to that pedalled by NASA, the teachers association and Wikipedia.

 

MORE OBSERVATION

There is another way to look at this question of the source of energy that heats the stratosphere and that is in terms of the diurnal range between day (abundant short wave radiation) and night (no short wave radiation from the sun at all).

Siedel et al in a paper that you can access here investigated the diurnal range of temperature at different elevations from the surface through to 10 hPa. The diurnal range at 10 hpa was found to be about half the range of that at the surface and one fifth of the range of actual skin temperature. Plainly, the small diurnal response to the presence of sunlight points towards a large role for outgoing long wave radiation in determining the temperature of the stratosphere. Between day and night there is an ON/OFF relationship between the availability of short wave radiation from the sun. The emission of long wave radiation continues across the 24 hour interval. Siedel et al found a smaller diurnal range of temperature over the ocean than over the land and a larger range in the summer when the diurnal temperature variation at the surface is greater, than in the winter. The timing of the peak in the daily temperature becomes less defined and is more variable as altitude increases. This indicates that the circulation of ozone, as a source of local heating is more important in determining atmospheric temperature than is the 24 hour rotation of the Earth on its axis and the resulting flux in the availability of short wave solar radiation. It confirms that the warmth of the stratosphere is primarily a direct response to the ability of ozone to intercept outgoing long wave radiation rather than direct heating in the process of photolysis or energy release via recombination phenomena.

 

 

 

Why worry about this you ask? The origin of the energy to heat the stratosphere is a matter of considerable importance because ozone heating in the winter hemisphere is the origin of the variation in surface weather and climate on all time scales. If one is not cognizant of the source of heating that gives rise to the stratosphere it is hard to conceive that the winter stratosphere can play a major role in the evolution of weather and climate. If one imagines that the temperature of the stratosphere is due to incoming short wave radiation alone then the source of the so called ‘coupling of the troposphere and the stratosphere’ becomes a baffling mystery. To be charitable, the misunderstanding of atmospheric processes amongst those who write UNIPCC reports has its roots in misconceptions, a failure to observe and disinterest based upon unshakable belief patterns. Science thrives on scepticism, curiosity, observation and checking. Dogma is the companion of superstition and fear. Dogma is also the source of inappropriate responses to natural phenomena. It has led to the burning of witches.  It has led to the demonization of carbon dioxide, a trace constituent in the atmosphere that represents plant food, a substance at the base of the food chain for which demand is so voracious that it has never been anything but a trace constituent of the atmosphere or the ocean. Today it stands at 400 parts per million in the atmosphere, the advance from 300 ppm leading already to a marked greening of semi arid climates. Give a plant more CO2 and it requires less water.

29 Comments leave one →
  1. Bob Weber permalink
    March 31, 2016 10:54 pm

    There’s also evidence of daily solar radiation and particle variations affecting ozone production, and thereby polar weather. Ozone maps can be used as a rough guide to polar and high latitude weather – ie surface temperatures and pressures, aka the polar vortex.

    Thanks Erl for continuing to focus on this vital subject.

    • April 1, 2016 4:41 am

      Ozone maps can be substituted directly for maps of air temperature, geopotential height and surface atmospheric pressure between the poles and the low mid latitudes. The relationship between ozone and surface pressure was known prior to the invention of the Dobson instrument used to measure total column ozone in the 1920s.

      By the 1950s people like RM Goody writing his ‘Physics of the Stratosphere’ in chapter 5 entitled ‘Winds and Turbulence’ wrote that , from the dynamical standpoint, the stratosphere and the troposphere should be treated as a single entity’.

      One can not be much plainer in expressing the relationship than that.

      Strangely, those who write on the ‘annular modes’; that define the changes in atmospheric pressure hitherto described as for instance the ‘Arctic Oscillation’ say quite plainly that they have no idea as to mode of causation. They should read Dobson and Goody. Then they might be able to understand the posited ‘coupling of the stratosphere and the troposphere’. They are aware that change begins in the stratosphere but they have forgotten or never learned what was discovered about the relationship between ozone and surface pressure in the first half of the last century. That is what a belief in the enhanced greenhouse effect can do to your modes of thinking. What is required is a ‘brainwash’ and start all over again.

  2. yonason permalink
    March 31, 2016 11:31 pm

    Been wanting to find something like this exposition for quite a while, but didn’t know exactly what I was looking for. Very nice. Thanks!

  3. April 1, 2016 12:12 am

    Reblogged this on Climate Collections and commented:
    “The temperature of the stratosphere is in large part due to the emission of infra-red radiation from the Earth, an entirely different story to that pedalled by NASA, the teachers association and Wikipedia.”

  4. Bob Weber permalink
    April 1, 2016 1:19 am

    Many medium range weather forecasters like Joe Bastardi from WeatherBell Analytics have talked about the onset of a polar vortex lobe into the US after this weekend. The UK MET office produced a similar forecast weeks ago. How do they know how and why to do that?

    I think it’s because someone learned in the past few years that geomagnetic storms have a tendency to produce polar vortex outbreaks, and they should know from watching various spaceweather prediction sources like the USAF daily F10.7cm and & Ap 45-day forecast, that Ap, the geomagnetic planetary index, is expected to spike high on April 3rd & 4th.

    A similar occurrence happened last month, roughly 27 days prior to this next hit, after which the polar vortex ultimately descended and covered most of the US, especially in the east in the first part of February.

    I also think outgoing long-wave spikes are generally preceded by spikes in solar radiation, which I should be able to be illustrate with data & product images.

    The 1980s ozone hole scare came during a high solar activity period where the attribution for it was misplaced from the sun’s higher activity to man-made CFCs, another scientific debacle.

  5. April 1, 2016 3:11 am

    “The profile of Earth emitted outgoing long wave radiation as measured by satellites reveals a deficit at 9-10 um reflecting infra-red energy lost to ozone in heating the stratosphere. ”

    Reflecting? I think you mean ‘representing’ or ‘indicating’. Reflecting is a word that can cause confusion in this sentence.

    • April 1, 2016 3:54 am

      Frederick. Good point about the use of the word ‘reflecting’. The words ‘due to absorption of part of that energy by the atmosphere’ would be a better way of putting it..

  6. April 1, 2016 1:52 pm

    Erl is on the right track but there are some differences of detail between his work and mine which only future observations will resolve.

    This is relevant here:

    http://joannenova.com.au/2015/01/is-the-sun-driving-ozone-and-changing-the-climate/

    • April 1, 2016 2:51 pm

      Hi Stephen,
      What is your version of why the stratosphere is warm?

      • April 1, 2016 3:52 pm

        Hi Erl,

        I suggest that a less active sun creates more ozone above 45km and that additional ozone feeds down from the mesosphere via the polar vortices.

        Over decades that eventually increases ozone globally but especially towards the poles such that the polar tropopauses become lower relative to the equatorial tropopause and polar air is forced equatorward more often and for longer.

        The result is increased global cloudiness, less solar energy into the oceans and a cooling world.

        It is a multidecadal process.

  7. April 1, 2016 4:18 pm

    Stephen, you did not answer my question.

    • April 1, 2016 4:36 pm

      I though I did.

      Ozone molecules absorb incoming solar energy so more ozone means a warmer stratosphere and vice versa.

      • April 1, 2016 4:44 pm

        To my mind it doesn’t matter where the ozone gets its warmth from. If the ozone in the stratosphere increases then the temperature in the stratosphere rises and the tropopause falls whether that warmth is derived from incoming solar shortwave or from longwave coming up from the surface.

      • Chaucer permalink
        April 1, 2016 9:20 pm

        You guys with your April fools!

  8. Bob Weber permalink
    April 1, 2016 9:38 pm

    Back up for what I said about ozone and the solar cycles. From http://www.bom.gov.au/climate/glossary/ozone.shtml

    “Is ozone being depleted?

    Ground based and satellite measurements show significant decreases in total column ozone in the middle to high latitudes of both hemispheres. The downward trends were larger in the 1980s than in the 1970s, and larger in the 1990s than the 1980s.”

    The downward trends occurred as solar activity ramped up from weak SC20 through two strong cycles SC21 & 22. SC23 was no slouch either.

    • April 1, 2016 10:58 pm

      Bob, the reanalysis record shows a very strong increase in the temperature of the stratosphere above Antarctica between 1948 and 1978 and decline thereafter except for the month of October, the month when the ozone hole over Antarctica peaks. That hole was first observed via measurement with a Dobson spectrophotometer in 1956 at Halley Bay. It was noticed that it increased in extent in the early 80s but has not affected the ozone content of the air in the upper stratosphere that accordingly has stayed warm in October between 1978 and today. In all other months the temperature of the upper stratosphere at 10hPa declined steadily from 1948, some months commencing their decline earlier and others later.

      Change in the the temperature of the stratosphere in the Arctic is similar in sign and in evolution but very much smaller in degree.

      • Bob Weber permalink
        April 1, 2016 11:24 pm

        Thank you Erl. SC19 was the highest solar cycle in our lifetimes, that peaked in 1957/8, and exhibited very high activity from 1956-60.

        I’ve been looking for an ozone time series for 1979-today that I can show with solar activity, to no avail. Lots of individual years shown in plots, but no data. Do you know where such a time series can be located?

  9. Bob Weber permalink
    April 1, 2016 11:30 pm

    If long wave IR is heating the stratosphere too, then the retained heat from prior higher solar activity / insolation that is stored in the oceans, that moderates temps when TSI falls, is the other source of energy the stratosphere is responding to, in addition to direct (current) TSI.

    My analysis of earth’s solar accumulated heat indicates that until this El Nino, which is done now, peak heat in the system occurred in 2004.

    I predict stratospheric temps will now fall until the next solar cycle peak, how fast is unknown.

    • April 2, 2016 1:11 am

      Hi Bob, Observation of ozone by satellite started about 1979. So, prior to that date you have to look at Total Column Ozone from Dobson’s instruments. So, you deal with individual station data. Otherwise I would see 30hPa temperature as a good proxy. You can pull it out by latitude here:http://www.esrl.noaa.gov/psd/cgi-bin/data/timeseries/timeseries1.pl

      The mid latitudes stations such as Tromso and Melbourne should give a fair indication of the hemispheric trends in column ozone.

      • Bob Weber permalink
        April 2, 2016 1:14 am

        Thank you very much! It’s been a pleasure learning from you Erl.

    • April 2, 2016 1:13 am

      Just spotted a typo here: “In all other months the temperature of the upper stratosphere at 10hPa declined steadily from 1948,” some months commencing their decline earlier and others later.

      That date should be 1978 or 1980.

  10. April 2, 2016 1:22 am

    Bob, how do you estimate the heat in the system? According to the reanalysis data emissions of long wave at top of atmosphere have not increased since 1998. That’s a fair indication that the energy in the system has not increased since that date.

    • Bob Weber permalink
      April 2, 2016 1:55 am

      While I import and plot OLR since 1979 in order to look at ’98 and beyond, which will take me a little while here, take a look at and compare the 7 day OLR to the 90 day OLR to see how much heat has disappeared recently.

      This all occurred as http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ocean/index/heat_content_index.txt has dropped over the past 90 days plus:

      2014 12 0.50 0.48 0.54
      2015 1 0.28 0.22 0.15
      2015 2 0.54 0.65 0.83
      2015 3 0.85 1.17 1.52
      2015 4 1.05 1.42 1.74
      2015 5 1.03 1.42 1.53
      2015 6 0.87 1.27 1.51
      2015 7 0.92 1.36 1.69
      2015 8 0.99 1.43 1.97
      2015 9 1.04 1.48 1.80
      2015 10 1.04 1.51 1.91
      2015 11 0.92 1.41 1.78
      2015 12 0.58 1.04 1.20
      2016 1 0.44 0.88 1.25
      2016 2 -0.03 0.32 0.58

      To fully answer the specific question about heat requires my graphics which are not on the net now, and won’t be until my paper is ready for uploading. Until then, the rough answer is the solar input peaked at the end of the modern maximum in solar activity in 2003.

      The accumulated heat in the ocean deposited by the sun post-1979 is running out now, per my calculations, and cooling is now underway from that ocean energy deficit and from current low solar activity.

  11. Andy DC permalink
    April 2, 2016 4:03 pm

    Sometimes in winter you get a large stratospheric warming that appears to be entirely natural and related to weather patterns. Often these warmings take place before big snowstorms in the mid-Atlantic and Northeast parts of the US.

    There was a very large warming, for example, during the early part of 1958, which was a very stormy winter in those regions.

    • Bob Weber permalink
      April 2, 2016 5:47 pm

      Andy, the warmings resulted from TSI spikes that drive rapid SST warming, evaporation, and precipitation northward off the tropics in the NH . That’s the short answer. The same thing happened last Nov/Dec when smoothed TSI spiked in Nov. It’s happened many times this year too on a smaller scale as TSI has been lower recently.

      It is the basic mechanism involved with extreme weather. I have used tornado data and tied tornado outbreaks directly to ocean evaporation and the resulting precipitation, which most of the time except for solar minimums, result from TSI spikes.

      From 1956-1960, there were 36 straight months where the F10.7cm solar flux exceeded 200. That means TSI was very high, the highest we know of in the 20th century. I listen to Joe Bastardi from Weatherbell Analytics every week and have him heard talk about the monster hurricanes from that era. High TSI did it!

    • April 2, 2016 11:34 pm

      Hi Andy,
      The extent to which the polar stratosphere is cold or warm at any time of the year is a matter of surface pressure. Its always warm in summer when surface pressure is low. Its warm also in winter when surface pressure is low.

      When the summer hemisphere warms it results in a transfer of atmospheric mass to the winter hemisphere increasing surface pressure in high latitudes. That results in a down flow of very cold air from the mesosphere at a temperature of minus 80°C. In the northern hemisphere it is commonly centred between Greenland and Lake Bakal in East Asia. You can see it at 70hPa here:http://earth.nullschool.net/#current/wind/isobaric/70hPa/overlay=temp/orthographic=-1.03,91.77,410/loc=-55.146,71.938

      Then toggle back day by day through to January and you can see the change happening. Looks as if we have had the final stratospheric warming for this year and its setting up for the summer pattern. Mesospheric air makes a strong contribution to the temperature of the air at 250hPa being found on the polar side of the Arctic vortex. Its low in ozone and stays cold.On the other side we have ozone rich stratospheric air. The interface between the two is called the polar front. Its marked by Jet Streams. The Jet stream is a wavy pattern that moves equatorwards in winter and more so when surface pressure at the pole is high.

      Surface pressure at any time, summer or winter is also a function of the ozone content of the air. Ozone levels increase in winter driving down surface pressure primarily over the Oceans in the North Pacific and North Atlantic. My post here is important because it shows how ozone gathers the energy to generate polar cyclones in the absence of sunlight. When the intensity of polar cyclones increases surface pressure falls. This is a mystery if you think that the stratosphere can only be heated by short wave radiation because there is very little of that sort of energy available in winter.

      Surface pressure in the Arctic changes over time with the ozone content of the air in a pattern describes as the ARCTIC OSCILLATION.Current trend is for increasing atmospheric pressure in the Arctic.The frequency of the sort of storms that you describe will increase as surface pressure builds. Antarctic Ice will recover.

Trackbacks

  1. Why is the Stratosphere Warm? | The Drinking Water Advisor

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: