Visualization process
Covered in the ‘big file’:
Algorithm, IDL, algorithm is basically a 2D histogram-binning process. Figure? …
time period covered here
(repeated for each of the variables, Temp, H2O, CH4, O3)
Okay, I’ve reshaped the water plots into ‘orange slices’ or sector plots.
The pictures & observations.
Water vapor & other variables
General / after solstice+1(2) – Jan/Jul, (Feb)
The temperature also may affect the equilibrium points and rates of the various chemical
reactions that occur in each part of the atmosphere. (
The HALOE contour plots can be thought of representing ‘equilibrium point’ positions or
reaction point values of the gases in each individual bin (pixel) of the plot because chemical
reaction rates are directly related to the multiplicative product of the reactant concentrations
divided by the product concentrations.
A portion of middle atmosphere water flows directly into the stratosphere from the troposphere.
Does this mean not through the tropopause? Maybe just the upwelling or lateral horizontal flow
into the summer polar region where the tropopause is lower?
About 3 ppmv, on average I presume. Actually, 3 ppmv is a concentration, not a rate. HALOE
contour plots appear to agree, showing a contour at that level across latitudes.
Flow suggests circulation.
I had though the story different at the poles—it seemed a lot of tropospheric water would up
from the summer pole through the stratosphere and up into the mesosphere. But, it appears that
the situation is better than yearly injections—there is mixing year-round between the
troposphere and the lower stratosphere (the tropopause is lower at higher latitudes than near the
equator). The summer upwelling appears to draw on air in the stratosphere, and expand it.
HALOE coverage is closer to the summer pole and doesn’t cover the winter pole.
Seen in the plots:
HALOE shows water distributed in the summer polar regions, about 60-75° latitude, as a thick
layer about 5.8 ppmv or more upwards from about 40 km to HALOE’s limit of observation at
about 87 km. Looking at the February plot, the water appears in two distinct layers with about
5.8 ppmv in the lower altitude range about 40-55 (or 60) km and up to about 6.5 ppmv in the
upper altitudes of about 70-85 km. Between these layers the mixing ratio is somewhat less,
varying about 5.1 to 5.8 ppmv. The layers extend towards the tropics and get closer to each
other: the upper layer is lower in altitude over the tropics, with a spotty approximately 6 ppmv
reaching as high as 75 km, and the lower layer is higher over the tropics. The lower layer seems
to have a gap over latitudes 30-15°S which corresponds to a region of higher methane and is near
the heat equator.
In contrast, the higher winter latitudes hold less water vapor overall (about 5.2 ppmv) distributed
in what is more like a taller less dense layer roughly at the altitude range of the summer pole’s
bottom layer and a little more dense at the bottom.
Why? The way I figure it …
Sunlight passing through the atmosphere is partly absorbed and filtered by the gases in the
atmosphere, so sunlight that enters at an angle is filtered (and weakened) more by the time it
reaches a particular altitude than sunlight that enters and travels straight down (radially) towards
the earth’s surface. Consequently, the sun’s rays penetrate the atmosphere more strongly in the
tropics than at polar latitudes and so they cause more photolysis a particular altitude in the
tropics than the weakened rays do at the same altitude over the poles. Effectively, this works to
make the top of the upper layer of water vapor lower in the tropics than at the poles: the approx
5 ppmv level (cyan color) is about 75 km in the tropics (year-round), whereas the corresponding
level is about 10 km or so higher over higher latitudes of polar summer.
If needed:
“The intense solar flux at 121.6 nm (The Lyman-alpha line) which penetrates deeply into the
upper mesosphere causes rapid solar photodissociation of water vapor above about 75 km.”
[Thomas, 1991p556b] This breaks water, into H2 gas, atomic oxygen and hydroxyl (OH), which
is an important oxidizing agent key to ozone destruction.
Of course, the lower layer is higher over the tropics because of the persistent tropical upwelling
(Hadley cell and Brewer-Dobson circulation) and because the concentrations of water vapor are
increased more at higher altitudes due to the contributions of methane oxidation. (The contour
plots of methane fit the water vapor plots like a jigsaw puzzle.) In fact, the separation layer
apparently corresponds to a layer of slightly higher methane levels and the upper water layer is
where methane is virtually completely depleted.
The lower layer also seems to conform to the stratopause, laying above the warmest part the
stratopause over most of the globe and persisting over most of the year. The lower layer is
more coincident over the pole in summer where and when the stratopause is warmest. The
separation layer appears to follow the contours of the temperature plots too, where the
temperature decreases with altitude in the mesosphere.
Farther down in the water contour plots, there appears a blue layer that is higher at the equator,
about 20 km than at mid and higher latitudes on both sides. This seems to correspond to the 3
ppmv water vapor of the tropopause. Below that is a void which is probably due to persistent
equatorial trains of clouds which block sunlight, and there are lighter areas where the air is more
often drier (and more transparent) and descends in Hadley cell circulation. (See the clouds
animation for the ever-present equatorial clouds.)
Time development 1
The atmosphere responds to changes in season and sunlight, e.g. equinox or solstice, but the
effects appear in the plots for the month following the change. Since the earth’s orbit is nearly
circular, the annual cycle is generally (but imperfectly) reflected in the opposite hemisphere with
a six month difference.
(upper layer: previous version)
The upper layer water appears to flow away from the summer pole and equatorward, but it does
not proceed all the way to the other pole. The mesospheric circulation cell may not flow fast
enough and long enough to carry the air (and water and dust) as far as the other pole.
(upper layer: newer version)
It appears that the upwelling at summer pole supplies the high concentration of water vapor in
the upper layer. The region of high concentration appears to move equatorward with the sun
through equinox and leave its origin (polar region) somewhat depleted as the upwelling supply
rate declines, but the region does not continue onward to reach the other pole. With the
equinoctial exchange in the hemispheres’ roles, mesospheric circulation reverses and
downwelling begins as the pole moves towards winter. The upper layer altitude appears most
depleted after winter through the month following the spring equinox—the light blue and green
in the plots have virtually disappeared there. As this pole moves towards summer again, the
upwelling resupplies high moisture levels to the upper layer.
Probably delete all this:
At first glance, the upper layer’s dense region appears to ‘follow the sun’ from one pole to the
other (like a ‘sloshing’ back and forth), but it is more of an increase over the summer pole and a
flow equatorward, an increase over the other pole in its summer and a flow equatorward. The
upper layer water appears not proceed all the way to the other pole. It appears that the
mesospheric circulation cell may not flow fast enough and long enough to carry the denser vapor
region (and everything else in the air there, like dust) as far as the other pole.
Thomas, indicates “a mean equatorward wind of the order of 10 m/s in summer and a similar
poleward flow in winter.” [Thomas, 1991 p. 561a] If the flow is 10 m/s in polar latitudes, may
be slower at lower latitudes because the flow is spread out over a larger volume. Otherwise,
(if it is at 10 m/s averaged over the globe) at that rate water vapor in the air should reach the
equator in about two weeks, unless diverted or destroyed. The 10 m/s over the globe then
implies a high rate of destruction as well as a high rate of supply. (somewhere I read that it takes
more than six months for air to pass the equatorial tropopause up to about 30 km.)
10 m/s * 60 s/min * 60 min/hr * 24 hr/d * 14 d = ~ 12096 km
Radius of earth~6400 km 6400 km * 3.14/2 = ~ 20,000 km
(864 km/d)
Thomas says that north-south winds can carry ice particles from a colder region over 1000km
during a particle lifetime. “The lifetime of an ice particle exponentially decreases to just a few
seconds as it approaches 150 K air. In the same way, vertically descending ice particles will
penetrate some small distance into warmer, unsaturated air before they are reduced to subvisible
sizes. It should be emphasized that variations in water vapor concentrations must als be a very
important driver for the occurrence of NLC. ... low temperature is a necessary but not sufficient
condition for NLC presence.” [560a-b]
Could the upper and lower layers be the results of gravity waves? Tropopause at 20, lower layer
about 40, upper layer about 60, …
Continued…
(lower layer)
The lower water layer over the poles appears to remain throughout the year, with mixing ratio
increased during the sunny season. There are high-vapor regions in the lower layer about 50-55
km (in Feb) that, taken in sequence, appear to move southward contrary to the sun Jan-Jul, and
these correspond to lower methane too. (This seems to be a sun effect where the region lies
between two ‘horns’ in Apr (right after equinox), roughly at 15-30° N and S, and the summer
horn grow larger, probably due to Brewer-Dobson circulation, bringing in more methane in drier
air making the anomalous /contrary region appear to move away.)
Summer solstice
In the month following each solstice, July in the north hemisphere and January in the south, the
summer polar mesosphere develops a very high level of water vapor on the order of 10 ppmv or
more about 81-83 km high. This shows on the plots at latitudes of about 65-70°N in July and
about 75°S in January. Interestingly, this ‘wet spot’ appears more intense farther from the north
pole in July when the earth is farthest from the sun (about July 4
[http://en.wikipedia.org/wiki/Earth] ) than it does from the south pole at perihelion (about Jan 3).
A couple of factors that may contribute to this small asymmetry may be: the energy input at
different orbital distances from the sun and the greater proportion of landmass in the northern
hemisphere which has a different heat capacity than the vast southern seas. [somewhere in
privileged planet, but I don’t know where?] (Here’s another observation: the distribution of
surface texture (that generates disturbance waves that couple the surface to the mesosphere) is
closer to the pole in the south than in the north.)
PMCs, insolation
The summer increase in water vapor and this ‘wet spot’ coincide with the development and
approximate location of polar mesospheric clouds of ice (50 miles or about 80.5 km high
[http://www.nasa.gov/mission_pages/aim/multimedia/first_view.html ]). The spot is at
HALOE’s latitude coverage boundary, and averaging in the plot may have made it appear to be
separate from the boundary. Whether the high vapor region extends farther towards the pole is
not shown by the plots; however, the correspondence with PMCs suggests that high vapor may
accompany PMCs that form farther over the pole and flow equatorward by mesospheric
circulation.
PMC season starts about 5 wks before solstice (when the sun’s declination is ~19.2° and extends
until about 7 wks after (when the sun’s declination is ~15.4°). Total insolation at the north pole
becomes a global maximum about when the sun’s declination reaches and exceeds 21° (using a
spherical model for the earth). For June 11, the date of the PMC picture below, the sun’s
declination was about 23°.
Figure 1: Arctic polar mesospheric clouds for June 11, 2007
The northernmost latitude of coverage appears to be about 85°N.
[http://www.nasa.gov/mission_pages/aim/multimedia/first_view.html]
In 1991, before PMCs were confirmed to be mostly water ice by Hervig in 2001, Thomas
questioned whether there was sufficient water to sustain ice existence, but measurements of
mesospheric water vapor at high latitudes were not yet available. Thomas thought 10 ppmv was
an 'unlikely high value', but did analysis with 10ppmv and found the frost points for 10 ppmv
and 2 ppmv to be over 140 K at the mesopause. [Thomas, 1991, p. 557b] He noted that “A
temperature of 150 K corresponds to a saturation water vapor mixing ratio of 7 to 15 ppmv,
depending upon the mesopause pressure.” [Thomas, 1991, p. 560a] and observed “PMC are seen
to occur only within the very cold region centered at 85 km during summer and located within
the 150 K contour [of his figure 2 rocket grenade measurements]” [Thomas, 1991, p. 559b]
Since then, HALOE shows averaged water vapor in excess of 10 ppmv at 65-70°N in July. The
temperature above the high water vapor spot at 85-95km is lower than 140K, maybe 135K.
Where the water vapor spot is at about 83 km the HALOE temperature measurement appears to
be around 150K. (Found by copy/pasting a patch of the contour color and sliding it over to the
temperature scale for a match.)
insolation
The ‘wet spot’ latitude for the northern hemisphere is also coincident with a local minimum in
daily total insolation, which occurs at the northernmost zone of the polar area’s day/night
terminator. The detected ‘wet spot’ lies low in a temperature depression about 80-95 km high.
(HALOE measured temperature at altitudes higher than it measured water vapor.)
Figure 2: relative zonal insolation overlay with HALOE July water vapor
showing near coincidence of minimum insolation and maximum water
Figure 3: Color enhanced to show PMC-region temperature,
high [H2O]location indicated by red square at 83 km, 65-60°N
It seems reasonable that where temperatures and moisture (supplied by polar upwelling) are
sufficient to support PMCs, a high vapor region would be nearby—high enough to help form the
PMCs or maintained high from PMC sublimation as they fade away. So, the presence of PMCs
closer to the pole suggests that the water layers extend closer to the pole too.
The arrangement of the pieces in the mesosphere, the polar upwelling, lateral deflection, flow of
moisture and the cold ‘ceiling’ (also a cold trap with an overlaying increasing thermal gradient in
the thermosphere) resembles the pieces in the troposphere’s tropical upwelling of the Hadley
cell at the tropopause, but the driving forces differ:

At the poles, the action of waves breaking in the mesosphere couple it to the surface
causing the zonal winds to be near-zero at the 90 km mesospause. This imposes
conditions that deflect the upwelling air laterally [Houghton, p. 157]. The resultant
equatorward flow combines with radiative forcing to induce ‘vigorous upward motion’
[Thomas 1991, p. 561a] which suctions up the polar air faster than buoyancy alone could
raise it. The forced expansion refrigerates the air in the mesopause to below 140 K as
seen in the HALOE temperature plots, making it colder over the sunny summer pole than
anywhere else.
Von Zahn and Meyer used falling sphere measurements to determine the temperature profile of
the mesosphere (e.g. between 95 km and 80 km about 69N in summer) . The frost (temperature)
point for 2 ppmv H2O is roughly 145K at 85 km and the temperature profile averaged from 30
falling sphere measurements is below the frost point between about 83 to 91 km with a
minimum of 130K about 88 km. Von Zahn and Meyer “concluded that ice clouds can exist in
polar regions even for average conditions and not just in the cold troughs of atmospheric waves.”
[Thomas, 1991, p 560 b]

In the tropics, buoyancy is lost due to the cold tropopause driving moisture out of the air.
Also, the temperature gradient of the stratosphere hinders or blocks the upwelling and
turns the airflow. (The stratosphere is heated by sunlight absorption, like by ozone.)
I guess buoyancy in the tropics doesn’t mean gravity waves have no effect there. The
vertical couplings article figure says “Middle atmospheric circulation is driven by solar
heating and by momentum drag resulting from gravity and planetary waves. These waves
couple tropospheric climate to the middle atmospheric circulation that in turn controls the
transport of radiatively and chemically active trace gases and exerts mechanical forcing
on the troposphere below.”
Whether the refrigerated zone and the water vapor layers seen in the August sector plots are
more like a halo or a cap is not shown in the plots. The PMC presence at 85°N in the NASA
picture suggests that the features may extend over the pole like a cap.
“SME satellite measurements indicate that PMC are ubiquitous within the heart of the season
although always spatially patchy. PMC approach 100% probability of occurrence near the
pole.” [Thomas, 1991, p. 558b]
“At lower latitude, PMC occurrence frequency falls below the level of detectability at about
60°N [Olivero and Thomas, 1986].” [Thomas, 1991, p. 559a]
The insolation distribution suggests a varying halo-like influence, but that might apply better to
the stratosphere where energy can be absorbed more, warming parts of the atmosphere more
poleward.
The water vapor distribution—any gas distribution will also depend on how strongly photolysis
or other processes may affect it. Chemistry, auroras, electrical effects, …
With the refrigeration caused by gravity waves generated from tropospheric disturbances, the
shape of the features would be influenced by the distribution of disturbance sources and how the
gravity waves propagate and spread. (It seems the disturbances would be stronger away from the
pole and small at the pole near the rotation axis.) “Wave activity almost certainly varies with
latitude.” [Thomas, 1991 p 559b in context of PMCs over summer mesopause]
This section probably should be removed—Houghton’s plot here may be model data, and I don’t
know what the dotting of contours means. Also, I don’t have Houghton’s permission to use the
figure.
If the zero-speed zonal winds are an indicator of the altitude where the cold region is and where
airflow is turned, then the idea that the features may be raised higher in altitude closer to the pole
is supported by Houghton p.62 [his fig 5.1] that shows a zero-speed contour rising past 70-75°N
towards the pole.
This is a scanned copy
Figure 4 Mean January and July zonal winds [m/s units]
[Houghton, p. 62, Fig 5.1(c): COSPAR, 1972]
(Compare with plots at http://www-paoc.mit.edu/labweb/atmos-obs/zonalwind.htm and
http://www-paoc.mit.edu/labweb/atmos-obs/relativehumidity.htm also)
Permission granted is on the website where this sketch is:
http://www.ccpo.odu.edu/SEES/#credit
Cite as:
NASA. Studying Earth's Environment From Space. June 2000. (the date you accessed these
materials) http://www.ccpo.odu.edu/SEES/index.html.
the contours of this sketch also suggest higher:
Figure 5Circulation in th e Middle Atmosphere
http://www.ccpo.odu.edu/SEES/ozone/class/Chap_2/index.htm
[NASA. Studying Earth's Environment From Space. June 2000. (accessed Sep 2008)
http://www.ccpo.odu.edu/SEES/index.html.]
Time development 2 more stuff:
At first glance, the upper layer’s dense region appears to ‘follow the sun’ from one pole to the
other (like a ‘sloshing’ back and forth), but it is more of a growth over a pole and then a move
equatorward, a growth at the other pole and a move equatorward.
Further, the displacement of this characteristic higher water vapor concentration region should be
considered somewhat like a wave: the waveform propagates long distances, but the molecules
move only short distances. Here, the airflow can move the water vapor, but source and sink
processes that depending on location, like photolysis depends on sunlight angle, can combine to
give a mixing-ratio contour that has gradients different from those of either airflow or sink
processes alone.
While the plot does not show the water vapor concentrations over the high polar latitudes, the
fact that this ‘wet-spot’ appears at the altitude, location, and time of year that PMCs do and the
fact that PMC detections from other satellites extend over the summer poles (at least one)
support high water vapor concentrations in the high polar latitudes at the summer pole .
Transition summer-equinox
The earth continues in its orbit from solstice towards equinox, and the sun’s effects on the
atmosphere in the summer hemisphere’s polar region decline. During the months after solstice,
the upper layer into equatorial latitudes and ‘follows the sun’.
Equinox-Spring
Dawn breaks in March in the Arctic(September in the Antarctic) and so starts the warming of the
north(south) polar regions. Where air had been descending during the polar winter, the
downwelling has slowed and the mesospheric circulation cell begins its reversal. Wave-induced
upwelling increases in the sunlit atmosphere over the region and the upward flux of water vapor
increases too, from the tropopause into the stratosphere and from the stratosphere into
mesosphere. Water vapor accumulates in the polar stratosphere, making the layer there denser.
An upper layer of water vapor begins to grow in the mesosphere over the northern(southern)
polar latitudes, beginning to appear the second month after dawn, in May(Nov), and raising the
approximately 5 ppmv ceiling from about 60 km to about 80 km in a single month.
A month past equinox the double layering over the tropics is somewhat more distinct with water
levels being a little higher in concentration, as high as about 6.5 ppmv (by imprecise color
swatch comparison with the scale). The tropics seems to have a relatively persistent ‘ceiling’ for
5+ ppmv levels about 75 km except when in July and January the ceiling briefly rises by about 5
km. At the same time, the mixing ratio decreases in the tropical bands, moreso in Jan-Feb than
in Jul-Aug
As the heat equator moves farther into the springtime hemisphere and the sun warms the
atmosphere even more, water vapor concentrations in the polar mesosphere increase and reach
their maximum values in the month after solstice in Jul(Jan).
Equinox-Fall
In Oct(Apr), the month following the polar equinoctial sunset, the high concentration water
vapor layer appears to have separated from the polar region to form a distinct band over the
equatorial/tropical regions. Also, the 5 ppmv cyan contour ‘top’ over the poles has begun to
descend: the concentrations of water in the mesosphere are no longer maintained by an
upwelling supply and the downwelling part of the annual cycle starts.
As the mesospheric circulation cell reverses, the upwelling starts in the opposite pole.
The extra concentration of water in the now-winter polar region upper layer has virtually
disappeared six months after it started to appear Nov(May). The band of upper layer water
remains distinct over the tropics until it merges with the newly growing polar water in Dec(Jun).
Methane
(magenta text was here first, black paragraphs added—some probably covered introduction
chapter.)
It is an established belief that water and methane rise from the troposphere by Hadley cell
circulation, but that most of the water precipitates back down at the tropopause 'cold trap',
leaving only about 3 ppmv to reach the stratosphere.
In the stratosphere, the approximately 1.6 ppmv of methane adds to the water budget as it is
photodissociated and chemically oxidized into 2 molecules of water for each molecule of
methane. The concentration of water increases upward to about 6-7 ppmv around 50-60 km,
“somewhat above the stratopause, marking the height at which methane has been largely
destroyed [Bevilacqua et all 1990]”
The approximately 1.6 ppmv methane is photodissociated and oxidized into 2 molecules of water
for each of molecule of methane. [Thomas 1991 p. 568a ] Together they account for 6.2 ppmv
of water vapor where the methane has been completely oxidized.
Water peaks “somewhat above the stratopause, marking the height at which methane has been
largely destroyed [Bevilacqua et all 1990]” and the water vapor mixing ratio falls steeply with
height over 60 km. “According to the model of LeTexier et al [1988], the total hydrogen content
of the air is in the form of H2O and the other half is in the form of H2.” [Thomas 1991, p. 568a]
Well, the plots show water up to 75-80 km over the tropics and higher at the summer pole, but I
mentioned that already… the lower layer
Methane lifetime in the troposphere is about 12 years and it takes another 2-3 years to reach the
mesopause (as water, the methane having been oxidized and the hydrogen continuing on in
water). “[Thomas, 1991] argued that unless the partitioning of total hydrogen changes, the
increase in water vapor at the mesopause can then be directly related to the change in CH4. Thus
without an atmospheric model it is possible to directly relate changes in methane with changes in
the supply of mesopheric water vapor. A direct link connecting tropospheric methane with NLC
is established simply through the principle of conservation of total hydrogen in a column.”
[Thomas, 1991, p 568a]
Thomas also indicates the the Krakatoa eruption of 1883 rapidly increased water vapor in the
mesosphere from 4.3 ppmv to 6 ppmv in approximately 2 to 3 years.
Observed in the plots:
Tropical methane appears to be more abundant and longer lasting during northern summers
(June-Sep) than southern summers (Dec-Jan), with lowest concentrations at higher altitudes in
Nov and Feb. Perhaps this is an effect of the asymmetry in land distribution and the methane
contribution of the attendant vegetation and land creatures upon it or nearby in the seas.
It is difficult to see a difference between hemispheres in mid latitude methane, possibly because
the methane is so well mixed by tropospheric turbulence. The mid latitudes do seem to have less
methane when the tropical methane is also less.
The methane distribution over the northern summer polar regions appears to be somewhat
uplifted in the upper part (above 50 km), producing a gap or bubble or balloon region about 4565 km where methane is reduced. This region corresponds to larger concentrations on the water
vapor plots, and the higher denser methane corresponds to lower water concentrations and even
the separation between water layering near the poles. This gap shows in southern summer
plots too, and the methane-water correspondence holds for the separation of the water layers at
other latitudes. Further, the gap corresponds to a region of fast eastern (labeled by ‘E’ and -35
not eastward, right?) zonal winds [See Houghton p 62, fig 5.1c]
The uplifted methane seems to be following Brewer-Dobson circulation upwards and polewards
from lower latitudes above 45 km or so. Where methane supply is slower in the gap region
equilibrium goes farther towards water.
(Upward motion in the stratosphere is supposed to take a long time, but the thermal gradient in
the mesosphere resembles the thermal gradient in the troposphere, so buoyancy favors warmer
less dense air.)
There is a marked difference in the south between Oct and Nov about 60-75°S where methane
increases in the southern springtime. The same seasonal response is hinted at in the northern
plots for Mar and Apr a little sooner after equinox, but it is shown near the edge of HALOE’s
coverage limit. It seems likely that these are due to the summer polar upwelling and not to a
seasonal increase in sunlight or photolysis (otherwise, why would there be more methane at
higher altitudes?). Subsequent months show the gap shrinking, which corresponds nicely with
the reversal of the mesospheric circulation cell.
Ozone
This continues on the subject of ozone, the ‘cold trap’
The ozone layer lies in the atmosphere from about 20 km to over 50 km sandwiched in the
stratosphere between the maximally warmed stratopause above and the cool tropopause which it
overshadows/shields below.
follows the sun with it over the course of the year. (Compare the ozone and green-red
temperature plots.)
Ozone has a simple response: peak ozone levels in the ozone layer around 40 km follow the sun.
There seems to be traces of ozone much higher about 90-95? km . The second layer appears
relatively continuous around equinox, but diminishes most and has gaps the month after solstice.
The ozone that is present around solstice is slightly greater at the poles than in the tropics.
Perhaps mesospheric circulation, which is slowed around equinox and most active around
solstices,
about half of the entire atmosphere lies below 30 km. This corresponds to a thickness of about
eight sheets of paper on a standard 12” diameter globe (at about 4 km per sheet).
Water vapor is central to ozone chemistry, using up atomic oxygen which otherwise would help
produce ozone and forming hydroxyl radicals which promotes ozone destruction by reacting with
its products
. Photolysis breaks down diatomic oxygen producing atomic oxygen and that is important in
ozone production, especially at the region where the ozone layer is.
Water vapor reacts with atomic oxygen to provide two hydroxyl radicals and so prevents that
atomic oxygen from combining with diatomic oxygen to reform ozone. Hydroxyl reacts with
products of reactions that consume ozone (e.g. NO2, HO2, Cl) thus favoring those reactions.
[Wayne p136,137]
This is methane and time development of methane
Plot distortions
The plots were originally made as rectangular altitude-latitude plots and were distorted later to
make curved sector plots to provide a more intuitive representation though the thickness is
exaggerated. Both versions are distorted. Because the sector plot has exaggerated height, the
parallel lines are not properly representative of rays of the sun: rays entering at 30°N should end
on the earth’s surface, not pass over the pole as shown. Inverse distortion of the sector plot back
to the rectangular plot shows how parallel rays of sunshine are now represented by curves.
Using a truer scale drawing also shows much less severe distortion which should apply to the
original rectangular plots.
The plots are monthly averages over 14 years of data and so cannot reveal processes that might
occur and vary on a day-to-day basis—only more general longer-term seasonal processes.
Figure 6: Distortion or C-plot and rectangular contour plot.
Both have exaggerated thickness and are . The innermost layer would be more representative of the
atmospheric scale.
Figure 7 A more realistic representation
Miscellany & Questions?
The water separation layer corresponds to higher methane levels. Why would there be slightly
higher methane levels above lower methane levels? Circulation seems to be the simplest
explanation.
The plots are generalizations through month-long averages over 14 years of data. (Look back to
the weekly water plots the separation is there, but I don’t have methane plots to go with them.)
(SR and SS for any particular latitude are from different years and so are not correlated.)
Could it be as simple as the air buoying up in the mesosphere like air buoys up in the
troposphere? In both layers the temperature decreases with height.
Methane must either accumulate or circulate in or there is a methane source. I don’t know of a
source. Can it relate to recombination on meteoric dust? The separation layer is within the range
of the meteoric dust layer between 65-75 km. Would recombination of water on dust increase
water vapor thereby nudging equilibrium of the methane oxidation reaction to slow it? Methane
oxidation is exothermic, right? The reverse reaction seems improbable.
The meteor dust recombination was trying to account for extra water—the methane
correspondence accounts for most of it, but the mixing ratio for recombination would be much
smaller and probably not easily seen on the contour plots—the profile plots would be more
appropriate.
It looks like we have water, or we have methane, or a combination that pretty much conserves
hydrogen.
Anything on the vortex, biennial osc, or Rossby waves? I guess not.