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| sneez |
Nitric oxide, natural thermostat of thermosphereI though I share some something that concerns my area of research which might be interesting for you.
abstract http://www.agu.org/pubs/crossref/2003/2003GL017693.shtml if someone is interested I can get that paper to you. |
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| billiards |
So how does the thermostat bit work? So far I see a mechanism for energy loss (or perhaps a kind of energy shield), does this mechanism get stronger as thhe earth heats up and weaker as the earth cools down? | ||
| sneez |
Absolutelly. The concept works as follows. Imagine huge solar eruption (Coronal Mass Ejection for example) sending tons of energetic particles toward earth which upon arrival heat up the thermosphere and also increasing the chemical potential of that region. Now there are several things that happen by which NO can acting as a "thermostat". The production of NO is increased (which reduces chemical potential) and internal energy of NO can increase by collisions with other constituents. NO radiates the excess of energy rather quickly. If the excess energy originated from kinetic collisions the NO effectivelly cools the thermosphere by emiiting photons to space and if the energy originated from chemical potential it lowers the amount of energy available for heat. This way the atmosphere is able to get rid of the energy in rather short time. The estimation is that 50% of the deposited energy to the upper atmosphere is lost this way. In temperature units, it is estimated to cool at ~160-200km by 2500K/day during the storm. Of cause when the storm effects die out (rather quickly 3-4 days), the energy loss from this region gets to normal given the condition of space weather (solar wind, electons, and geomagnetics) which is something around 400-500K/day . It might be interesting that CO2 at 15microns is only effective 2.3% of that of NO efficency. Heat conduction 3.8% of that of NO. These numbers are during the storm. Hence the NO emission is the primary mechanism by which the energy is lost from the thermosphere bellow 210km and it is spoken of as "thermostat effecct". |
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| billiards |
Vrey interesting stuff sneez, Nitrogen is very prominent in the atmosphere (I guess NO too?) so this should be very important. I guess we should try to look at some palaeoclimatology evidence, to see if there is good correlation. | ||
| sneez |
NO has significant concentration only up from middle mesosphere and through thermosphere. For example at 120km, NO (vmr -volume mixing ratio) is a magnitude higher than CO2 during quite conditions. When enhanced it can be 3 orders of magnitude higher than CO2. (Rough numbers)
The NO plays role even in tropospheric chemistry and stratospheric chemistry, but as infrared radiator its significant only in thermosphere. In troposphere it is involved in producing ozone which is a pollutant in troposphere. here is some line profiles put into perspetive: http://haloedata.larc.nasa.gov/browse/index.php HINT: Select year and month -> in the prameter select (well log NO vmr) later one can see whatever one is interested -> click submit -> than click on particular day of the month to see image with line profile. (There are number of line profiles up to 15-which corresponds to the number of orbits a day that instrument makes) This d ata are from Halogen Occultation Experiment which was very succesful with lots of data. O3, H2O, temp, and NO almost standard in atmos science. Be carefull not to overinterpret tropospheric data. |
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