Tropopause temperature

Some of the earliest proposed descriptions of stratospheric transport were based on observations of chemical species. The first observations of stratospheric water vapor densities showed that the stratosphere was extremely dry, exhibiting mixing ratios of the order of a few parts per million by volume, in marked contrast to the troposphere, where water vapor abundance reaches a few percent. Brewer (1949) suggested that the dryness of the stratosphere was determined primarily by condensation and that the water vapor content of an air parcel rising from the troposphere to the stratosphere would therefore be determined by the lowest temperature experienced by the parcel, which would normally correspond to the tropopause. He also noted that the tropopause temperatures in the tropics were low enough to yield stratospheric water vapor densities as low as those observed, while the... 

Table 1-5. Tropopause Temperatures, Pressures, Densities, and Number Densities...

Since the temperature was assumed to be constant in deriving (l.S), a temperature at which to evaluate H must be selected. A reasonable choice is the mean temperature of the troposphere. Taking a surface temperature of 288 K (Table A.8) and a tropopause temperature of 217 K, the mean tropospheric temperature is 253 K. At 253 K, H = 7.4 km. 

Upward diffusion of water vapor through the cold temperatures of the tropopause is very inefficient in fact, the upper limit of cloud formation often occurs at the tropopause. Thus the stratosphere is so dry as to prevent rain formation, and particles and gases have very much longer residence times there than in the troposphere. Stratospheric removal requires diffusion back through the tropopause, which then may be followed by precipitation scavenging. 

The temperature inversion at the tropopause prevents mixing between the stratosphere and troposphere, with hotter air (less dense) sitting on top of cooler air (more dense). Pollutants (such as chlorofluorocarbons) present in the stratosphere have very long lifetimes (of order 30 years) and become persistent problems, especially... 

Tropopause The point of temperature inversion in the atmosphere at 10-15 km when the temperature stops falling and begins to rise. 

Courtina R. and Kimb S. J. (2002). Mapping of Titan s tropopause and surface temperatures from Voyager IRIS spectra, Planetary and Space Science 50 309-321. Davis W. L. and McKay C. P. (1996). Origins of Life a comparison of theories and applications to Mars. Origins of Life and Evolution of the Biosphere 26 61-73. 

However, at the tropopause the temperature profile changes, increasing with altitude throughout the stratosphere. The reason for this increase is a critical series of photochemical reactions involving ozone and molecular oxygen. The Chapman cycle, reactions (l)-(4), hypothesized in the 1930 s by Sir Sydney Chapman,... 

The transition zones between the various regions of the atmosphere are known as the tropopause, stratopause, and mesopause, respectively. Their locations, of course, are not fixed, but vary with latitude, season, and year. Thus Fig. 1.1 represents an average profile for mid-latitudes. Specific temperatures, pressures, densities, winds, and the concentrations of some atmospheric constituents as a function of altitude, geographic position, and time are incorporated into a NASA model, the Global. Reference Atmosphere Model (GRAM) information on obtaining this model and data is included in Appendix IV. 

In addition, there is an obseived correlation between total column ozone and the El Nino Southern Oscillation (ENSO) in the tropical troposphere, with decreases in total ozone in middle and sometimes polar latitudes following the ENSO by several months the period associated with the ENSO is 43 months (Zerefos et al., 1992). While the association between the ENSO and ozone is not well understood, it has been proposed that the warming of the troposphere in the tropics over the Pacific Ocean causes increases in the upper troposphere air temperatures and tropopause height and an upwelling in the lower stratosphere. If sufficiently large, this could have more widespread impact than just in the tropics (e.g., see Zerefos et al., 1992 and Kalicharran et al., 1993). 

Figure 19.1 Examples of noninterface boundaries. ( ) The thermocline between the epilimnion and the hypolimnion of Greifensee (Switzerland) characterized by a strong change of water temperature (line) and a corresponding distinct gradient of atrazine concentration (dots), a herbicide. From Ulrich et al., 1994. (b) The tropopause is the boundary between the troposphere and the stratosphere while the stratopause separates the stratosphere from the mesosphere, (c) The Straight of Gibraltar represents a boundary between the saline water of the Mediterranean and the less saline North Atlantic. The lines denote zones of constant salinity (standard salinity units). From Price et al., 1993.

It should be apparent that the allocation of a particular element to a particular class is a function of both the matrix material (considering condensation temperature and compound formation) and the conditions of the event. A nuclear explosion in the atmosphere gives rise to a cloud of debris which within a few minutes cools to the temperature of the tropopause a nuclear explosion conducted underground, for example to loosen up a gas-bearing formation, cools rapidly only to the melting point of the surrounding rock. 

Fig. VIII—1-4. Proposed temperature profile of Jupiter s Atmosphere. The tropo-pause is chosen as height reference since there is no evidence of a solid surface. The temperature at the tropopause is 9S.5°K and the number density is 2 x I01 cm 3. Contrary to the case of the upper atmosphere of earth, there appears to be no boundary between stratosphere and mesosphere. The observed cloud deck is believed to be solid ammonia. (M) signifies the number of molecules per cm3. From Hunten (490b), reprinted by permission of the American Meteorological Society. 

The model tropopause is defined by a PV level of 3.5 pvu poleward of 20° latitude, and by a -2 K km 1 temperature lapse rate equatorward of 20° latitude. Consequently, in this study the troposphere is defined as the volume between the surface and the simulated tropopause. Because the model does not consider typical stratospheric chemical reactions explicitly, ozone concentrations are prescribed from 1-2 levels above the model tropopause up to the top of the model domain at 10 hPa. In both hemispheres we apply monthly and zonally averaged distributions from a 2D stratospheric chemistry model [31]. In the present version of the model, we use the simulated PV and the regression analysis of the MOZAIC data (Section 2) to prescribe ozone in the NH extratropical lower stratosphere, which improves the representation of ozone distributions influenced by synoptic scale disturbances [32, 33]. Furthermore, the present model contains updated reaction rates and photodissociation data [34]. 

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