Vertical and off-diagonal eddy diffusivities in the Northern Hemispheric stratosphere and lower mesosphere

Kao, S. K.; Kau, Wen-Shung

doi:10.1007/bf01593046

Cited by 2 publications

(2 citation statements)

References 5 publications

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“…The thermal diffusivities (K yy ) in Table 1 (∼10 9 cm 2 s −1 for atmosphere above ocean, 40 times greater for atmosphere above land) might seem surprisingly large for Earth; in fact, however, they comport with what is expected when a process that involves large-scale advective motions is modeled as being purely diffusive (Kao & Kau 1980;Keeling & Heimann 1986). 13 Alternatively, we may write a fully nondimensional version of Equation (1) by mapping t → P orb t * , T → T 0 T * , I → I 0 I * , and S → I 0 S * , with I 0 ≡ σ T 0 4 (σ is the Stefan-Boltzmann constant).…”

Section: Dimensional Analysis Of Ebmmentioning

confidence: 96%

“…We find that over land, thick ice, thin ice, and ocean, τ diff has the following respective values: ∼4 months, ∼7 months, ∼3 years, and ∼12 years. The thermal diffusivities (K yy ) in Table 1 (∼ 10 9 cm 2 s −1 for atmosphere above ocean, 40 times greater for atmosphere above land) might seem surprisingly large for Earth; in fact, however, they comport with what is expected when a process that involves large-scale advective motions is modeled as being purely diffusive (Kao & Kau 1980;Keeling & Heimann 1986). 5…”

Section: Dimensional Analysis Of Ebmmentioning

confidence: 97%

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Generalized Milankovitch Cycles and Long-Term Climatic Habitability

Spiegel

Raymond

Dressing

et al. 2010

ApJ

122

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Although Earth's orbit is never far from circular, terrestrial planets around other stars might experience substantial changes in eccentricity. Eccentricity variations could lead to climate changes, including possible "phase transitions" such as the snowball transition (or its opposite). There is evidence that Earth has gone through at least one globally frozen, "snowball" state in the last billion years, which it is thought to have exited after several million years because global ice-cover shut off the carbonate-silicate cycle, thereby allowing greenhouse gases to build up to sufficient concentration to melt the ice. Due to the positive feedback caused by the high albedo of snow and ice, susceptibility to falling into snowball states might be a generic feature of water-rich planets with the capacity to host life. This paper has two main thrusts. First, we revisit one-dimensional energy balance climate models as tools for probing possible climates of exoplanets, investigate the dimensional scaling of such models, and introduce a simple algorithm to treat the melting of the ice layer on a globally frozen planet. We show that if a terrestrial planet undergoes Milankovitch-like oscillations of eccentricity that are of great enough magnitude, it could melt out of a snowball state. Second, we examine the kinds of variations of eccentricity that a terrestrial planet might experience due to the gravitational influence of a giant companion. We show that a giant planet on a sufficiently eccentric orbit can excite extreme eccentricity oscillations in the orbit of a habitable terrestrial planet. More generally, these two results demonstrate that the long-term habitability (and astronomical observables) of a terrestrial planet can depend on the detailed architecture of the planetary system in which it resides.

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Section: Dimensional Analysis Of Ebmmentioning

confidence: 96%

Section: Dimensional Analysis Of Ebmmentioning

confidence: 97%

Generalized Milankovitch Cycles and Long-Term Climatic Habitability

Spiegel

Raymond

Dressing

et al. 2010

ApJ

122

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A two‐dimensional photochemical model of the atmosphere: 1. Chlorocarbon emissions and their effect on stratospheric ozone

Gidel¹,

Crutzen²,

Fishman³

1983

J. Geophys. Res.

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A two-dimensional photochemical model is used to examine changes to the ozone layer caused by emissions of CFC13, CF2C12, CH3CC13 and CCI,•. The influence of a possible secular increase in tropospheric methane up to 2% per year was found to be small, although it acts to mask decreases in total ozone caused by the chlorocarbons. Increasing NO,, emissions caused by industrialization also tend to mask decreases in total ozone and may have caused total ozone to increase by ~ 1%. The model calculated ozone decreases are estimated to be about 3% by 1980. This estimate is higher than estimates by similar models, although we note that CCI,• and CH3CC13 emissions are included in the model in addition to CFC13 and CF2C12. This is significant because the model indicates that CCI,• has dominated the ozone depletions so far, and knowledge of the historical emission rate of CCI,• to the atmosphere is incomplete. There remain sufficient significant disagreements between theoretical and observed concentrations and variabilities, particularly for odd nitrogen and C10, to caution against assigning too much confidence in the calculated ozone depletion. Wofsy and McElroy, 1974;Crutzen, 1974] after Molina and Rowland [1974] expressed concern that CI and CIO in the stratosphere would increase substantially when stable chlorine compounds in industrial use were transported upwar• to the stratosphere. Mainly above 30 km, these stable compounds are photodissociated to yield CI and CIO, which catalytically keep destroying ozone until they are converted to HCI by reaction with CH,•, H2, or HO2. As long as it remains in the stratosphere, most of the HCI is photochemically recycled to yield CI and CIO again. Only the transport of HC1 to the troposphere, where it is removed by rainout, can stop the active role of chlorine in the ozone chemistry and close the cycle that began with the release of a stable anthropogenic chlorine compound at the earth's surface. INTRODUCTION Interest was first focused on the catalytic role of CI and CIO in stratospheric ozone destruction [Stolarski and Cicerone In addition to the globally averaged vertical distributions of the chlorocarbons and ozone depletions that can be obtained with one-dimensional models, it is important to know thelatitudinal and seasonal variations in order to assess the biological and climato!ogical impacts of chlorocarbon releases to the atmosphere. Among those identified by the National Academy of Sciences [1979] were an increase in the penetration of biologically damaging ultraviolet radiation, leading to increased skin cancer incidence in mankind; reduced crop yields; and killing of marine algae. Among the climatic effects identified were an average warming of the earth's surface by a few tenths of a degree Celsius and changes in the stratospheric temperature patterns, which in turn may affect the chemistry of all trace gases, including ozone. While the expected depletions in total ozone are presently believed to be small compared to the seasonal variations in total ozone, such small ...

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Vertical and off-diagonal eddy diffusivities in the Northern Hemispheric stratosphere and lower mesosphere

Cited by 2 publications

References 5 publications

Generalized Milankovitch Cycles and Long-Term Climatic Habitability

Generalized Milankovitch Cycles and Long-Term Climatic Habitability

A two‐dimensional photochemical model of the atmosphere: 1. Chlorocarbon emissions and their effect on stratospheric ozone

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