Reduction of Stratospheric Ozone from High-flying Aircraft, Studied in a Two-dimensional Photochemical Model with Transport

1974 ◽  
Vol 52 (8) ◽  
pp. 1592-1598 ◽  
Author(s):  
Eigil Hesstvedt
Keyword(s):  
Reasonable Agreement ◽  
Column Density ◽  
Stratospheric Ozone ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Supersonic Aircraft ◽  
Stratospheric Ozone Layer ◽  
Two Dimensional Model ◽  
Flight Level ◽  
Ozone Column

A steady state two-dimensional model of the stratospheric ozone layer is presented. Chemical reactions involving oxygen, hydrogen, and nitrogen are considered along with the effect of a parameterized, two-dimensional transport, by mean motion and by eddies. The model is in reasonable agreement with observed ozone data. The reduction of ozone from emission of NOx from high flying aircraft is studied, assuming a fleet of 500 supersonic aircraft in transatlantic operation, flying at given altitudes. The effect is found to depend critically upon flight level. For mid-latitude, summer, the ozone column density is reduced by 0.3% for a flight level of 18 km. For flight levels of 23 and 28 km the reduction is 2 and 5%, respectively. Accordingly, the increase in u.v. radiation amounts to approximately 0.6, 4, and 10% for the same flight levels.

Modelling the global sources and sinks of radiatively active gases

1995 ◽  
Vol 351 (1696) ◽  
pp. 397-411 ◽  
Keyword(s):  
Numerical Models ◽  
Stratospheric Ozone ◽  
Trace Gases ◽  
Three Dimensional ◽  
Relative Importance ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Sources And Sinks ◽  
Two Dimensional Model

The use of numerical models in understanding the budgets of atmospheric trace gases is discussed. The budget of methane is calculated in a two-dimensional model. The contrasting behaviour of the Northern and Southern Hemisphere reflects changes in the relative importance of emissions, transport and chemistry. Models can also be used to test hypotheses. An example of such a study is presented in which it is shown that changes in stratospheric ozone could have played a significant role in the dramatic change in methane trend observed in the early 1990s. Finally, use of a three-dimensional model to study tropospheric trace gases is introduced.

Commitment to pro- versus counter-attitudinal behavior and the dynamics of social representations

2002 ◽  
Vol 61 (1) ◽  
pp. 34-44 ◽  
Author(s):  
Eric Tafani ◽  
Lionel Souchet
Keyword(s):  
Higher Education ◽  
Social Representations ◽  
Cognitive Restructuring ◽  
Social Representation ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Social Actions ◽  
The Social ◽  
Two Dimensional Model ◽  
Students Attitudes

This research uses the counter-attitudinal essay paradigm ( Janis & King, 1954 ) to test the effects of social actions on social representations. Thus, students wrote either a pro- or a counter-attitudinal essay on Higher Education. Three forms of counter-attitudinal essays were manipulated countering respectively a) students’ attitudes towards higher education; b) peripheral beliefs or c) central beliefs associated with this representation object. After writing the essay, students expressed their attitudes towards higher education and evaluated different beliefs associated with it. The structural status of these beliefs was also assessed by a “calling into question” test ( Flament, 1994a ). Results show that behavior challenging either an attitude or peripheral beliefs induces a rationalization process, giving rise to minor modifications of the representational field. These modifications are only on the social evaluative dimension of the social representation. On the other hand, when the behavior challenges central beliefs, the same rationalization process induces a cognitive restructuring of the representational field, i.e., a structural change in the representation. These results and their implications for the experimental study of representational dynamics are discussed with regard to the two-dimensional model of social representations ( Moliner, 1994 ) and rationalization theory ( Beauvois & Joule, 1996 ).

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