摘要:

A General Circulation Model is used to simulate the O3seasonal variations in the Southern Hemisphere at high latitudes. The model reproduces many features of the stratospheric circulation and the ozone distribution.In particular a very cold and intense polar vortex develops from mid‐winter through spring and lasts until early November. The ozone content is minimum in the polar vortex, below 300 Dobsons, in spring. This value is still significantly higher than the amounts near 200 Dobsons recently measured in several Dobson stations in Antarctica. The possible deficiencies of the model photochemistry responsible for this discrepancy are discussed.The rapid polar ozone increase which follows the final warming is fairly well reproduced by the model. The warming starts in early November and is associated with an increase of the planetary wave 1 amplitude beyond 60° of latitude. The polar vortex follows a westward trajectory which starts from the pole and crosses over the Argentine Islands before vanishing at midlatitudes, in good agreement with observatio

ISSN:0094-8276    

DOI:10.1029/GL013i012p01304

年代:1986

数据来源: WILEY

摘要:

An attempt is made to put the phenomenon of Antarctic ozone hole in a global perspective by pointing out that there is a much larger and more persistent "hole" over the tropics. The thermal structure of the Antarctic lower stratosphere in winter is more similar to the tropical lower stratosphere than the Arctic lower stratosphere in winter. The dynamical transport that is responsible for creating the two column ozone minima has similar relationship to the thermal structure in the lower stratosphere in the two regions.

ISSN:0094-8276    

DOI:10.1029/GL013i012p01308

年代:1986

数据来源: WILEY

摘要:

A trajectory analysis of air parcels for the Southern Hemisphere winter is performed with observed data. The low‐dispersive region exists around 60°S and poleward in the lower stratosphere. This low‐dispersive feature is probably related to the low ozone density over the Antarctica in wi

ISSN:0094-8276    

DOI:10.1029/GL013i012p01312

年代:1986

数据来源: WILEY

摘要:

A hypothesis is advanced that natural dynamical processes might explain much of the observed late winter ozone decreases over Antarctica. For this to be the case, sometime after 1979 there must have been a substantial reduction of the wintertime planetary‐scale disturbance activity in the Southern Hemisphere troposphere. The expected stratospheric response to such a natural process is to reduce wintertime polar ozone, prolong the life of the polar vortex, reduce the transport of ozone out of the middle stratosphere, and to increase the possibility of polar rising motion shortly after the return of the sun to high latitudes. All of these effects are in qualitative agreement with the observed ozone change

ISSN:0094-8276    

DOI:10.1029/GL013i012p01316

年代:1986

数据来源: WILEY

摘要:

Using a two‐dimensional circulation model the possible influence on the polar ozone column of modifications to lower stratospheric heating rates, both within the polar vortex and in middle latitudes, has been examined. Using reasonable heating rates it is not possible to change the model ozone to reproduce observed ozone losses in Antarctica. If an additional model heating is introduced at, or just before, the end of the southern hemisphere polar night, the time scales are such that appreciable ozone changes do not occur for at least three month

ISSN:0094-8276    

DOI:10.1029/GL013i012p01320

年代:1986

数据来源: WILEY

摘要:

We have conducted several numerical 1‐D model experiments in an attempt to simulate the behaviour of AntarcticO3throughout the year and in particular to account for the observed downward trend ofO3in October. The vertical and horizontal transports were parameterized by a vertical velocity formulation. We find that the observed low OctoberO3can be simulated by an increase in the intensity of the vertical transport in the polar night and early spring or by a delay in the transition from the winter to summer thermal regimes. In addition, the effect of atmospheric transports on the totalO3is shown to be important throughout the year. We speculate that dynamical changes in the winter vortex, possibly caused by stratospheric cooling due to the greenhouse effect, may be even more important than photochemical changes in the striking enhancement of the AntarcticO3hol

ISSN:0094-8276    

DOI:10.1029/GL013i012p01323

年代:1986

数据来源: WILEY

摘要:

Antarctic ozone depletion is estimated in a 2‐D global model as a result of increase in chlorine levels from 1 ppb to 2.7 ppb and an increase in bromine levels from 15 ppt to 30 ppt. The adopted increase is assumed to be the anthropogenic influence on the stratospheric concentrations of chlorine and bromine species in 1985. Heterogeneous formation of ClO from the reaction between ClONO2and HCl is included in the calculations, hypothesizing this is the dominant reaction path for chlorinated species on particle surfaces. A total ozone depletion as high as 14‐20% may have occurred during the month of October at 80°S when maximum depletion is obtained. Both the magnitude and the time period when the maximum depletion occurs, agree with observed depletion over the last 8 y

ISSN:0094-8276    

DOI:10.1029/GL013i012p01327

年代:1986

数据来源: WILEY

摘要:

Simple models are used to investigate the effect of a spring‐time depletion of ozone in the Antarctic on stratospheric temperatures. It is shown that coolings in excess of 5 K are possible in the lower stratosphere. No evidence for such changes exist. One possible mechanism that could offset this cooling involves the loss of water vapour from the lower stratosphere due to desiccation processes associated with polar stratospheric cloud

ISSN:0094-8276    

DOI:10.1029/GL013i012p01331

年代:1986

数据来源: WILEY

摘要:

The 1982 balloon measurements of temperature, ozone, humidity, and ground‐based measurements of turbidity at Syowa station (69°S, 39°E) in Antarctica are used to study the solar and thermal radiative effects due to gases and aerosols. Our calculations indicated that, with the observed temperature, the thermal radiative cooling due to CO2and O3emissions yielded a net radiative cooling in the lower stratosphere throughout the year if the effects of aerosols were excluded. However, the results are very sensitive to the reported ambient temperature. Contribution by aerosols to solar heating was found to be smaller than that due to O3absorption. The aerosols played a more important role in the long‐wave radiation by providing a thermal heating from March to September. During the winter months the thermal heating almost compensated for the cooling due to CO2and O3emissions resulting in a near radiative equilibrium state. This sets the stage for a net radiative warming in spring from absorption of solar energy, which may provide energy for an upwelling motion responsible for the ozone hole. Both the temperature distribution and aerosol properties should be studied in more detail in connection with the dynamical thesis for the O3hole and its interannual varia

ISSN:0094-8276    

DOI:10.1029/GL013i012p01335

年代:1986

数据来源: WILEY

摘要:

A radiative transfer model is used to compute the net heating and diabatic circulation from observed temperature and ozone data in the Southern Hemisphere during September and October of 1979, 1980, and 1984. There is an increase in net heating near the pole from September to October, which is associated with an upward cell in the diabatic circulation. This is consistent with dynamical theories of the observed intraseasonal changes in total ozone which postulate the development of an upward circulation at the pole. However, estimates of the mass circulation at the pole suggest that an additional heat source of at least 0.5 K/day is required to maintain the upward cell. Increased net heating at the pole from 1979 to 1980 and decreased net cooling at mid to subpolar latitudes from 1979 to 1984 is also found, which suggests a trend toward increased upward circulation at the poles and downward motion at mid‐latitudes consistent with the observed changes in total ozon

ISSN:0094-8276    

DOI:10.1029/GL013i012p01339

年代:1986

数据来源: WILEY