摘要:

Ozone measurements from 1970 to 1984 from the Nimbus 4 backscattered ultraviolet (BUV) and the Nimbus 7 solar backscattered ultraviolet (SBUV) spectrometers show significant decrease in total ozone only after 1979. The downward trend is most apparent in October south of 70°S in the longitude zone 0° to 30°W where planetary wave activity is weak. Outside this longitude region, the trend in total Ozone is much smaller due to strong interannual variability of wave activity. This paper gives a phenomenological description of ozone depletion in the Antarctic region based on vertical advection and transient planetary wav

ISSN:0094-8276    

DOI:10.1029/GL013i012p01224

年代:1986

数据来源: WILEY

摘要:

Seven years (1979‐1985) of NMC data are used to analyze Southern Hemisphere middle stratosphere winter‐to‐summer circulation transitions. These transitions are classified into two extreme categories: 1) a mid‐October final warming accompanied by a major mid‐October wave event (1979 and 1982), and 2) a mid‐November final warming with no strong October wave event (1980 and 1981). After the final warming a wave event in late November‐early December results in the disappearance of the polar vortex. All of these wave events in conjunction with zonal mean mass motions act to reduce zonal mean gradients of potential vorticity and ozone through horizontal mixing, and hence they act to destroy the vortex and fill the ozone hole. Additionally, it is noted that the final warming and the vortex breakdown are two distinct events separated by 15‐40 days. Finally, past studies show that the time of these events has not ra

ISSN:0094-8276    

DOI:10.1029/GL013i012p01228

年代:1986

数据来源: WILEY

摘要:

The final warming in the Southern Hemisphere stratosphere during the period 1 September ‐ 30 November for the years 1978‐1983 is studied. The change in zonally averaged temperatures during that period is almost the same for each year. However, there is substantial interannual variability in the time evolution of the warming as events of enhanced wave, mean‐flow interaction associated with bursts of upward propagating planetary waves develop at different times in different years. Polar temperatures in the middle stratosphere can increase as much as about 20 K in 4 days during these events. Such dynamical processes can play a significant role in the interannual variability of stratospheric ozone and other constit

ISSN:0094-8276    

DOI:10.1029/GL013i012p01232

年代:1986

数据来源: WILEY

摘要:

Since 1979, from late September to the end of November, the total ozone over the southern polar region has declined by up to 30%, compared with the ozone average for 1957‐78. During the rest of the year there are no indications of a major decline. Neither are there significant changes in the middle latitudes surrounding Antarctica except those related to the QBO. More than 85% of the entire ozone deficiency is observed between 10 and 24 km. The rapid ozone and temperature increase in spring usually occurs in mid October and shows a 2 month lag, compared to the Arctic. The increase is related to the time of the breakdown of the winter stratospheric polar vortex. During the last six years the breakdown has occurred around mid‐November, extending the period with circumpolar circulation by 3‐4 weeks. It is suggested that weak upward motions within the vortex, in the order of 0.1 cm sec−1during September and October, could cause part of the ozone

ISSN:0094-8276    

DOI:10.1029/GL013i012p01236

年代:1986

数据来源: WILEY

摘要:

Nearly 5500 mean‐monthly low‐stratospheric temperatures at 100, 50 and 30 mb at 16 Antarctic stations have been extracted from "Monthly Climatic Data for the World" for the interval 1958‐1985. About 450 mean‐monthly total‐ozone values at 4 Antarctic stations have been extracted from "Ozone Data for the World" for the same interval. There has been an impressive in‐phase relation between seasonal variations in low‐stratospheric temperature and total ozone in Antarctica. This relation extends not only to the large total‐ozone and low‐stratospheric temperature decreases since 1978 in the Southern Hemisphere spring (approximately 30% and 6‐8°C, respectively, based on smoothed data), but also to relatively minor fluctuations in this and other seasons. The springtime stratospheric temperature decreases since 1978 are indicated to have been greatest along the Antarctic coast between about 30°W and 60°E, including the stations of Halley Bay and Syowa; there has been practically no low‐stratospheric temperature decrease at stations 10 degrees of latitude further north on the Antarctic Peninsula. The springtime temperature decrease has been pretty much confined to the Antarctic stratosphere, or to l

ISSN:0094-8276    

DOI:10.1029/GL013i012p01240

年代:1986

数据来源: WILEY

摘要:

The magnitude and structure of the global total ozone minimum between 1958 and 1962 is similar to that observed between 1979 and 1983. Analysis of the single station data that exhibit the most pronounced minima suggest that the spatial structure of the global minimum is different from the currently observed reduction. Very low north polar values were observed, but there is no indication of anomalously low ozone in Antarctica. The temporal relationship to the sun spot cycle is similar in both time periods. Rather than solar terrestrial interaction, however, a more likely explanation of the early 1960's reduction is normal climatology caused by a persistent period of planetary wave activity. Such a natural explanation may also be appropriate for the current depletion.

ISSN:0094-8276    

DOI:10.1029/GL013i012p01244

年代:1986

数据来源: WILEY

摘要:

Mean monthly total ozone data obtained at South Pole, Antarctica, during 1964‐1985 are presented. Preliminary analysis of the data suggests that total ozone has decreased at South Pole by roughly 20% since the mid‐1960's. Largest decreases have occurred during October and November months, but autumn and winter months also exhibit a decrease. During February months, ozone has increased slightly. Superimposed on the long‐term downward ozone trend are episodic decreases in ozone dating back to 1965 that have occurred at intervals of 4‐6 years. These decreases are shown to be related to delays in stratospheric warmings in Antarctica and the transport of ozone into Antarctica each

ISSN:0094-8276    

DOI:10.1029/GL013i012p01248

年代:1986

数据来源: WILEY

摘要:

Balloonborne measurements of ozone and aerosol concentrations at McMurdo Station in Antarctica in November 1985, indicated large variations, apparently associated with movement of the polar vortex. Extremely low ozone concentrations were observed, on one occasion to altitudes in excess of 30 km. Low ozone was accompanied by the absence of optically active aerosol and an enhancement of condensation nuclei while the opposite was the case with normal ozone. The ozone measurements are consistent with a springtime Antarctic vortex ozone minimum (popularly called the “ozone hole”) and variations in the aerosol size distribution appear to be associated with the thermal history of the relevant air par

ISSN:0094-8276    

DOI:10.1029/GL013i012p01252

年代:1986

数据来源: WILEY

摘要:

Anomalously high radiances from the ozone channel of the Limb Infra‐red Monitor of the Statosphere (LIMS) sounding instrument have been observed in the Northern Hemisphere winter lower stratosphere. Such events, thought to be due to polar stratospheric clouds (PSCs) are examined further by computing relative humidities using Stratospheric Sounding Unit (SSU) temperatures and water vapour measurements from the LIMS Map Archive Tape (MAT) analyses. Regions identified as PSCs are found to correspond closely to regions of high humidity. While instances of saturation were found, the average humidity at the centres of 39 PSCs was calculated to be 58%. Possible reasons for this apparent discrepancy are discussed.Applying a similar approach to the Southern Hemisphere, in 1979, virtually no PSCs are found in the vortex after 10 September at 20 km. This result has important implications for a number of proposed explanations for the Antarctic ozone hol

ISSN:0094-8276    

DOI:10.1029/GL013i012p01256

年代:1986

数据来源: WILEY

摘要:

Ground based measurements of stratospheric NO2made from Arrival Heights, Antarctica, are compared with TOMS satellite total ozone measurements and upper air meteorological data. The observations show the seasonal effects of partitioning on NO2, and the influence of wave driven transport on both the NO2and O3column in spring. We conclude that stratospheric air appearing over our site in spring during low pressure conditions is representative of the cold core of the polar vortex, which has effectively been isolated from lower latitude air. Within this core, photochemical processes influencing the ozone column amount and NO2levels can proceed without marked influence from transport effects.

ISSN:0094-8276    

DOI:10.1029/GL013i012p01260

年代:1986

数据来源: WILEY