Stratospheric ozone in the lower troposphere —I. Presentation and interpretation of aircraft measurements

Johnson, Warren B.; Viezee, W.

doi:10.1016/0004-6981(81)90325-5

Cited by 131 publications

(76 citation statements)

References 16 publications

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“…5). Such a feature is commonly associated with STE (e.g., Johnson and Viezee, 1981), but it appears to have been too far north to strongly affect tropopause heights over Harrow.…”

Section: Gem-flexpart and Auramsmentioning

confidence: 99%

Transport analysis of ozone enhancement in Southern Ontario during BAQS-Met

Tarasick

Hocking

et al. 2011

Atmos. Chem. Phys.

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Abstract. Twice-daily ozonesondes were launched from Harrow, in southwestern Ontario, Canada, during the BAQSMet (Border Air Quality and Meteorology Study) field campaign in June and July of 2007. A co-located radar windprofiler measured tropopause height continuously. These data, in combination with continuous surface ozone measurements and geo-statistical interpolation of satellite ozone observations, present a consistent picture and indicate that a number of significant ozone enhancements in the troposphere were observed that were the result of stratospheric intrusion events. The combined observations have also been compared with results from two Environment Canada numerical models, the operational weather prediction model GEM (as input to FLEXPART), and a new version of the regional air quality model AURAMS, in order to examine the ability of these models to accurately represent sporadic crosstropopause ozone transport events. The models appear to reproduce intrusion events with some skill, implying that GEM dynamics (which also drive AURAMS) are able to represent such events well. There are important differences in the quantitative comparison, however; in particular, the poor vertical resolution of AURAMS around the tropopause causes it to bring down too much ozone in individual intrusions.Correspondence to: H. He (huixia.he@ec.gc.ca) These campaign results imply that stratospheric intrusions are important to the ozone budget of the mid-latitude troposphere, and appear to be responsible for much of the variability of ozone in the free troposphere. GEM-FLEXPART calculations indicate that stratospheric ozone intrusions contributed significantly to surface ozone on several occasions during the BAQS-Met campaign, and made a moderate but significant contribution to the overall tropospheric ozone budget.

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“…5). Such a feature is commonly associated with STE (e.g., Johnson and Viezee, 1981), but it appears to have been too far north to strongly affect tropopause heights over Harrow.…”

Section: Gem-flexpart and Auramsmentioning

confidence: 99%

Transport analysis of ozone enhancement in Southern Ontario during BAQS-Met

Tarasick

Hocking

et al. 2011

Atmos. Chem. Phys.

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“…Johnson and Viezee, 1981). This in turn can influence the radiative flux balance in the troposphere and lower stratosphere, which has implications for the radiative forcing of the global climate (Ramaswamy et al, 1992).…”

Section: Introductionmentioning

confidence: 99%

Variability in the characteristics of cut‐off low pressure systems over subtropical southern Africa

Singleton

Reason

2006

Intl Journal of Climatology

103

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Abstract:Variability in the characteristics of cut-off low pressure systems over subtropical southern Africa is examined for the 1973-2002 period. These characteristics include their seasonality, frequency, duration, location and size. It is found that on average 11 cut-off lows occur over southern Africa south of 20°S per year and are most common in the MarchMay season. Potential relationships between the number of cut-off lows over southern Africa with the El Niño Southern Oscillation (ENSO), the Pacific South America pattern, the wave number 3 pattern and the semi-annual oscillation (SAO) are discussed. La Niña years appear to be associated with above average annual frequencies of cut-off lows but the reverse is generally not true for El Niño years. There was a shift in the preferred season for cut-off lows from March-May to June-August in the 1980s, which coincided with a weakening of the SAO and a shift in zonal wave number 3. This period also showed a change in the preferred location of these systems from southwestern subtropical southern Africa to the northeast of the region. The results suggest that there may be a relationship between cut-off lows over subtropical southern Africa, the wave number 3 pattern in the Southern Hemisphere and the SAO.

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“…Such relatively high RH suggests that the ozone-rich air masses were not from the stratosphere. This is because the air mass from the stratosphere in recent history is usually dry with low RH [Johnson and Viezee, 1981]. Chan et al [1998a], and Newell et al [1997] report that the high water vapor air masses observed in the middle to upper troposphere over Hong Kong are originated in the tropical region.…”

Section: Introductionmentioning

confidence: 99%