Abstract:Abstract. Analyses of stratospheric ozone data determined from Dobson-Umkehr measurements since 1977 at the Syowa (69.0 • S, 39.6 • E), Antarctica, station show a significant decrease in ozone at altitudes higher than that of the 4 hPa pressure level during the 1980s and 1990s. Ozone values over Syowa have remained low since 2001. The time series of upper stratospheric ozone from the homogenized NOAA SBUV (Solar Backscatter Ultraviolet Instrument)(/2) 8.6 overpass data (±4 • , 24 h) are in qualitative agreemen… Show more
“…Because O 3 variability in the upper polar stratosphere is mainly driven by chemistry, this region is commonly used for the detection of ozone hole recovery [ Miyagawa et al ., ]. The results of this study suggest that EPP‐induced O 3 variations on a decadal time scale might be of importance in the analysis of upper stratospheric O 3 trends.…”
Geomagnetic activity is thought to affect ozone and, possibly, climate in polar regions via energetic particle precipitation (EPP) but observational evidence of its importance in the seasonal stratospheric ozone variation on long time scales is still lacking. Here we fill this gap by showing that at high southern latitudes, late winter ozone series, covering the 1979–2014 period, exhibit an average stratospheric depletion of about 10–15% on a monthly basis caused by EPP. Daily observations indicate that every austral winter EPP‐induced low ozone concentrations appear at about 45 km in late June and descend later to 30 km, before disappearing by September. Such stratospheric variations are coupled with mesospheric ozone changes also driven by EPP. No significant correlation between these ozone variations and solar ultraviolet irradiance has been found. This suggests the need of including the EPP forcing in both ozone model simulations and trend analysis.
“…Because O 3 variability in the upper polar stratosphere is mainly driven by chemistry, this region is commonly used for the detection of ozone hole recovery [ Miyagawa et al ., ]. The results of this study suggest that EPP‐induced O 3 variations on a decadal time scale might be of importance in the analysis of upper stratospheric O 3 trends.…”
Geomagnetic activity is thought to affect ozone and, possibly, climate in polar regions via energetic particle precipitation (EPP) but observational evidence of its importance in the seasonal stratospheric ozone variation on long time scales is still lacking. Here we fill this gap by showing that at high southern latitudes, late winter ozone series, covering the 1979–2014 period, exhibit an average stratospheric depletion of about 10–15% on a monthly basis caused by EPP. Daily observations indicate that every austral winter EPP‐induced low ozone concentrations appear at about 45 km in late June and descend later to 30 km, before disappearing by September. Such stratospheric variations are coupled with mesospheric ozone changes also driven by EPP. No significant correlation between these ozone variations and solar ultraviolet irradiance has been found. This suggests the need of including the EPP forcing in both ozone model simulations and trend analysis.
“…Trends are statistically different from zero at the 95% confidence interval above 330 K (~11 km). A recent study using ground-based UV reflectance (Umkehr) measurements capable of detecting ozone averaged over 5–10 km thick layers in the Antarctic showed similar values of about −2 to −3%/year at the lower stratospheric Umkehr layers 32 .Figure 2Vertical structure of Antarctic ozone recovery: ( a ) The ozone trends estimated from ozonesonde data in the Antarctic vortex in spring (SON) with ≥65° S EqL criterion (“standard”, black cures), Nash et al . 20 vortex criterion (“Nash-96”, blue curves) and without considering the vortex boundaries (“no VORTEX”, red curves) for the 1979–2001 (dash) and 2001–2013 (solid) periods.…”
Section: Drivers Of Ozone Change and Past Trendsmentioning
Absorption of solar radiation by stratospheric ozone affects atmospheric dynamics and chemistry, and sustains life on Earth by preventing harmful radiation from reaching the surface. Significant ozone losses due to increases in the abundances of ozone depleting substances (ODSs) were first observed in Antarctica in the 1980s. Losses deepened in following years but became nearly flat by around 2000, reflecting changes in global ODS emissions. Here we show robust evidence that Antarctic ozone has started to recover in both spring and summer, with a recovery signal identified in springtime ozone profile and total column measurements at 99% confidence for the first time. Continuing recovery is expected to impact the future climate of that region. Our results demonstrate that the Montreal Protocol has indeed begun to save the Antarctic ozone layer.
“…It has been reported that the mean age of air in the Antarctic upper stratosphere and lower mesosphere reached 10 years (Stiller et al 2008). Miyagawa et al (2014) showed that assuming 10 years of age of air gave the best fit of ODS trend to ozone concentration in the upper stratosphere and lower mesosphere over Antarctic Syowa Station. Figure S3 shows the composite differences obtained by taking a break point at 2005 instead of 1995.…”
Research on the effects of energetic particle precipitation (EPP) on earth's atmosphere is rapidly growing. However, these effects have not been well distinguished from those of other climate forcings. This study extracts EPP effects on the middle atmosphere in the southern hemisphere from the latest reanalysis datasets using multiple regression analysis and composite analysis. Statistically significant temperature anomalies in the winter polar upper stratosphere and lower mesosphere are found, but a simple dynamical signature explaining the anomalies is not evident. On the other hand, it is found that a negative temperature anomaly extending from the polar lower mesosphere to the midlatitude upper stratosphere in July is driven by anomalous Eliassen-Palm flux divergence in the midlatitude lower mesosphere. This result suggests that EPP effects are distinguishable from other climate forcings in the latest reanalysis data.(Citation: Tomikawa, Y., 2017: Response of the middle atmosphere in the Southern Hemisphere to energetic particle precipitation in the latest reanalysis data. SOLA, 13A, 1−7,
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