نتایج جستجو برای: stratospheric ozone
تعداد نتایج: 24237 فیلتر نتایج به سال:
Future stratospheric ozone concentrations will be determined both by changes in the concentration of ozone depleting substances (ODSs) and by changes in stratospheric and tropospheric climate, including those caused by changes in anthropogenic greenhouse gases (GHGs). Since future economic development pathways and resultant emissions of GHGs are uncertain, anthropogenic climate change could be ...
Vertical and latitudinal changes in the stratospheric ozone in the post-chlorofluorocarbon (CFC) era are investigated using simulations of the recent past and the 21st century with a coupled chemistry-climate model. Model results reveal that, in the 2060s when the stratospheric halogen loading is projected to return to its 1980 values, the extratropical column ozone is significantly higher than...
[1] The published literature debates the extent to which naturally occurring stratospheric ozone intrusions reach the surface and contribute to exceedances of the U.S. National Ambient Air Quality Standard (NAAQS) for ground-level ozone (75 ppbv implemented in 2008). Analysis of ozonesondes, lidar, and surface measurements over the western U.S. from April to June 2010 show that a global high-re...
Whether stratospheric cooling due to increases in well-mixed greenhouse gases (WMGHG) could increase the depletion of Arctic stratospheric ozone has been the subject of scientific and public attention for decades. Here we provide evidence that changes in the concentrations of ozone-depleting substances (ODS), not WMGHG, have been the primary driver of observed Arctic lower stratospheric trends ...
Results from a global climate model including an interactive parameterization of stratospheric chemistry show how upper stratospheric ozone changes may amplify observed, 11-year solar cycle irradiance changes to affect climate. In the model, circulation changes initially induced in the stratosphere subsequently penetrate into the troposphere, demonstrating the importance of the dynamical coupli...
[1] Observations from satellites and balloons suggest that ozone abundances have decreased in the tropical lower stratosphere since the late 1970s, but this long-term change is occurring in a region of large interannual variability. Three different ozone databases provide regression fits to the ozone observations, and are available for use in model studies of the influence of ozone changes on s...
Dissociation induced by cosmic rays of chlorofluorocarbons (CFC) and HCl on the surfaces of polar stratospheric clouds (PSC) has been suggested as playing a significant role in causing the ozone hole. However, observed stratospheric CFC distributions are inconsistent with a destruction of CFC on PSC surfaces and no significant correlation exists between ozone levels and cosmic-ray activity insi...
[1] Recent studies suggest that ozone turnaround (the second stage of ozone recovery) is near. Determining precisely when this occurs, however, will be complicated by greenhouse gas‐induced stratospheric cooling as ozone trends derived from profile data in different units and/or vertical co‐ordinates will not agree. Stratospheric cooling leads to simultaneous trends in air density and layer thi...
[1] Stratospheric ozone is expected to increase during the 21st century as the abundance of halogenated ozone‐depleting substances decrease to 1960 values. However, climate change will likely alter this “recovery” of stratospheric ozone by changing stratospheric temperatures, circulation, and abundance of reactive chemical species. Here we quantify the contribution of different mechanisms to ch...
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 (S...
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