Decadal-scale responses in middle and upper stratospheric ozone from SAGE II version 7 data

摘要

Stratospheric Aerosol and Gas Experiment (SAGE II) version 7 (v7) ozoneprofiles are analyzed for their decadal-scale responses in the middle andupper stratosphere for 1991 and 1992–2005 and compared with those from itsprevious version 6.2 (v6.2). Multiple linear regression (MLR) analysis isapplied to time series of its ozone number density vs. altitude data for arange of latitudes and altitudes. The MLR models that are fit to the timeseries data include a periodic 11 yr term, and it is in-phase with that ofthe 11 yr, solar UV (Ultraviolet)-flux throughout most of the latitude/altitude domain ofthe middle and upper stratosphere. Several regions that have a response thatis not quite in-phase are interpreted as being affected by decadal-scale,dynamical forcings. The maximum minus minimum, solar cycle (SC-like) responses forthe ozone at the low latitudes are similar from the two SAGE II data versionsand vary from about 5 to 2.5% from 35 to 50 km, although they areresolved better with v7. SAGE II v7 ozone is also analyzed for 1984–1998, inorder to mitigate effects of end-point anomalies that bias its ozone in 1991and the analyzed results for 1991–2005 or following the Pinatubo eruption.Its SC-like ozone response in the upper stratosphere is of the order of4% for 1984–1998 vs. 2.5 to 3% for 1991–2005. The SAGE IIv7 results are also recompared with the responses in ozone from the HalogenOccultation Experiment (HALOE) that are in terms of mixing ratio vs. pressurefor 1991–2005 and then for late 1992–2005 to avoid any effects followingPinatubo. Shapes of their respective response profiles agree very well for1992–2005. The associated linear trends of the ozone are not as negative in1992–2005 as in 1984–1998, in accord with a leveling off of the effects ofreactive chlorine on ozone. It is concluded that the SAGE II v7 ozone yieldsSC-like ozone responses and trends that are of better quality than those fromv6.2.