Characterization of Odin-OSIRIS ozone profiles with the SAGE II dataset

[摘要] The Optical Spectrograph and InfraRed Imaging System (OSIRIS) on board theOdin spacecraft has been taking limb-scattered measurements of ozone numberdensity profiles from 2001–present. The Stratospheric Aerosol and GasExperiment II (SAGE II) took solar occultation measurements of ozone numberdensities from 1984–2005 and has been used in many studies of long-termozone trends. We present the characterization of OSIRIS SaskMART v5.0×against the new SAGE II v7.00 ozone profiles for 2001–2005, the period overwhich these two missions had overlap. This information can be used to mergeOSIRIS with SAGE II into a single ozone record from 1984 to the present, ifother satellite ozone measurements are included to account for gaps in theOSIRIS dataset in the winter hemisphere. Coincident measurement pairs wereselected for ±1 h, ±1° latitude, and ±500 km.The absolute value of the resulting mean relative difference profile is<5% for 13.5–54.5 km and <3% for 24.5–53.5 km.Correlation coefficients R > 0.9 were calculated for 13.5–49.5 km,demonstrating excellent overall agreement between the two datasets.Coincidence criteria were relaxed to maximize the number of measurementpairs and the conditions under which measurements were taken. With the broadcoincidence criteria, good agreement (< 5%) was observed undermost conditions for 20.5–40.5 km. However, mean relative differences doexceed 5% for several cases. Above 50 km, differences between OSIRIS andSAGE II are partly attributed to the diurnal variation of ozone. OSIRIS dataare biased high compared with SAGE II at 22.5 km, particularly at highlatitudes. Dynamical coincidence criteria, using derived meteorologicalproducts, were also tested and yielded similar overall results, with slightimprovements to the correlation at high latitudes. The OSIRIS opticstemperature is low (<16 °C) during May–July, when thesatellite enters the Earth's shadow for part of its orbit. During thisperiod, OSIRIS measurements are biased low by 5–12% for 27.5–38.5 km.Biases between OSIRIS ascending node (northward equatorial crossing time~18:00 LT – local time) and descending node (southward equatorial crossingtime ~06:00 LT) measurements are also noted under someconditions. This work demonstrates that OSIRIS and SAGE II have excellentoverall agreement and characterizes the biases between these datasets.

[学科分类] 几何与拓扑