Exploring the Spatial and Temporal Structure of Ozone in the Mesosphere and Lower Thermosphere: An Investigation of the Sudden Stratospheric Warming Events of 2009 – 2013

Abstract:

Sudden stratospheric warmings are classified as dramatic fluid dynamical events that lead to an intensified and accelerated temperature rise in the winter polar stratosphere accompanied by the downward descent of polar air and strongly impact the entire middle atmosphere up to the thermosphere. The influence of atmospheric dynamics on polar ozone in the mesosphere-lower thermosphere (MLT) during SSW events is analyzed in this study by using satellite observations. Ozone profiles in the MLT region (60 – 100 km) are retrieved from four satellite instruments and compared. Ozone measurements made at 0.292 μm by the Solar Occultation for Ice Experiment (SOFIE) instrument on the Aeronomy of Ice in the Mesosphere (AIM) is used as the basis of comparison. SOFIE makes sunrise and sunset observations in the latitude range of 65^o- 85^o in both hemispheres at a high vertical resolution (~ 1.6 km). Other measurements are from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER), the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) and the Atmospheric Chemistry Experiment – Fourier Transform Spectrometer (ACE – FTS) instruments. Comparisons of each instrument’s data with SOFIE using coincident profiles to study “daytime” ozone and its spatial and temporal variance in the “secondary” (90 - 105 km) and “tertiary” (70 - 75 km) maxima for active (2009, 2010, 2012 and 2013) and quiet (2011) years indicate agreement in the basic vertical profile but also show organized differences. The evolution of ozone can be attributed to the anomalous vertical residual motion during an SSW event. Local time is a strong determinant of the latitude-altitude ozone structure in the MLT region even while restricting the observations to daytime-only for the SSW period. Atomic oxygen profiles calculated from the ozone observations made by the four satellite instruments at daytime between 60 – 100 km show a consistency in the altitudes for which maximum and minimum concentrations are observed.