AN INVESTIGATION OF OZONE VARIABILITY AND ASSOCIATED UNCERTAINTIES OVER HIGH NORTHERN LATITUDES

• Main Author: Bahramvash Shams, Shima
• Format: Text
• Language: English
• Published: Washington State University 2022
• Subjects: Emission Fourier transform infrared FTIR; Northern High latitude; Stratospheric dynamic; Sudden Stratospheric Warming; Ozone; Arctic; Greenland; Merra
• Online Access: https://dx.doi.org/10.7273/000002397; https://rex.libraries.wsu.edu/esploro/outputs/doctoral/99900606653101842

Ozone is influenced by various dynamical and chemical processes over the northern high latitudes. Moreover, as an important trace gas, ozone variability over the Artic modulates global climate, influences surface temperature, and impacts tropospheric weather regimes. Despite the critical importance of ozone, the uncertainties and sparsity in the datasets hinder many studies at high latitudes. This dissertation provides a comprehensive investigation of ozone over the northern high latitudes using various types of observations. Using the long record of in situ measurements, the seasonality, variability, and trends of ozone are analyzed at four high latitude sites. The contribution of various dynamical variables on deseasonalized ozone fluctuations is investigated using stepwise multiple regression analysis. The results indicate the critical importance of residual circulations and associated parameters on Arctic ozone. Sudden stratospheric warmings (SSWs) are the most significant disruptions of residual circulation and consequently dramatically influence the ozone over the Arctic. A comprehensive comparison of the Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) ozone data to ground-based remote sensing data and in situ observations during the SSWs shows the capability of MERRA-2 in capturing ozone variation in the middle stratosphere but indicate higher uncertainties at lower atmospheric levels. The impact of six major SSWs from 2004 to 2020 on ozone in the middle stratosphere over high northern latitudes is analyzed using MERRA-2. The results show a strong connection between the structure of the polar vortex and the impact of SSWs on Arctic ozone. The investigation of dynamical parameters emphasizes the key role of vertical advection in ozone fluctuations in the middle stratosphere during the SSWs. To mitigate the higher uncertainties of MERRA-2 and satellite ozone estimates in the lower atmosphere, a retrieval framework using emission Fourier transform infrared (FTIR) interferometer is developed to estimate ozone over Summit Station, Greenland. A climatology of MERRA-2 uncertainties is derived using the ozonesonde observations and is used to focus the retrieval on atmospheric layers with the largest uncertainties. The retrieved ozone amounts improved the prior information from MERRA-2 below 10 km in comparison to ozonesondes.