Total Ozone Columns from the Environmental Trace Gases Monitoring Instrument (EMI) Using the DOAS Method

Yuanyuan Qian,Yuhan Luo,Taiping Yang,Haijin Zhou,Dongshang Yang,Fuqi Si,Liang Xi

doi:10.3390/rs13112098

Abstract

Global measurements of total ozone are necessary to evaluate ozone hole recovery above Antarctica. The Environmental Trace Gases Monitoring Instrument (EMI) onboard GaoFen 5, launched in May 2018, was developed to measure and monitor the global total ozone column (TOC) and distributions of other trace gases. In this study, some of the first global TOC results of the EMI using the differential optical absorption spectroscopy (DOAS) method and validation with ground-based TOC measurements and data derived from Ozone Monitoring Instrument (OMI) and TROPOspheric Monitoring Instrument (TROPOMI) observations are presented. Results show that monthly average EMI TOC data had a similar spatial distribution and a high correlation coefficient (R ≥ 0.99) with both OMI and TROPOMI TOC. Comparisons with ground-based measurements from the World Ozone and Ultraviolet Radiation Data Centre also revealed strong correlations (R > 0.9). Continuous zenith sky measurements from zenith scattered light differential optical absorption spectroscopy instruments in Antarctica were also used for validation (R = 0.9). The EMI-derived observations were able to account for the rapid change in TOC associated with the sudden stratospheric warming event in October 2019; monthly average TOC in October 2019 was 45% higher compared to October 2018. These results indicate that EMI TOC derived using the DOAS method is reliable and has the potential to be used for global TOC monitoring.

Highlights

Stratospheric ozone, distributed at an altitude of approximately 20–35 km, plays an important role in protecting human health and the Earth’s ecological balance [1,2] by providing a shield against strong UV radiation (200–300 nm) [3]
Global total ozone column (TOC) in October 2018 from Environmental Trace Gases Monitoring Instrument (EMI), TROPOspheric Monitoring Instrument (TROPOMI), and Ozone Monitoring Instrument (OMI) are shown in Figure 5a,c,e, at a resampled spatial resolution of 0.25◦ × 0.5◦
It is apparent that global TOC retrieved from EMI shows a similar spatial distribution to OMI and TROPOMI

Summary

Introduction

Stratospheric ozone, distributed at an altitude of approximately 20–35 km, plays an important role in protecting human health and the Earth’s ecological balance [1,2] by providing a shield against strong UV radiation (200–300 nm) [3]. Stratospheric ozone is involved in numerous photochemical reactions, especially the activation of Br and Cl, which can destroy the ozone layer [4,5]. The hole in the ozone layer was first found by Farman in the Argentine Islands (65◦ S, 64◦ W) and Halley Bay (76◦ S, 27◦ W) [6]. Chlorofluorocarbons (CFCs), a leading cause of ozone depletion, were phased out by the Montreal Protocol [7], and in response, the total ozone column (TOC) above Antarctica is recovering and the ozone hole is reducing [8,9,10]. Satelliteborne instruments with a high spatial resolution can obtain more accurate information on regional trace gases, which have facilitated research in atmospheric chemistry, including ozone hole monitoring and the analysis of stratospheric dynamics [11].

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Results

Conclusion