Variations in the vertical profile of ozone at four high-latitude Arctic sites from 2005 to 2017

Abstract

Abstract. Understanding variations in atmospheric ozone in the Arctic is difficult because there are only a few long-term records of vertical ozone profiles in this region. We present 12 years of ozone profiles from February 2005 to February 2017 at four sites: Summit Station, Greenland; Ny-Ålesund, Svalbard, Norway; and Alert and Eureka, Nunavut, Canada. These profiles are created by combining ozonesonde measurements with ozone profile retrievals using data from the Microwave Limb Sounder (MLS). This combination creates a high-quality dataset with low uncertainty values by relying on in situ measurements of the maximum altitude of the ozonesondes (∼30 km) and satellite retrievals in the upper atmosphere (up to 60 km). For each station, the total column ozone (TCO) and the partial column ozone (PCO) in four atmospheric layers (troposphere to upper stratosphere) are analyzed. Overall, the seasonal cycles are similar at these sites. However, the TCO over Ny-Ålesund starts to decline 2 months later than at the other sites. In summer, the PCO in the upper stratosphere over Summit Station is slightly higher than at the other sites and exhibits a higher standard deviation. The decrease in PCO in the middle and upper stratosphere during fall is also lower over Summit Station. The maximum value of the lower- and middle-stratospheric PCO is reached earlier in the year over Eureka. Trend analysis over the 12-year period shows significant trends in most of the layers over Summit and Ny-Ålesund during summer and fall. To understand deseasonalized ozone variations, we identify the most important dynamical drivers of Arctic ozone at each level. These drivers are chosen based on mutual selected proxies at the four sites using stepwise multiple regression (SMR) analysis of various dynamical parameters with deseasonalized data. The final regression model is able to explain more than 80 % of the TCO and more than 70 % of the PCO in almost all of the layers. The regression model provides the greatest explanatory value in the middle stratosphere. The important proxies of the deseasonalized ozone time series at the four sites are tropopause pressure (TP) and equivalent latitude (EQL) at 370 K in the troposphere, the quasi-biennial oscillation (QBO) in the troposphere and lower stratosphere, the equivalent latitude at 550 K in the middle and upper stratosphere, and the eddy heat flux (EHF) and volume of polar stratospheric clouds throughout the stratosphere.

Analyzing ozone variations and uncertainties at high latitudes during Sudden Stratospheric Warming events using MERRA-2

“…Ozonesondes have been used to monitor ozone for decades as the most direct measurement of the vertical ozone profile (Tiao et al, 1986;Logan, 1994;Logan et al, 1999;Stolarski, 2001;Gaudel et al, 2015;Bahramvash-Shams et al, 2019). Ozonesonde profiles provide a good standard for validation because they have high accuracy, fine vertical resolution of less than 100 m, yearround launches, and low sensitivity to clouds (McDonald et al, 1999;Ancellet et al, 2016;Sterling et al, 2017).…”

“…Dynamical variability plays a critical role in fluctuations of stratospheric ozone (Holton et al, 1995;Fusco and Salby, 1999;Rao et al, 2004;Bahramvash-Shams et al, 2019). Planetary waves modulate poleward ozone transport through the Brewer-Dobson circulation (BDC) (Lindzen and Holton, 1968;Holton and Lindzen, 1972;Wallace, 1973;Holton et al, 1995).…”

“…The structure of ozone anomalies in the zonal minus Greenland sector is similar to the zonal average, therefore it is not included in further analysis. The Greenland sector has been shown to be uniquely sensitive to dynamical forcing associated with the Quasi-Biennial Oscillation (QBO) (Anstey and Shepherd, 2014;Bahramvash-Shams et al, 2019). Moreover, the Greenland sector exhibits a very strong isolated stratospheric air circulation during wintertime, as…”

Vertical ozone profiles in the atmosphere over the Antarctic Peninsula and Kyiv by Umkehr observations

“…Standard Umkehr observations consist of mea-surements of a pair of C lines (311.45 nm, 332.4 nm) at 14 zenith angles (Komhyr & Evans, 2008). The Um kehr method for determining the vertical ozone distribution in the atmosphere has been first proposed by Götz et al (1934) and is currently applied to ozone studies with Dobson spectrophotometer (Stone et al, 2015;Bahramvash Shams et al, 2019). The Umkehr technique is based on the analysis of the brightness ratio of zenith sky at a pair of ultraviolet wavelengths (Komhyr & Evans 2008;Stone et al, 2015).…”

Dark Glacier Surface of Greenland’s Largest Floating Tongue Governed by High Local Deposition of Dust

“…Considering the available values of the 500 nm aerosol optical depth (<0.1) at Thule and Ittoqqortoormiit (since there are no available station in the study area), we used as input data a visibility of 40 km. The total columnar ozone content was selected referencing to Bahramvash Shams et al [41] and we used as input values 400 and 300 DU, respectively for April 2017 and July 2017, The aerosol type was selected to be maritime and the atmosphere type as mid latitude winter, following the indications of König M and N [42]. The preparation of a L2A final product, with 10 m resolution and surface reflectance, has provided information about the spectral optical behaviour (12 bands with wavelengths ranging from 440 nm to 2200 nm) of the surface at selected dates characterized by a low cloud coverage.…”