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<p>High-resolution, laboratory, absorption spectra of the <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M4" display="inline" overflow="scroll" dspmath="mathml"><mrow><msup><mi>a</mi><mn mathvariant="normal">1</mn></msup><msub><mi mathvariant="normal">Δ</mi><mi mathvariant="normal">g</mi></msub><mo>←</mo><msup><mi>X</mi><mn mathvariant="normal">3</mn></msup><msubsup><mi mathvariant="normal">Σ</mi><mi mathvariant="normal">g</mi><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="70pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="24c52f34846fb84350c0ac82403f5fd1"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="amt-12-35-2019-ie00001.svg" width="70pt" height="17pt" src="amt-12-35-2019-ie00001.png"/></svg:svg></span></span> oxygen (<span class="inline-formula">O₂</span>) band measured using cavity ring-down spectroscopy were fitted using the Voigt and speed-dependent Voigt line shapes. We found that the speed-dependent Voigt line shape was better able to model the measured absorption coefficients than the Voigt line shape. We used these line shape models to calculate absorption coefficients to retrieve atmospheric total columns abundances of <span class="inline-formula">O₂</span> from ground-based spectra from four Fourier transform spectrometers that are a part of the Total Carbon Column Observing Network (TCCON). Lower <span class="inline-formula">O₂</span> total columns were retrieved with the speed-dependent Voigt line shape, and the difference between the total columns retrieved using the Voigt and speed-dependent Voigt line shapes increased as a function of solar zenith angle. Previous work has shown that carbon dioxide (<span class="inline-formula">CO₂</span>) total columns are better retrieved using a speed-dependent Voigt line shape with line mixing. The column-averaged dry-air mole fraction of <span class="inline-formula">CO₂</span> (<span class="inline-formula">XCO₂</span>) was calculated using the ratio between the columns of <span class="inline-formula">CO₂</span> and <span class="inline-formula">O₂</span> retrieved (from the same spectra) with both line shapes from measurements taken over a 1-year period at the four sites. The inclusion of speed dependence in the <span class="inline-formula">O₂</span> retrievals significantly reduces the air mass dependence of <span class="inline-formula">XCO₂</span>, and the bias between the TCCON measurements and calibrated integrated aircraft profile measurements was reduced from 1&thinsp;% to 0.4&thinsp;%. These results suggest that speed dependence should be included in the forward model when fitting near-infrared <span class="inline-formula">CO₂</span> and <span class="inline-formula">O₂</span> spectra to improve the accuracy of <span class="inline-formula">XCO₂</span> measurements.</p>