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<p>Ethane (<span class="inline-formula">C₂H₆</span>) is an important greenhouse gas and plays a significant role in tropospheric chemistry and climate change. This study first presents and then quantifies the variability, sources, and transport of <span class="inline-formula">C₂H₆</span> over densely populated and highly industrialized eastern China using ground-based high-resolution Fourier transform infrared (FTIR) remote sensing along with atmospheric modeling techniques. We obtained a retrieval error of 6.21 <span class="inline-formula">±</span> 1.2 (1<span class="inline-formula"><i>σ</i></span>)% and degrees of freedom (DOFS) of 1.47 <span class="inline-formula">±</span> 0.2 (1<span class="inline-formula"><i>σ</i></span>) in the retrieval of <span class="inline-formula">C₂H₆</span> tropospheric column-averaged dry-air mole fraction (troDMF) over Hefei, eastern China (32<span class="inline-formula">^∘</span> N, 117<span class="inline-formula">^∘</span> E; 30 <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M12" display="inline" overflow="scroll" dspmath="mathml"><mrow class="unit"><mi mathvariant="normal">m</mi><mspace width="0.125em" linebreak="nobreak"/><mi mathvariant="normal">a</mi><mo>.</mo><mi mathvariant="normal">s</mi><mo>.</mo><mi mathvariant="normal">l</mi><mo>.</mo></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="36pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="d5af2e0a2caa5fbd9f04cb396c6b57b4"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-11759-2021-ie00001.svg" width="36pt" height="10pt" src="acp-21-11759-2021-ie00001.png"/></svg:svg></span></span>). The observed <span class="inline-formula">C₂H₆</span> troDMF reached a minimum monthly mean value of 0.36 <span class="inline-formula">±</span> 0.26 <span class="inline-formula">ppbv</span> in July and a maximum monthly mean value of 1.76 <span class="inline-formula">±</span> 0.35 <span class="inline-formula">ppbv</span> in December, and showed a negative change rate of <span class="inline-formula">−</span>2.60 <span class="inline-formula">±</span> 1.34 <span class="inline-formula">% yr⁻¹</span> from 2015 to 2020. The dependencies of <span class="inline-formula">C₂H₆</span> troDMF on meteorological and emission factors were analyzed using generalized additive models (GAMs). Generally, both meteorological and emission factors have positive influences on <span class="inline-formula">C₂H₆</span> troDMF in the cold season (December–January–February/March–April–May, DJF/MAM) and negative influences on <span class="inline-formula">C₂H₆</span> troDMF in the warm season (June–July–August/September–October–November, JJA/SON). GEOS-Chem chemical model simulation captured the observed <span class="inline-formula">C₂H₆</span> troDMF variability and was, thus, used for source attribution. GEOS-Chem model sensitivity simulations concluded that the anthropogenic emissions (fossil fuel plus biofuel emissions) and the natural emissions (biomass burning plus biogenic emissions) accounted for 48.1 % and 39.7 % of <span class="inline-formula">C₂H₆</span> troDMF variability over Hefei, respectively. The observed <span class="inline-formula">C₂H₆</span> troDMF variability mainly results from the emissions within China (74.1 %), where central, eastern, and northern China dominated the contribution (57.6 %). Seasonal variability in <span class="inline-formula">C₂H₆</span> transport inflow and outflow over the observation site is largely related to the midlatitude westerlies and the Asian monsoon system. Reduction in <span class="inline-formula">C₂H₆</span> abundance from 2015 to 2020 mainly results from the decrease in local and transported <span class="inline-formula">C₂H₆</span> emissions, which points to air quality improvement in China in recent years.</p>