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<p>In this study, we developed an approach that integrated multiple patterns of timescale for box modeling (MCMv3.3.1) to better understand the O<span class="inline-formula">₃</span>–precursor relationship at multiple sites and through continuous observations. A 5-month field campaign was conducted in the summer of 2019 to investigate the ozone formation chemistry at three sites in a major prefecture-level city (Zibo) in Shandong Province of northern China. It was found that the relative incremental reactivity (RIR) of major precursor groups (e.g., anthropogenic volatile organic compounds (AVOCs), NO<span class="inline-formula">_<i>x</i></span>) was overall consistent in terms of timescales changed from wider to narrower (four patterns: 5-month, monthly, weekly, and daily) at each site, though the magnitudes of RIR varied at different sites. The time series of the photochemical regime (using RIR<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M5" display="inline" overflow="scroll" dspmath="mathml"><msub><mi/><mrow><msub><mi mathvariant="normal">NO</mi><mi>x</mi></msub></mrow></msub></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="18pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="5dd9bf43f826d73eb3e731219b5d50a7"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-23-2649-2023-ie00001.svg" width="18pt" height="10pt" src="acp-23-2649-2023-ie00001.png"/></svg:svg></span></span> <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M6" display="inline" overflow="scroll" dspmath="mathml"><mo>/</mo></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="073414a2b77546d8d5847ae97897d626"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-23-2649-2023-ie00002.svg" width="8pt" height="14pt" src="acp-23-2649-2023-ie00002.png"/></svg:svg></span></span> RIR<span class="inline-formula">_AVOC</span> as an indicator) in weekly or daily patterns further showed a synchronous temporal trend among the three sites, while the magnitude of RIR<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M8" display="inline" overflow="scroll" dspmath="mathml"><msub><mi/><mrow><msub><mi mathvariant="normal">NO</mi><mi>x</mi></msub></mrow></msub></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="18pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="c29bd353f4248df6ae6ad05a91e7df87"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-23-2649-2023-ie00003.svg" width="18pt" height="10pt" src="acp-23-2649-2023-ie00003.png"/></svg:svg></span></span> <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M9" display="inline" overflow="scroll" dspmath="mathml"><mo>/</mo></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="880d1b22cfae9b4167ff115d05c6894c"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-23-2649-2023-ie00004.svg" width="8pt" height="14pt" src="acp-23-2649-2023-ie00004.png"/></svg:svg></span></span> RIR<span class="inline-formula">_AVOC</span> was site-to-site dependent. The derived RIR ranking (top 10) of individual AVOC species showed consistency between three patterns (i.e., 5-month, monthly, and weekly). It was further found that the campaign-averaging photochemical regimes showed overall consistency in the sign but non-negligible variability among the four patterns of timescale, which was mainly due to the embedded uncertainty in the model input dataset when averaging individual daily patterns into different timescales. This implies that utilizing narrower timescales (i.e., daily pattern) is useful for deriving reliable and robust O<span class="inline-formula">₃</span>–precursor relationships. Our results highlight the importance of quantifying the impact of different timescales to constrain the photochemical regime, which can formulate more accurate policy-relevant guidance for O<span class="inline-formula">₃</span> pollution control.</p>