Measurements of molecular chlorine (Cl
2), nitryl chloride (ClNO
2), and dinitrogen pentoxide (N
2O
5) were taken as part of the DISCOVER-AQ Texas 2013 campaign with a High Resolution Time-of-Flight Chemical Ionization Mass Spectrometer (HR-ToF-CIMS) using iodide (I-)
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Measurements of molecular chlorine (Cl
2), nitryl chloride (ClNO
2), and dinitrogen pentoxide (N
2O
5) were taken as part of the DISCOVER-AQ Texas 2013 campaign with a High Resolution Time-of-Flight Chemical Ionization Mass Spectrometer (HR-ToF-CIMS) using iodide (I-) as a reagent ion. ClNO
2 concentrations exceeding 50 ppt were regularly detected with peak concentrations typically occurring between 7:00 a.m. and 10:00 am. Hourly averaged Cl
2 concentrations peaked daily between 3:00 p.m. and 4:00 p.m., with a 29-day average of 0.9 ± 0.3 (1σ) ppt. A day-time Cl
2 source of up to 35 ppt∙h
−1 is required to explain these observations, corresponding to a maximum chlorine radical (Cl
•) production rate of 70 ppt∙h
−1. Modeling of the Cl
2 source suggests that it can enhance daily maximum O
3 and RO
2• concentrations by 8%–10% and 28%–50%, respectively. Modeling of observed ClNO
2 assuming a well-mixed nocturnal boundary layer indicates O
3 and RO
2• enhancements of up to 2.1% and 38%, respectively, with a maximum impact in the early morning. These enhancements affect the formation of secondary organic aerosol and compliance with air quality standards for ozone and particulate matter.
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