Figure A1-3a: Relationship between NOx and NO2/NOx at the Penrose, Auckland, site for one-hour average concentrations (based on monitoring data during 2002−2004)
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Source: Data courtesy of NIWA
Text description of figure
Figure A1-3a shows the relationship between the fraction of all oxides of nitrogen that are nitrogen dioxide (i.e. NO2/NOx), against all oxides of nitrogen (NOx) measured as a 1-hr average. Values are negatively correlated with a sudden decrease in NO2/NOx out to 250 µg/m3 NOx. Lower concentrations of overall NOx (< 100 µg/m3) correlate with higher levels of NO2/NOx (>0.8) and vice versa. This relationship is based on monitoring data collected over 2002 – 2004 at the Auckland Regional Council Penrose monitoring site in Auckland.
