Measurements of H2O2 and HCHO by Tunable Diode Laser Absorption Spectroscopy During the 1986 Carbonaceous Species Methods Comparison Study in Glendora, California

An improved, high sensitivity, tunable diode laser spectrometer system designed for tropospheric air measurements (TAMS-150) was employed during the 1986 Carbonaceous Species Methods Comparison Study at Glendora, CA. The TAMS-150 made simultaneous measurements of H 2 O 2 and HCHO with a time response of 3 minutes per data point. The minimum detection limits were respectively 0.1 ppbv and 0.15 ppbv for HCHO and H 2 O 2 and the estimated accuracies were ± 20% for both species. During the first 5 days of the study H 2 O 2 showed little diurnal variation ranging between 0.25 and 0.5 ppbv with maximum values occurring at 15:30 PDT. During the final 4 days H 2 O 2 showed stronger diurnal behavior with mixing ratios ranging from below the detection limits during some nighttime periods to as high as 1.8 ppbv during midday maxima which occurred about 15:30 PDT. HCHO showed strong diurnal behavior throughout the study with rapid changes in concentration in the early morning and evening. Mixing ratios were typically in the range 5-20 ppbv with maxima at about 10:00 and 14:00 PDT.