Temperature dependence of the atmospheric photolysis rate coefficient for NO₂

Abstract

Direct measurements were made of the temperature dependence of the photolysis rate coefficient of NO2 (j1) at temperatures from −70° to 30° C in sunlight for relatively cloudless summer days in Boulder, Colorado. The ratio of the J1 values (J1(30°C)/j1(T°C) for T = −20° and −70° C are, respectively: 1.046±0.040 and 1.070±0.031 (95% confidence limits). The J1 ratios were independent of solar zenith angle (22° < Z < 47°). Theoretical estimates of the temperature dependent J1 ratios based upon recently reported cross section (σ) and quantum yield (ø) data are more consistent with these experimental measurements than those based upon the currently accepted σ and ø data.

Photolysis frequency of NO2: Measurement and modeling during the International Photolysis Frequency Measurement and Modeling Intercomparison (IPMMI)

“…Differences due to aerosol assumptions are also more difficult to quantify. The photolysis of NO 2 is only weakly dependent on the temperature [ Shetter et al , 1988; Roehl et al , 1994], so differences in temperatures used by the models should lead to differences of no more than 2%.…”

Measurement of Photolysis Frequencies in the Atmosphere

“…For example, the photodissociation of O 3 → O 1 D exhibits a strong temperature dependence (Dickerson et al, 1982;Bohn et al, 2004), while the NO 2 photolysis is only weakly temperature dependent (Dickerson et al, 1982;Shetter et al, 1988). In few cases, a notable pressure dependence has been observed, such as in the formation of H 2 + CO in the photolysis of HCHO (Moortgat et al, 1983).…”

Actinometer and Eppley radiometer measurements of the NO2 photolysis rate coefficient during the Mauna Loa Observatory photochemistry experiment

“…The direct measurements of JNO2 are complicated experimentally [Stedman and Niki, 1973;Jackson et al, 1975;Harvey et al, 1977;Zafonte et al, 1977;Ritter et al, 1979;Bahe, 1980;Dickerson, 1980;Dickerson and Stedman, 1980;Dickerson et al, 1982;Parrish et al, 1983;Madronich et al, 1984Madronich et al, , 1985Madronich, 1987a;Trainer et al, 1987;Shetter et al, 1988], and the use of the UV radiometer, appears to offer a good replacement for the actinometer systems, at least for certain well defined atmospheric conditions (clear or completely overcast skies) and selected locations (flat terrain with unobstructed horizon). Madronich [1987a] derived correlations from his review of the existing simultaneous Eppley radiometer and direct actinometer measurements of JNO2 that suggest reasonably good accuracy can be expected for JNO2 values calculated from radiometer measurements.…”