Preprints
https://doi.org/10.5194/egusphere-2023-557
https://doi.org/10.5194/egusphere-2023-557
30 Mar 2023
 | 30 Mar 2023
Status: this preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).

Inferring the Photolysis Rate of NO2 in the Stratosphere Based on Satellite Observations

Jian Guan, Susan Solomon, Sasha Madronich, and Douglas Kinnison

Abstract. NO and NO2 (NOx) play major roles in both tropospheric and stratospheric chemistry. This paper provides a novel method to obtain a global and accurate photodissociation coefficient for NO2 based on satellite data. The photodissociation coefficient JNO2 dominates the daytime diurnal variation of NOx photochemistry. Here the spatial variation of JNO2 in 50° S–90° S in December from 20–40 km is obtained using data from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) experiment. Because NO and NO2 exchange rapidly with one another in the daytime, the JNO2 can be attained assuming steady state, and the results are shown to be consistent with model results. The JNO2 value decreases as the solar zenith angle increases and has a weak altitude dependence. A key finding is that the satellite-derived JNO2 increases in the polar regions in good agreement with model predictions, due to the effects of ice and snow on surface albedo. Thus, the method presented here provides an observations-based check on the role of albedo in driving polar photochemistry.

Jian Guan et al.

Status: open (until 18 Jun 2023)

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Jian Guan et al.

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Short summary
This paper provides a novel method to obtain a global and accurate photodissociation coefficient for NO2 based on satellite data, and the results are shown to be consistent with model results. The JNO2 value decreases as the solar zenith angle increases and has a weak altitude dependence. A key finding is that the satellite-derived JNO2 increases in the polar regions in good agreement with model predictions, due to the effects of ice and snow on surface albedo.