Nitrogen oxides in the arctic stratosphere: Implications for ozone abundances. Ph.D. Thesis
In the high latitude winter stratosphere, NO2 sequesters chlorine compounds which are extremely efficient at destroying ozone. During the nighttime, NO2 reacts with ozone to form N2O5 which acts as a reservoir of NO2. Under heavy aerosol loading, N2O5 may react with water on aerosol surfaces to form HNO3, a reservoir more resistant to photolysis. This heterogeneous reaction results in reduced NO2 concentration when the sun returns at the end of the winter. A spectrograph system has been developed to measure scattered zenith skylight and thereby determine stratospheric NO2 slant column abundance. Conversion of the measured slant column abundance to vertical column abundance requires dividing by the air mass. The air mass is the enhancement in the optical path for the scattered twilight as compared to a vertical path. Air mass values determined using a multiple scattering radiative transfer code have been compared to those derived using a Monte Carlo code and were found to agree to within 6% at a 90 deg solar zenith angle for a stratospheric absorber. Six months of NO2 vertical column abundance measured over Fairbanks during the winter 1992-93 exhibited the daylight diminished and increased as the sunlight hours lengthened. The overall seasonal behavior was similar to high-latitude measurements made in the Southern Hemisphere. The ratios of morning to evening column abundance were consistent with predictions based on gas-phase chemistry. The possible heterogeneous reaction of N2O5 on sulfate aerosols was investigated using FTIR Spectrometer measurements of HNO3 column abundance and lidar determinations of the aerosol profile. Using an estimated N2O5 column abundance and aerosol profile as input to a simple model, significant HNO3 production was expected. No increase in HNO3 column abundance was measured. From this set of data, it was not possible to determine whether significant amounts of N2O5 were converted to HNO3 by this heterogeneous reaction.
- Research Organization:
- Alaska Univ., College, AK (United States)
- OSTI ID:
- 264016
- Report Number(s):
- N-96-23666; NIPS-96-08911; TRN: 9623666
- Resource Relation:
- Other Information: TH: Ph.D. Thesis; PBD: Jan 1994
- Country of Publication:
- United States
- Language:
- English
Similar Records
A new numerical model of the middle atmosphere. 2: Ozone and related species
Ozone and NO2 air-mass factors for zenith-sky spectrometers: Intercomparison of calclations with different radiative transfer models