Measurements of stratospheric NO and NO2 from the last four flights of the Oxford radiometer are compared with predictions by a diurnal photochemical model. The rapid sunrise and sunset changes predicted by the model and detected on previous flights are confirmed. The observations suggest agreement with model predictions of the night time decay of NO2 associated with N2O5 production but do not fully verify them. For three of the flights this is due to insufficient measurement precision and short flight duration, and in the other flight it is due to disruption of the diurnal cycle by viewing parts of the stratosphere of different composition. The 1982 flight showed both NO and NO2 to be greatly reduced between 30 and 35 km. We attribute this to the eruption of the El Chichon volcano. Possible mechanisms for this reduction are discussed.

Simultaneous measurements of stratospheric NO and NO2 and their comparison with model predictions

L’histoire des sciences de l’environnement a, jusqu’a present, peu documente l’apport des chimistes de l’atmosphere, qui formalisent les reactions chimiques se produisant au sein de l’atmosphere. Cette these porte specifiquement sur la chimie atmospherique globale. La chimie de l’atmosphere a ete au centre de l’expertise sur la destruction anthropique de la couche d’ozone a partir de 1970. Les chimistes de l’atmosphere ont egalement participe a l’elaboration des rapports du GIEC (Groupe d’experts intergouvernemental sur l'evolution du climat) a partir de la fin des annees 1980, ainsi qu’a des travaux au sein de la science dite « du systeme Terre ». En combinant differentes approches de l’etude des sciences et des techniques, ce memoire de these fait une histoire "sociale" du champ d’etude sur la chimie atmospherique globale depuis les annees 1920. Le cœur du recit porte sur l’evolution des pratiques scientifiques de la chimie atmospherique globale, les reconfigurations disciplinaires et sociales, et l’apparition de nouvelles formes d’expertise et de figures d’expert propres a ce champ d’etude. L’auteur examine dans le detail trois "moments": les deux premieres decennies de la Guerre froide ; le "tournant environnemental(iste)" des sciences de l’atmosphere dans les annees 1970- 80 ; la gouvernance du changement climatique.

Une histoire de la chimie atmosphérique globale

A new system for NO2 detection has been developed for use on the NASA ER-2 aircraft. The system converts NO2 to NO using UV photolysis with the NO product subsequently detected with an on-board chemiluminescence detector. The new system is compact, light weight, has high time resolution (approximately 1 s), and is significantly more efficient then some previous designs. Details of the system design and airborne performance are discussed.

New photolysis system for NO2 measurements in the lower stratosphere

The Middle Atmosphere Nitrogen TRend Assessment (MANTRA) series of high‐altitude balloon flights is being undertaken to investigate changes in the concentrations of northern hemisphere mid‐latitude stratospheric ozone, and of nitrogen and chlorine compounds that play a role in ozone chemistry. Four campaigns have been carried out to date, all from Vanscoy, Saskatchewan, Canada (52°01'N, 107°02'W, 511.0 m). The first MANTRA mission took place in August 1998, with the balloon flight on 24 August 1998 being the first Canadian launch of a large high‐altitude balloon in about fifteen years. The balloon carried a payload of instruments to measure atmospheric composition, and made measurements from a float altitude of 32–38 km for one day. Three of these instruments had been flown on the Stratoprobe flights of the Atmospheric Environment Service (now the Meteorological Service of Canada) in the 1970s and early 1980s, providing a link to historical data predating the onset of mid‐latitude ozone loss. The...

https://www.atmosp.physics.utoronto.ca/MANTRA/publications/Strong_overview_AO_Dec2005.pdf

MANTRA - A balloon mission to study the odd-nitrogen budget of the stratosphere

The stratospheric concentrations of many minor constituents change rapidly at sunrise or sunset. If this happens, there is an inherent error when retrieving the vertical profiles of the constituents from measurements of their absorption of sunlight. For retrievals of NO at sunset the error can be estimated from in-situ measurements alone, without appeal to a model of stratospheric photochemistry. Below 20 km this error can approach 100% so that the retrieved NO is zero. But at 40 km, and at 25 km when the absorption is strong and Lorentzian, it can be less than 20%. Precise calculations of the error, even if small, require model calculations of the sunset and sunrise changes. With a model, we have calculated the error for NO, NO2, OH and ClO.

Measurements of solar occultation - The error in a naive retrieval if the constituent's concentration changes

Major intercomparisons of balloon-borne stratospheric sensors took place in fall 1982 and spring 1983. In each campaign, 4 gondolas were launched close together from Palestine, Texas. Profiles of many constituents were determined by a variety of instruments, both radiometric and spectrometric, some observing the sun and some sensing atmospheric emission. Column amounts of some constituents were determined by supporting spectroscopic measurements from the ground and from aircraft.

Onera

Papers

Intercomparison of Stratospheric Measurements of NO and NO2