Skip to main content

Balloon-borne profile measurements and modelling for studying the chemistry of the lower stratosphere

Exploitable results

The overall rationale of the CHELOSBA project is to characterise the seasonal cycle of a major part of the odd nitrogen (NO(y)) and halogen (ClO(x), BrO(x) and IO) chemicals that promote the stratospheric ozone loss. The investigation is based on remote sensing of the species vertical profiles by means of three different spectroscopic methods differential optical absorption spectroscopy (DOAS), Fourier transform infrared spectrometry (FTIR), Michelson interferometer for passive atmospheric sounding (MIPAS) employed on two balloon platforms. Within the project 9 balloon soundings are performed at middle and high latitudes in different seasons. The measured profiles of the involved species are compared with expectations based on coupled dynamic/photochemical model simulations. From the comparison new information is obtained on the fate of many man-made chemicals released into the atmosphere and their potential effects on the stratospheric ozone layer. In particular, by accurate measurements of the stratospheric BrO abundance (the major inorganic stratospheric Br(y) species at daytime) new constraints on the atmospheric halon burden and the stratospheric photochemistry of bromine is obtained. Or, the simultaneous measurements of a suite of stratospheric NO(y) species (NO, NO(2), N(2)O(5), HNO(2), HNO(3), HNO(3), ClNO(2) together with its major photochemical source gas, N(2)O, serves to assess accurately the stratospheric chemistry of odd nitrogen. In addition, the potential detection of stratospheric IO will allow estimation of the role of iodine-bearing source gases on the stratospheric chemistry of ozone.