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O3, NO2, CH2O, O4, BrO, OCIO, IO and OIO profile measurements in the upper troposphere and lower stratosphere aboard balloon (MIPAS-B and LPMA) and aircraft (Geophysica) platforms

Subject Area Atmospheric Science
Term from 2006 to 2014
Project identifier Deutsche Forschungsgemeinschaft (DFG) - Project number 18120532
 
Final Report Year 2014

Final Report Abstract

The present project addressed the development of airborne UV/vis/near IR absorbing miniDOAS limb instruments, and their deployment on research aircrafts (DLR-Falcon, Geophysica, and NASA Global Hawk) and high-flying research balloons into the lower and middle atmosphere. The instruments are able to measure time and space-dependent vertical profiles of some critical radicals and trace gases (e.g., O3, HONO, NO2, C2H2O2, CH2O, O4, BrO, OClO, IO, and OIO) in the targeted atmospheric region. Within the project, some key features of the miniDOAS instrument were improved, such as (a) its low weight and power consumption which was necessary due to limitations with the host vehicles, (b) a stable optical imaging for in largely changing ambient conditions (temperature and pressures), as well as (c) an actively control of the telescope pointing for all miniDOAS instruments assembled on host vehicles providing their attitude data to scientific users. Also predictions of a fully spherical and refractive radiative transfer (RT) model were validated by field observations made within the project. The thus validated RT model was also extensively used to forward model of (each) limb measurement. Further a scattering code was developed which in future may help to interpret the near IR limb measurements with respect to the optical properties, size and shape of liquid and solid particles. Finally, in support of the data evaluation and the profile retrieval, a master retrieval algorithm was developed which includes measured and ‘a priori’ information either obtained from complementary sensors assembled on the same host vehicle, or from process oriented and/or global models, as well as other external information (atmospheric temperature and pressure, solar zenith and azimuth angles, altitude, yaw, pitch and roll angle of the host payload, et cetera) necessary in the data retrieval. Major scientific applications of the airborne UV/vis/near IR limb technique included studies on the photochemistry and kinetics of halogen and nitrogen oxides in the stratosphere, trend assessment of the ozone-depleting halogens bromine and iodine, the photochemistry and budget of bromine (and eventually iodine) within the tropical tropopause layer, detection of halogen oxides within the polar and tropical troposphere as well as of some key intermediates in the oxidation chain of volatile organic compounds. Using the data collected within the present project, ongoing and future studies may not only address yet unexplored photochemical processes but also microphysical and radiative processes relevant for climate change, such as the formation of sub-visible cirrus within the tropical tropopause layer, the radiative transfer in mixed-phased clouds, or aerosol-cloud interactions in polluted and unpolluted air masses.

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