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Projekt Druckansicht

DOAS Messungen von der NASA Global Hawk während des NASA-ATTREX Projektes

Fachliche Zuordnung Physik und Chemie der Atmosphäre
Förderung Förderung von 2013 bis 2017
Projektkennung Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 242853511
 
Erstellungsjahr 2018

Zusammenfassung der Projektergebnisse

Within the present project, a novel mini-DOAS instrument was assembled and successfully deployed on the Global Hawk in support of the NASA ATTREX missions (https://www.nasa.gov/centers/ames/events/2013/attrex.html). Within the NASA ATTREX project, three research campaigns were performed including 15 research flights of the Global Hawk, which flew into the tropical tropopause layer of the eastern and western Pacific (in late 2011, early 2013 and 2014). During all ATTREX missions the mini-DOAS instrument performed well, so that the collected data could be processed for the detection of the essential absorbers in the UV/vis/nearIR spectral range (e.g., O2, O3, O4, NO2, BrO, gaseous H2O and ice) expected in the TTL. All of this work was done in close cooperation with Prof. Jochen Stutz at the University of California, Los Angeles (UCLA), USA. Considerable progress has been made in the following major areas: (1) The retrieval mixing ratios (or absolute concentrations) of the targeted species under all (clear and cloudy) skies from UV/vis/nearIR skylight monitored in limb direction. Noteworthy to be reminded of here is that the interpretation of UV/vis/nearIR limb observations is rather challenging since (the a priori unconstrained) multiple scattering of skylight due to the presence of varying amounts of aerosols and clouds complicates the calculations of realistic photon path length distributions necessary to calculate absolute concentrations (molecules/cm3) from measured slant column amounts. Therefore, two novel retrieval methods, i.e. the scaling method designed for the interpretation of measurements in UV/visible spectral range, and a full spectral fit method for the interpretation of the measurements in the nearIR spectral range were developed and tested within the project. (2) From the concentration of O3, NO2, and BrO, the adopted photochemistry of ozone, NOx/NOy and of reactive bromine was tested, and inorganic bromine (Bryinorg) was inferred for the TTL. Furthermore, from the combination of our inferred Bryinorg with the simultaneous measurements of all relevant organic brominated source gases, for the first time novel information on the relative influx of CH3Br, the halons, very short-lived species (VSLS) and Bryinorg into the lowermost tropical stratosphere could be inferred. This aspect is rather exciting since TTL composition largely determines the composition of the whole stratosphere. In addition, the PhD thesis of Lisa Scalone addressed the first retrieval of the optical thickness and ice water content for TTL cirrus clouds using a full spectral fit in the nearIR spectral range. Even though her study primarily addressed the feasibility of such an approach, the obtained results are exciting in that the understanding of UV/vis/nearIR spectra provide the most direct approach to elucidate the short-wave forcing of the TTL cirrus, known to be an important ingredient for the global climate. Finally, the results obtained within the present project also served to validate the agreements made under international Protocol of Montreal 1987 and its amendments. Hence the results obtained during the present project are also reported in the upcoming ‘Assessment of Stratospheric Ozone’, published by the World Meteorological Organization/United Nation Environmental Programme (WMO/UNEP), later in 2018.

Projektbezogene Publikationen (Auswahl)

 
 

Zusatzinformationen

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