TY  - THES
AU  - Clemens, Jan Heinrich
TI  - Multi-scenario, high-resolution Lagrangian transport modeling for the analysis of the Asian tropopause aerosol layer
VL  - 648
PB  - Bergische Universität Wuppertal
VL  - Dissertation
CY  - Jülich
M1  - FZJ-2024-00660
SN  - 978-3-95806-792-9
T2  - Reihe Energie & Umwelt / Energy & Environment
SP  - 143
PY  - 2024
N1  - Dissertation, Bergische Universität Wuppertal, 2023
AB  - The Asian tropopause aerosol layer (ATAL) is a layer of polluted air above Asia duringthe summer monsoon season, which has a global and regional impact on climate. Thesource regions that contribute to the formation of the ATAL are still under discussion. Thisthesis investigates the source regions and transport pathways of the ATAL in 2016 overNainital (India) with the help of a multi-scenario Lagrangian backward transport analysisof balloon-borne measurements using two Lagrangian transport models, the MPTRACand the CLaMS, and the high-resolution ERA5 reanalysis Transport from the planetary boundary layer to the ATAL is characterized by fast ver-tical transport (e.g. by convection) in the troposphere and subsequent slow diabatic up-ward transport and large-scale horizontal transport in the upper troposphere and lowerstratosphere. Therefore, in this thesis, the Lagrangian transport model MPTRAC wasequipped with diabatic transport calculations, which are known to improve calculations inthe stratosphere. Due to the high computational performance of MPTRAC, it allows theemployment of a large number of scenarios with the ERA5 reanalysis. Vertical transportprocesses can be better resolved by the high resolution of ERA5, and the large numberof scenarios provides a comprehensive picture of robust results and remaining uncer-tainties. MPTRAC also contains parameterizations of convection and unresolved winds.The transport scheme built into MPTRAC was evaluated in detail by comparing it withthe transport scheme of CLaMS. In this thesis, it is shown that MPTRAC and CLaMSwith ERA5 have negligible deviations from each other compared to uncertainties suchas reanalysis uncertainties. Furthermore, it is shown that diabatic transport calculationswith the fully resolved ERA5 reanalysis cannot be replaced by kinematic calculations orcalculations with a larger grid width without significant differences, which corroborates thetransition to optimized models with diabatic, fully resolved calculations.The optimized models were used to determine the source regions and transport path-ways that influenced the measurements over Nainital. It was shown that despite the large uncertainties related to vertical velocity approaches, resolved and parameterized convec-tion, and reanalyses, the largest air mass contribution originates from the Indo-GangeticPlain, the Tibetan Plateau, and the foothills of the Himalayas. However, the analysis alsoshowed that uncertainties remain about the role of local, unresolved convection over theIndo-Gangetic Plain and the foothills of the Himalayas, as well as in relation to convectionover China. The correlation between the backscattering strength of the ATAL during themeasurement campaign in August and the contributions from different regions providesan indication as to what influence different regions have on the ATAL. Using all scenar-ios, it was robustly shown that increasing contributions from the Tropical Western Pacific,which was under the influence of tropical storms, correlate with a decrease in the mea-sured backscatter. Wide but not complete agreement was found for the Indo-GangeticPlain; larger contributions from this region are positively correlated with the backscatter-ing of the ATAL. In contrast to previous studies, no robust correlation could be foundbetween the backscatter and the contributions from the Tibetan Plateau, which showsthe strength of the presented multi-scenario analysis, i.e., the exposure of existing uncer-tainties. Overall, the analysis emphasizes the role of anthropogenic source regions onthe Indian subcontinent in the formation of the ATAL over Nainital.
LB  - PUB:(DE-HGF)3 ; PUB:(DE-HGF)11
DO  - DOI:10.34734/FZJ-2024-00660
UR  - https://juser.fz-juelich.de/record/1021219
ER  -