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@ARTICLE{Hottmann:890288,
      author       = {Hottmann, Bettina and Hafermann, Sascha and Tomsche, Laura
                      and Marno, Daniel and Martinez, Monica and Harder, Hartwig
                      and Pozzer, Andrea and Neumaier, Marco and Zahn, Andreas and
                      Bohn, Birger and Stratmann, Greta and Ziereis, Helmut and
                      Lelieveld, Jos and Fischer, Horst},
      title        = {{I}mpact of the {S}outh {A}sian monsoon outflow on
                      atmospheric hydroperoxides in the upper troposphere},
      journal      = {Atmospheric chemistry and physics},
      volume       = {20},
      number       = {21},
      issn         = {1680-7324},
      address      = {Katlenburg-Lindau},
      publisher    = {EGU},
      reportid     = {FZJ-2021-00869},
      pages        = {12655 - 12673},
      year         = {2020},
      abstract     = {During the OMO (Oxidation Mechanism Observation) mission,
                      trace gas measurements were performed on board the HALO
                      (High Altitude Long Range) research aircraft in summer 2015
                      in order to investigate the outflow of the South Asian
                      summer monsoon and its influence on the composition of the
                      Asian monsoon anticyclone (AMA) in the upper troposphere
                      over the eastern Mediterranean and the Arabian Peninsula.
                      This study focuses on in situ observations of hydrogen
                      peroxide (H2O2obs) and organic hydroperoxides (ROOHobs) as
                      well as their precursors and loss processes. Observations
                      are compared to photostationary-state (PSS) calculations of
                      H2O2PSS and extended by a separation of ROOHobs into methyl
                      hydroperoxide (MHPPSS) and inferred unidentified
                      hydroperoxide (UHPPSS) mixing ratios using PSS calculations.
                      Measurements are also contrasted to simulations with the
                      general circulation ECHAM–MESSy for Atmospheric Chemistry
                      (EMAC) model. We observed enhanced mixing ratios of H2O2obs
                      $(45 \%),$ MHPPSS $(9 \%),$ and UHPPSS $(136 \%)$ in
                      the AMA relative to the northern hemispheric background.
                      Highest concentrations for H2O2obs and MHPPSS of 211 and
                      152 ppbv, respectively, were found in the tropics outside
                      the AMA, while for UHPPSS, with 208 pptv, highest
                      concentrations were found within the AMA. In general, the
                      observed concentrations are higher than steady-state
                      calculations and EMAC simulations by a factor of 3 and 2,
                      respectively. Especially in the AMA, EMAC underestimates the
                      H2O2EMAC (medians: 71 pptv vs. 164 pptv) and ROOHEMAC
                      (medians: 25 pptv vs. 278 pptv) mixing ratios.
                      Longitudinal gradients indicate a pool of hydroperoxides
                      towards the center of the AMA, most likely associated with
                      upwind convection over India. This indicates main
                      contributions of atmospheric transport to the local budgets
                      of hydroperoxides along the flight track, explaining strong
                      deviations from steady-state calculations which only account
                      for local photochemistry. Underestimation of H2O2EMAC by
                      approximately a factor of 2 in the Northern Hemisphere (NH)
                      and the AMA and overestimation in the Southern Hemisphere
                      (SH; factor 1.3) are most likely due to uncertainties in the
                      scavenging efficiencies for individual hydroperoxides in
                      deep convective transport to the upper troposphere,
                      corroborated by a sensitivity study. It seems that the
                      observed excess UHPPSS is excess MHP transported to the west
                      from an upper tropospheric source related to convection in
                      the summer monsoon over Southeast Asia.},
      cin          = {IEK-8},
      ddc          = {550},
      cid          = {I:(DE-Juel1)IEK-8-20101013},
      pnm          = {243 - Tropospheric trace substances and their
                      transformation processes (POF3-243)},
      pid          = {G:(DE-HGF)POF3-243},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000584387800003},
      doi          = {10.5194/acp-20-12655-2020},
      url          = {https://juser.fz-juelich.de/record/890288},
}