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@PHDTHESIS{Hartick:1018702,
      author       = {Hartick, Carl},
      title        = {{I}ntegrated {T}errestrial {S}imulations over {E}urope:
                      {G}roundwater-{A}tmosphere {F}eedbacks with {A}ltered
                      {W}ater {T}ables {I}ncluding the {E}ffect of {R}ecent
                      {D}roughts},
      school       = {University of Bonn},
      type         = {Dissertation},
      reportid     = {FZJ-2023-04996},
      pages        = {117p},
      year         = {2023},
      note         = {Dissertation, University of Bonn, 2023},
      abstract     = {The groundwater flow is an essential part of the
                      terrestrial system encompassing the atmosphere, land
                      surface, and subsurface. In past research, there was usually
                      no focus on water in the subsurface because climate models
                      worked with simplified free drainage assumptions. However,
                      recent research has shown that the groundwater table has a
                      vital memory function, especially in hydrometeorological
                      extremes. Droughts are remembered for long timescales, but
                      surpluses in groundwater can also mitigate current water
                      deficits. Groundwater can also interact in feedback loops
                      altering the water and energy cycle.Suited to investigate
                      these research questions in a modeling environment is the
                      Terrestrial Systems Modeling Platform (TSMP). TSMP couples
                      an atmospheric, land surface and subsurface model to
                      simulate the whole water cycle from the bedrock to the cloud
                      top. Three studies exploring groundwater interactions
                      utilizing TSMP over Europe are combined in this thesis.
                      First, groundwater memory and predictability are
                      investigated by combining three states of recent droughts
                      with past atmospheric boundary conditions leading to a model
                      ensemble with varying drought initial conditions. The
                      ensemble was simulated for one year resembling atmospheric
                      uncertainty and natural variability. The results show the
                      increased probability of ongoing drought conditions and the
                      dominant influence of the initial condition on the timescale
                      of one year over atmospheric forcing.Secondly, the results
                      of the drought ensembles are compared to the original
                      realization of the years not influenced by drought
                      conditions. The comparison reveals changes in the energy
                      cycle with more available energy at the surface. Together
                      with changes in cloud properties, the results indicate a
                      drought feedback loop where the persisting water deficits
                      contribute to higher and thinner clouds leading to increased
                      incoming shortwave radiation at the ground.Lastly, potential
                      feedback processes between groundwater and precipitation are
                      further investigated, showing that a climatology with a
                      shallower water table due to changed parameters also
                      influences rainfall at the continental scale. This feedback
                      connecting groundwater and precipitation makes calibration
                      impossible in a fully coupled system. Furthermore, the
                      feedback highlights the potential influence of altered water
                      tables due to climate change in the future.The results of
                      this thesis highlight the importance of incorporating
                      groundwater in climate models, especially in
                      hydrometeorological extremes. Significant interactions are
                      observed between all components of the terrestrial system,
                      which would otherwise be overlooked. While including a
                      complex groundwater representation is connected to
                      additional computational costs, feedback processes strongly
                      influencing atmospheric processes are essential for climate
                      projections. Further improvement of the physical
                      representation of numerical models and increased resolutions
                      might additionally emphasize the connections in the future.},
      cin          = {JSC / IBG-3},
      cid          = {I:(DE-Juel1)JSC-20090406 / I:(DE-Juel1)IBG-3-20101118},
      pnm          = {5111 - Domain-Specific Simulation $\&$ Data Life Cycle Labs
                      (SDLs) and Research Groups (POF4-511) / 2173 -
                      Agro-biogeosystems: controls, feedbacks and impact
                      (POF4-217)},
      pid          = {G:(DE-HGF)POF4-5111 / G:(DE-HGF)POF4-2173},
      typ          = {PUB:(DE-HGF)11},
      url          = {https://juser.fz-juelich.de/record/1018702},
}