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@PHDTHESIS{Zhang:1038891,
      author       = {Zhang, Lijie},
      title        = {{M}odelling {S}econdary {C}irculation in {C}onvective
                      {B}oundary {L}ayer {U}sing {L}arge {E}ddy {S}imulation},
      volume       = {652},
      school       = {Bonn},
      type         = {Dissertation},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2025-01702},
      isbn         = {978-3-95806-799-8},
      series       = {Schriften des Forschungszentrums Jülich Reihe Energie $\&$
                      Umwelt / Energy $\&$ Environment},
      pages        = {84},
      year         = {2024},
      note         = {Dissertation, Bonn, 2024},
      abstract     = {Mesoscale secondary circulations, which frequently arise
                      over heterogeneous land surfaces, profoundly influence
                      atmospheric structure and characteristics. Its structure is
                      primarily shaped by the combined effects of wind shear and
                      buoyancy. The turbulence generated by the secondary
                      circulation can considerably influence the fluxes, including
                      estimations employed in the Monin–Obukhov similarity
                      theory and measurements in eddy covariance systems. An
                      ever-increasing body of evidence points to secondary
                      circulations as the primary source of the reported
                      underestimation of heat flux (i.e., flux imbalance, FI) by
                      $10\%$ to $30\%$ across various sites. A series of large
                      eddy simulations (LES) were conducted in this PhD work to
                      investigate the formation of secondary circulations under
                      different conditions and to quantify its impact on flux
                      estimations. These included one-dimensional strip-like soil
                      moisture distribution with ambient wind speeds ranging from
                      0.5 𝑚𝑚𝑠𝑠−1 to 16 𝑚𝑚𝑠𝑠−1 in
                      various wind directions (Chapter 3), two-dimensional
                      checkerboard soil moisture distribution with heterogeneous
                      scales varying from 50 m to 2,400 m (Chapter 4). A secondary
                      circulation strength metric is proposed and found to have a
                      positive correlation with the Bowen ratio and heterogeneity
                      parameter, and a negative correlation with wind speeds when
                      the wind direction is perpendicular to the direction of
                      heterogeneity. It was observed that as the strength of the
                      secondary circulation increased, the turbulent heat flux
                      decreased, maintaining the same soil moisture conditions.
                      Two distinct secondary circulation schemes are identified
                      based on the heterogeneity scale: thermallyinduced secondary
                      circulations (TMCs) and turbulent organized structures
                      (TOS). The results of the LES were used to evaluate four
                      selected FI prediction models. These models demonstrated an
                      ability to capture the FI accurately. A novel first-order
                      nonlocal turbulence closure scheme has been proposed
                      (Chapter 5), namely the flux imbalance and K-theory (FLIMK),
                      which employs the FI prediction model to account for the
                      nonlocal processes and the conventional K-theory for the
                      local processes. The FLIMK scheme has been demonstrated to
                      reduce the flux imbalance from $15\%$ to $6\%$ in LES and
                      from $16\%$ to $6.7\%$ in numerical weather prediction (NWP)
                      models.},
      cin          = {IBG-3},
      cid          = {I:(DE-Juel1)IBG-3-20101118},
      pnm          = {2173 - Agro-biogeosystems: controls, feedbacks and impact
                      (POF4-217)},
      pid          = {G:(DE-HGF)POF4-2173},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
      urn          = {urn:nbn:de:0001-2502130838099.131982955189},
      doi          = {10.34734/FZJ-2025-01702},
      url          = {https://juser.fz-juelich.de/record/1038891},
}