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Comparing Lagrangian and Eulerian models for CO 2 transport-a step towards Bayesian inverse modeling using WRF/STILT-VPRM

Pillai, D.; Gerbig, C.; Kretschmer, R.; Beck, V.; Karstens, U. LU ; Neininger, B. and Heimann, M. (2012) In Atmospheric Chemistry and Physics 12(19). p.8979-8991
Abstract

We present simulations of atmospheric CO 2 concentrations provided by two modeling systems, run at high spatial resolution: the Eulerian-based Weather Research Forecasting (WRF) model and the Lagrangian-based Stochastic Time-Inverted Lagrangian Transport (STILT) model, both of which are coupled to a diagnostic biospheric model, the Vegetation Photosynthesis and Respiration Model (VPRM). The consistency of the simulations is assessed with special attention paid to the details of horizontal as well as vertical transport and mixing of CO 2 concentrations in the atmosphere. The dependence of model mismatch (Eulerian vs. Lagrangian) on models' spatial resolution is further investigated. A case study using airborne... (More)

We present simulations of atmospheric CO 2 concentrations provided by two modeling systems, run at high spatial resolution: the Eulerian-based Weather Research Forecasting (WRF) model and the Lagrangian-based Stochastic Time-Inverted Lagrangian Transport (STILT) model, both of which are coupled to a diagnostic biospheric model, the Vegetation Photosynthesis and Respiration Model (VPRM). The consistency of the simulations is assessed with special attention paid to the details of horizontal as well as vertical transport and mixing of CO 2 concentrations in the atmosphere. The dependence of model mismatch (Eulerian vs. Lagrangian) on models' spatial resolution is further investigated. A case study using airborne measurements during which two models showed large deviations from each other is analyzed in detail as an extreme case. Using aircraft observations and pulse release simulations, we identified differences in the representation of details in the interaction between turbulent mixing and advection through wind shear as the main cause of discrepancies between WRF and STILT transport at a spatial resolution such as 2 and 6 km. Based on observations and inter-model comparisons of atmospheric CO 2 concentrations, we show that a refinement of the parameterization of turbulent velocity variance and Lagrangian time-scale in STILT is needed to achieve a better match between the Eulerian and the Lagrangian transport at such a high spatial resolution (e.g. 2 and 6 km). Nevertheless, the inter-model differences in simulated CO 2 time series for a tall tower observatory at Ochsenkopf in Germany are about a factor of two smaller than the model-data mismatch and about a factor of three smaller than the mismatch between the current global model simulations and the data. © 2012 Author(s).

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publishing date
type
Contribution to journal
publication status
published
subject
in
Atmospheric Chemistry and Physics
volume
12
issue
19
pages
13 pages
publisher
Copernicus Gesellschaft Mbh
external identifiers
  • scopus:84869043646
ISSN
1680-7316
DOI
10.5194/acp-12-8979-2012
language
English
LU publication?
no
id
836e0375-26a0-4ac7-b227-0f843a65c36c
date added to LUP
2016-08-31 11:02:39
date last changed
2017-03-16 14:19:24
@article{836e0375-26a0-4ac7-b227-0f843a65c36c,
  abstract     = {<p>We present simulations of atmospheric CO <sub>2</sub> concentrations provided by two modeling systems, run at high spatial resolution: the Eulerian-based Weather Research Forecasting (WRF) model and the Lagrangian-based Stochastic Time-Inverted Lagrangian Transport (STILT) model, both of which are coupled to a diagnostic biospheric model, the Vegetation Photosynthesis and Respiration Model (VPRM). The consistency of the simulations is assessed with special attention paid to the details of horizontal as well as vertical transport and mixing of CO <sub>2</sub> concentrations in the atmosphere. The dependence of model mismatch (Eulerian vs. Lagrangian) on models' spatial resolution is further investigated. A case study using airborne measurements during which two models showed large deviations from each other is analyzed in detail as an extreme case. Using aircraft observations and pulse release simulations, we identified differences in the representation of details in the interaction between turbulent mixing and advection through wind shear as the main cause of discrepancies between WRF and STILT transport at a spatial resolution such as 2 and 6 km. Based on observations and inter-model comparisons of atmospheric CO <sub>2</sub> concentrations, we show that a refinement of the parameterization of turbulent velocity variance and Lagrangian time-scale in STILT is needed to achieve a better match between the Eulerian and the Lagrangian transport at such a high spatial resolution (e.g. 2 and 6 km). Nevertheless, the inter-model differences in simulated CO <sub>2</sub> time series for a tall tower observatory at Ochsenkopf in Germany are about a factor of two smaller than the model-data mismatch and about a factor of three smaller than the mismatch between the current global model simulations and the data. © 2012 Author(s).</p>},
  author       = {Pillai, D. and Gerbig, C. and Kretschmer, R. and Beck, V. and Karstens, U. and Neininger, B. and Heimann, M.},
  issn         = {1680-7316},
  language     = {eng},
  number       = {19},
  pages        = {8979--8991},
  publisher    = {Copernicus Gesellschaft Mbh},
  series       = {Atmospheric Chemistry and Physics},
  title        = {Comparing Lagrangian and Eulerian models for CO 2 transport-a step towards Bayesian inverse modeling using WRF/STILT-VPRM},
  url          = {http://dx.doi.org/10.5194/acp-12-8979-2012},
  volume       = {12},
  year         = {2012},
}