Abstract. Atmospheric transport model errors are one of the main
contributors to the uncertainty affecting CO2 inverse flux estimates.
In this study, we determine the leading causes of transport errors over the
US upper Midwest with a large set of simulations generated with the Weather
Research and Forecasting (WRF) mesoscale model. The various WRF simulations
are performed using different meteorological driver datasets and physical
parameterizations including planetary boundary layer (PBL) schemes, land
surface models (LSMs), cumulus parameterizations and microphysics
parameterizations. All the different model configurations were coupled to
CO2 fluxes and lateral boundary conditions from the CarbonTracker
inversion system to simulate atmospheric CO2 mole fractions. PBL
height, wind speed, wind direction, and atmospheric CO2 mole fractions
are compared to observations during a month in the summer of 2008, and
statistical analyses were performed to evaluate the impact of both physics
parameterizations and meteorological datasets on these variables. All of the
physical parameterizations and the meteorological initial and boundary
conditions contribute 3 to 4 ppm to the model-to-model variability in
daytime PBL CO2 except for the microphysics parameterization which has
a smaller contribution. PBL height varies across ensemble members by 300 to
400 m, and this variability is controlled by the same physics
parameterizations. Daily PBL CO2 mole fraction errors are correlated
with errors in the PBL height. We show that specific model configurations
systematically overestimate or underestimate the PBL height averaged across
the region with biases closely correlated with the choice of LSM, PBL
scheme, and cumulus parameterization (CP). Domain average PBL wind speed is overestimated in nearly
every model configuration. Both planetary boundary layer height (PBLH) and PBL wind speed biases show coherent
spatial variations across the Midwest, with PBLH overestimated averaged
across configurations by 300–400 m in the west, and PBL winds overestimated
by about 1 m s−1
on average in the east. We find model configurations with
lower biases averaged across the domain, but no single configuration is
optimal across the entire region and for all meteorological variables. We
conclude that model ensembles that include multiple physics
parameterizations and meteorological initial conditions are likely to be
necessary to encompass the atmospheric conditions most important to the
transport of CO2 in the PBL, but that construction of such an ensemble
will be challenging due to ensemble biases that vary across the region.
Analysis of Boundary Layer Effects Due to Usual Boundary Conditions or Geometrical Defects in Elastic Plates Under Bending: An Improvement of the Love-Kirchhoff Model
