Decadal evaluation of regional climate, air quality, and their interactions over the continental US and their interactions using WRF/Chem version 3.6.1
The Weather Research and Forecasting model with Chemistry (WRF/Chem) v3.6.1 with the Carbon Bond 2005 (CB05) gas-phase mechanism is evaluated for its first decadal application during 2001–2010 using the Representative Concentration Pathway 8.5 (RCP 8.5) emissions to assess its capability and appropr...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-02-01
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| Series: | Geoscientific Model Development |
| Online Access: | http://www.geosci-model-dev.net/9/671/2016/gmd-9-671-2016.pdf |
| Summary: | The Weather Research and Forecasting model with Chemistry (WRF/Chem) v3.6.1
with the Carbon Bond 2005 (CB05) gas-phase mechanism is evaluated for its
first decadal application during 2001–2010 using the Representative
Concentration Pathway 8.5 (RCP 8.5) emissions to assess its capability and
appropriateness for long-term climatological simulations. The initial and
boundary conditions are downscaled from the modified Community Earth System
Model/Community Atmosphere Model (CESM/CAM5) v1.2.2. The meteorological
initial and boundary conditions are bias-corrected using the National Center
for Environmental Protection's Final (FNL) Operational Global Analysis data.
Climatological evaluations are carried out for meteorological, chemical, and
aerosol–cloud–radiation variables against data from surface networks and
satellite retrievals. The model performs very well for the 2 m temperature
(T2) for the 10-year period, with only a small cold bias of
−0.3 °C. Biases in other meteorological variables including
relative humidity at 2 m, wind speed at 10 m, and precipitation tend to be
site- and season-specific; however, with the exception of T2, consistent
annual biases exist for most of the years from 2001 to 2010. Ozone mixing
ratios are slightly overpredicted at both urban and rural locations with a
normalized mean bias (NMB) of 9.7 % but underpredicted at rural locations
with an NMB of −8.8 %. PM<sub>2.5</sub> concentrations are moderately
overpredicted with an NMB of 23.3 % at rural sites but slightly
underpredicted with an NMB of −10.8 % at urban/suburban sites. In
general, the model performs relatively well for chemical and meteorological
variables, and not as well for aerosol–cloud–radiation variables.
Cloud-aerosol variables including aerosol optical depth, cloud water path,
cloud optical thickness, and cloud droplet number concentration are generally
underpredicted on average across the continental US. Overpredictions of
several cloud variables over the eastern US result in underpredictions of
radiation variables (such as net shortwave radiation – GSW – with a mean
bias – MB – of −5.7 W m<sup>−2</sup>) and overpredictions of shortwave and
longwave cloud forcing (MBs of ∼ 7 to 8 W m<sup>−2</sup>), which are
important climate variables. While the current performance is deemed to be
acceptable, improvements to the bias-correction method for CESM downscaling
and the model parameterizations of cloud dynamics and thermodynamics, as well
as aerosol–cloud interactions, can potentially improve model performance for
long-term climate simulations. |
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| ISSN: | 1991-959X 1991-9603 |