A comparative study of two-way and offline coupled WRF v3.4 and CMAQ v5.0.2 over the contiguous US: performance evaluation and impacts of chemistry–meteorology feedbacks on air quality

Wang, Kai; Zhang, Yang; Yu, Shaocai; Wong, David C.; Pleim, Jonathan; Mathur, Rohit; Kelly, James T.; Bell, Michelle

doi:https://doi.org/10.5194/gmd-14-7189-2021

Articles | Volume 14, issue 11

https://doi.org/10.5194/gmd-14-7189-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/gmd-14-7189-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 14, issue 11

Model evaluation paper

|

26 Nov 2021

Model evaluation paper |

| 26 Nov 2021

A comparative study of two-way and offline coupled WRF v3.4 and CMAQ v5.0.2 over the contiguous US: performance evaluation and impacts of chemistry–meteorology feedbacks on air quality

Kai Wang, Yang Zhang, Shaocai Yu, David C. Wong, Jonathan Pleim, Rohit Mathur, James T. Kelly, and Michelle Bell

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Final revised paper (published on 26 Nov 2021)
Supplement to the final revised paper
Preprint (discussion started on 03 Sep 2020)
Supplement to the preprint

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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- Supplement

RC1: 'comment on gmd-2020-218', Anonymous Referee #1, 01 Oct 2020
- AC1: 'Reply on RC1', Kai Wang, 15 Jul 2021
RC2: 'Review of Wang et al. - A Comparative Study of Two-way and Offline Coupled WRF v3.4 and CMAQ v5.0.2 over the Contiguous U.S.: Performance Evaluation and Impacts of Chemistry-Meteorology Feedbacks on Air Quality', Anonymous Referee #2, 28 Oct 2020
- AC2: 'Reply on RC2', Kai Wang, 15 Jul 2021

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

AR by Kai Wang on behalf of the Authors (16 Jul 2021) Author's response Author's tracked changes Manuscript

ED: Referee Nomination & Report Request started (02 Aug 2021) by Tim Butler

RR by Anonymous Referee #1 (12 Aug 2021)

Suggestions for revision or reasons for rejection

General Comments:
The revised manuscript ‘A comprehensive study of two-way and offline coupled WRF v3.4 and CMAQ v5.0.2 over the contiguous U.S.: Performance evaluation and impacts of chemistry-meteorology feedbacks on air quality’ presented the comprehensive comparison of offline (i.e., traditional) CMAQ and two-way coupled CMAQ over the CONUS. I appreciate the authors’ work to address my concerns, especially by adding the trend analysis. As commented by other reviewer, seasonal analysis has been added and figures are replaced appropriately in the supplemental material. The presentation quality has been significantly improved from original version. Here I have two further comments on the revised manuscript. Please clarify these issues.

1. Long-term trends of meteorology and pollutants: I appreciate to include 5-yr trends analysis in the revised manuscript. The additional discussion in Fig. 3 is important to consider the modeling performances. In the discussion of trends in PM2.5, the authors stated that “Overall, the model performs well for PM2.5 for most of years and better over CSN than IMPROVE sites with general underpredictions in most years. The observations for both CSN and IMPROVE show a general decreasing trend (except for 2010 over CSN) especially over IMPROVE sites.”. I impressed different understanding in this trend found over CSN. I guess CSN also showed gradual decreasing trend from 2008 to 2012 but the year of 2009 posed strong drop. This lower value found in 2009 is consistently seen both by model and observation, but interestingly, IMPROVE sites did not the drop on 2009. If there is specific reason to cause this drop, it is useful to include the short statement on this feature.

2. Satellite data comparison for column abundant: I understood that AK is not considered and only the valid pixels by satellite observations are considered when paring model results. However, for example as shown in Fig. 12, satellite observed NO2 and HCHO showed deficit at northern border of domain (over Canada) whereas model calculated values over this area. If the deficit is treated as same in model analysis, the deficit (marked by white color in this figure) grid should be consistent (this concern is also noticed on AOD presented in Fig. 4 and CDNC presented in Figs. 6 and 7). It is highly recommended to confirm the analysis procedure again. Regarding this figure, winter time HCHO posed inhomogeneous signals. In the revised manuscript, “except for column HCHO in winter” is stated in line 553 (track-mode), but is the satellite measurement itself reliable?

Technical points:
Fig. 2: It is better to add DJF and JJA for the legend of TMPA and PRISM.
Fig. 3: The title of y-axis shown as “RH” should be “RH2” to be consistent in the discussion in main text.

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ED: Publish subject to minor revisions (review by editor) (12 Aug 2021) by Tim Butler

AR by Kai Wang on behalf of the Authors (26 Aug 2021) Author's response Author's tracked changes Manuscript

ED: Publish as is (30 Aug 2021) by Tim Butler

AR by Kai Wang on behalf of the Authors (09 Sep 2021)

Short summary

The two-way coupled WRF-CMAQ model accounting for complex chemistry–meteorology feedbacks has been applied to the long-term predictions of regional meteorology and air quality over the US. The model results show superior performance and importance of chemistry–meteorology feedbacks when compared to the offline coupled WRF and CMAQ simulations, which suggests that feedbacks should be considered along with other factors in developing future model applications to inform policy making.