the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Updates and evaluation of NOAA’s online-coupled air quality model version 7 (AQMv7) within the Unified Forecast System
Abstract. Air quality forecasting system is an essential tool widely used by environmental managers to mitigate adverse health effects of air pollutants. This work presents the latest development of the next generation regional air quality model (AQM) forecast system within the Unified Forecast System (UFS) framework in the National Oceanic and Atmospheric Administration (NOAA). The UFS air quality model incorporates the U.S. Environmental Protection Agency (EPA)’s Community Multiscale Air Quality (CMAQ) model as its main chemistry component. In this system, CMAQ is integrated as a column model to solve gas and aerosol chemistry while the transport of chemical species is processed by UFS. The current AQM version 7 (AQMv7) is coupled with an earlier version of CMAQ (version 5.2.1). Here we describe the development of the updated AQMv7 by coupling to a ‘state-of-the-science’ CMAQ version 5.4. The updates include improvements in gas and aerosol chemistry, dry deposition processes, and structural changes to the Input/Output (IO) interface, enhancing both computational efficiency and the representation of air-surface exchange processes. A simulation was conducted for the period of August 2023 to assess the effects of these updates on the forecast performance of ozone (O3) and fine particulate matter (PM2.5), two major air pollutants over the continental United States (CONUS). The results show that the updated model demonstrates a significantly enhanced capability in simulating O3 over the CONUS by reducing the positive bias during both day and night, leading to a reduction of the mean bias by 50 % and 72 % for hourly and the maximum daily 8-hour average O3, respectively. Spatially, the updated model lowers the positive bias of hourly O3 in all of the ten EPA regions, particularly within the Great Plains. Similarly, the updates induce uniformly lower fine particulate matter (PM2.5) concentrations across the CONUS domain, reducing the positive bias in the northeast and central Great Plain and exacerbating the negative bias in the west and south. The updated model does not improve model performance for PM2.5 in the vicinity of fire emission sources as compared to AQMv7, thus indicating a focal point of model uncertainty and needed improvement. Despite these challenges, the study highlights the importance of the ongoing refinements for reliable air quality predictions from the UFS-AQM model, which is the future replacement of NOAA’s current operational air quality forecast system.
- Preprint
(2106 KB) - Metadata XML
-
Supplement
(1421 KB) - BibTeX
- EndNote
Status: final response (author comments only)
-
RC1: 'Comment on gmd-2024-107', Anonymous Referee #1, 23 Jul 2024
The manuscript “Updates and evaluation of NOAA’s online-coupled air quality model version 7 (AQMv7) within the Unified Forecast System” provides a thorough evaluation of the updated NOAA’s air quality model version 7 (AQMv7) within the Unified Forecast System (UFS), incorporating the recent scientific improvements from the CMAQv5.4. The authors conducted two experiments in August 2023 to assess the performance of updates. The updated version (AQMv7_new) significantly improved the spatial and temporal persistent high positive biases of the ozone mixing ratios. The AQMv7_new demonstrated reduced PM2.5 in all regions of Contiguous United States (CONUS). This study indicates that the community air quality model of CMAQ could be well accommodated in the UFS-AQM framework. This manuscript is well written, and offers a valuable contribution into the evolution of NOAA’s air quality models. Therefore, it is recommended to accept this manuscript after addressing some minor revisions.
Minor Revisions:
- Is there aerosol/chemistry feedback to the host atmospheric model in AQMv7 and AQMv7_new?
- The wet deposition is also very important for the aerosol and chemical processes. However, the wet deposition is not mentioned in this manuscript. What kind of wet deposition is used in AQMv7_new?
- Lines 104-105: “while other transport terms, such as advection and diffusion, are more appropriately handed in the FV3 physics”. Please clarify whether the advection and diffusion are handled in the FV3 physics or dynamics?
- Line 409: replace "AQMv_new" with "AQMv7_new” for consistency.
Citation: https://doi.org/10.5194/gmd-2024-107-RC1 -
RC2: 'Comment on gmd-2024-107', Anonymous Referee #2, 10 Sep 2024
Overview
The paper reports on an update of the CMAQ model with respect to chemistry and dry deposition. CMAQ is used as column model as part of UFS air quality forecasting system. The model changes are described and the performance of the UFS air quality forecast with and without the CMAQ update are evaluated with surface ozone and PM2.5 concentrations over the CONUS for August 2023. The evaluation shows reduced ozone and PM2.5 concentrations with the upgrade, which means an improved performance for ozone and more mixed results for PM2.5
General comments
The paper is clear and well written and gives a good overview of the model updates.
A considerable limitation of the the paper is the evaluation period (August 2023) of just one month in summer. At least a winter month needs to be included to fully understand the impact of the changes for PM2.5. After all, the UFS air quality forecasting system is an operational system that probably runs continuously over the whole year. Also, some of the discussed changes to ozone deposition over snow can only be evaluated in a winter period. I also believe that one month is too short to derive robust statistics. So it is recommended as good scientific practise to do the evaluation evaluation for a 3-months summer and winter period. It is also worth considering that the chosen month was affected by wildfire emissions but none of the upgraded elements seemed to have the potential to improve the AQ forecast in a wildfire dominated situation.
Specific comments:
L 124: Please provider more details on this aspect. Is this a deposition term or a gas-phase chemistry term ?
L 143: Is the increase in organic aerosol and PM2.5 primarily confirmed by the evaluation with PM2.5 observations?
L 151: The impact of this change can only be demonstrated with a wintertime simulation.
L 160: Please provide here or in table 1 information about the used land cover and vegetation data
L 216: Please provide more details on the calculation of the IOA
L 235: Including an evaluation of the meteorology is an interesting aspect and I would recommend to move some plots from the appendix to the main paper. Please confirm that the error of the meteorological fields is exactly the same for both the reference and the upgrade. Please add more details what ozone and PM2.5 error are mostly likely to be introduced by the increased stability. Is there a possibility that the CMAQ upgrades compensates error coming from the meteorology ?
L 305. Please discuss in more detail the contributions from deposition and or halogen chemistry. I got the impression halogen chemistry is more important in coastal areas.
L 433 Please mention earlier that the fire emissions do not include an VOC, or even not other gases ?
Citation: https://doi.org/10.5194/gmd-2024-107-RC2
Viewed
HTML | XML | Total | Supplement | BibTeX | EndNote | |
---|---|---|---|---|---|---|
376 | 130 | 27 | 533 | 40 | 10 | 13 |
- HTML: 376
- PDF: 130
- XML: 27
- Total: 533
- Supplement: 40
- BibTeX: 10
- EndNote: 13
Viewed (geographical distribution)
Country | # | Views | % |
---|
Total: | 0 |
HTML: | 0 |
PDF: | 0 |
XML: | 0 |
- 1