the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 05 Nov 2024
Sensitivity Studies of Four‐Dimensional Local Ensemble Transform Kalman Filter Coupled With WRF-Chem Version 3.9.1 for Improving Particulate Matter Simulation Accuracy
Abstract. Accurately simulate severe haze events through numerical models remains challenging because of uncertainty in anthropogenic emissions and physical parameterizations of particulate matter (PM2.5 and PM10). In this study, a coupled WRF-Chem/four-dimension local ensemble transform Kalman filter (4D-LETKF) data assimilation system has been successfully developed to optimize particulate matter concentration by assimilating hourly ground-based observations in winter over the Beijing-Tianjin-Hebei region and surrounding provinces. The effectiveness of 4D-LETKF system and its sensitivity to ensemble member size and length of assimilation window have been investigated. The promising results show that significant improvements have been made by analysis in the simulation of particulate matter during severe haze event. The assimilation reduces root mean square errors of PM2.5 from 69.93 to 31.19 µg m-3 and of PM10 from 106.88 to 76.83µg m-3. Smaller RMSEs and larger correlation coefficients in the analysis of PM2.5 and PM10 are observed across nearly all verification stations, indicating that the 4D-LETKF assimilation optimizes the simulation of PM2.5 and PM10 concentration efficiently. Sensitivity experiments reveal that the combination of 48 hours of assimilation window length and 40 ensemble members shows best performance for reproducing severe haze event. In view of the performance of ensemble members, increasing ensemble member size improves divergence among each forecasting member, facilitates the spread of state vectors about PM2.5 and PM10 information in the first guess, favors the variances between each initial condition in the next assimilation cycle and leads to better simulation performance both in severe and moderate haze events. This study advances our understanding about the selection of basic parameters in the 4D-LETKF assimilation system and the performance of ensemble simulation in a particulate matter polluted environment.
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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Preprint
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Supplement
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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Supplement
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- Final revised paper
Journal article(s) based on this preprint
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2024-3321', Anonymous Referee #1, 24 Dec 2024
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AC1: 'Reply on RC1', Lin jianyu, 24 Jan 2025
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2024/egusphere-2024-3321/egusphere-2024-3321-AC1-supplement.pdf
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AC1: 'Reply on RC1', Lin jianyu, 24 Jan 2025
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RC2: 'Comment on egusphere-2024-3321', Anonymous Referee #2, 29 Dec 2024
The manuscript does a good job of communicating a complex topic with clarity and logical progression. WRF-Chem 3.9.1 is a classical atmospheric chemical transport model, and the manuscript combines this model and assimilation method to analyse the air pollutant concentration well. On this basis, the influences of parameter selection about ensemble member size and assimilation windows length on simulation under heavy pollution conditions are explored. The manuscript also summarizes the general experience of parameter selection for PM2.5 and PM10 simulation in initial condition assimilation. Finally, in order to study conclusions applicable range, the manuscript discusses the case in moderate pollution conditions.
I think it is an important work that advances our understanding about the selection of basic parameters in the 4D-LETKF assimilation system and the performance of ensemble simulation in a particulate matter polluted environment. In my opinion, the manuscript is well written, the investigation is an interesting topic that fits well within the scope of journal, so it is suitable to be published in GMD. Before that, there are some points that should be better considered for discussion. I list the general and additional minor comments. I hope this revision will be of help to improve the manuscript.
General comments:
1 As shown in the line 182, this study generates different emission samples by adding perturbations to the emission source inventory. This perturbation is spatially and temporally related, but this perturbation seems to be relatively strict. What is the reason for using this disturbance? Are there other disturbances that can be added to the emission inventory?
2 Picture 2 is the Flow chart of the WRF-Chem/4D-LETKF assimilation system for particulate matter. In the picture, the emission adds a disturbance to produce first-guess, and then combined with the observation and 4D-LETKF to produce the analysis result. The analysis results are used as input for the next assimilation cycle. No perturbations are added to emissions in the second cycle. Why manuscript only adds one times of perturbations into emissions at the first cycle of assimilation? Continuously adding perturbations to emissions during each assimilation cycle will increase the standard deviation in the first-guess field to produce more accurate simulation results?
3 In Table 3, ΔRMSE is basically negative, ΔCORR is positive, and the larger AE indicates the higher assimilation efficiency. It shows that the neighboring provinces outside the Beijing-Tianjin-Hebei region also gained greater assimilation gains. The main source of these gains is local initial field assimilation? or they come from the assimilation of the Beijing-Tianjin-Hebei region?
4 In Figure8, the sensitivity experiments are conducted by the selection of ensemble member size and the length of assimilation window. What are the main reasons for the selection of 20, 40, 60 for ensemble member size and 24, 48 72 hours for the length of assimilation window?
5 PM2.5 and PM10 have similar aerosol components, such as sea salt, and dust in GOCART scheme. And the state variables include these matters. However, As shown in Figure4 and Figure5, the RMSE of PM2.5 in Severe-40m-48h is 31.19 and 76.83 µg m-3 for PM10. Why the performance of PM10 prediction in Severe-40m-48h shows more uncertainty than those of PM2.5?
A handful of additional minor comments:
1 Write the formulation about correlation coefficient and root mean square error.
2 Replace the “peak” in line 308 by the “peak value of”.
3 Add the units in Figure 5.
4 Replace “air quality index” in line 307, 319, 611 by “AQI”.
5 Add the units in Figure6.
6 Add the units in table 3.
7 Replace “larger” in line 314 by “all larger”, replace “below” in line 315 by “all below”.
8 Replace “adjustment” in line 324 and 600 by “initial condition adjustment”.
9 Replace “Beijing-Tianjin Hebei” in line 408 by “BTH”.
10 Replace “provide” in line 105 by “providing”.
11 Replace “event” in line 106 by “events”.
12 Replace “dimensions” in line 426 by “dimensions”.
13 Replace “investigated” in line 628 by “the investigated”.
Citation: https://doi.org/10.5194/egusphere-2024-3321-RC2 -
AC2: 'Reply on RC2', Lin jianyu, 24 Jan 2025
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2024/egusphere-2024-3321/egusphere-2024-3321-AC2-supplement.pdf
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AC2: 'Reply on RC2', Lin jianyu, 24 Jan 2025
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EC1: 'Comment on egusphere-2024-3321', Luke Western, 24 Jan 2025
Dear Jianyu Lin,
Thank you for revising your manuscript and responding to the reviewers' comments.
In some cases the reviewers have asked for clarity or more explanation about certain topics. While you have responded to the reviewers through an interactive comment, this clarification has not been addressed in the manuscript itself.
For example, Reviewer #1 comment 3 and Reviewer #2 comment 1 both question the rationale for the approach to perturbation used and ask for a discussion of the impact of using a different perturbation approach. Could you please address the comments made by the reviewers in the manuscript itself, where relevant?
Additionally, could you please ensure that your equations are properly numbered and punctuated (see e.g., https://www2.math.uconn.edu/~khlee/math2784s10/writingtips.pdf)?
Kind regards,
Luke Western
Citation: https://doi.org/10.5194/egusphere-2024-3321-EC1 -
AC3: 'Reply on EC1', Lin jianyu, 27 Jan 2025
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2024/egusphere-2024-3321/egusphere-2024-3321-AC3-supplement.pdf
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AC3: 'Reply on EC1', Lin jianyu, 27 Jan 2025
Interactive discussion
Status: closed
-
RC1: 'Comment on egusphere-2024-3321', Anonymous Referee #1, 24 Dec 2024
-
AC1: 'Reply on RC1', Lin jianyu, 24 Jan 2025
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2024/egusphere-2024-3321/egusphere-2024-3321-AC1-supplement.pdf
-
AC1: 'Reply on RC1', Lin jianyu, 24 Jan 2025
-
RC2: 'Comment on egusphere-2024-3321', Anonymous Referee #2, 29 Dec 2024
The manuscript does a good job of communicating a complex topic with clarity and logical progression. WRF-Chem 3.9.1 is a classical atmospheric chemical transport model, and the manuscript combines this model and assimilation method to analyse the air pollutant concentration well. On this basis, the influences of parameter selection about ensemble member size and assimilation windows length on simulation under heavy pollution conditions are explored. The manuscript also summarizes the general experience of parameter selection for PM2.5 and PM10 simulation in initial condition assimilation. Finally, in order to study conclusions applicable range, the manuscript discusses the case in moderate pollution conditions.
I think it is an important work that advances our understanding about the selection of basic parameters in the 4D-LETKF assimilation system and the performance of ensemble simulation in a particulate matter polluted environment. In my opinion, the manuscript is well written, the investigation is an interesting topic that fits well within the scope of journal, so it is suitable to be published in GMD. Before that, there are some points that should be better considered for discussion. I list the general and additional minor comments. I hope this revision will be of help to improve the manuscript.
General comments:
1 As shown in the line 182, this study generates different emission samples by adding perturbations to the emission source inventory. This perturbation is spatially and temporally related, but this perturbation seems to be relatively strict. What is the reason for using this disturbance? Are there other disturbances that can be added to the emission inventory?
2 Picture 2 is the Flow chart of the WRF-Chem/4D-LETKF assimilation system for particulate matter. In the picture, the emission adds a disturbance to produce first-guess, and then combined with the observation and 4D-LETKF to produce the analysis result. The analysis results are used as input for the next assimilation cycle. No perturbations are added to emissions in the second cycle. Why manuscript only adds one times of perturbations into emissions at the first cycle of assimilation? Continuously adding perturbations to emissions during each assimilation cycle will increase the standard deviation in the first-guess field to produce more accurate simulation results?
3 In Table 3, ΔRMSE is basically negative, ΔCORR is positive, and the larger AE indicates the higher assimilation efficiency. It shows that the neighboring provinces outside the Beijing-Tianjin-Hebei region also gained greater assimilation gains. The main source of these gains is local initial field assimilation? or they come from the assimilation of the Beijing-Tianjin-Hebei region?
4 In Figure8, the sensitivity experiments are conducted by the selection of ensemble member size and the length of assimilation window. What are the main reasons for the selection of 20, 40, 60 for ensemble member size and 24, 48 72 hours for the length of assimilation window?
5 PM2.5 and PM10 have similar aerosol components, such as sea salt, and dust in GOCART scheme. And the state variables include these matters. However, As shown in Figure4 and Figure5, the RMSE of PM2.5 in Severe-40m-48h is 31.19 and 76.83 µg m-3 for PM10. Why the performance of PM10 prediction in Severe-40m-48h shows more uncertainty than those of PM2.5?
A handful of additional minor comments:
1 Write the formulation about correlation coefficient and root mean square error.
2 Replace the “peak” in line 308 by the “peak value of”.
3 Add the units in Figure 5.
4 Replace “air quality index” in line 307, 319, 611 by “AQI”.
5 Add the units in Figure6.
6 Add the units in table 3.
7 Replace “larger” in line 314 by “all larger”, replace “below” in line 315 by “all below”.
8 Replace “adjustment” in line 324 and 600 by “initial condition adjustment”.
9 Replace “Beijing-Tianjin Hebei” in line 408 by “BTH”.
10 Replace “provide” in line 105 by “providing”.
11 Replace “event” in line 106 by “events”.
12 Replace “dimensions” in line 426 by “dimensions”.
13 Replace “investigated” in line 628 by “the investigated”.
Citation: https://doi.org/10.5194/egusphere-2024-3321-RC2 -
AC2: 'Reply on RC2', Lin jianyu, 24 Jan 2025
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2024/egusphere-2024-3321/egusphere-2024-3321-AC2-supplement.pdf
-
AC2: 'Reply on RC2', Lin jianyu, 24 Jan 2025
-
EC1: 'Comment on egusphere-2024-3321', Luke Western, 24 Jan 2025
Dear Jianyu Lin,
Thank you for revising your manuscript and responding to the reviewers' comments.
In some cases the reviewers have asked for clarity or more explanation about certain topics. While you have responded to the reviewers through an interactive comment, this clarification has not been addressed in the manuscript itself.
For example, Reviewer #1 comment 3 and Reviewer #2 comment 1 both question the rationale for the approach to perturbation used and ask for a discussion of the impact of using a different perturbation approach. Could you please address the comments made by the reviewers in the manuscript itself, where relevant?
Additionally, could you please ensure that your equations are properly numbered and punctuated (see e.g., https://www2.math.uconn.edu/~khlee/math2784s10/writingtips.pdf)?
Kind regards,
Luke Western
Citation: https://doi.org/10.5194/egusphere-2024-3321-EC1 -
AC3: 'Reply on EC1', Lin jianyu, 27 Jan 2025
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2024/egusphere-2024-3321/egusphere-2024-3321-AC3-supplement.pdf
-
AC3: 'Reply on EC1', Lin jianyu, 27 Jan 2025
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Jianyu Lin
Lifang Sheng
Weihang Zhang
Shangfei Hai
Yawen Kong
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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(2162 KB) - Metadata XML
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Supplement
(1182 KB) - BibTeX
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- Final revised paper