the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Assimilation of Meteosat Third Generation (MTG) Lightning Imager (LI) observations in AROME-France – Proof of Concept
Felix Erdmann
Olivier Caumont
Eric Defer
Abstract. This study develops a Lightning Data Assimilation (LDA) scheme for the regional, convection-permitting NWP model AROME-France. The LDA scheme intends to assimilate total lightning, i.e., cloud-to-ground (CG) and inter- and intra-cloud (IC), of the future Meteosat Third Generation (MTG) Lightning Imager (LI). MTG-LI proxy data are created and Flash Extent Density (FED) fields are derived. An FED forward observation operator (FFO) is trained based on modeled, column integrated graupel mass from 24 storm days in 2018. The FFO is successfully verified for 2 independent storm days. With the FFO, the LDA adapts a 1-dimensional Bayesian (1DBay) retrieval followed by a 3-dimensional variational (3DVar) assimilation approach that is currently run operationally in AROME-France for radar reflectivity data. The 1DBay retrieval derives relative humidity profiles from the background by comparing the FED observations to the FED inferred from the background. Retrieved relative humidity profiles are assimilated as sounding data. The evaluation of the LDA comprises different LDA experiments and four case studies. It is found that all LDA experiments can increase the background integrated water vapor (IWV) in regions where the observed FED exceeds the FED inferred from AROME-France outputs. In addition, IWV can be reduced where spurious FED is modeled. A qualitative analysis of 6-hour accumulated rainfall fields reveals that the LDA is capable of locating and initiating some local precipitation fields better than a radar data assimilation (RDA) experiment. However, the LDA also leads to too high rainfall accumulations at some locations. Fractions Skill Scores (FSSs) of 6-hour accumulated rainfall are overall similar for the developed LDA and RDA experiments. An approach aiming at mitigating effects due to differences in the optical extents of lightning flashes and the area of the corresponding cloud was developed and included in the LDA, however, it does not always improve the FSS.
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Notice on discussion status
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
(7292 KB)
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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.
- Preprint
(7292 KB) - Metadata XML
- BibTeX
- EndNote
- Final revised paper
Journal article(s) based on this preprint
Felix Erdmann et al.
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2022-637', Anonymous Referee #1, 19 Aug 2022
Review of the paper
Assimilation of Meteosat Third Generation (MTG) Lightning Imager (LI) observations in AROME-France – Proof of Concept
By:
Felix Erdmann, Olivier Caumont, and Eric Defer
General comment
This paper shows a proof of concept of a method to assimilate lightning in the AEROME model. The method is based on the 1D-3Dvar method elaborated by Caumont et al. (2010) and used for radar reflectivity data assimilation. A function to compute the FED (Flash Extent Density) is proposed based on the graupel mass simulated by AEROME model.
The paper is well written and interesting and I suggest the publication of the paper with some corrections. These corrections are suggested as sticky noted to the pdf of the paper.
Major points
It is not very clear what it is shown in Figure 3. In the text explanation it is stated that the graupel mass column is considered. The value should be mm. In the Figure there is graupel mass [kg]. Please clarify better.
Section 7.1: I suggest to add a Figure to support the discussion.
Sections 7.1.3: It is important to highlight that this result is not general because of the limited number of cases considered in this paper.
Minor points
There are several minor points that the authors can consider before the publication of this paper. They are reported as sticky notes to the attached pdf of the paper.
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AC1: 'Reply on RC1', Felix Erdmann, 31 Mar 2023
Response to RC 1
We thank the anonymous reviewer for her/his valuable feedback. We like to hear that the referee finds our work interesting and supports a publication after some corrections. We address the major points in the following in italic font and answer the sticky notes in the attached PDF file.
Stated line numbers refer to the previously submitted manuscript to be consistent with the comments below.
Major points
It is not very clear what it is shown in Figure 3. In the text explanation it is stated that the graupel mass column is considered. The value should be mm. In the Figure there is graupel mass [kg]. Please clarify better.
We stated that "column integrated graupel mass" (line 188) is used, as suggested by Deierling et al. (2008). We believe that the unit kg is correct in the plot and consistent with the explanation.Section 7.1: I suggest to add a Figure to support the discussion.
We added maps of 500 hPa pressure and a surface analysis on 08 Aug. 2018, 1200UTC to support the description (as new Figure 5).Sections 7.1.3: It is important to highlight that this result is not general because of the limited number of cases considered in this paper.
The section about the FSS was revised accordingly.
Minor points
Please see the answers to the sticky notes in the attached PDF file.
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AC1: 'Reply on RC1', Felix Erdmann, 31 Mar 2023
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RC2: 'Comment on egusphere-2022-637', Anonymous Referee #2, 27 Sep 2022
- AC2: 'Reply on RC2', Felix Erdmann, 31 Mar 2023
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2022-637', Anonymous Referee #1, 19 Aug 2022
Review of the paper
Assimilation of Meteosat Third Generation (MTG) Lightning Imager (LI) observations in AROME-France – Proof of Concept
By:
Felix Erdmann, Olivier Caumont, and Eric Defer
General comment
This paper shows a proof of concept of a method to assimilate lightning in the AEROME model. The method is based on the 1D-3Dvar method elaborated by Caumont et al. (2010) and used for radar reflectivity data assimilation. A function to compute the FED (Flash Extent Density) is proposed based on the graupel mass simulated by AEROME model.
The paper is well written and interesting and I suggest the publication of the paper with some corrections. These corrections are suggested as sticky noted to the pdf of the paper.
Major points
It is not very clear what it is shown in Figure 3. In the text explanation it is stated that the graupel mass column is considered. The value should be mm. In the Figure there is graupel mass [kg]. Please clarify better.
Section 7.1: I suggest to add a Figure to support the discussion.
Sections 7.1.3: It is important to highlight that this result is not general because of the limited number of cases considered in this paper.
Minor points
There are several minor points that the authors can consider before the publication of this paper. They are reported as sticky notes to the attached pdf of the paper.
-
AC1: 'Reply on RC1', Felix Erdmann, 31 Mar 2023
Response to RC 1
We thank the anonymous reviewer for her/his valuable feedback. We like to hear that the referee finds our work interesting and supports a publication after some corrections. We address the major points in the following in italic font and answer the sticky notes in the attached PDF file.
Stated line numbers refer to the previously submitted manuscript to be consistent with the comments below.
Major points
It is not very clear what it is shown in Figure 3. In the text explanation it is stated that the graupel mass column is considered. The value should be mm. In the Figure there is graupel mass [kg]. Please clarify better.
We stated that "column integrated graupel mass" (line 188) is used, as suggested by Deierling et al. (2008). We believe that the unit kg is correct in the plot and consistent with the explanation.Section 7.1: I suggest to add a Figure to support the discussion.
We added maps of 500 hPa pressure and a surface analysis on 08 Aug. 2018, 1200UTC to support the description (as new Figure 5).Sections 7.1.3: It is important to highlight that this result is not general because of the limited number of cases considered in this paper.
The section about the FSS was revised accordingly.
Minor points
Please see the answers to the sticky notes in the attached PDF file.
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AC1: 'Reply on RC1', Felix Erdmann, 31 Mar 2023
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RC2: 'Comment on egusphere-2022-637', Anonymous Referee #2, 27 Sep 2022
- AC2: 'Reply on RC2', Felix Erdmann, 31 Mar 2023
Peer review completion
Journal article(s) based on this preprint
Felix Erdmann et al.
Felix Erdmann et al.
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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.
- Preprint
(7292 KB) - Metadata XML