Observation and simulation of neutral air density in the middle atmosphere during the 2021 sudden stratospheric warming event

Yang, Junfeng; Wang, Jianmei; Liu, Dan; Guo, Wenjie; Zhang, Yiming

doi:https://doi.org/10.5194/egusphere-2023-3162

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https://doi.org/10.5194/egusphere-2023-3162

Preprints

19 Jan 2024

| 19 Jan 2024

Observation and simulation of neutral air density in the middle atmosphere during the 2021 sudden stratospheric warming event

Junfeng Yang, Jianmei Wang, Dan Liu, Wenjie Guo, and Yiming Zhang

Abstract. Sudden stratospheric warmings (SSWs) are dramatic events in the polar winter stratosphere that are accompanied by atmospheric parameter anomalies in the stratosphere and mesosphere. Microwave Limb Sounder and Global Navigation Satellite System Occultation Sounder observations on board the Chinese FengYun 3 satellites indicate a rapid increase of over 50 % in the mesospheric density at high latitudes around the onset date during the 2021 major SSW event. The amplification of the zonal mean density around the onset is proportional to the latitude increase with a maximum increment of 83.3 % at 59 km above 80° N, which is more than three times larger than the climatological standard deviation (23.1 %). The horizontal density distributions are influenced by the changing polar vortex fields. A simulation using a specified dynamics version of the Whole Atmosphere Community Climate Model is consistent overall with the observations and presents a severe change in the planetary wave forcing and residual meridional circulation mass flux followed by a change in the density tendency. These results demonstrate that the observed enhanced density is primarily attributed to the altered planetary waves and residual circulation during the SSW event. The observations and simulations also indicate that the density anomalies could extend to middle latitudes. Obvious density disturbances in the upper stratosphere and mesosphere were observed by lidar deployed in Beijing (40.3° N, 116.2° E).

Received: 31 Dec 2023 – Discussion started: 19 Jan 2024

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Journal article(s) based on this preprint

12 Sep 2024

Observation and simulation of neutral air density in the middle atmosphere during the 2021 sudden stratospheric warming event

Junfeng Yang, Jianmei Wang, Dan Liu, Wenjie Guo, and Yiming Zhang

Atmos. Chem. Phys., 24, 10113–10127, https://doi.org/10.5194/acp-24-10113-2024,https://doi.org/10.5194/acp-24-10113-2024, 2024

Short summary

Junfeng Yang, Jianmei Wang, Dan Liu, Wenjie Guo, and Yiming Zhang

Interactive discussion

Status: closed

RC1:
'Comment on egusphere-2023-3162', Anonymous Referee #1, 03 Apr 2024
Comments on “Observation and simulation of neutral air density in the middle atmosphere during the 2021 sudden stratospheric warming event” by Yang et al. 2024

Summary
The SSWs could cause the dramatic change in the temperature, winds and components in the middle atmosphere, which has been widely reported in literature. In contrast, the neutral density evolution during the SSW is less reported. However, the density is one of the most important parameters for the atmosphere drag force calculation in the design of aircraft design. This research reports on the density evolution during the middle atmosphere during the 2021 major SSW event using the observation and simulation. The satellites data show a rapid increase of over 50% in the mesospheric density at high latitudes around the onset date during the SSW. The global view shows that the influenced area extends to the the middle latitudes. Beijing lidar observed obvious density disturbances during the SSW event. The simulation using SD-WACCM demonstrates that the observed enhanced density is primarily attributed to the altered planetary waves and residual circulation during the SSW event. The density variation at altitude layers during the SSW is different from a simple inference by the temperature at certain pressure levels. This study is interesting and the results are sound. However, there are still some very minor concerns that should be considered. Therefore, I recommend a minor revision.

Major comments:
The authors emphasize the importance of the BD circulation for the density change during the SSW, and say that the BDC transport denser air from lower latitudes to higher latitudes. However, the climatological distribution of the air density is not shown in the paper, which is a core plot. Based on Figure 3, I do not see very clearly the contrast of the air density between lower and higher latitudes. Only showing the pressure, the key message is not clearly present.

Some jargons should be defined in the main text or in the figure captions. The authors claim that they show the deviation for the air density relative to the climatology. But the legend shows the relative change with a unit %. So where can the readers find the definition for the air density deviation (or relative deviation)?

The authors only emphasize the dynamics importance for the change of the air density. But actually, the ideal state equation also explains the change of the air density in some circumstances. P=rho*R*T. You might find that the P and the T increase suddenly during the SSW, so which increases faster? If the P increases faster than the T, the increase in rho is also true, and the ideal state equation can also explain the change in the air density. I suggest to include a comparison between the thermodynamics and dynamics.

Minor comments:
Line 23: Please be more specific for the “upper air model”. I do not understand.

Line 32: These references are too old and some most recent publications for the Southern Hemisphere SSW should be mentioned (doi: 10.1029/2020JD032723)

Line 54: Please clarify the necessity of the density investigation.

Line 98: When introducing Beijing lidar, consider providing the detection principle or
method.

Figure 3: The negative values are all too weak. Please modify the legend colors to match the figure well.

Line 230: Revised the sentence “the lidar density data constitute a directed parameter”.

Figure 5: Here is not the PW1/2, but the wave amplitude? (see Line 234)

Line 267: I can not see the climatological density contrast between the lower latitudes and higher latitudes.

Line 300: The sharp increase in air density is observed during the 2021 SSW. Whether the similar variations have occurred during other SSWs and what is the difference?
Citation: https://doi.org/10.5194/egusphere-2023-3162-RC1
- AC1: 'Reply on RC1', Junfeng Yang, 09 May 2024
  
  We would like to thank the reviewer for helpful comments. We have responded to the reviewer's comments in the pdf attached.
  
  Citation: https://doi.org/10.5194/egusphere-2023-3162-AC1
RC2:
'Comment on egusphere-2023-3162', Anonymous Referee #2, 12 Apr 2024

Review of "Observation and simulation of neutral air density in the middle atmosphere during the 2021 sudden stratospheric warming event" by Yang et al. (https://doi.org/10.5194/egusphere-2023-3162)
The present study explores the spatial and temporal distributions of (neutral) air density in the 2021 sudden stratospheric warming event using observational data (AURA/MLS, GNSS-RO and lidar) and global modeling whose dynamics is constrained using the reanalysis (SD-WACCM).
This study emphasizes the importance of density distributions in association with the evolution of anticyclonic and cyclonic vortices during the SSW event. However, flow evolution during the SSW event has been extensively studied using the concept of potential vorticity (e.g,, Harvey et al. 2002; Greer et al. 2013; Lu et al. 2021). Potential vorticity is the dynamic variable that combines the thermodynamic process, and it has good property that it is conserved following fluid elements in the absence of heat and dissipation. That is, there is already good and well-known material invariant quantity that can be used for studies of polar vortex evolutions and mass transport around vortices. Hence, reviewer is not convinced about why we need air density as another key physical quantity for better understanding of vortex evolution.
As authors discussed, mass transport is important in mean-flow evolution associated with planetary waves, and the mass circulation can be approximately described by the residual circulation. Importance of mass circulation in polar vortex dynamics is not new, and the importance of "mass" transport would not require the use of air density as an additional diagnostic quantity. Reviewer agrees that the importance of neutral air density in the altitudes (z = 200-1000 km) of (Very) Low-Earth Orbit satellites in terms of air drag, but the topic of this study is the middle atmospheric phenomena in which substantial amount of mass transport would be due to radiative heating/cooling, planetary waves and gravity waves. In this sense, referring low-thermospheric studies like Oberhide et al. (2020) is not appropriate. Tidal waves rather than planetary waves would contribute more to mass circulation in the lower thermosphere.
Reviewer thinks this manuscript need to be rewritten such that this study either focus more on the middle atmospheric dynamics during the 2021 SSW in more meteorological context or focus more on the lower thermospheric impacts of the 2021 SSW using upper atmospheric observations and SD-WACCM-X. For this reason, reviewer would not recommend this manuscript for publication to ACP, although authors made significant efforts for comprehensive and quantitative analysis.
References
Harvey, V. L., Pierce, R. B., & Hitchman, M. H. (2002), A climatology of stratospheric polar vortices and anticyclones, J. Geophys. Res., 107(D20), 4442, https://doi.org/10.1029/2001JD001471
Greer, K., Thayer, J. P., & Harvey, V. L. (2013), A climatology of polar winter stratopause warmings and associated planetary wave breaking, J.Geophys. Res. Atmos., 118, 4168–4180, https://doi.org/10.1002/jgrd.50289
Lu, H., Gray, L. J., Martineau, P., King, J. C., & Bracegirdle, T. J. (2021), Regime behavior in the upper stratosphere as a precursor of stratosphere-troposphere coupling in the Northern winter. J. Climate, 34, 7677-7696, https://doi.org/10.1175/JCLI-D-20-0831.1
Obserheide, J., Pedatella, N. M., Gan, Q., Kumari, K., Burns, A. G., & Eastes, R. W. (2020), Thermospheric composition O/N response to an altered meridional mean circulatioin during sudden stratospheric warmings observed by GOLD, Geophys. Res. Lett., 47, e2019GL086313, https://doi.org/10.1029/2019GL086313

Citation: https://doi.org/10.5194/egusphere-2023-3162-RC2
- AC2: 'Reply on RC2', Junfeng Yang, 09 May 2024
  
  We would like to thank the reviewer for helpful comments. We have responded to the reviewer's comments in the pdf attached.
  
  Citation: https://doi.org/10.5194/egusphere-2023-3162-AC2

Interactive discussion

Status: closed

RC1:
'Comment on egusphere-2023-3162', Anonymous Referee #1, 03 Apr 2024
Comments on “Observation and simulation of neutral air density in the middle atmosphere during the 2021 sudden stratospheric warming event” by Yang et al. 2024

Summary
The SSWs could cause the dramatic change in the temperature, winds and components in the middle atmosphere, which has been widely reported in literature. In contrast, the neutral density evolution during the SSW is less reported. However, the density is one of the most important parameters for the atmosphere drag force calculation in the design of aircraft design. This research reports on the density evolution during the middle atmosphere during the 2021 major SSW event using the observation and simulation. The satellites data show a rapid increase of over 50% in the mesospheric density at high latitudes around the onset date during the SSW. The global view shows that the influenced area extends to the the middle latitudes. Beijing lidar observed obvious density disturbances during the SSW event. The simulation using SD-WACCM demonstrates that the observed enhanced density is primarily attributed to the altered planetary waves and residual circulation during the SSW event. The density variation at altitude layers during the SSW is different from a simple inference by the temperature at certain pressure levels. This study is interesting and the results are sound. However, there are still some very minor concerns that should be considered. Therefore, I recommend a minor revision.

Major comments:
The authors emphasize the importance of the BD circulation for the density change during the SSW, and say that the BDC transport denser air from lower latitudes to higher latitudes. However, the climatological distribution of the air density is not shown in the paper, which is a core plot. Based on Figure 3, I do not see very clearly the contrast of the air density between lower and higher latitudes. Only showing the pressure, the key message is not clearly present.

Some jargons should be defined in the main text or in the figure captions. The authors claim that they show the deviation for the air density relative to the climatology. But the legend shows the relative change with a unit %. So where can the readers find the definition for the air density deviation (or relative deviation)?

The authors only emphasize the dynamics importance for the change of the air density. But actually, the ideal state equation also explains the change of the air density in some circumstances. P=rho*R*T. You might find that the P and the T increase suddenly during the SSW, so which increases faster? If the P increases faster than the T, the increase in rho is also true, and the ideal state equation can also explain the change in the air density. I suggest to include a comparison between the thermodynamics and dynamics.

Minor comments:
Line 23: Please be more specific for the “upper air model”. I do not understand.

Line 32: These references are too old and some most recent publications for the Southern Hemisphere SSW should be mentioned (doi: 10.1029/2020JD032723)

Line 54: Please clarify the necessity of the density investigation.

Line 98: When introducing Beijing lidar, consider providing the detection principle or
method.

Figure 3: The negative values are all too weak. Please modify the legend colors to match the figure well.

Line 230: Revised the sentence “the lidar density data constitute a directed parameter”.

Figure 5: Here is not the PW1/2, but the wave amplitude? (see Line 234)

Line 267: I can not see the climatological density contrast between the lower latitudes and higher latitudes.

Line 300: The sharp increase in air density is observed during the 2021 SSW. Whether the similar variations have occurred during other SSWs and what is the difference?
Citation: https://doi.org/10.5194/egusphere-2023-3162-RC1
- AC1: 'Reply on RC1', Junfeng Yang, 09 May 2024
  
  We would like to thank the reviewer for helpful comments. We have responded to the reviewer's comments in the pdf attached.
  
  Citation: https://doi.org/10.5194/egusphere-2023-3162-AC1
RC2:
'Comment on egusphere-2023-3162', Anonymous Referee #2, 12 Apr 2024

Review of "Observation and simulation of neutral air density in the middle atmosphere during the 2021 sudden stratospheric warming event" by Yang et al. (https://doi.org/10.5194/egusphere-2023-3162)
The present study explores the spatial and temporal distributions of (neutral) air density in the 2021 sudden stratospheric warming event using observational data (AURA/MLS, GNSS-RO and lidar) and global modeling whose dynamics is constrained using the reanalysis (SD-WACCM).
This study emphasizes the importance of density distributions in association with the evolution of anticyclonic and cyclonic vortices during the SSW event. However, flow evolution during the SSW event has been extensively studied using the concept of potential vorticity (e.g,, Harvey et al. 2002; Greer et al. 2013; Lu et al. 2021). Potential vorticity is the dynamic variable that combines the thermodynamic process, and it has good property that it is conserved following fluid elements in the absence of heat and dissipation. That is, there is already good and well-known material invariant quantity that can be used for studies of polar vortex evolutions and mass transport around vortices. Hence, reviewer is not convinced about why we need air density as another key physical quantity for better understanding of vortex evolution.
As authors discussed, mass transport is important in mean-flow evolution associated with planetary waves, and the mass circulation can be approximately described by the residual circulation. Importance of mass circulation in polar vortex dynamics is not new, and the importance of "mass" transport would not require the use of air density as an additional diagnostic quantity. Reviewer agrees that the importance of neutral air density in the altitudes (z = 200-1000 km) of (Very) Low-Earth Orbit satellites in terms of air drag, but the topic of this study is the middle atmospheric phenomena in which substantial amount of mass transport would be due to radiative heating/cooling, planetary waves and gravity waves. In this sense, referring low-thermospheric studies like Oberhide et al. (2020) is not appropriate. Tidal waves rather than planetary waves would contribute more to mass circulation in the lower thermosphere.
Reviewer thinks this manuscript need to be rewritten such that this study either focus more on the middle atmospheric dynamics during the 2021 SSW in more meteorological context or focus more on the lower thermospheric impacts of the 2021 SSW using upper atmospheric observations and SD-WACCM-X. For this reason, reviewer would not recommend this manuscript for publication to ACP, although authors made significant efforts for comprehensive and quantitative analysis.
References
Harvey, V. L., Pierce, R. B., & Hitchman, M. H. (2002), A climatology of stratospheric polar vortices and anticyclones, J. Geophys. Res., 107(D20), 4442, https://doi.org/10.1029/2001JD001471
Greer, K., Thayer, J. P., & Harvey, V. L. (2013), A climatology of polar winter stratopause warmings and associated planetary wave breaking, J.Geophys. Res. Atmos., 118, 4168–4180, https://doi.org/10.1002/jgrd.50289
Lu, H., Gray, L. J., Martineau, P., King, J. C., & Bracegirdle, T. J. (2021), Regime behavior in the upper stratosphere as a precursor of stratosphere-troposphere coupling in the Northern winter. J. Climate, 34, 7677-7696, https://doi.org/10.1175/JCLI-D-20-0831.1
Obserheide, J., Pedatella, N. M., Gan, Q., Kumari, K., Burns, A. G., & Eastes, R. W. (2020), Thermospheric composition O/N response to an altered meridional mean circulatioin during sudden stratospheric warmings observed by GOLD, Geophys. Res. Lett., 47, e2019GL086313, https://doi.org/10.1029/2019GL086313

Citation: https://doi.org/10.5194/egusphere-2023-3162-RC2
- AC2: 'Reply on RC2', Junfeng Yang, 09 May 2024
  
  We would like to thank the reviewer for helpful comments. We have responded to the reviewer's comments in the pdf attached.
  
  Citation: https://doi.org/10.5194/egusphere-2023-3162-AC2

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload

AR by Junfeng Yang on behalf of the Authors (09 May 2024) Author's response Author's tracked changes Manuscript

ED: Reconsider after major revisions (20 May 2024) by John Plane

ED: Referee Nomination & Report Request started (22 May 2024) by John Plane

RR by Anonymous Referee #3 (31 May 2024)

Suggestions for revision or reasons for rejection

This is the revised version. However, I am quite struggle to understand some results partly due to my poor English. Based on the results in the manuscript, it seems to be very tough and challenging to get the clear message of the atmospheric density changes due to the large temperature changes because of SSW.
I would suggest the authors apply similar method for other SSW events occurred in January (for example, 2006, 2009, 2019) if you can get similar results and conclusions. Sorry for the extra works to the authors but It is necessary not only for double check purpose but you will may also see some similarities/differences. Below are the listed comments for the consideration:

1) Lines 37-38. I am not sure where "approximately once every 2 years in the winter stratosphere over North Pole"
comes from. This will cause some confusion and misleading. Note that the frequency event (~ 6 events per decade, the past major SSW events are listed at
https://csl.noaa.gov/groups/csl8/sswcompendium/majorevents.html
does not mean "~ once every 2 years".

2) Line 39. Again not sure which SSW year had 60 K stratospheric temperature increase over a few years as mentioned
"sudden warming of 40–60 K in the polar stratospheric temperature over a few days". I guess it is probably from the model results
because some models have bias cold polar temperature which makes this possible. However, it should be based on observational data for this.

3) Line 52: It is not clear that the cited "O/N2 column density depletion of more than 10% at the onset of SSW"
indicates which altitude range.

4) Lines 56-59. This reads quite weird. What do you mean "atmospheric variations"? The variations of atmosphere have many atmospheric
dynamics/chemistry fields etc including the temperature, total electron content, trace gases mentioned above.
Since the "atmospheric density" can be expressed as a relationship of pressure and temperature based on thermodynamics equation,
so it is understandable how it changes when temperature and pressure change.
Therefore, the sentence "The atmospheric density is always neglected..., resulting in the density evolution during SSW events rarely being reported"
is confusing. Looking at section of Satellite datasets, the satellite don't have direct measures of neutral air density, which is diagnosed based on temperature....

5) Line 66. How Beijing lidar can detect "horizontal distributions of the neutral air density" since it is located at one single location.

6) Line 67. Please add a reference for SD-WACCM when it is first mentioned.

7) Line 85, it looks that the unit for g is wrong, which should be m/s2.

8) Line 91, add a reference for "EGM96 Geopotential Model"

9) Lines 99-100, add some examples/references for the data validation and applications.

10) Lines 105-106, it is vague and unclear how "the reference density" is derived. It seems that the latter results indicate it is climatological mean density.

11) Section 2.2, needs more information about Lidar system. For example, what is the accuracy of lidar temperature and its performance based on the previous publications...

12) Section 2.4. Needs more information about WACCM version. Is it WACCM4 based on CESM1 or WACCM6 based on CESM2?
Has the model simulation carried out in China or did the the authors make the simulations by their own?
If so, how did they implement the required input data (for example, solar, emissions etc) which is current not public available beyond year 2015?

13) Lines 156-158. Not clear why cites Lu et al. (2021) here? Do you want to highlight this is the longest SSW events(?)
Please keep in mind that Lu et al used ERA5. Does MERRA2 show similar results?

14) Line 164. Not sure if the authors describe the results correctly/properly. For example,
It is weird to say something like "colder stratopause", please keep in mind what the definition of stratopause is.
Somehow MLS data did not show clearly the elevated stratopause temperature mid-late January/early Feb after the SSW from the current analysis (because current uses a very narrow latitude band average?).

15) Figure 1(d) and (f). The caption on these Figures is wrong. It is not "zonal mean density" which should be relative density change.

16) Figure 1. "during the SSW event" is not necessary for the description of Figure 1 (d) and (f).
Actually I am concerned the Figure 1 (d) and (f) since it is well known that the atmospheric density decreases exponentially with increases altitude.
Maybe there won't big atmospheric density changes in the stratosphere but I expect some big changes in the stratopause,
especially after the SSW (for example we expect some significant stratopause changes from the past studies for example SSW events in February 2006 and January 2009,
which should show some big effects on the density changes).
However, the current figures won't support my initial thought.
For example, Figure 1(c) and (e) shows stratopause altitude is around 45 km, but why the largest density changes in around 60 km?
I understand there is large annual variability in the high latitude in the Northern hemisphere.
Maybe the best way to add similar results of the relative temperature and pressure changes for double check Figure 1(d) and (f).
Not sure if the authors need to be cautions(to be specified, the SSW events during 2004-2021 should be removed, rather than using the climatology values in the current manuscript).
My understanding is that the current manuscript used the 2021 daily atmospheric density value minus 2004-2021 DJF mean density (Figure 1d) or 2013-2021 DJF mean density (Figure 1f), then divide the mean to obtain the relative density deviation.

17) Lines 181-193. Not clear what the message and key points the authors would like to highlight.
It seems OK to use the global mean density in Figure 2a,b,c assuming the mass is conserved for individual days.
However, these figures only show the relative percentage changes of zonal mean atmospheric density over different latitudes with respect to the global mean density.

18) Lines 184, Figure 2. Which date should be (1 Feb or 7 January). Same comments for Figures 3, 4 and Line 216 etc.

19) Line 206. It is confusing using "standard deviation" in many places, which also makes mean to try very hard to understand Figure 3d and Figure4.

20) I am really sorry that I am total lost in Lines 206-207. The caption in Figure 2d is "DJF Climate mean" and the decription also says "climate winter average", so I thought they are the DJF climate mean of relative percentage change of zonal mean density with respect to the global mean density averaged over the winter DJF during 2004-2021. But standard deviation is different term! I don't see anything in Figure 2d related to the possible explanation based on Smith et al. (2012). This requires further clarification.

21) Lines 222-228: polar vortex. Please bear in mind the low pressure is not the only criteria for the polar vortex!

22) Lidar temperature data. Not sure why the derived temperature from Beijing lidar is only available between ~35-65 km.
As commented for Section 2.2, there are some important information is missing, for example, how temperature and density are retrieved.
What are key parameters are used and where are the from? for example, reference height and reference atmospheric density etc.

23) Lines 237-238. It reads weird. Please note that Beijing is at mid-latitude.

24) Lines 240-241 and Figure 5b, 5d. I understand maybe Lidar did not have enough data to build the climatology.
However, based on Figure 4, there are large temporal variation (though I guess 7 January is a typo in Figure 4) and spatial variation.
So maybe the pattern could be different using climate averaged or Dec 2020-Feb 2021 as a reference.
It is also not clear how you sampled the MLS over Beijing? Do you just simple weight averaged around Beijing location using the processed
every 5 latitude x 20 longitude degree data? Anyway, it will be better to use Dec 2020-Feb 2021 average for MLS.
Another related question is that Beijing lidar temperature was observed during night time, did you also set a time constrain criteria for MLS?

25) Figure 4. Based on the pressure contours in Figure 4 (k) I guess this is the day for 1 Feb 2021. Somehow Figure (c) shows two low pressure centres at 80 km if I read the figure correctly.

26) Lines 261-267. Some discrepancies between MLS and SD-WACCM in the mesosphere should be expected.
Comparing the temperature profiles in Figure 6a and Figure 2a, these differences are not SMALL "excepting some small differences in detail within the topmost altitudes".
I understand the MLS temperature above ~88 km or higher (?) is outside the scientific use, however, somehow the mesopause altitude from MLS is around 80 km (?) (Figure 2a) while WACCM has much higher mesopause altitude (??) than MLS. So this is not only the difference as mentioned "The mesopause temperature is slightly colder than the observations around the onset date."
The result "a decrease in the density appears above 80km" may come from Figure 6b, however, this is the relative percentage density change!
Density is decreasing with increasing altitude is well known!
I am also not convinced by some simple explanations here.

27) Figures 10 versus Figure 1. I am worried about the inconsistent of "density deviation". The results came from the same data and uses different coordinate.
Clearly temperature profiles/evolution/magnitude etc are consistent.However, why don't see similar pattern/magnitude for density change? The results here may cause confusion or may be misleading.

Hide

RR by Anonymous Referee #1 (06 Jul 2024)

ED: Publish as is (22 Jul 2024) by John Plane

AR by Junfeng Yang on behalf of the Authors (24 Jul 2024) Manuscript

Journal article(s) based on this preprint

12 Sep 2024

Observation and simulation of neutral air density in the middle atmosphere during the 2021 sudden stratospheric warming event

Junfeng Yang, Jianmei Wang, Dan Liu, Wenjie Guo, and Yiming Zhang

Atmos. Chem. Phys., 24, 10113–10127, https://doi.org/10.5194/acp-24-10113-2024,https://doi.org/10.5194/acp-24-10113-2024, 2024

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Junfeng Yang, Jianmei Wang, Dan Liu, Wenjie Guo, and Yiming Zhang

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Atmospheric drag, a direct function of the atmospheric density, is vary seriously over several aircraft flights. This indicates that the natural density evolution needs to be acutely analyzed. However, the middle atmospheric density response to sudden stratospheric warming events has rarely been reported. In this study, the air density anomaly distribution and mass transport process are illustrated based on observation data and global numerical model simulations during the 2021 major SSW event.


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