the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 04 Feb 2021
Climatology of migrating and non-migrating tides observed by three meteor radars in the southern equatorial region
Abstract. We present a study of migrating and non-migrating tidal winds observed simultaneously by three meteor radars situated in the southern equatorial region. The radars are located at Cariri (7.4° S, 36.5° W), Brazil, Kototabang (0.2° S, 100.3° E), Indonesia and Darwin (12.3° S, 130.8° E), Australia. Harmonic analysis was used to obtain amplitudes and phases for diurnal and semidiurnal solar migrating and non-migrating tides between 80 and 100 km altitude during the period 2005 to 2008. They include the important tidal components of diurnal westward-propagating zonal wavenumber 1 (DW1), diurnal eastward-propagating zonal wavenumber 3 (DE3), semidiurnal westward-propagating zonal wavenumber 2 (SW2), and semidiurnal eastward-propagating zonal wavenumber 2 (SE2). In addition, we also present a climatology of these wind tides and analyze the reliability of the fitting through the reference to Whole Atmosphere Community Climate Model (WACCM) winds. The analysis suggests that the migrating tides could be well fitted by the three different radars, but the non-migrating tides might be overestimated. The results based on observations were also compared with the Climatological Tidal Model of the Thermosphere (CTMT). In general, climatic features between observations and model migrating tides were satisfactory in both wind components. However, the features of the DW1, DE3 and SW2 amplitudes in both wind components were slightly different from the results of the CTMT models. This result is probably because tides could be enhanced by the 2006 northern hemisphere stratospheric sudden warming (NH-SSW) event.
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RC1: 'Review of acp-2021-33', Anonymous Referee #1, 06 Feb 2021
The study is well performed, and the article is clearly written. I think ground-based remote sensing of MLT tides is important though the authors did not explain why the ground-based tidal measurments are complementary to satellite observations. They should add a paragraph about this topic in order to enhance the significance of their study which is well suited for a publication in ACP.
Minor comments:
abstract
page 2, line 13 … could be well fitted by the radars ….
This sounds strange. I would suggest: … could be well observed by the radars …
page 2, line 14 unclear formulation:…. might be overestimated
overestimated by the model or by the observations?
what is the reason for the overestimation? The data analysis?page 2, line 18 unclear: … slightly different …
is it again an underestimation of the amplitudes by the model ?page 3 , line 13 : … to fit migrating and …
I think „fit“ is the wrong formulation since the observations are not fitted to the sine waves. The sine waves are fitted to the observations! Here I would write:
… to derive migrating and …page 3, line 20 … also demonstrated …
better: … also derived ….page 3 Introduction: I am missing 1-2 sentences about the complementarity of tidal measurements from ground and space Why are ground-based observations necessary?
page 7 line 15 … zonal wavenumber greater than or equal to two cannot be considered …
How can you derive SW2, DE3 and SE2 which have wavenumbers greater equal 2?
page 11 line 28 The CTMT is a 2-dimensional model ….By the way it seems to be three dimensional (time, height, latitude)
Section 4 is quite long and covering different topics. I would make 2-3 subsections so that the structure of the discussion becomes more visible
Citation: https://doi.org/10.5194/acp-2021-33-RC1 -
AC1: 'Reply on RC1', Jianyuan Wang, 18 Jun 2021
The comment was uploaded in the form of a supplement: https://acp.copernicus.org/preprints/acp-2021-33/acp-2021-33-AC1-supplement.pdf
-
AC1: 'Reply on RC1', Jianyuan Wang, 18 Jun 2021
-
RC2: 'Comment on acp-2021-33', Anonymous Referee #2, 28 Apr 2021
General Comments
Tides are important dynamic motions in the MLT region, and they are believed to play a central role in the vertical coupling of the atmosphere and ionosphere specifically for the equatorial region. In this work, the authors present their analysis of the climatology of migrating and nonmigrating diurnal and semidiurnal tides using the multi-year zonal and meridional wind observations by three meteor radars near the equator. The authors attempt to use the Whole Atmosphere Community Climate Model (WACCM) simulations to determine the dominant tidal components and to guide their analysis of the radar observations. Limiting to the dominant tidal components, they analyze the DW1, DE3, SW2 and SE2 tides and compare the seasonal variations of these tides with the WACCM and CTMT results.
The paper is straightforwardly arranged. However, the description of the method and approach is not adequate (noted below), and the manuscript contains many grammatical errors (not listed).
Specific Comments
The analysis presented here, that attempts to decompose various tidal components from three meteor radar observations is an interesting piece of work. However, the manuscript has several problems that I believe need to be addressed before it is considered for publication. These problems include:
- The method used in this study for fitting the radar observations over three longitudes to DW1, SW2, DE3 and SE2 tidal components is flawed. As the manuscript states, “the fits of the tides with zonal wavenumbers greater than or equal to two cannot be considered (P7, Lines 15-16).” The fits to DE3 (wavenumber-3) is thus not reliable.
- The model results (shown in Figure 3) show large amplitudes for D0, DE1 and DE2 components in addition to DW1 and DE3. Specifically, D0 and DE1 are shown to have larger amplitudes than DE3 and both are stronger than semidiurnal components. However, the authors fit the data to only DW1, SW2, DE3 and SE2 (stated in P7, lines 16-17) and other components are not included. Also, DE2 tides can approach large amplitudes as demonstrated in previous climatological studies (e.g. Forbes et al., 2008), thus should be included.
Forbes, J. M., X. Zhang, S. Palo, J. Russell, C. J. Mertens, and M. Mlynczak (2008), Tidal variability in the ionospheric dynamo region, J. Geophys. Res., 113, A02310, doi:10.1029/2007JA012737.
- This work uses the model results to infer tidal components that dominate in the meteor radar observations, but no validation of the model is provided or referenced. The modeled tides should be compared with other observational data for the same time periods as the radar data. In addition, the tidal amplitudes have a large seasonal variation, so the model-observation comparisons should be conducted for individual seasons. These model validations are lacking in the manuscript.
Citation: https://doi.org/10.5194/acp-2021-33-RC2 -
AC2: 'Reply on RC2', Jianyuan Wang, 18 Jun 2021
The comment was uploaded in the form of a supplement: https://acp.copernicus.org/preprints/acp-2021-33/acp-2021-33-AC2-supplement.pdf
Status: closed
-
RC1: 'Review of acp-2021-33', Anonymous Referee #1, 06 Feb 2021
The study is well performed, and the article is clearly written. I think ground-based remote sensing of MLT tides is important though the authors did not explain why the ground-based tidal measurments are complementary to satellite observations. They should add a paragraph about this topic in order to enhance the significance of their study which is well suited for a publication in ACP.
Minor comments:
abstract
page 2, line 13 … could be well fitted by the radars ….
This sounds strange. I would suggest: … could be well observed by the radars …
page 2, line 14 unclear formulation:…. might be overestimated
overestimated by the model or by the observations?
what is the reason for the overestimation? The data analysis?page 2, line 18 unclear: … slightly different …
is it again an underestimation of the amplitudes by the model ?page 3 , line 13 : … to fit migrating and …
I think „fit“ is the wrong formulation since the observations are not fitted to the sine waves. The sine waves are fitted to the observations! Here I would write:
… to derive migrating and …page 3, line 20 … also demonstrated …
better: … also derived ….page 3 Introduction: I am missing 1-2 sentences about the complementarity of tidal measurements from ground and space Why are ground-based observations necessary?
page 7 line 15 … zonal wavenumber greater than or equal to two cannot be considered …
How can you derive SW2, DE3 and SE2 which have wavenumbers greater equal 2?
page 11 line 28 The CTMT is a 2-dimensional model ….By the way it seems to be three dimensional (time, height, latitude)
Section 4 is quite long and covering different topics. I would make 2-3 subsections so that the structure of the discussion becomes more visible
Citation: https://doi.org/10.5194/acp-2021-33-RC1 -
AC1: 'Reply on RC1', Jianyuan Wang, 18 Jun 2021
The comment was uploaded in the form of a supplement: https://acp.copernicus.org/preprints/acp-2021-33/acp-2021-33-AC1-supplement.pdf
-
AC1: 'Reply on RC1', Jianyuan Wang, 18 Jun 2021
-
RC2: 'Comment on acp-2021-33', Anonymous Referee #2, 28 Apr 2021
General Comments
Tides are important dynamic motions in the MLT region, and they are believed to play a central role in the vertical coupling of the atmosphere and ionosphere specifically for the equatorial region. In this work, the authors present their analysis of the climatology of migrating and nonmigrating diurnal and semidiurnal tides using the multi-year zonal and meridional wind observations by three meteor radars near the equator. The authors attempt to use the Whole Atmosphere Community Climate Model (WACCM) simulations to determine the dominant tidal components and to guide their analysis of the radar observations. Limiting to the dominant tidal components, they analyze the DW1, DE3, SW2 and SE2 tides and compare the seasonal variations of these tides with the WACCM and CTMT results.
The paper is straightforwardly arranged. However, the description of the method and approach is not adequate (noted below), and the manuscript contains many grammatical errors (not listed).
Specific Comments
The analysis presented here, that attempts to decompose various tidal components from three meteor radar observations is an interesting piece of work. However, the manuscript has several problems that I believe need to be addressed before it is considered for publication. These problems include:
- The method used in this study for fitting the radar observations over three longitudes to DW1, SW2, DE3 and SE2 tidal components is flawed. As the manuscript states, “the fits of the tides with zonal wavenumbers greater than or equal to two cannot be considered (P7, Lines 15-16).” The fits to DE3 (wavenumber-3) is thus not reliable.
- The model results (shown in Figure 3) show large amplitudes for D0, DE1 and DE2 components in addition to DW1 and DE3. Specifically, D0 and DE1 are shown to have larger amplitudes than DE3 and both are stronger than semidiurnal components. However, the authors fit the data to only DW1, SW2, DE3 and SE2 (stated in P7, lines 16-17) and other components are not included. Also, DE2 tides can approach large amplitudes as demonstrated in previous climatological studies (e.g. Forbes et al., 2008), thus should be included.
Forbes, J. M., X. Zhang, S. Palo, J. Russell, C. J. Mertens, and M. Mlynczak (2008), Tidal variability in the ionospheric dynamo region, J. Geophys. Res., 113, A02310, doi:10.1029/2007JA012737.
- This work uses the model results to infer tidal components that dominate in the meteor radar observations, but no validation of the model is provided or referenced. The modeled tides should be compared with other observational data for the same time periods as the radar data. In addition, the tidal amplitudes have a large seasonal variation, so the model-observation comparisons should be conducted for individual seasons. These model validations are lacking in the manuscript.
Citation: https://doi.org/10.5194/acp-2021-33-RC2 -
AC2: 'Reply on RC2', Jianyuan Wang, 18 Jun 2021
The comment was uploaded in the form of a supplement: https://acp.copernicus.org/preprints/acp-2021-33/acp-2021-33-AC2-supplement.pdf
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