the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 02 Aug 2021
A strong link between variations in sea-ice extent and global atmospheric pressure?
Abstract. Abstract. This paper reports spectral analyses, using Singular Spectral Analysis, of variations of the Arctic and Antarctic sea-ice extents (SI), and of the atmospheric surface pressure (AP) in both hemispheres (NH and SH). The ice-extents are dominated by a quasi-linear trend over the 42 yr period when data are available (1978–2020) and an annual component. Taken together, these two components represent more than 98 % of the signal variance. Both ice-extent series share the same 5 set of harmonics of the annual component (1/2, 1/3, 1/4 and 1/5 yr). The multi-decadal trends of sea-ice extent in the Arctic and Antarctic are of opposite sign. The series of harmonics of 1 year are consequences of the Earth’s revolution about the Sun. The components with period longer than a year form a set of even harmonics of the Schwabe cycle. The pressure series also exhibits the four harmonics of 1 year, that is not found in many series previously analysed in the same way. This could suggest a connection between variations in pressure and sea-ice extent. Geographical pressure structures (SSA trends) are stable on a 10 decadal to centennial time scale and exhibit a three-fold symmetry in the NH. In the SH that order-3 symmetry is altered by the Ross-Weddell “dipole” pressure anomaly. This anomaly is seen in maps of correlations of variations in sea-ice extent with atmospheric pressure, surface temperature and winds. It fits topographic forcing. There is phase opposition between the annual components of SI and AP in the SH, and the same decreasing phase lag from −30 to −60 days over 42 years for the four harmonic components of SHSI and SHAP. The (negative) sign of the trend of pressure and (positive) sign of the trend of temperature 15 beg for an explanation. The relative change in pressure over the past 50 years is two orders of magnitude smaller than that of warming. This relatively strong warming would be expected to have a larger effect on pressure. The ratio of relative changes of sea-ice extent vs pressure is 400 for the NH and 17 for the SH. The SSA components reported in this paper should help in understanding the mechanisms that govern changes in sea-ice extent: these changes reflect forcings related to the Earth’s revolution about the Sun on the shorter period side, and on the longer period side to the Sun and planets (Jupiter). Advanced 20 explanation of the physics underling these observations may need advances in solving the generalized Navier-Stokes equations, which is very difficult in the spherical case.
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CC1: 'Comment on tc-2021-216', Paul PUKITE, 12 Aug 2021
I have a basic comment relating to correlations of a common-moe type. Consider Fig 5 with caption "The variation of Sun-Earth distance since 1978 (in black) is compared to the annual component of SHSI (in red). 330 (bottom) The phase difference between the two."
Why look at Sun-Earth distance when the simple seasonal cycle will likelyy give the same correlation? And surface atmospheric pressure relates to temperature most straightforwardly by the ideal gas law, which also shows a seasonal pattern. I don't understand pursuing these common-mode-related correlations.
Citation: https://doi.org/10.5194/tc-2021-216-CC1 -
CC2: 'Reply on CC1', Fernando Lopes, 18 Aug 2021
After having extracted with SSA the quasi-periods (cyclicities) of the series of sea-ice extent and atmospheric pressure, the main point we
wish to stress in this paper is the contribution of celestial mechanics in explaining these cyclicities, not to try and find a thermodynamic relation explaining the cyclicities. As we have shown in Courtillot et al (2021) regarding sunspots and in Lopes et al (2021) regarding the motion of the Earth's rotation pole, the angular momentum of planets plays a very important and often underestimated role on our star as well as on Earth. When trying to identify the signature of the Jovian planets, we found an unusually perfect harmonic sequence of 1 year : 1, 1/2, 1/3, 1/4 and 1/5 of a year. This can only have been forced by the variation of the Earth-Sun distance (see Lambeck 2005). The constant phase variation of 60 days (see Figure 05) as well as the regularity of the amplitudes of the other components argue for a simple
linear relationship. It is still not possible to this day (refs in the paper) to solve analytically the Navier-Sockes equations in a fluid
sphere in the turbulent regime (the solution is not unique unlike in the cylindrical case). We hope that our results, in addition to highlighting the presence of this remarkable harmonic series, will help towards a solution of that problem.Citation: https://doi.org/10.5194/tc-2021-216-CC2 -
CC3: 'Reply on CC2', Paul PUKITE, 19 Aug 2021
Thank you. These are all interesting possibilities and hope that you can make some progress. For your consideration, we have also pursued some of these ideas relating to a unification of orbits and geophysical measures by matching the known tidal forcing cycles..
Citations:
Pukite, Paul. "Nonlinear long-period tidal forcing with application to ENSO, QBO, and Chandler wobble." EGU General Assembly Conference Abstracts. 2021. https://ui.adsabs.harvard.edu/abs/2021EGUGA..2310515P/abstract
Pukite, Paul, Dennis Coyne, and Daniel Challou. "Mathematical Geoenergy", John Wiley & Sons, 2019.
Citation: https://doi.org/10.5194/tc-2021-216-CC3
-
CC3: 'Reply on CC2', Paul PUKITE, 19 Aug 2021
-
CC2: 'Reply on CC1', Fernando Lopes, 18 Aug 2021
-
RC1: 'Comment on tc-2021-216', Anonymous Referee #1, 13 Aug 2021
The comment was uploaded in the form of a supplement: https://tc.copernicus.org/preprints/tc-2021-216/tc-2021-216-RC1-supplement.pdf
-
CC4: 'Reply on RC1', Fernando Lopes, 03 Sep 2021
The comment was uploaded in the form of a supplement: https://tc.copernicus.org/preprints/tc-2021-216/tc-2021-216-CC4-supplement.pdf
-
CC4: 'Reply on RC1', Fernando Lopes, 03 Sep 2021
-
RC2: 'Comment on tc-2021-216', Anonymous Referee #2, 06 Dec 2021
General Comments
“A strong link between variations in sea-ice extent and global atmospheric pressure” by Le Mouël et al applies the singular spectrum analysis (SSA) method to both Arctic and Antarctic sea ice and sea-level pressure (SLP) time series to identify and compare common sets of harmonics between the respective time series. Further, temporal comparisons are made between sub-annual to multidecadal harmonics, and those of longer periodicity in the ice cover and SLP data are related to astronomical and astrophysical forcing cycles. A researcher with expertise in such cycles would be better equipped to evaluate and offer an opinion on the validity of such arguments in the context of both past and modern cryospheric change. However, that said, it is not apparent what the key, novel findings are from the study. My additional comments herein mainly encompass data and methodology concerns.
Seasonal change has a clear impact on ice growth and melt, but how climate change and related oceanic and atmospheric warming of the last two plus decades factor into the interpretation of these results is unclear. Further, to provide longer-term context to the results, the conclusions attempt to offer some insights between ice cover and SLP beyond the satellite era. This is problematic due to sparse data over the polar oceans (especially Southern Ocean) until the 1950s and thus likely impacts confidence in the the sea ice and SLP periodicities calculated over that period, though no error estimates are provided accounting for this shortcoming. Below I outline more detailed concerns along these and editorial lines.
Specific Comments
1) To reiterate, seasonal temperature and pressure changes due to annual earth-sun relations certainly impact the annual cycle of ice growth and melt and presence and strength of climatological pressure features. From SSA applied to sea ice and pressure time series, we would expect related “cycles” to emerge at seasonal and annual scales through time. The rates of Earth’s air/ocean temperature changes, however, are not nearly as consistent through time. Is SSA an appropriate methodology to measure such evolving and covarying sea ice and SLP change? How does global climate change and related oceanic and atmospheric warming exacerbated at both poles during at least the last two decades (i.e., Arctic amplification) factor into the interpretation of your results and the purported astronomical and astrophysical forcings linked with non-stationary sea ice and perhaps SLP behaviors?
2) For satellite-era comparisons against sea ice variability, why use the coarse resolution HadSLP2 and not a newer, higher spatiotemporal resolution product such ERA5? There is quite a difference in spatial resolution between these two products and ERA5 assimilates lots of new data sources. At minimum, more justification for HadSLP2 over a newer product like ERA5 needs to be provided. The data quality/quantity issue further plays into the longer-term interpretation of results mentioned in the following comment.
3) In providing long-term context to the core study results, the conclusions need to be modified. Meteorological data including surface pressure is very sparse for the Southern Ocean and Antarctica, especially prior to the IGY (~1957-1958). This data quantity issue is recognized in the conclusions of Allan and Ansell (2006), which provides an overview of the HadSLP2 dataset used in the paper. Further, many gridded products have questionable data quality with a scarce number of observations included before the first half of the twentieth century (Fogt et al., 2018 J. Climate). How sparse are Southern Ocean data observations comprising the HadSLP product pre-dating the satellite era, let alone during this era from which the main results are built? Much like the passive microwave ice cover record, a description of the HadSLP dataset construction and available observations through the pressure record need to be discussed and results emphasized for periods when the data quality/quantity are most robust. These dataset issues need to be kept in perspective when interpreting the results back beyond the IGY and to the 1840s.
Technical Corrections
Some editorial remarks and clarifications are listed by line number (L):
L17: “It fits topographic forcing.” – what does? Please clarify.
L44: Change “identifications” to “identification”
L48: Spell out the climate indices (e.g., AO, AAO) where first introduced.
L51-52: The AO is commonly a statistical solution based on a univariate geopotential height field (e.g., NOAA CPC uses the 1000 hPa GPH field). Please clarify this description.
L63: Remove “lod”
L67: This sentence is confusing. Please re-write to clarify its intent.
L84: “quoting Cavalieri et al” with what? Methods? Please clarify what is meant here.
L116: The Allan and Ansell paper was published in 2006 not 2004.
L120: In addition to specific comments above, references to previous studies that have used the data for polar research would help support the statement.
Figure 2 (and others): Y axis labels referencing surface pressure should consistently list “hPa.” Check that these pressure units are consistently referenced through the paper.
L297: Reference and description of the earth-sun distance data should be provided in the data section.
Citation: https://doi.org/10.5194/tc-2021-216-RC2 -
AC1: 'Reply on RC2', Fernando Lopes, 14 Dec 2021
The comment was uploaded in the form of a supplement: https://tc.copernicus.org/preprints/tc-2021-216/tc-2021-216-AC1-supplement.pdf
-
AC1: 'Reply on RC2', Fernando Lopes, 14 Dec 2021
Status: closed
-
CC1: 'Comment on tc-2021-216', Paul PUKITE, 12 Aug 2021
I have a basic comment relating to correlations of a common-moe type. Consider Fig 5 with caption "The variation of Sun-Earth distance since 1978 (in black) is compared to the annual component of SHSI (in red). 330 (bottom) The phase difference between the two."
Why look at Sun-Earth distance when the simple seasonal cycle will likelyy give the same correlation? And surface atmospheric pressure relates to temperature most straightforwardly by the ideal gas law, which also shows a seasonal pattern. I don't understand pursuing these common-mode-related correlations.
Citation: https://doi.org/10.5194/tc-2021-216-CC1 -
CC2: 'Reply on CC1', Fernando Lopes, 18 Aug 2021
After having extracted with SSA the quasi-periods (cyclicities) of the series of sea-ice extent and atmospheric pressure, the main point we
wish to stress in this paper is the contribution of celestial mechanics in explaining these cyclicities, not to try and find a thermodynamic relation explaining the cyclicities. As we have shown in Courtillot et al (2021) regarding sunspots and in Lopes et al (2021) regarding the motion of the Earth's rotation pole, the angular momentum of planets plays a very important and often underestimated role on our star as well as on Earth. When trying to identify the signature of the Jovian planets, we found an unusually perfect harmonic sequence of 1 year : 1, 1/2, 1/3, 1/4 and 1/5 of a year. This can only have been forced by the variation of the Earth-Sun distance (see Lambeck 2005). The constant phase variation of 60 days (see Figure 05) as well as the regularity of the amplitudes of the other components argue for a simple
linear relationship. It is still not possible to this day (refs in the paper) to solve analytically the Navier-Sockes equations in a fluid
sphere in the turbulent regime (the solution is not unique unlike in the cylindrical case). We hope that our results, in addition to highlighting the presence of this remarkable harmonic series, will help towards a solution of that problem.Citation: https://doi.org/10.5194/tc-2021-216-CC2 -
CC3: 'Reply on CC2', Paul PUKITE, 19 Aug 2021
Thank you. These are all interesting possibilities and hope that you can make some progress. For your consideration, we have also pursued some of these ideas relating to a unification of orbits and geophysical measures by matching the known tidal forcing cycles..
Citations:
Pukite, Paul. "Nonlinear long-period tidal forcing with application to ENSO, QBO, and Chandler wobble." EGU General Assembly Conference Abstracts. 2021. https://ui.adsabs.harvard.edu/abs/2021EGUGA..2310515P/abstract
Pukite, Paul, Dennis Coyne, and Daniel Challou. "Mathematical Geoenergy", John Wiley & Sons, 2019.
Citation: https://doi.org/10.5194/tc-2021-216-CC3
-
CC3: 'Reply on CC2', Paul PUKITE, 19 Aug 2021
-
CC2: 'Reply on CC1', Fernando Lopes, 18 Aug 2021
-
RC1: 'Comment on tc-2021-216', Anonymous Referee #1, 13 Aug 2021
The comment was uploaded in the form of a supplement: https://tc.copernicus.org/preprints/tc-2021-216/tc-2021-216-RC1-supplement.pdf
-
CC4: 'Reply on RC1', Fernando Lopes, 03 Sep 2021
The comment was uploaded in the form of a supplement: https://tc.copernicus.org/preprints/tc-2021-216/tc-2021-216-CC4-supplement.pdf
-
CC4: 'Reply on RC1', Fernando Lopes, 03 Sep 2021
-
RC2: 'Comment on tc-2021-216', Anonymous Referee #2, 06 Dec 2021
General Comments
“A strong link between variations in sea-ice extent and global atmospheric pressure” by Le Mouël et al applies the singular spectrum analysis (SSA) method to both Arctic and Antarctic sea ice and sea-level pressure (SLP) time series to identify and compare common sets of harmonics between the respective time series. Further, temporal comparisons are made between sub-annual to multidecadal harmonics, and those of longer periodicity in the ice cover and SLP data are related to astronomical and astrophysical forcing cycles. A researcher with expertise in such cycles would be better equipped to evaluate and offer an opinion on the validity of such arguments in the context of both past and modern cryospheric change. However, that said, it is not apparent what the key, novel findings are from the study. My additional comments herein mainly encompass data and methodology concerns.
Seasonal change has a clear impact on ice growth and melt, but how climate change and related oceanic and atmospheric warming of the last two plus decades factor into the interpretation of these results is unclear. Further, to provide longer-term context to the results, the conclusions attempt to offer some insights between ice cover and SLP beyond the satellite era. This is problematic due to sparse data over the polar oceans (especially Southern Ocean) until the 1950s and thus likely impacts confidence in the the sea ice and SLP periodicities calculated over that period, though no error estimates are provided accounting for this shortcoming. Below I outline more detailed concerns along these and editorial lines.
Specific Comments
1) To reiterate, seasonal temperature and pressure changes due to annual earth-sun relations certainly impact the annual cycle of ice growth and melt and presence and strength of climatological pressure features. From SSA applied to sea ice and pressure time series, we would expect related “cycles” to emerge at seasonal and annual scales through time. The rates of Earth’s air/ocean temperature changes, however, are not nearly as consistent through time. Is SSA an appropriate methodology to measure such evolving and covarying sea ice and SLP change? How does global climate change and related oceanic and atmospheric warming exacerbated at both poles during at least the last two decades (i.e., Arctic amplification) factor into the interpretation of your results and the purported astronomical and astrophysical forcings linked with non-stationary sea ice and perhaps SLP behaviors?
2) For satellite-era comparisons against sea ice variability, why use the coarse resolution HadSLP2 and not a newer, higher spatiotemporal resolution product such ERA5? There is quite a difference in spatial resolution between these two products and ERA5 assimilates lots of new data sources. At minimum, more justification for HadSLP2 over a newer product like ERA5 needs to be provided. The data quality/quantity issue further plays into the longer-term interpretation of results mentioned in the following comment.
3) In providing long-term context to the core study results, the conclusions need to be modified. Meteorological data including surface pressure is very sparse for the Southern Ocean and Antarctica, especially prior to the IGY (~1957-1958). This data quantity issue is recognized in the conclusions of Allan and Ansell (2006), which provides an overview of the HadSLP2 dataset used in the paper. Further, many gridded products have questionable data quality with a scarce number of observations included before the first half of the twentieth century (Fogt et al., 2018 J. Climate). How sparse are Southern Ocean data observations comprising the HadSLP product pre-dating the satellite era, let alone during this era from which the main results are built? Much like the passive microwave ice cover record, a description of the HadSLP dataset construction and available observations through the pressure record need to be discussed and results emphasized for periods when the data quality/quantity are most robust. These dataset issues need to be kept in perspective when interpreting the results back beyond the IGY and to the 1840s.
Technical Corrections
Some editorial remarks and clarifications are listed by line number (L):
L17: “It fits topographic forcing.” – what does? Please clarify.
L44: Change “identifications” to “identification”
L48: Spell out the climate indices (e.g., AO, AAO) where first introduced.
L51-52: The AO is commonly a statistical solution based on a univariate geopotential height field (e.g., NOAA CPC uses the 1000 hPa GPH field). Please clarify this description.
L63: Remove “lod”
L67: This sentence is confusing. Please re-write to clarify its intent.
L84: “quoting Cavalieri et al” with what? Methods? Please clarify what is meant here.
L116: The Allan and Ansell paper was published in 2006 not 2004.
L120: In addition to specific comments above, references to previous studies that have used the data for polar research would help support the statement.
Figure 2 (and others): Y axis labels referencing surface pressure should consistently list “hPa.” Check that these pressure units are consistently referenced through the paper.
L297: Reference and description of the earth-sun distance data should be provided in the data section.
Citation: https://doi.org/10.5194/tc-2021-216-RC2 -
AC1: 'Reply on RC2', Fernando Lopes, 14 Dec 2021
The comment was uploaded in the form of a supplement: https://tc.copernicus.org/preprints/tc-2021-216/tc-2021-216-AC1-supplement.pdf
-
AC1: 'Reply on RC2', Fernando Lopes, 14 Dec 2021
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Cited
3 citations as recorded by crossref.
- On the Link Between Global Volcanic Activity and Global Mean Sea Level S. Dumont et al. 10.3389/feart.2022.845511
- On the external forcing of global eruptive activity in the past 300 years J. Le Mouël et al. 10.3389/feart.2023.1254855
- On the Annual and Semi-Annual Components of Variations in Extent of Arctic and Antarctic Sea-Ice F. Lopes et al. 10.3390/geosciences13010021