ENSO Modulation of the QBO Periods in GISS E2.2 Models

Zhou, Tiehan; DallaSanta, Kevin J.; Orbe, Clara; Rind, David H.; Jonas, Jeffrey A.; Nazarenko, Larissa; Schmidt, Gavin A.; Russell, Gary

doi:https://doi.org/10.5194/egusphere-2023-774

Preprints

https://doi.org/10.5194/egusphere-2023-774

Preprints

15 May 2023

| 15 May 2023

Status: this preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).

ENSO Modulation of the QBO Periods in GISS E2.2 Models

Tiehan Zhou, Kevin J. DallaSanta, Clara Orbe, David H. Rind, Jeffrey A. Jonas, Larissa Nazarenko, Gavin A. Schmidt, and Gary Russell

Abstract. Observational studies have shown that the El Niño–Southern Oscillation (ENSO) exerts an influence on the Quasi-Biennial Oscillation (QBO). The downward propagation of the QBO tends to speed up and slow down during El Niño and La Niña, respectively. Recent results from general circulation models have indicated that the ENSO modulation of the QBO requires a relatively high horizontal resolution, and that it does not show up in the climate models with parameterized but temporally constant gravity wave sources. Here, we demonstrate that the NASA GISS E2.2 models can capture the observed ENSO modulation of the QBO period with a horizontal resolution of 2° latitude by 2.5° longitude and its gravity wave sources parameterized interactively. This is because El Niño events lead to more vigorous gravity wave sources generating more absolute momentum fluxes over the equatorial belt, as well as less filtering of these waves into the tropical lower stratosphere through a weakening of the Walker circulation. Various components of the ENSO system such as the SSTs, the convective activities, and the Walker circulation are intimately involved in the generation and propagation of parameterized gravity waves, through which ENSO modulates the QBO period in GISS E2.2 models.

Received: 20 Apr 2023 – Discussion started: 15 May 2023

Tiehan Zhou et al.

Status: open (until 26 Jun 2023)

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RC1: 'Comment on egusphere-2023-774', Anonymous Referee #1, 04 Jun 2023 reply

Comments on “ENSO Modulation of the QBO Periods in GISS E2.2 Models” by Zhou et al.
Summary

In this study, the authors focus the possible impact of the ENSO on the QBO cycle using the observations and the model simulations from GISS E2.2. However, the modulation of the QBO cycle by the El Nino and La Nina is not consistent among the model configurations. The authors concluded that the model physics are important to simulate the impact of the ENSO on the QBO period. In general, the authors well explored the possible impact of ENSO on the QBO period. However, I also found some relevant concerns, which should be well addressed. Therefore, I suggest a major revision at the present time.
Major comments

1. The relationship between the ENSO and QBO should be well reviewed in the introduction. The possible impact of ENSO on the QBO amplitude and phase should mentioned. Further, ENSO and QBO phase coincidence should also be mentioned. Before 1980s, El Nino tends to appear during EQBO, and La Nina tends to appear during WQBO. After 1980s, El Nino tends to appear during WQBO, and La Nina tends to appear during EQBO (DOI: 10.1175/JCLI-D-19-0087.1; 10.1175/JCLI-D-20-0024.1).
2. Previous studies also found that the relationship between ENSO and QBO is not universal among models (DOI: 10.1175/JCLI-D-20-0024.1). This paper only emphasizes the possible impact of ENSO on the QBO, is there a possibility that the QBO can impact the ENSO occurrence and amplitude.
3. Further, this paper is too long and too dispersal and include too many contents. This paper is not aimed to evaluate the model configurations. However, the comparison between AMIP and CMIP simulations and that between SP and AP physics accounts for a large portion of the paper. I suggest to remove the experiments that fail to reproduce the impact of ENSO on the QBO period. Including those results that do not simulate a significant difference between the QBO periods during El Nino and La Nina, the paper is not convinced at all.
4. The paper should provide a section named “Data and method” or something like. Without a data description and experiment introduction, this paper reads weird and readers fail to find the experimental setup.
Other comments

1. L30, L43-45: There are too many papers concerning the possible impact of ENSO and QBO on the climate (DOI: 10.1175/JCLI-D-19-0663.1; 10.1029/2020GL089149; 10.1175/JCLI-D-20-0960.1). I suggest to include more recent publication in the citations.
2. L59-60: There are also some studies that focus on the possible impact of the QBO on ENSO. The authors should present some review.
3. L145-146: The ENSO amplitude in observations and CMIP models are not identical (DOI: 10.3878/AOSL20140055). If you use the same criterion, will the results be not convincing.
4. L153-154: Other studies also performed the EOF analysis for the QBO wind profiles (See Figure 3 in Rao and Ren 2018CD, doi: 10.1007/s00382-017-3998-x).
5. L168: Here is programming language. I suggest to use the science language: φ =atan(PC2/PC1)
6. L233: You should provide a detailed introduction for the calculation steps in a method section.
7. L254: modulates of => modelate (remove “of”)
8. L259: Section 3.1, and 3.2 : Should move to a method section.
9. L404-406: I also download historical runs from the GISS-E2 models for CMIP6. But I did not see the spontaneous QBO. Is the model in this paper same configured as for CMIP6?
10. Section 4.1: Should move to the method section.
11. L439-441: Can you explain why the relationship is not stable?
12. L475: help => helps
13. L495-497: Please also see Domeisen et al. 2019 (RG) and references therein.
14. L531-532: Most CMIP models simulate a smaller ENSO amplitude as compared with the observations (DOI: 10.3878/AOSL20140055). This model is different and simulate a stronger ENSO.
15. L588-593: This paragraph describes the ERA5 reanalysis and should be moved to the method section.
16. L591: during in => during
17. L605-606: This sentence repeats many times. You can provide a section describing the data and methods. There is no need to repeat the methods time by time.
18. L732-735: The ENSO amplitude has so larger a bias. To what extent can we trust the results?
19. L743, Figure 14: This figure is redundant and fail to connect with the topic of this study.
20. L760: Do you mean that none of the results are robust in this study? I also did not see that the QBOi also explore the ENSO modulation of the QBO cycle.

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Citation: https://doi.org/10.5194/egusphere-2023-774-RC1

Tiehan Zhou et al.

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Short summary

The El Niño–Southern Oscillation (ENSO) tends to speed up and slow down the phase speed of the Quasi-Biennial Oscillation (QBO) during El Niño and La Niña, respectively. The ENSO modulation of the QBO does not show up in the climate models with parameterized but temporally constant gravity wave sources. We show that the GISS E2.2 models can capture the observed ENSO modulation of the QBO period with a horizontal resolution of 2° by 2.5° and its gravity wave sources parameterized interactively.


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