Changes in global teleconnection patterns under global warming and stratospheric aerosol intervention scenarios
Abstract. We investigate the potential impact of Stratospheric Aerosol Intervention (SAI) on the spatiotemporal behavior of large-scale climate teleconnection patterns represented by the North Atlantic Oscillation (NAO), Pacific Decadal Oscillation (PDO), El Niño/Southern Oscillation (ENSO) and Atlantic Multidecadal Oscillation (AMO) indices using simulations from the Community Earth System Models (CESM1 and CESM2). The leading Empirical Orthogonal Function of sea surface temperature (SST) anomalies indicates that greenhouse gas forcing is accompanied by increases in variance across both the North Atlantic (i.e., AMO) and North Pacific (i.e., PDO) and a decrease over the tropical Pacific (i.e., ENSO); however, SAI effectively reverses these global warming-imposed changes. The projected spatial patterns of SST anomaly related to ENSO show no significant change under either global warming or SAI. In contrast, the spatial anomaly patterns pertaining to AMO (i.e., in the North Atlantic) and PDO (i.e., in the North Pacific) changes under global warming are effectively suppressed by SAI. For AMO, the low contrast between the cold-tongue pattern and its surroundings in the North Atlantic, predicted under global warming, is restored under SAI scenarios to similar patterns as in the historical period. The frequencies of El Niño and La Niña episodes increase with greenhouse gas emissions in the models, while SAI tends to compensate for them. All climate indices’ dominant modes of inter-annual variability are projected to be preserved in both warming and SAI scenarios. However, the dominant decadal and interdecadal variability mode changes induced by global warming are exacerbated by SAI, particularly in the Atlantic-based AMO.
Abolfazl Rezaei et al.
Status: final response (author comments only)
RC1: 'Comment on egusphere-2022-974', Anonymous Referee #1, 08 Dec 2022
- AC1: 'Reply on RC1', Abolfazl Rezaei, 17 Dec 2022
RC2: 'Comment on egusphere-2022-974', Anonymous Referee #2, 14 Dec 2022
- AC2: 'Reply on RC2', Abolfazl Rezaei, 13 Jan 2023
Abolfazl Rezaei et al.
Abolfazl Rezaei et al.
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In general, I would not recommend this manuscript for publication as-is. A lot of the claims made in the text are not supported by the data presented in the figures (more details in the major comments). I also have a few minor comments on typos and clarifications. I would gladly review a revision of the manuscript.
Major comments :
- L.295-7 The data shown in figure 6 does not support the conclusion that there is an increase in the peak interval, height, and width with SAI relative to GHG only. For CESM1, there is virtually no difference between the two. For CESM2, there are modest increases in the median value for some of the measures, but if you consider the upper and lower quantiles, the values are not that different. I would include more caveats in your statement. And unless there is in fact a significant difference, I would remove the arrows between the medians as I find some slightly misleading.
- L.320-3 The evidence for these claims do not seem very robust, given that the historical simulation has only one ensemble member. Is there a better way of quantifying the importance of the differences between the green and blue/red lines?
- L. 338 Why is the power of the historical NAO considerably smaller than that of the SSP585 and SAI runs?
- L. 344 Confused by the use of “counter-productive” here. It seems like the AMO in SSP585 is closer to historical than the SAI simulations (fig. 8e), but that is not the case for the NAO (fig. 8f).
- L.348 I am a little confused about how to interpret "the dominant 35-55 year mode in historical NAO" in fig 8f, given that its power is so much smaller than that of the SSP585 and SAI simulations.
- L.349-351, Maybe it is clearer to say that the 10-20 and 50-70 year modes present in the historical simulations are not present in both the SSP585 and SAI simulations, and the latter two are similar to eachother.
Minor comments :
Typo “relatted” figure 1
L.238-240 “broaden” typo?
L.290-1 With increases in greenhouse gases
Figure 6 CESM2 panel, 1.95 between panel h and k.
Figure 6, add in the title what the red line, box, and whiskers represent.
L.366 use 2xCO2 and 0.5xCO2
L.400 rephrase : how good each model’s simulations are?
L.422 usual -> more likely?
L.424 Explain “devil’s staircase” or remove.
L.442-3 Models are different from obs, but they are not “simulating a different system”.
L.445 actuality -> observations
L.447-8 rephrase, I am confused. Remove “that is … response of the system”?
L.468-9 I would remove the last sentence.
L.475 Some historical data cover more years than that.
L.489 impact them -> restore them?
L.498 Caution is warranted due to …