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AMOC variabilities in PI, Paleo and historical runs
ORGANIC simulation (PI)
AMOC timeseries
Frequency analysis
| Power spectrum |
Wavelet spectrum |
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EOF of MOC
Power spectrum
| PC1 | PC2 | PC3 |
| :---: | :---: | :---: |
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COMMENT:
- EOF1 represents whole Atlantic basin varaibility; EOF2 represents North and South Atlantic variability; EOF3 represents subtropical gyre and subpolar gyre variability
- How to extract other features connecting this?
- Intepretation of power spectrum?
EOF of SPG
Power spectrum
| PC1 | PC2 | PC3 |
| :---: | :---: | :---: |
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COMMENT:
- EOF1 represents North Atlantic Current varaibility; EOF2 represents subtropical gyre and subpolar gyre variability; EOF3 represents variabilities of western and eastern basin
- EOF2 of spg is connected to MOC PC3? No in-phase correlation, but opposite correlation at immediate 1 year lead and lag.
EOF of PSL
Power spectrum
| PC1 | PC2 | PC3 |
| :---: | :---: | :---: |
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COMMENT:
- Connections with MOC, SPG and covectivive activitilies?
AMOC components: FC, Ekman and UMO
| Components |
model output vs components |
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Power spectrum of AMOC components
PI control 1001-3000 (left figure), and its power spectrum (right figure)
| Power spectrum | Filtered timeseries |
| :---: | :---: |
| Florida Current | |
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| Ekman transport | |
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| UMO transport | |
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Power spectrums of randonly selected 100 years timeseries from the 2000 years PI control run
| Years 1401-1500 | Years 1701-1800 |
| --- | --- |
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| Years 2001-2100 |
Years 2301-2400 |
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| Years 2601-2700 |
Years 2901-3000 |
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AMOC in forced simulations
Compared to RapidMOC
| 20thC forcing |
NCEP forcing 1 |
NCEP forcing 2 |
| AMOC from 1871-2009 |
AMOC from 1948-2016 |
AMOC from 1948-2016 |
| Model grid: tnx1v1 (not BCCR Fast version) |
Model grid: mnp2 (old MICOM-ICE alone stand version) |
Model grid: tnx1v1 (BCCR Fast vesion, by Jörg Schwinger) |
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| 20CR AMOC, 1995-2014,without SSS relax |
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Power spectrum
| 20CR forcing |
NCEP forcing 1 |
NCEP forcing 2 |
| total |
total |
total |
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| Florica Current |
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| Ekman transport |
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| Upp-mid ocean transport |
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AMOC in paleo-simulations
- Marine isotope stage 3b (mis3b)
- Eemian periods: 115ka, 120ka, 125ka, 130ka
- Control preindustrial simulation: 1000-2000 years
- Model grid: tnx1v1 (BCCR Fast version)
AMOC timeseries
Power spectrum
| Eemian 115ka |
Eemian 120ka |
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| Eemian 125ka |
Eemian 130ka |
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| MIS 3b |
PI control 1001-2000 |
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ORGANIC simulation (PI)
Years of strong and weak AMOC
AMOC from PI years 10001-3000
(Gray-dashed lines are $$\pm 1.5 \sigma$$ AMOC)
Phase composite: strong/weak AMOCs
- Stronger overturning at about 1500 m, also more AABW water northward
- Stronger SPG and North Atlantic Current
- Warmer and Saliner water in the eastern Subpolar North Atlantic and the Greenland Sea
- Heat loss anomaolies in the NAC and the Nordic Seas, and heat gain anomaly in the subpolar North Atlantic
- MLD changes consistent with hflx, but is small.
- Fice change is consistent with sst change
- Weaker zonal wind stress in the subpolar North Atlantic and the Southern Ocean, stronger zonal wind stress in the subpolar North Pacific
mmflxd
| mean (yrsmax) |
diff (yrsmax-yrsmin) |
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mmflxd (filtered)
| lowpass diff (yrsmax-yrsmin) |
highpass diff (yrsmax-yrsmin) |
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strmf
| mean (yrsmax) |
diff (yrsmax-yrsmin) |
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sst
| mean (yrsmax) |
diff (yrsmax-yrsmin) |
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sss
| mean (yrsmax) |
diff (yrsmax-yrsmin) |
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sealv
| mean (yrsmax) |
diff (yrsmax-yrsmin) |
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hflx
| mean (yrsmax) |
diff (yrsmax-yrsmin) |
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mld March
| mean (yrsmax) |
diff (yrsmax-yrsmin) |
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mld Annual
| mean (yrsmax) |
diff (yrsmax-yrsmin) |
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fice
| mean (yrsmax) |
diff (yrsmax-yrsmin) |
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wdstres
| mean (yrsmax) |
diff (yrsmax-yrsmin) |
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SLP
Phase of strong AMOC minus weak AMOC
| mean (yrsmax) |
diff (yrsmax-yrsmin) |
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TS
| mean (yrsmax) |
diff (yrsmax-yrsmin) |
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COMMENT: Bentsen2004 (figur19) shows positive NAO anomaly and warm NA/cool spg pattern. Here, shows negative NAO pattern (also wind stress)
Correlation
AMOC1
| AMO |
MLD_LS |
MLD_IS |
MLD_GIN |
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| NHICEA |
SHICEA |
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COMMENTS:
- SH sea ice positive lead AMOC1 by about 20a. NH sea ice is more complicate lag/lead?
AMOC2
| NHICEA |
SHICEA |
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AMOC3
COMMENT: AMOC3 and SPG2 have similar spatial pattern, and interesting temporal correlations
MLD
| LS vs IS |
LS vs GIN |
IS vs GIN |
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COMMENT: LS and IS is in phase, with IS leads the LS for about 1 year (consistent with Bentsen2004); GIN lead LS by 10-15 years (Bentsen2004, GIN and LS in opposite phase, linked to NAO as observations suggest)
MLD LS vs ...
| SPG1 | SPG2 | SPG3 |
| --- | --- | --- |
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MLD IS vs ...
| SPG1 | SPG2 | SPG3 |
| --- | --- | --- |
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MLD GIN vs ...
| SPG1 | SPG2 | SPG3 |
| --- | --- | --- |
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FC
| NHICEA |
SHICEA |
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| MLD PC1 |
MLD_GIN |
MLD_IS |
MLD_LS |
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Comment: FC transport is positively correlated with all (3) PC of NAO
Ekman
Comment: Ekman transport is negatively correlated with NAO?
UMO
| MLD1 |
MLD LS |
MLD IS |
MLD GIN |
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Regression
TS
| 90a high-pass |
90a low-pass |
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COMMENT: Park and Latif 2008 (figure 4ab) shows negative regression on multicentennial scal and positive on multidecadal scale variability. Here not.
Trend
AMOC
COMMENT: The RAPID AMOC Index at 26°N shows a decline trend ( 0.265 Sv/yr) over the 12-year period of 2004–2015(Yan et al, GRL2018)
