Correspondences
What is linked, what is not
Each arc joins two phenomena tested on this site. Green and animated: clear link (correlation significant at 5 % after correcting for autocorrelation, or a response outside chance in an event study). Grey: inconclusive test. A statistical link alone does not establish causation.
- Clear link
- Inconclusive
Hypotheses tested
37
Clear links
25
Causation demonstrated
0
Arc width from |r| of the stored result; several tests between the same phenomena are drawn as stacked arcs.
Hypothesis tested: An El Niño deepens the Aleutian low, strengthens the planetary waves rising into the stratosphere and weakens the polar vortex; a La Niña acts the other way, less clearly (Garfinkel and Hartmann, 2007; Butler and Polvani, 2011; Domeisen et al., 2019).
No data imported yet. Run: php bin/console --no-debug app:analysis:compute enso-vortex
Method and sources
Niño 3.4: PSL monthly anomaly, mean of December to February. Vortex: zonal-mean zonal wind at 60° N and 10 hPa from NASA’s MERRA-2/GEOS analyses, same months. One point per winter since 1979/80; Pearson, effective sample size of Bretherton et al., 3-year block bootstrap; test repeated after removing variations longer than 21 years.
Reading this result
No visible link on the winter means: r ≈ −0.05, and El Niño and La Niña winters have vortices of the same strength on average. This negative result does not contradict the literature, which sees the effect mostly in late winter and in the frequency of sudden warmings, from samples of a few dozen winters only; the QBO, the Sun and the vortex’s own variability blur the signal over 47 winters. Correlation is not causation: common factors (seasons, cycles, trends) or coincidence can produce it. The p-values account for autocorrelation (effective n) but not for preprocessing choices; the confidence interval comes from a block bootstrap. The limits of the source data apply.
SOURCES OF THIS PAGE
- Niño 3.4 SST anomaly (NOAA PSL, ERSSTv5)
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NOAA PSL, Niño 3.4 index: monthly SST anomaly (5°N–5°S, 170°–120°W) from ERSSTv5, climatology 1991–2020.
· source page ↗
Licence : U.S. Government work, public domain · retrieved on Oct 23, 2026 · SHA-256 879cf3cb31d7… - Northern stratosphere: polar vortex, polar-cap temperature and wave heat flux, daily (NASA GSFC, MERRA-2 and GEOS FP)
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NASA GSFC Atmospheric Chemistry and Dynamics Laboratory, Annual Meteorological Statistics (Northern Hemisphere), from MERRA-2 (Gelaro, R., et al., 2017, Journal of Climate, 30, 5419–5454) and GEOS FP.
· doi:10.1175/JCLI-D-16-0758.1 · source page ↗
Licence : NASA data, no restriction on use (NASA Earth science data policy); cite MERRA-2 (Gelaro et al., 2017). The GEOS forecasts are experimental and given for research · retrieved on Nov 2, 2026 · SHA-256 7df51d62c772… - Garfinkel et al. (2007)
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Garfinkel, C. I., & Hartmann, D. L. (2007). Effects of the El Niño–Southern Oscillation and the Quasi-Biennial Oscillation on polar temperatures in the stratosphere. Journal of Geophysical Research, 112, D19112.
· doi:10.1029/2007JD008481
Licence : Published literature; cited - Butler et al. (2011)
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Butler, A. H., & Polvani, L. M. (2011). El Niño, La Niña, and stratospheric sudden warmings: A reevaluation in light of the observational record. Geophysical Research Letters, 38, L13807.
· doi:10.1029/2011GL048084
Licence : Published literature; cited - Domeisen et al. (2019)
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Domeisen, D. I. V., Garfinkel, C. I., & Butler, A. H. (2019). The teleconnection of El Niño Southern Oscillation to the stratosphere. Reviews of Geophysics, 57(1), 5–47.
· doi:10.1029/2018RG000596
Licence : Published literature; cited