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
28
Clear links
21
Causation demonstrated
0
Arc width from |r| of the stored result; several tests between the same phenomena are drawn as stacked arcs.
Hypothesis tested: Gray (1984) found more hurricanes when the QBO is in its westerly phase (positive wind at 30 hPa), over 1950–1982. Camargo and Sobel (2010) showed that the link no longer held afterwards: a textbook case of a non-stationary correlation.
Pearson correlation r (lag 0 year(s))
0.05
95% interval [-0.16; 0.25] (block bootstrap)
Aligned points
78
effective n ≈ 78 (autocorrelation)
p-value
0.661
two-sided, Fisher z transform, effective n
r from 1948 to 1982
0.38
p = 0.032, n = 35
r from 1983 to 2025
-0.09
p = 0.565, n = 43
Period analysed
1948 → 2025
computed on Oct 25, 2026 · engine v1.0
Aligned series (standard deviations, after preprocessing)
Show the data as a table
Correlation by lag (year(s))
Show the data as a table
Method and sources
Mean zonal wind at 30 hPa from August to October (NOAA PSL, NCEP/NCAR reanalysis, since 1948); season ACE (HURDAT2). Lag fixed at zero; Pearson, effective size, 2-year block bootstrap. Separate correlations over 1948–1982 (the sample of the original study, extended two years back) and 1983–last season.
Computation parameters
{
"x": "mean zonal wind at 30 hPa of August–October (NOAA PSL)",
"y": "North Atlantic ACE of the season (HURDAT2), 10^4 kt²",
"lag": "fixed at 0",
"bootstrap": {
"seed": 20261023,
"block": 2,
"draws": 1000
},
"subperiods": [
[
"first year",
1982
],
[
1983,
"last year"
]
]
}Inputs : psl.qbo30.monthly (938 pts, run #3734) · hurdat2.ace.yearly (175 pts, run #21)
Reading this result
The link shows over the first period and disappears afterwards: over the whole record nothing is left. The lesson holds for every correspondence: a correlation found over one period can be fortuitous or depend on a climate state that changes; it must be checked on independent data. The proposed mechanism (wind shear and tropical convection) is still debated. 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
- Quasi-biennial oscillation, 30 hPa equatorial zonal wind (NOAA PSL)
-
NOAA PSL climate index QBO: zonal-mean zonal wind at 30 hPa at the equator from the NCEP/NCAR reanalysis (Kalnay, E., et al., 1996, Bull. Amer. Meteor. Soc., 77, 437–471).
· doi:10.1175/1520-0477(1996)077<0437:TNYRP>2.0.CO;2 · source page ↗
Licence : U.S. Government work, public domain; cite NOAA PSL and the NCEP/NCAR reanalysis (Kalnay et al., 1996) · retrieved on Oct 25, 2026 · SHA-256 2d06ed3d14b2… - HURDAT2 Atlantic hurricane database (NOAA NHC)
-
Landsea, C. W., Franklin, J. L. (2013). Atlantic hurricane database uncertainty and presentation of a new database format. Monthly Weather Review 141, 3576–3592 (HURDAT2, NOAA NHC).
· doi:10.1175/MWR-D-12-00254.1 · source page ↗
Licence : U.S. Government work, public domain · retrieved on Oct 23, 2026 · SHA-256 75202780ce56… - Gray (1984)
-
Gray, W. M. (1984). Atlantic seasonal hurricane frequency. Part I: El Niño and 30 mb quasi-biennial oscillation influences. Monthly Weather Review, 112(9), 1649–1668.
· doi:10.1175/1520-0493(1984)112<1649:ASHFPI>2.0.CO;2
Licence : Published literature; cited - Camargo et al. (2010)
-
Camargo, S. J., & Sobel, A. H. (2010). Revisiting the influence of the quasi-biennial oscillation on tropical cyclone activity. Journal of Climate, 23(21), 5810–5825.
· doi:10.1175/2010JCLI3575.1
Licence : Published literature; cited