Figure 1: Map and time series showing the relationship of Taiwan tree-ring δ18O with regional sea-surface temperature (SST).
From: Recent enhancement of central Pacific El Niño variability relative to last eight centuries
(a) Map of the composite Taiwan tree-ring δ18O record regressed upon global SSTs52 (https://www.esrl.noaa.gov/psd/data/gridded/data.kaplan_sst.html) from 1900 to 2007 AD. Colours define areas of statistically significant correlations (P<0.05). The black rectangle denotes the NIÑO4 region. The shaded numbers denote the locations of proxy records mentioned in the text: 1—Taiwan tree-ring 18O; 2—Fujian, China tree-ring δ18O (ref. 27, 25° 59′ N, 106° 26′ E, 1901–2004 AD); 3—Mu Cang Chai, Laos tree-ring δ18O (ref. 28, 21° 40′ N, 104° 06′ E, 1705–2005 AD); 4—PhuLeuy Mountain, Vietnam tree-ring δ18O (ref. 29, 20° 17′ N, 103° 55′ E, 1688–2002 AD); 5—Maiana coral δ18O (ref. 33, 1° N, 173° E, 1840–1995 AD); 6—Palmyra coral δ18O (ref. 12, 6° N, 162° W, 1635–1703 AD, 1886–1998 AD). (b) Comparison of the annually resolved SST anomaly (SSTA) between Taiwan tree-ring δ18O-based NIÑO4 index (red) and the Kaplan instrumental NIÑO4 index21 averaged from March to May (blue) of each year (P<0.05). Note that the significance of all correlations reported in this study have been assessed using effective degrees of freedom that account for autocorrelation in the time series27. Map of a was created by http://climexp.knmi.nl/corfield.cgi.
