Supplementary figures
Supplementary Figure 1.
Figure S1. Long-term mean (1979-2004) Climate Prediction Center Merged Analysis of
Precipitation (CMAP)1 seasonal precipitation totals (in mm) for December-February (left) and
July-September (right). Precipitation over SE Brazil in DJF is related to the southward expansion
and intensification of the South American summer monsoon, while in JAS precipitation is of
extratropical nature and associated with midlatitude cyclonic activity over the South Atlantic.
The South Atlantic Convergence Zone (SACZ), one of the main components of the SASM,
appears on the map as an elongated NW-SE convective band that originates in the Amazon
Basin, extending toward southeastern Brazil in summer and protruding into the subtropical South
Atlantic Ocean2. The mean position of the SACZ on the Atlantic coast is at 24ºS, but it is also
the primary source of summer precipitation in the study area. Numbers indicate locations
mentioned in text: 1- Botuverá Cave, 2- IAEA station in Porto Alegre, Brazil.
1
Xie, P. & Arkin, P.A. Global Precipitation: A 17-year monthly analysis based on gauge
observations, satellite estimates, and numerical model outputs. Bull. Amer. Meteor. Soc., 78,
2539–2558 (1997).
2
Carvalho, L, C. Jones & B. Liebmann. Extreme precipitation events in southeastern South
America and large-scale convective patterns in the South Atlantic convergence zone. J. Climate,
15, 2377–2394 (2002).
Supplementary Figure 2.
a
Mean monthly temperature (°C)
26
24
22
20
18
16
14
jan feb mar april may june july aug sept oct nov dec
Mean monthly rainfall amount (mm)
b
140
120
100
80
60
jan feb mar april may june july aug sept oct nov dec
-2
-3
-4
-5
-6
-7
dec
nov
oct
sept
aug
july
may
june
april
mar
-8
jan
18
Weighted mean monthly  O (‰)
-1
feb
c
Figure S2. Meteorological and isotopic data for precipitation from IAEA station at Porto Alegre:
(a) monthly temperature, (b) monthly rainfall amount, (c) weighted mean monthly δ18O. Data
from IAEA/WMO, 1994, Global Network for Isotopes in Precipitation (GNIP)12 Database.
Supplementary Figure 3.
b
a
-4.4
-2.8
A
B
C
-4.8
13
18
 C
 O
-3.0
-3.2
-5.2
-5.6
-3.4
-6.0
0
1
2
3
4
5
6
7
Distance along growth layer (cm)
c
-3.4
-3.2
-3.0
-2.8
18
 O
-3.0
-3.5
-4.0
13
 C
-4.5
-5.0
-5.5
-6.0
-6.5
2
R = 0.0441
n = 690
-7.0
-5
-4
-3
-2
-1
0
18
 O
Figure S3. Isotope profiles and cross-plots (Hendy tests) for individual layers (plots a and b) and
the entire along-axis data set (plot c) for stalagmite BT2. All layers have values of 18O <
0.4‰ and, with one exception, a lack of correlation between 13C and 18O. The distance from
top for layers A, B and C is 39.3cm, 34.6cm, 16.5cm, respectively. The average width of
stalagmite is 9cm at the level of layers A and B and 7cm at the level of layer C. The cross plot
for the entire data set measured along the stable isotope longitudinal profile (c) shows an almost
complete lack of correlation between 18O and 13C (r2 = 004) indicating a lack of kinetic
fractionation effects.
Supplementary Figure 4
Figure S4. Spectral analysis of the BT2 δ18O time series. Left hand figure is a color-contoured
wavelet Morlet analysis of spectral power (interpolated data set has 100 years resolution; 1151
data points), with y axis the Fourier period (in ky) and the bottom axis age (in ky). The black
contours enclose regions of greater than 95% confidence above a red-noise process. Spectral
power is highest at a period of ~23 ky throughout the time series (b) Right hand figure is the
global wavelet power spectrum (black line). The dashed line is the 95% significance level for a
red-noise background. The center of the highest peak above the red noise is at a period of 23 ky.