A coral-based reconstruction of Intertropical Convergence Zone variablity over Central America since 1707

Journal Article · Sun May 15 04:00:00 EDT 1994 · Journal of Geophysical Research

DOI:https://doi.org/10.1029/94JC00360· OSTI ID:135960

Linsley, B K; Dunbar, R B; Mucciarone, D A ^[1]; Wellington, G M ^[2]

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1. Rice Univ., Houston, TX (United States)
2. Univ. of Houston, TX (United States); and others

Seasonal movements of the Intertropical Convergence Zone (ITCZ) control precipitation patterns and cloud cover throughout the tropics. In this study the authors have reconstructed seasonal and interannual variability of the eastern Pacific ITCZ from 1984 to 1707 using subseasonal {delta}{sup 18}O analyses on a massive coral from Secas Island (7{degrees}59{prime}N, 82{degrees}3{prime}W) in the Gulf of Chiriqui, Panama. The land area that drains into the Gulf of Chiriqui has served to amplify the rainfall effect on nearshore surface waters and coral {delta}{sup 18}O{sub ppt} composition. During the protracted wet season in Panama, the {delta}{sup 18}O of precipitation ({delta}{sup 18}O{sub ppt}) is reduced on average by 10{per_thousand} and sea surface salinity (SSS) along the western coast is reduced up to 11{per_thousand}. Calibration of the coral {delta}{sup 18}O{sub ppt} from Secas Island against instrumental sea surface temperature (SST), SSS, precipitation and {delta}{sup 18}O{sub ppt} data indicate that seasonal rainfall induced variations in seawater {delta}{sup 18}O are responsible for {approximately}80% of the annual {delta}{sup 18}O variance. The regularity of the reconstructed seasonal ITCZ cycle indicates that over the length of the record the zone of maximum rainfall in the eastern Pacific has always expanded north to at least Panama in every northern hemisphere summer. Significant interannual and interdecadal {delta}{sup 18}O oscillations occur at average periods near 9, 3-7 (ENSO band), 17 and 33 years (listed in order of decreasing variance). As the Gulf of Chiriqui coral {delta}{sup 18}O time series is the first paleoclimatic record of past variations in the ITCZ, other seasonal-resolution reconstructions of the past behavior of the ITCZ are required to test whether the interannual and long-term variability observed in the eastern Pacific ITCZ is more than regional in scale. 79 refs., 13 figs., 2 tabs.

• OSTI ID: 135960
• Journal Information: Journal of Geophysical Research, Journal Name: Journal of Geophysical Research Journal Issue: C5 Vol. 99; ISSN JGREA2; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
ANNUAL VARIATIONS
CENTRAL AMERICA
CLOUDS
CORALS
OXYGEN 18
PALEOCLIMATOLOGY
PRECIPITATION
TRACER TECHNIQUES