Internal and forced variability of the Equatorial Pacific on millenial and centennial time scales

• Main Author: Kalansky, Julie
• Format: Text
• Language: unknown
• Published: No Publisher Supplied 2014
• Subjects: Pacific; Planktonic foraminifera
• Online Access: https://dx.doi.org/10.7282/t3ww7g4c; https://rucore.libraries.rutgers.edu/rutgers-lib/45307/

Although the equatorial Pacific (EP) is important to climate on interannual and decadal time scales relatively little is known about its variability and its role in the climate system on longer time scales. The main objectives of this thesis are to examine the centennial and millennial temperature variability of different regions in the EP, to determine the cause of this variability and to understand the impact of this variability on the climate system. The primary temperature proxy used is Mg/Ca from Neogloboquadrina dutertrei, a planktonic foraminifera that lives between &5-150 m. Other proxies include alkenone Uk’3& ratios to reconstruct sea surface temperature (SST) and Mg/Ca from benthic foraminifera to reconstruct bottom water temperature. Additionally, δ18O is used as a temperature and salinity proxy and δ13C is used as a water mass tracer. Reconstructions are from the eastern equatorial Pacific (EEP) in chapter 2 and 3, and the reconstruction in chapter 4 is from the Indonesian Throughflow (ITF). The second chapter focuses on the entire Holocene and the third and fourth chapters focus on the Common Era. The primary results from both locations and all timescales suggest the millennial and centennial dynamics are distinct from interannual and decadal dynamics. Prior to 8 ii kyr B.P. EEP thermostad temperatures are warm which is arguably caused by the Southern Westerly Winds being located farther South. After 8 kyr, thermostad temperatures show millennial and centennial variability, implying that in absence of a strong climate signal from the southern high latitudes, centennial variability in the EEP thermodstad is dominated by intrinsic variability. Intrinsic variability also affects SSTs in the EEP for the last 2,500 as SSTs are not responding solar variability or Northern Hemisphere temperatures. In the ITF, thermocline temperatures vary due to modulations in the regional monsoon. Neither data from the EEP nor ITF indicate that ENSO modulations are influencing centennial variability. The results from both regions caution against using ENSO to explain centennial variability and suggest the role of the EP in the climate system on centennial and longer time scales is more moderate than on interannual to decadal time scales.