Abstract
Abstract. Marine sediments have greatly improved our understanding of the climate system, but their interpretation often assumes that certain climate mechanisms operate consistently over all timescales of interest and that variability at one or a few sample sites is representative of an oceanographic province. In this study, we test these assumptions using modern observations in an idealized manner mimicking paleo-reconstruction to investigate whether sea surface temperature and productivity proxy records in the Southern California Current System can be used to reconstruct Ekman upwelling. The method uses extended empirical orthogonal function (EEOF) analysis of the covariation of alongshore wind stress, chlorophyll, and sea surface temperature as measured by satellites from 2002 to 2009. We find that EEOF1 does not reflect an Ekman upwelling pattern but instead much broader California Current processes. EEOF2 and 3 reflect upwelling patterns, but these patterns are timescale dependent and regional. Thus, the skill of using one site to reconstruct the large-scale dominant patterns is spatially dependent. Lastly, we show that using multiple sites and/or multiple variables generally improves field reconstruction. These results together suggest that caution is needed when attempting to extrapolate mechanisms that may be important on seasonal timescales (e.g., Ekman upwelling) to deeper time but also the advantage of having multiple proxy records.
Highlights
The climate system varies across multiple timescales and is driven by both stochastic processes and deterministic forcings (Huybers and Curry, 2006)
This study aimed to evaluate assumptions commonly made in paleoclimate studies: (1) a certain mechanism operates in the past on all timescales of interest, and (2) large-scale phenomena can explain the most variance in a small location
We tested these assumptions by focusing on the Southern California Current System and used observational records to understand whether it is possible to reconstruct Ekman upwelling using multiple sedimentary records
Summary
The climate system varies across multiple timescales and is driven by both stochastic processes and deterministic forcings (Huybers and Curry, 2006). One applies modern large-scale climatology to explain changes observed in paleoclimate records (e.g., Abram et al, 2016; Goni et al, 2006; Leduc et al, 2010a; MARGO, 2009; McGregor et al, 2007; Vargas et al, 2007) While these comparisons have improved our understanding about paleoclimate significantly, uncertainties and oversimplifications may often result in overly broad interpretations and assertions. This approach typically assumes that (1) certain climate mechanisms always operate over the past at all timescales of interest, and (2) large-scale phenomena can be linked to variability at one or a few sample sites (i.e., a paleoclimate record location). Some have found a substantial difference in SST reconstruction at nearby sites (e.g., Leduc et al, 2010b, and references therein)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
