ASSESSING LOCAL WATER BALANCE AND OCEAN-ATMOSPHERE DYNAMICS UTILIZING MULTIPLE PROXY RECORDS FROM A SOUTHERN CALIFORNIA SPELEOTHEM OVER THE LAST MILLENNIUM

Precipitation in Southwestern North America (SWNA) is highly seasonal and has been linked to Pacific and Atlantic sea surface temperature (SST) regimes. Proxy reconstructions reveal substantial interannual-to-centennial scale variability in moisture transport and precipitation amount over the last millennium including episodes of significantly decreased precipitation that were of greater magnitude and longer duration than any episode seen in the 20th century. Understanding the underlying dynamics and spatial and temporal characteristics of this variability is critical for improving projections of future change. A speleothem δ¹⁸O (CRC-3) record from Crystal Cave located in the southwestern flank of the Sierra Nevada Mountains CA, was shown to record variations in moisture source region and storm track from 854 to 2007 AD, with lower values reflecting transport from the North Pacific and higher values reflecting transport from the tropical Pacific. As CRC-3 δ¹⁸O values are more strongly influenced by atmospheric circulation patterns than by local precipitation amount, we investigated the potential of additional proxies that may be more sensitive to local water balance. Here we will present the results of 1,028 δ¹³C and trace element (Mg, Sr, Ba) measurements conducted on CRC-3, assess their utility as proxies of local water balance at Crystal Cave, and compare them with other high-resolution paleoclimate records from the region to investigate the relationship between North Pacific SST patterns and SWNA hydroclimate. Variations in speleothem δ¹³C and trace elemental composition likely reflect local hydrologic variability rather than remote climate changes. The combination of speleothem δ¹⁸O with δ¹³C and trace element measurements from an individual speleothem can provide a powerful approach to reconstruct large-scale ocean-atmosphere dynamics and local hydroclimate in order to gain a better mechanistic understanding of past droughts.