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Charles, CD, Wright JD, Fairbanks RG.  1993.  Thermodynamic Influences on the Marine Carbon-Isotope Record. Paleoceanography. 8:691-697.   10.1029/93pa01803   AbstractWebsite

Air-sea exchange represents an important controlling factor for the distribution of carbon isotopes in the modern ocean, even below the surface mixed layer. Here we show that this thermodynamic influence varies between water masses with a magnitude which is large relative to the amplitude of typical deep sea sediment delta(13)C records. Thus, changes in air-sea exchange processes must be regarded as a significant source of variability for any marine delta(13)C signal.

Charles, CD, Rind D, Healy R, Webb R.  2001.  Tropical cooling and the isotopic composition of precipitation in general circulation model simulations of the ice age climate. Climate Dynamics. 17:489-502.   10.1007/s003820000126   AbstractWebsite

We test the climate effects of changes in the tropical ocean by imposing three different patterns of tropical SSTs in ice age general circulation model simulations that include water source tracers and water isotope tracers. The continental air temperature and hydrological cycle response in these simulations is substantial and should be directly comparable to the paleoclimatic record. With tropical cooling imposed, there is a strong temperature response in mid- to high-latitudes resulting from changes in sea ice and disturbance of the planetary waves; the results suggest that tropical/subtropical ocean cooling leads to significant dynamical and radiative feedbacks that might amplify ice age cycles, The isotopes in precipitation generally follow the temperature response at higher latitudes, but regional delta O-18/air temperature scaling factors differ greatly among the experiments. In low-latitudes, continental surface temperatures decrease congruently with the adjacent SSTs in the cooling experiments. Assuming CLIMAP SSTs, O-18/O-16 ratios in low-latitude precipitation show no change from modern values. However, the experiments with additional cooling of SSTs produce much lower tropical continental delta O-18 values, and these low values result primarily from an enhanced recycling of continental moisture (as marine evaporation is reduced). The water isotopes are especially sensitive to continental aridity, suggesting that they represent an effective tracer of the extent of tropical cooling and drying. Only one of the tropical cooling simulations produces generalized low-latitude aridity. These results demonstrate that the geographic pattern of cooling is most critical for promoting much drier continents, and they underscore the need for accurate reconstructions of SST gradients in the ice age ocean.

Sanchez, SC, Charles CD, Carriquiry JD, Villaescusa JA.  2016.  Two centuries of coherent decadal climate variability across the Pacific North American region. Geophysical Research Letters. 43:9208-9216.   10.1002/2016gl069037   AbstractWebsite

The decadal variability of the Pacific Ocean and North American hydroclimate are subjects of immediate concern for society, yet the length of the instrumental record limits full mechanistic understanding of this variability. Here we introduce a 178year, seasonally resolved coral oxygen isotopic record from Clarion Island (18 degrees N, 115 degrees W), a sampling a subtropical region that is strongly influenced by the decadal-scale fluctuations of the North Pacific Gyre Oscillation and a region that serves as a critical locus for the communication of climate anomalies with the tropics. This Mexican Pacific coral record is highly correlated to coral records from the central tropical Pacific and tree ring records from western North America. Significant changes in the amplitude of oceanic decadal variability in the early nineteenth century are mirrored in the drought reconstructions in western North America. The spatial manifestation of this relationship was relatively invariant, despite notable changes in the climatic mean state.