Both biotic ²³¹Pa and ²³⁰Th and abiotic ²³¹Pa and ²³⁰Th have been implemented in the ocean model of CESM. Under present-day climate forcing, our model is able to simulate water column ²³¹Pa and ²³⁰Th activity and the sediment ²³¹Pa-to-²³⁰Th activity ratio in good agreement with observations. In HOSING experiments, the biotic and abiotic sediment ²³¹Pa-to-²³⁰Th activity ratios behave similarly over large areas of low productivity, but can differ substantially in some regions of high productivity.

Here with a simple coupled model that simulates typical scale interactions in the climate system, we study the optimal OTWs for the coupled media so that climate signals can be most accurately recovered by CDA. Results show that an optimal OTW determined from the de-correlation timescale provides maximal observational information that best fits the characteristic variability of the coupled medium during the data blending process.

This paper is the documentation of the implementation of neodymium (Nd) isotopes in the ocean model of CESM. Our model can simulate both Nd concentration and Nd isotope ratio in good agreement with observations. Our Nd-enabled ocean model makes it possible for direct model-data comparison in paleoceanographic studies, which can help to resolve some uncertainties and controversies in our understanding of past ocean evolution. Therefore, our model provides a useful tool for paleoclimate studies.

We use complex climate model simulations to study how the intensity of El Niño-Southern Oscillation (ENSO) changed for the last 300 thousand years. We consider external climatic forcings like orbital variations, greenhouse gases and ice-sheets. We find that orbital forcing dominates slow ENSO evolution by modulating the change of the coupled ocean-atmosphere instability, while the effects of GHGs and ice-sheet forcing tend to compensate each other.

In this paper, we challenge the usefulness of temperature effect and amount effect, the basic assumptions in past climate reconstruction using a stable water isotope proxy, in East Asia on multiple timescales. By modeling several time slices in the past 22 000 years using an isotope-enabled general circulation model, we suggest great caution when interpreting δ¹⁸O records in this area as indicators of surface temperature and/or local monsoonal precipitation, especially on a millennial timescale.

Carbon isotopes have been added to the ocean model of the Community Earth System Model version 1 (CESM1). This paper describes the details of how the abiotic 14C tracer and the biotic 13C and 14C tracers were added to the existing ocean model of the CESM. In addition, it shows the first results of the new model features compared to observational data for the 1990s.

All regional monsoons belong to a cohesive global monsoon circulation system, albeit thateach regional subsystem has its own indigenous features. A comprehensive review of global monsoon variability reveals that regional monsoons can vary coherently across a range of timescales, from interannual up to orbital and tectonic. Study of monsoon variability from both global and regional perspectives is imperative and advantageous for integrated understanding of the modern and paleo-monsoon dynamics.