Analyzing the effects of unforced natural variability and anthropogenic forcing on ENSO variability using CESM

Climate;El niño-southern oscillation (ENSO);Variability;Community earth system model (CESM);El Niño

Vega-Westhoff, Benjamin Aaron ; Sriver ; Ryan

关键词: Climate;    El niño-southern oscillation (ENSO);    Variability;    Community earth system model (CESM);    El Niño;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/95507/VEGA-WESTHOFF-THESIS-2016.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

The El Niño-Southern Oscillation (ENSO) is an important contributor to Earth’s inter-annual climate variability, with worldwide weather effects (Whetton and Rutherfurd, 1994; Hoerling and Zhong, 1997; Dai and Wigley, 2000). Understanding how ENSO may change with climate is a major challenge, given the internal variability of the system and relatively short observational record (Wittenberg, 2009). Much recent research has used multi-model ensembles to address the effects of climate change on ENSO (Stevenson, 2012; Cai et al., 2014; Kim et al., 2014). Here we analyze ENSO in a Community Earth System Model (CESM) ensemble that samples internal variability of the coupled Earth system. We present results from a 50-member climate change ensemble experiment, using historical climate forcings (1850-2005) and projections to 2100 following the representative concentration pathway 8.5 (RCP8.5). With this ensemble, and a ~5000 year control run with constant pre-industrial conditions, we examine ENSO variability under different forcing regimes. We compare the effects of anthropogenic climate change with the effects of natural modulations on ENSO sea surface temperature (SST). We find that any changes in ENSO SST due to climate change are secondary to natural modulations.