(Oldeman et al. 2021) & (Pontes et al. 2022) explored ENSO in Pliocene by using dataset from PlioMIP2. They found robust weakening of ENSO variability among PlioMIP2 ensembles.
ENSO in Miocene simulations
The assignment investigates the ENSO in Miocene simulations. Although the purpose of the experiments is studying the importance of modifying aerosols and dust emission in Miocene simulations, the ENSO amplitude could be affected by the modification of aerosols and dust emission.
1. Decide ENSO index
(Oldeman et al. 2021): correlate ENSO indices with the PC1 of sea surface temperature (SST) in the tropical Pacific to check which domain is representative for ENSO variability.
- Domain of the tropical Pacific: (23°S-23°N, 140°E-80°W)
(1) EOF Analysis
(2) ENSO indices (3) Correlation between PC & ENSO indices
The correlation between Nino4 and PC1 in Mio_Mio in the highest in the experiment. Although the Correlation between Nino3.4 and PC1 in Mio_Pi in the highest in the experiment, I selected Nino4 as the index for the investigation to more easily and directly compare ENSO in Mio_Pi and Mio_Mio.
Thus, I selected Nino4 as the ENSO index in the following research.
- (Oldeman et al. 2021) used standard deviation to invetigate the ENSO amplitude. In our results, the ENSO amplitude is slightly larger in Mio_Mio experiment.
(4) Composite Precipitation based on Nino4
Caveat: the variation of ENSO could be different in different segment of time series you choose. (Burls & Fedorov 2014)