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Assessing Tropical Pacific-induced Predictability of Southern California Precipitation Using a Novel Multi-input Multi-output Autoencoder
  • Linsey Sara Passarella,
  • Salil Mahajan
Linsey Sara Passarella
University of Tennessee

Corresponding Author:[email protected]

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Salil Mahajan
Oak Ridge National Laboratory (DOE)
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Abstract

We construct a novel Multi-Input Multi-Output Autoencoder-decoder (MIMO-AE) to capture the non-linear relationship of Southern California precipitation (SC-PRECIP) and tropical Pacific Ocean sea surface temperature (TP-SST). The MIMO-AE is trained on both monthly TP-SST and SC-PRECIP anomalies simultaneously. The co-variability of the two fields in the MIMO-AE shared nonlinear latent space can be condensed into an index, termed the MIMO-AE index. We use a transfer learning approach to train a MIMO-AE on the combined dataset of 100 years of output from a historical simulation with the Energy Exascale Earth Systems Model version 1 (E3SMv1) and a segment of observational data. We further use Long Short-Term Memory (LSTM) networks to assess sub-seasonal predictability of SC-PRECIP using the MIMO-AE index. We find that the MIMO-AE index provides enhanced predictability of SC-PRECIP for a lead-time of up-to four months as compared to Nino 3.4 index and the El Nino Southern Oscillation Longitudinal Index.