Bulk connectivity of global SST and land precipitation variations

The land climate predictability at seasonal and interannual time scales is largely due to the influence of the ocean. The connections between global sea surface temperature anomaly (SSTA) and precipitation anomaly over land as a whole are assessed using observations and Atmospheric Model Intercomparison Project (AMIP) simulations for 1957-2018 in this work. With a novel bulk connectivity matrix, the regions of SSTA having the most significant connections with global land precipitation anomaly are identified and the monthly evolution is evaluated. The similarities and differences between the observations and AMIP simulations are examined. In both the observations and AMIP simulations, SSTA in the tropical central and eastern Pacific connects strongly with the global land precipitation anomaly. Compared with that in the tropical Pacific, the connections with SSTA along the equatorial Indian and Atlantic Oceans are weaker. The global connection between SSTA and land precipitation anomaly is the strongest (weakest) in October (June) in the observations and the average of 17-individual members of the AMIP simulations, and in February (June) in the 17-member ensemble mean of the AMIP simulations. Compared with the observation, the strength of the connectivity is overestimated in the ensemble mean, and underestimated in an individual member of the AMIP simulations. The results of the bulk connectivity matrix in this work can serve as a benchmark to evaluate the connection of SSTA with global land precipitation variation in climate models.

Automated summary

The study investigates the predictability of land climate at seasonal and interannual time scales, attributing it largely to the influence of the ocean. Connections between global sea surface temperature anomaly (SSTA) and land precipitation anomaly are examined using observations and Atmospheric Model Intercomparison Project (AMIP) simulations for the period 1957-2018. The results show that SSTA in the tropical central and eastern Pacific has strong connections with global land precipitation anomaly, with weaker connections observed in the equatorial Indian and Atlantic Oceans.