1000 years of the Pacific Decadal Oscillation: variability and drivers from a climate field reconstruction
Abstract
The Pacific Decadal Oscillation (PDO) represents an important component of low-frequency climate variability with large-scale impacts on weather and economic activity. Direct observations of sea surface temperature (SST) anomalies suggest the PDO phase oscillates over a multi-decadal period, but the length of record is too short for high confidence that this is always the case. The proxy record is one way to estimate PDO variability over a much longer time. However, previous studies using statistical reconstruction techniques, which rely on multi-proxy calibration against the modern PDO record, often show inconsistent behavior prior to the instrumental period.
Here, a new coupled ocean-atmosphere climate field reconstruction using the Last Millennium Reanalysis (LMR) framework provides 1000 years of climate information that we use to investigate the PDO. We use a statistical approximation of the Community Climate System Model 4 (CCSM4) last millennium simulation and proxy records from the LMR proxy database (2000+ records) to reconstruct: SST, sea surface salinity, upper-ocean heat content (0-700m), sea-level pressure, precipitation, and 500 hPa geopotential heights. PDO values are calculated from reconstructed SST anomalies and compared against the instrumental record, previous reconstructions, and climate model output. Additionally, we investigate dynamical linkages over time to ENSO and Aleutian Low variability. We find, for example, a correlation of 0.4 between the reconstructed PDO and the NCEI PDO record from 1860 - 2000. The North Pacific Index (NPI), an analogue for Aleutian Low strength, explains roughly 30% of the reconstructed PDO variance, while the reconstructed Niño 3.4 index explains less than 2% of the PDO variance at both annual and interdecadal (>6 years) time scales.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMPP41A..01P
- Keywords:
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- 3305 Climate change and variability;
- ATMOSPHERIC PROCESSESDE: 1620 Climate dynamics;
- GLOBAL CHANGEDE: 1630 Impacts of global change;
- GLOBAL CHANGEDE: 4928 Global climate models;
- PALEOCEANOGRAPHY