Modeling North Pacific Decadal Variations and Their Teleconnection Patterns Speaker/ Pei-Ning Kirsten Feng Advisor/ Yu-Heng Tseng

Outline Overview Motivation Objective Data and Model Recent Result Summary and future work

Motivation Since the long tern climate is impacted by the ocean- atmospheric interactions, if we want to use modeling to simulate the climate, it is necessary to know what kind of low-frequency oscillation is referred. Further it is found that PDO can not explain the oscillations in the ocean, however NPGO seems more related to the variations. Thus we want to know its relationship with other oscillations and climate.

Global Pattern and Teleconnection AO AL ←→ PDO ENSO / EPW WP CPW NAO NPO ←→ NPGO KOE PNA How these oscillations play roles in the long term climate?

Di Lorenzo et al., 2008

Tseng, 2010

Terms

Pacific Decadal Variations [Di Lorenzo et al., 2008] PDO AREA

North Pacific – AL/PDO The Pacific Decadal Oscillation (PDO) Index is defined as the leading principal component of North Pacific monthly sea surface temperature (SST) variability (poleward of 20N). [Mantua et al., 1997] Warm Phase Cool Phase

North Pacific – AL/PDO The Pacific Decadal Oscillation (PDO) Index is defined as the leading principal component of North Pacific monthly sea surface temperature (SST) variability (poleward of 20N).

North Pacific – NPO/NPGO North Pacific Gyre Oscillation, NPGO: The NPGO is defined as the second dominant mode of SSHa variability in the Northeast Pacific [180°–110°W; 25°N–62°N] and is correlated with the second mode of North Pacific SSTa. [Di Lorenzo et al., 2008]

Atmosphere-Ocean Interaction [Di Lorenzo et al., 2010]

Teleconnection

Pacific Pattern -- WP

Atlantic Pattern -- NAO

Global Pattern -- AO

Motivation Low-frequency oscillations are not known well. Why there are so many decadal variations with similar patterns on time series? Are the related? What might be the possible mechanism for those oscillations?

Objective First we want to summarize the oscillations and determine their relations, especially stressed on the Pacific area. We want to compare the model simulation to the observations and see if those oscillations are shown in the resolutions.

Data source

Hadley SST Hadley SLP NCEP/NCAR Reanalysis

Methods and Model

Model

Atmosphere-Ocean Interaction PDO –SSTa PC-1 NPGO –SSHa PC-2 ENSO AL & NPO forcings Model reconstruction –A. PDO (corrcoef) –B. NPGO (corrcoef) –C. Teleconnections Observation data: –SLP : Hadley SLP –SST : HadISST

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