2010/ 11/ 16 Speaker/ Pei-Ning Kirsten Feng Advisor/ Yu-Heng Tseng Modeling North Pacific Decadal Variations and Their Teleconnection Patterns 2010/ 11/ 16 Speaker/ Pei-Ning Kirsten Feng Advisor/ Yu-Heng Tseng

Outline Literature Review Motivation Objective Data and Model Preliminary work Summary

-- 500 hPa Height -- Sea Level Pressure -- Sea Surface Temperature Teleconnections -- 500 hPa Height -- Sea Level Pressure -- Sea Surface Temperature

High Level – Low Level Interaction Structure 500 hPa – EOF1 PNA SLP – EOF1 North Hemisphere -- AO Pacific -- ENSO/ PDO (SSHa EOF1) Atlantic – NAO SST – EOF1 500 hPa – EOF2 WP SLP – EOF2 Pacific -- NPO SST – EOF2 Pacific – Victoria Mode(NPGO, SSHa EOF2) High Level – Low Level Interaction Surface Interaction

500 hPa Height EOF1 -- PNA Pacific / North American Pattern (PNA) The Pacific/ North American teleconnection pattern (PNA) is one of the most prominent modes of low-frequency variability in the Northern Hemisphere extratropics. [NOAA CPC http://www.cpc.ncep.noaa.gov]

NH 1000 hPa Height EOF1 -- AO Arctic Oscillation (AO) The loading pattern of the AO is defined as the leading mode of Empirical Orthogonal Function (EOF) analysis of monthly mean 1000mb height. [NOAA CPC http://www.cpc.ncep.noaa.gov]

Pacific SLP EOF1 – AL Aleutian Low (AL) The first co-variability mode captures the mature phase of ENSO and its atmospheric teleconnections to the AL. [Di Lorenzo et al., 2008]

Atlantic SLP EOF1 -- NAO North Atlantic Oscillation (NAO) One of the most prominent teleconnection patterns in all seasons is the North Atlantic Oscillation (NAO). It combines parts of the East-Atlantic and West Atlantic patterns with a north-south dipole of anomalies [NOAA CPC http://www.cpc.ncep.noaa.gov]

Atlantic Long-term SSTa -- AMO Atlantic Multidecadal Oscillation (NPO) The Atlantic Multi-decadal Oscillation (AMO) is a mode of natural variability occurring in the North Atlantic Ocean and which has its principle expression in the sea surface temperature (SST) field. http://www.aoml.noaa.gov/phod/amo_faq.php

Pacific SST EOF1 – PDO/ENSO Pacific Decadal Oscillation / El Nino-Southern Oscillation (PDO/ENSO) Warm Phase Cool Phase The PDO is highly correlated with the dominant mode of sea surface height anomalies (SSHa). 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]

Pacific SST EOF1 – PDO/ENSO Pacific Decadal Oscillation / El Nino-Southern Oscillation (PDO/ENSO) The first leading mode is well-known as the ENSO pattern. And the mid-high latitude is shown as the PDO pattern (red rectangle). This is now thought that those mid-latitude variation may be the footprint of tropical forcing . [Di Lorenzo et al., 2008]

Why Second Mode PDO index can’t explain those variations in the ocean. NPGO is the dominant mode of the salinity and the nutrients. [Wright et al., 2009]

Why Second Mode The NPGO leads decadal variations in the strength of the Kuroshio-Oyashio connecting California and Japan. Di Lorenzo et al., 2008

500 hPa Height EOF2 -- WP Western Pacific Pattern (WP) The western pacific pattern (WP) is the SLP EOF2 pattern during DJFM in the region of 20～85N, 120E～120W. [Barnston and Livezey, 1987]

Pacific SLP EOF2 – NPO North Pacific Oscillation (NPO) NPO, the second mode of North Pacific SLPa, dominantly forces the North Pacific Gyre Oscillation (NPGO). [Di Lorenzo et al., 2008]

Pacific SST EOF2 – Victoria Mode SSH EOF2 -- North Pacific Gyre Oscillation (NPGO) In the midlatitude and the North Pacific, the spatial pattern of the SSTa SEOF2 is nearly identical to the SSTa expression of the NPGO and of the second EOF of North Pacific SSTa, which has been referred to as the Victoria Mode [Bond et al., 2003]. [Di Lorenzo et al., 2008]

Motivation / Objective

Motivation Decadal and low-frequency climate variabilities in the Pacific and other basins are not well understood.   What are the underlying physical mechanisms for these low-frequency climate variability?   Can the latest AOGCM capture these climate patterns and variabilities for better future prediction?   What is the role of atmospheric-ocean interaction? Are these climate variabilities related?

Objective To summary and clarify the low frequency variability in the North Pacific Ocean and their links with the global patterns.   To assess and evaluate the coupled climate model capability in capturing the patterns of variability in the North Pacific.   To understand and verify the underlying physical mechanisms in North Pacific climate variability.   To bridge the regional climate variability in the North Pacific with a complete picture of global climate change throughout the Pacific basin.

Data Source Model Methods Methods and Model Data Source Model Methods

Data source Hadley SST Hadley SLP NCEP/NCAR Reanalysis 1 1º x 1º HadISST1 from 1900 to 2009. Hadley SLP 5º x 5º HadSLP2 from 1900 to 2009 NCEP/NCAR Reanalysis 1 2.5º x 2.5º Reanalysis 500 Height from 1950 to 2009

Ongoing Work Future Work Preliminary Work Ongoing Work Future Work

500 hPa Height EOF1 -- PNA Pacific / North American Pattern (PNA) Corrcoef = 0.501

500 hPa Height EOF2 -- WP Western Pacific Pattern (WP) The western pacific pattern (WP) is the SLP EOF2 pattern during DJFM in the region of 20~85N, 120E~120W. Corrcoef = 0.528 [Barnston and Livezey, 1987]

NH SLP EOF1 -- AO Arctic Oscillation (AO)

Pacific SLP EOF1 -- AL Aleutian Low (AL) Corrcoef = 0.898

Pacific SLP EOF2 -- NPO North Pacific Oscillation (NPO) Corrcoef = 0.486

Atlantic SLP EOF1 -- NAO North Atlantic Oscillation (NAO) Corrcoef = 0.670

Atlantic Long-term SSTa -- AMO Atlantic Multidecadal Oscillation (NPO) Corrcoef = 0.442

Pacific SST EOF1 – PDO/ENSO Pacific Decadal Oscillation / El Nino-Southern Oscillation (PDO/ENSO) Corrcoef = 0.898

Pacific SST EOF2 – Victoria Mode SSH EOF2 -- North Pacific Gyre Oscillation (NPGO) Corrcoef = 0.486

Future Work To assess and evaluate the coupled climate model capability in capturing the patterns of variability in the North Pacific. compare the atmospheric and the teleconnection patterns between these models and observations. evaluate the characteristics of modeled ENSO and the two associated types in the coupled runs. To understand and verify the underlying physical mechanisms in North Pacific climate variability. Verify the framework of the North Pacific Climate Variability To bridge the regional climate variability in the North Pacific with a complete picture of global climate change throughout the Pacific basin.

Model ( ECHAM5 / SIT / DIECAST ) Year: 1871 to 2008 ECHAM5 – AGCM, running at various resolutions. SIT – a one-column snow/ice/ocean model with 41-level ocean+ 2-level ice + 2-level snow. DIECAST – OGCM with 2 degree in the equator, covering from 60°S to 60°N, with 31 levels. ECHAM (AGCM) 19 levels T31 SIT (Air/Snow/Ice/Thermocline) 2snow+2ice+41 water levels DIECAST (OGCM) 31 Levels (2 deg)

Summary

Summary The leading EOF patterns in the 500hPa, SLPa, and SSTa in the North Pacific are all related to the Aleutian Low. And the ENSO pattern may impact the mid-high latitude variations by atmosphere. The second mode in the Pacific now becomes more important because its time series is highly related to the changes of ocean variables. The further we want to realize is about what role other teleconnections play in the north hemisphere.

Atmosphere-Ocean Interaction PNA / AO / NAO ? WP ? [Di Lorenzo et al., 2010]

Thank You ～To Be Continued～