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Adviser:Huang-Hsiung Hsu

Speaker:Ming-Ying Lee

01Jul2008

Decadal Teleconnection in the Decadal Teleconnection in the Northern HemisphereNorthern Hemisphere

Decadal Teleconnection in the Decadal Teleconnection in the Northern HemisphereNorthern Hemisphere

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How many Decadal to Mutidecadal fluctuations in the Northern Hemisphere ?

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From: http://jisao.washington.edu/pdo/

Typical wintertime Sea Surface Temperature (colors),

 Sea Level Pressure (contours) and surface windstress (arrows) anomaly patterns during warm and cool phases of PDO

Warm phase Cool phase

Pacific Decadal Oscillation (PDO)

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Upper panel: AMO index: the ten-year running mean of detrended Atlantic sea surface temperature anomaly (SSTA, °C) north of the equator. Lower panel: Correlation of the AMO index with gridded SSTA over the world ocean (all seasons). The thick contour is zero and thin contours denote the 95% significance level.

Form:http://www.aoml.noaa.gov/phod/amo_fig.php

Atlantic Multidecadal Oscillation (AMO)

5 From:http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.shtml

Arctic Oscillation (AO)

6 From : http://www.ldeo.columbia.edu/res/pi/NAO/

Positive NAO Negative NAO

North Atlantic Oscillation(NAO)

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A new Decadal to Mutidecadal fluctuation in the NH?? A new Decadal to Mutidecadal fluctuation in the NH??

??

AOcor = -0.75

ENSOcor =0.51

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EOF analysis Northern Hemisphere

COR=0.97

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Cor=0.87

All index had performed 9-yrs running except the AMO uesd 25-yrs running

PC2 and Climate Index

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Red and blue colored dots represent positive and negative correlations of Northern Hemisphere summer rainfall with the AMO index. When the AMO is positive (warm Atlantic) there is less rainfall over most of the United States and northeastern South America, and more rainfall in southern Alaska, northern Europe, west Africa and Florida.

Form:http://www.aoml.noaa.gov/phod/amo_fig.php

What are the impacts of the AMO?

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During warm phases of the AMO, the numbers of tropical storms that mature into severe hurricanes is much greater than during cool phases, at least twice as many. Since the AMO switched to its warm phase around 1995, severe hurricanes have become much more frequent and this has led to a crisis in the insurance industry.

Form:http://www.aoml.noaa.gov/phod/amo_fig.php

AMO & hurricanes

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Analysis

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P1(1958~66) P2(1990~2001)N(1970~85)

→ Composite:P1&P2 minus N

(9yrs) (16yrs) (12yrs)

Normalize of PC2

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Composite

Significant at the 5% level are shaded

GeopotentialVerticla profile(40 ° ~60°N)

Temperature

Annual mean of H200 and H500

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Composite

H200(JJA) H200(SON)

H200(MAM)H200(DJF)Seasonal

Significant at the 5% level are shaded

17 Note:BADC(Britich Atmospheric Data Centre)

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25yrs running

Detrend,running

NHSH

PC2

AMO

Data from: NCDC (ftp://ftp.ncdc.noaa.gov)

°C

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SummarySummaryA decadal to mutidecadal pattern in NH is identified.

Major characteristics:Coherent geopentential height (and temperature) perturbation in the upper troposphere, which almost encircles the middle to high latitude of the NH.

The pattern is most apparent over the high-latitude Eurasia continent and the north Pacific in annual mean. Similar signal also appears during the boreal autumn and winter season, but with weaker amplitude.

Decreasing trend in the late 1960s and increasing trend after the late 1980s.

Temporal fluctuation almost coincides with the fluctuation of the AMO and NH mean surface temperature.

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Thanks!!

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EOF1 ≡Global Warming

Parker et al.(2007)

EOF2 ≡ PDO

10.2%

55.7%

EOF3 ≡ AMO

8.0%

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ERA40 Geopotential

500hPa

850hPa

200hPa

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CompositeAnnual mean

Significant at the 5% level are shaded

Kaplan SST ERA40 T2m

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Line:annual meanBar:9 yrs running

Projection of annual H200 onto EOF2

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Composite

JJA SON

MAM

DJF Annual

200hPa Zonal wind

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H200 .vs. PC1

H200 .vs. PC2

Correlation

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Is it a Global fluctuation?

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EOF analysisTropics Southern Hemisphere

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EOF analysis

89.6%

EOF 1

300S~300N

90.2%700S~300S

47.9%300N~700N

30.4%