Upload
konane
View
39
Download
2
Embed Size (px)
DESCRIPTION
Decadal Teleconnection in the Northern Hemisphere. Adviser: Huang-Hsiung Hsu Speaker:Ming-Ying Lee. 01Jul2008. How many Decadal to Mutidecadal fluctuations in the Northern Hemisphere ?. Pacific Decadal Oscillation (PDO). - PowerPoint PPT Presentation
Citation preview
1
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
2
How many Decadal to Mutidecadal fluctuations in the Northern Hemisphere ?
3
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)
4
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)
7
A new Decadal to Mutidecadal fluctuation in the NH?? A new Decadal to Mutidecadal fluctuation in the NH??
??
AOcor = -0.75
ENSOcor =0.51
8
9
EOF analysis Northern Hemisphere
COR=0.97
10
Cor=0.87
All index had performed 9-yrs running except the AMO uesd 25-yrs running
PC2 and Climate Index
11
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?
12
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
13
Analysis
14
P1(1958~66) P2(1990~2001)N(1970~85)
→ Composite:P1&P2 minus N
(9yrs) (16yrs) (12yrs)
Normalize of PC2
15
Composite
Significant at the 5% level are shaded
GeopotentialVerticla profile(40 ° ~60°N)
Temperature
Annual mean of H200 and H500
16
Composite
H200(JJA) H200(SON)
H200(MAM)H200(DJF)Seasonal
Significant at the 5% level are shaded
17 Note:BADC(Britich Atmospheric Data Centre)
18
25yrs running
Detrend,running
NHSH
PC2
AMO
Data from: NCDC (ftp://ftp.ncdc.noaa.gov)
°C
19
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.
20
Thanks!!
21
EOF1 ≡Global Warming
Parker et al.(2007)
EOF2 ≡ PDO
10.2%
55.7%
EOF3 ≡ AMO
8.0%
22
ERA40 Geopotential
500hPa
850hPa
200hPa
23
CompositeAnnual mean
Significant at the 5% level are shaded
Kaplan SST ERA40 T2m
24
Line:annual meanBar:9 yrs running
Projection of annual H200 onto EOF2
25
Composite
JJA SON
MAM
DJF Annual
200hPa Zonal wind
26
H200 .vs. PC1
H200 .vs. PC2
Correlation
27
Is it a Global fluctuation?
28
EOF analysisTropics Southern Hemisphere
29
EOF analysis
89.6%
EOF 1
300S~300N
90.2%700S~300S
47.9%300N~700N
30.4%