Atmospheric sciences, Yonsei university

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2013.0408-0410.FOCRAII . On the Relationship between East Asia Jet and North Pacific Atmospheric Circulation Pattern during the Boreal Winter. Jae-Heung Park, Soon-Il An. Atmospheric sciences, Yonsei university. Contents. - PowerPoint PPT Presentation

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Atmospheric sciences, Yonsei university2013.0408-0410.FOCRAII

Jae-Heung Park, Soon-Il AnOn the Relationship between East Asia Jet and North Pacific Atmospheric Circulation Pattern during the Boreal WinterHello, every one.My name is Jae-Heung Park form Yonsei university in Korea.The title of my presentation is On the Relationship between East Asia Jet And North Pacific Atmosphere Circulation Pattern during the Boreal Winter.Although the subject of this study is a little different from that of this FOCRAIIplease, be interested in my presentation. Then lets start my presentation.1ContentsAtmospheric sciences, Yonsei universityOn the Relationship between East Asia Jet and North Pacific Atmospheric Circulation Pattern during the Boreal WinterIntroduction

Data

Result

Discussion

5. Summary Contents are like this.Introduction, data, result, and discussion & Summary.2Atmospheric sciences, Yonsei universityIntro.Recently, as global warming continues, NPGO/NPO frequently appears compared to the past. This result is corresponding to the tropical climate change such as frequent generation of CP El Nino and temperature increase in Warm Pool. Since atmosphere leads oceans in the North Pacific, NPO becomes more important. (Yeh et al, 20011; Di Lorenzo et al 2010; Park et al, 2012; Furtado et al, 2011)

However, contrary to the study of AL, that of NPO or other atmosphere pattern is not arranged well. They are needed to be focused more.

In the North Pacific1st mode:: Pacific Decadal Oscillation (PDO) Aleutian Low (AL)2nd mode :: North Pacific Gyre Oscillation (NPGO) North Pacific Oscillation (NPO)On the Relationship between East Asia Jet and North Pacific Atmospheric Circulation Pattern during the Boreal WinterIn the North Pacific, There are two famous climate modes.First modes Pacific decadal oscillation, PDO, in ocean and Aleutian Low, AL, in atmosphere.Which are characterized by horseshoe and monopole pattern.Seconds are North Pacific Gyre oscillation, NPGO in ocean. And North Pacific Oscillation in atmosphere.They are distinguished by tri-pole and dipole pattern respectively.

Recently, as global warming continues,The second mode NPGO and NPO appears more compared to the past.And some scientists argued that this result is corresponding to the tropical climate change such asCentral Pacific El Nino and Warm Pool temperature increase.

It is known that over the North Pacific, atmosphere affects and lead ocean.Thus, NPO or other atmosphere pattern should be more investigated,However, contrary to the study of AL, that of NPO or other atmosphere patternIs not well arranged well. They are needed to be more focused.

3Atmospheric sciences, Yonsei universityIntro.Previous studies Wallace and Gutzler (1981) :: WPO (GPH 500hPa) & NPO (PSL) Nigam (2003) :: WPO & Asian-Pacific Jet (whole range of Pacific) Linkin and Nigam (2007) :: NPO & WPO.

In this study, we investigate the relationship between East Asia jet stream and atmosphere pressure over the North Pacific. It is suggested that this relationship can be connected to the Tropics.

On the Relationship between East Asia Jet and North Pacific Atmospheric Circulation Pattern during the Boreal WinterIn the past,Wallace and Gutzler, Nigam, Linkin and Nigam, studied the relationshipNPO at surface, WPO at mid-atmosphere, and jet stream at upper atmosphere.and told that they are related to each other.

In this study. We investigate the relationship between East Asia jet stream and atmosphere pressureOver the north Pacific.And It is suggested that this relationship can be connected to the tropical climate change.4Atmospheric sciences, Yonsei universityData:: NCEP-R1 reanalysis data (1949~2007, 708montly data DJF mean 58 yearly data)

:: Used variable - Zonal wind (U) - Geopotential Height (GPH) - Sea Level Pressure (SLP) - Omega - Temperature On the Relationship between East Asia Jet and North Pacific Atmospheric Circulation Pattern during the Boreal WinterIn this study, NCEP-R1 reanalysis data is used,Ranging from 1949 to 2007.Used variables are zonal wind, GPH, PSL, Omega, and temperature.All variables are averaged focused on winter, December to February.5ResultAtmospheric sciences, Yonsei universityEast Asia Jet (EA Jet)East Asian Jet stream (> 70m/s)

2. Parallel to the latitude

Upstream region of North Pacific

EA Jet Axis Index

EA Jet region (120-160E, 25-45N):: It indicates the north-south movement of EA jetFind latitudes where the strongest U exists at each longitude within EA jet regionAverage the latitudes

On the Relationship between East Asia Jet and North Pacific Atmospheric Circulation Pattern during the Boreal WinterThis figure shows winter-mean zonal wind at 200 hPa.The core is located at south part of Japan, and we named this region as EA jet region, marked by rectangular.EA jet region is relatively located at upstream part of North Pacific. The speed exceed 70 meter per second.And the axis is parallel to the latitude.

Here, we focused on the north-south movement of jet rather than its speed.So, we made EA jet axis index which indicates north-south displacement of EA jet.To obtain the index, first, the latitude where the strongest zonal wind exist at each longitude within EA jet region are found, and these latitudes are averaged.

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ResultAtmospheric sciences, Yonsei universityComposite Analysis :: zonal wind (200hPa) is composited with respect to the highest and lowest 10% of EA Jet axis index

When EA jet is located at north (south). zonal wind is strong (weak)

Shapes of jet in both period are similar in EA jet region, however, they are different in jet exit region. :: when EA jet locates at north(south), jet axis over the eastern North Pacific is toward northward(southward).

It implies that small difference of north-south displacement of EA jet is associated to the large change in atmosphere flow over the North Pacific.Solid EA jet axis index (mean=32.5N, std. 0.53) Dotted 9-year running mean of the index increasing trend(95% significant level) EA jet is moving northward. On the Relationship between East Asia Jet and North Pacific Atmospheric Circulation Pattern during the Boreal WinterThis graph shows EA jet axis index, solid line, and its 9-year running mean, dotted line.There is a increasing trend with 95% significant level, it is known that East Asia jet is moving northward.

Based on the highest and lowest 10% of this index, Zonal wind is composited.

Comparing the two figures, we can known thatWhen jet locates at further north, zonal wind becomes strong.And although the figure of EA jet region in both period is similar to each other, However, those are quite different in the jet exit region.

When EA jet located at north, jet axis in the exit region is toward northward.And reverse is true.

It implies that EA jet north-south movement is related to atmosphere flow over the north Pacific.

7ResultAtmospheric sciences, Yonsei university

Regression Analysis :: EA Jet axis index is regressed onto the GPH(200hPa) & SLP.1. Dipole pattern. (Northwest-low, Southeast-high) Similarity to NPO (scorr.=0.63)

2. Equivalent barotropic structure.

3. Simple regression relationship (SLPa) If EA jet axis moves northward by 3 7.5hPa (250Pa x 3) increase and decrease at each center.

:: Shading (95% significant level) Statistically apparent relationship between EA jet location and dipole pressure pattern over the North Pacific.

:: This result indicates EA jet location plays an important role in making dipole structure.

What controls EA jet displacement??On the Relationship between East Asia Jet and North Pacific Atmospheric Circulation Pattern during the Boreal WinterThe EA jet axis index is regressed onto the GPH and SLP.In both figure, northwest-southeast diploe pattern is shown.Considering the location of North center, it seems to be similar to the NPO.Their correlation is 0.63.

Using simple regression relationship, we can notice that If EA jet moves northward by 3 degree, then SLP decrease and increase at each center by 7.5hPa.

This results indicates that jet location plays an important role in inducing such a dipole pattern.Then, here raised a question What controls EA jet displacement.8ResultAtmospheric sciences, Yonsei university

Relationship between EA Jet & Hadley Circulation:: Subtropical jet is located at the inner section of Hadley circulation boundary.

:: At the boundary, tropopause height decreases abruptly.

jet:: Using this information, Hadley circulation boundary (HCB) index is made. (local Hadley circulation, 120-160E, same to longitudinal range of EA jet region)

:: The correlation between EA jet axis index and HCB index is 0.79 (95%) (closely linked)

Hadley circulation controls the location of EA jet.On the Relationship between East Asia Jet and North Pacific Atmospheric Circulation Pattern during the Boreal WinterGenerally, subtropical jet is located at the inner section of Hadley circulation boundary.At the boundary, Tropopause height decreases abruptly.

This shows tropopause height change with respect to latitude.Here, red elliptic indicates the location of Hadley circulation boundary.

So using this information, Hadley circulation boundary index is made and when it is correlated to EA jet axis index, the correlation coefficient is 0.79.

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ResultAtmospheric sciences, Yonsei universityCorrelation Map :: HCB index is correlated to Omega(500hPa) and Surface Air Temperature(SAT).1.