Dominant Modes of the East Asian Summer Monsoon Using Equivalent

Potential Temperature

Jun-Hyeok Son and Kyong-Hwan Seo

Department of Atmospheric Sciences, Pusan National University, Koreaemail: j-hson@pusan.ac.kr

East Asian Summer MonsoonEast Asian Summer Monsoon

EPT and dEPT/dy June

EPT and dEPT/dy July

Color : 850-hPa Equivelant potential temperature (EPT)Contour : Meridional gradient of EPT

Climate and Atmospheric Dynamics Lab

A method for determining stationary frontA method for determining stationary front

- Surface water chart (KMA)

- Meridional gradient of 850-hPa equivalent potential temperature (EPT)

서 론 서 론

Color : precipitation meanContour : interannual STD

East Asian Summer MonsoonEast Asian Summer Monsoon

Precipitation

June

July Aug.

JJA

Climate and Atmospheric Dynamics Lab

- 850-hPa EPT (color)- 850-hPa wind (vector)

General characteristics during the Changma General characteristics during the Changma periodperiod

Okhotsk Sea high is strong in June.WNPSH is dominant in July.

June July

Multi-variables EOF using EPT, u-wind and v-wind in 850-hPa

Climate and Atmospheric Dynamics Lab

General characteristics during the Changma General characteristics during the Changma periodperiod

Wave-train from Western North Pacific (July)

Wave-train from North Atlantic Ocean (June)

Climate and Atmospheric Dynamics Lab

General characteristics during the Changma General characteristics during the Changma periodperiod

June MAM(0) July MAM(0)

June JJA(0) July JJA(0)

- Correlation of SST (color)

동아시아 몬순 예측 동아시아 몬순 예측Quick summeryQuick summeryCorrelation matrix EOF for

EPT

Dominent modes of EASM in JulyDominent modes of EASM in July

First three modes of EOF (color) and regressed precipitation (contour)

동아시아 몬순 예측 동아시아 몬순 예측Quick summeryQuick summeryDominent modes of EASM in JulyDominent modes of EASM in July

PC1 PC2 PC3

JJA

DJF

MAM

DJF(-1)

SST correlation map

동아시아 몬순 예측 동아시아 몬순 예측

Color : PrecipitationVector : 500-hPa wind

Westerly wind

Low

High

Low

Quick summeryQuick summeryDominent modes of EASM in JulyDominent modes of EASM in JulyDynamical mechanism (mode

1)

동아시아 몬순 예측 동아시아 몬순 예측

Color : T500, Contour : Z500, Vector : 200-hPa wind

Low

High

Quick summeryQuick summeryDominent modes of EASM in JulyDominent modes of EASM in JulyDynamical mechanism (mode

2)

동아시아 몬순 예측 동아시아 몬순 예측

Color : Precipitation, Vector : 500-hPa wind

Westerly

High

Quick summeryQuick summeryDominent modes of EASM in JulyDominent modes of EASM in JulyDynamical mechanism (mode

3)

Low

동아시아 몬순 예측 동아시아 몬순 예측

P = + 0.82A(May) - 0.72B(Mar. ~ Apr.) + 0.50C(May – Apr.) + 0.68D(Apr.)

Domain of PRCP : [116.25 ~ 141.25°E, 31.25 ~ 41.25°N]

Quick summeryQuick summeryWork in progress......Work in progress......Physical-statistical prediction

model

동아시아 몬순 예측 동아시아 몬순 예측

GMSS (0.67)

Forecast

Above Normal Below

OBS

Above 2006, 2009, 2012

2003, 2007, 2011

Normal 2005, 2010

1995, 1996, 1997, 1998, 2001

1999

Below 1994, 2000, 2002, 2004, 2008

- Observation- Forecast

Quick summeryQuick summeryWork in progress......Work in progress......Development of physical-

statistical prediction model

Forecast using previous spring (until May) SST

Interannual variation of East Asian summer monsoon is dominated by different mode in June and July. - June : Okhotsk Sea high (mP) - July : WNPSH (mT)

Based on these analysis, physical-statistical prediction model is built up for the forecast of the precipitation in July. (correlation : 0.78, RMSE : 0.75).

The CP El-Nino, PDO and Indian Ocean basin wide warming affect to the East Asian summer monsoon in July. These boundary forcing make atmospheric waves and significantly intensify the East Asian summer monsoon front.

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3

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SummerySummery

Climate and Atmospheric Dynamics Lab

Thank you.Thank you.

Climate and Atmospheric Dynamics Lab