Climate category (1)

Made by : Anna, Annie

Content

• East Asia Monsoon• Intertropical Convergence Zone

– Influence

• ENSO– Pacific temperature– El Nino and La Nina– Influence to Taiwan

• Warm winter• More spring rain• Less typhoon

– Southern Oscillation Index

Monsoon

(Image from: http://sq.k12.com.cn/discuz/attachment.php?aid=63993&noupdate=yes)

The monsoon is the wind that changes direction with the seasons.

黑線圍繞的區域是根據二度空間的大氣環流定義出來的亞洲季風區、非洲季風區和澳洲季風區。暗紅色陰影區則是依地面觀測定義出來的季風區。

• 圖片來源： http://earth.fg.tp.edu.tw/learn/esf/magazine/980303.htm

• The East Asian monsoon covers the countries like China, Japan, North Korea, South Korea, Taiwan, etc.

Do you know why the wind changes direction with the seasons?

• The sea is harder to be heated or cooled down than the land. So the land temperature drops faster in winter than the sea. The sea temperature is higher than the land temperature in winter. In winter, the density of the colder air above the land is higher than the density of the hotter air above the sea. Therefore, the air goes from the land to the sea. The monsoon forms because of this.

• How about summer? Why does the summer monsoon go from the sea to the land?

• This picture shows the directions of the monsoon in winter. The winds are from the continents. It’s usually the dry and cold monsoon.

• (Image source: http://earth.fg.tp.edu.tw/learn/esf/magazine/980303.htm)

• This picture shows the directions of the monsoon in summer. It’s the hot and wet monsoon. It brings a lot of rain.

• (Image

source ： http://earth.fg.tp.edu.tw/learn/esf/magazine/980303.htm)

• The storm caused by monsoon (圖片來源： http://zh.wikipedia.org/wiki/File:Bombay_flooded_street.jpg)

• It scopes including the South China Sea and the northwest Pacific rim area.

Intertropical Convergence Zone

• Region: Near the equator, from about 5° north and 5° south ， it effects over land ventures farther north or south than the ITCZ over the oceans, and it causes the variation in land temperatures.

• Influence: a plethora of precipitation - solar heating in the region forces air to rise through convection which results in

• The ITCZ is a key component of the global circulation system.

Influence

• the northeast, southeast trade winds : the subtropical highs or horse latitudes low pressure zone (ITCZ)

Subtropical high (horse latitude)

North east trade winds

South east trade windsITCZ

equator

What is ENSO

• El Niño-Southern Oscillation• “Southern” : near the equator .

“Oscillation” : The change in the air pressure in the east and the west.

The temperature of the Pacific

• ENSO is a cyclic warming and cooling of centre and eastern Pacific.

• three influences to the temperature of the Pacific

1.The northeastern trade winds

2.cold ocean current up the coast of Chile

3.cold deep current of Peru

North east trade wind

Ocean current

El Nino- ( Pacific surface temperature)

• El Nino -December, 1997 ocean surface temperature

• the temperature around the equator at Eastern Pacific is five Celsius higher than usual

The temperature here is 5 Celsius higher then

normal

La Nina- ( Pacific surface temperature)

• The temperature of the Pacific cools down

the temperature of the Pacific is low

El Nino and La Nina

El Nino- The cold sources wane air pressure :east is high, west is low influence: South America (west)- flood Australia ,Taiwan (east)-drought

La Nina- The cold sources intense air pressure: east is low ,west is high.

influence: South America- drought

Australia- flood

El Nino – air pressure

Low air pressure: flood

High air pressure: drought

La Nina- air pressure

Low air pressure: flood High pressure : drought

Southern Oscillation Index

•  It shows the ups and downs of the sea level pressure in index form

– sea level pressure - the temperature difference of the pacific

– The "index" number- the pressure measurement difference between Darwin and Tahiti

SOI

• Positive SOI- La Nina• Negative SOI- El Nino

Influences to Taiwan (El Nino)

• Less typhoon in Taiwan

• Warm winter

• More spring rain

Typhoon, Warm winter

• The monsoonal characteristic in southern Taiwan is clear: summer- rainy winter -dry. ( north eastern wind)

anomalous circulations

North eastern wind

El Nino anticyclonic weaken

La Nina cyclonic enhance

ENSO-more rain

moistdry

El El NinoNino

La La NinaNina

More More rainrain

Less Less rainrain

hsu.as.ntu.edu.tw/group_meeting/20080923_Chen.ppt

moist

dry

The red numbers are the one that had big difference among the two

The amount of rain in Taiwan ( Jan )

The difference between El Nino and Neutral ENSO

The west has more rainThe west has more rain

The west

The red numbers are the one that had big difference among the two

The east has more rainThe east has more rain

The amount of rain in Taiwan ( Jan )

The difference between El Nino and Neutral ENSO

The east

Conclude

• The precipitation in Feb and Mar have larger amounts The precipitation in Feb and Mar have larger amounts because of ENSObecause of ENSO

• In January, when there is an El Nino there is more rain in the west of Taiwan,. When there is a La Nina there is more rain in the east.

• El Nino brings more spring rain to Taiwan