Sunday, April 18, 2010

El Nino ……. Hangat hangat hangat

by gjoy

El Nino – and What is the Southern Oscillation Anyway?!


El Nino, an abnormal warming of surface ocean waters in the eastern tropical Pacific, is one part of what’s called the Southern Oscillation. The Southern Oscillation is the see-saw pattern of reversing surface air pressure between the eastern and western tropical Pacific; when the surface pressure is high in the eastern tropical Pacific it is low in the western tropical Pacific, and vice-versa. Because the ocean warming and pressure reversals are, for the most part, simultaneous, scientists call this phenomenon the El Nino/Southern Oscillation or ENSO for short. South American fisherman have given this phenomenon the name El Nino, which is Spanish for “The Christ Child,” because it comes about the time of the celebration of the birth of the Christ Child-Christmas.

To really understand the effects of an El Nino event, compare the normal conditions of the Pacific region and then see what happens during El Nino below.



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Normal Conditions (Non El Nino)

In general, the water on the surface of the ocean is warmer than at the bottom because it is heated by the sun. In the tropical Pacific, winds generally blow in a easterly direction. These winds tend to push the surface water toward the west also. As the water moves west it heats up even more because it’s exposed longer to the sun.
Meanwhile in the eastern Pacific along the coast of South America an upwelling occurs. Upwelling is the term used to decribe when deeper colder water from the bottom of the ocean moves up toward the surface away from the shore. This nutrient-rich water is responsible for supporting the large fish population commonly found in this area. Indeed, the Peruvian fishing grounds are one of the five richest in the world.




normal
Normally, strong trade winds blow from the east along the equator, pushing warm water into the Pacific Ocean. The thermocline layer of water is the area of transition between the warmer surface waters and the colder water of the bottom.


Because the trade winds push surface water westward toward Indonesia, the sea level is roughly half a meter higher in the western Pacific than in the east. Thus you have warmer, deeper waters in the western Pacific and cooler, shallower waters in the east near the coast of South America. The different water temperatures of these areas effects the types of weather these two regions experience.


depth
TOPEX/POSEIDON global topography maps are used to study ocean surface circulation. Here the highest sea elevation (shown in red) is in the western Pacific Ocean.


In the east the water cools the air above it, and the air becomes too dense to rise to produce clouds and rain. However; in the western Pacific the air is heated by the water below it, increasing the buoyancy of the lower atmosphere thus increasing the likelihood of rain. This is why heavy rain storms are typical near Indonesia while Peru is relatively dry.


El-Nino Conditions


El Nino happens when weakening trade winds (which sometimes even reverse direction) allow the warmer water from the western Pacific to flow toward the east. This flattens out the sea level, builds up warm surface water off the coast of South America, and increases the temperature of the water in the eastern Pacific.


elnino
An El Nino condition results from weakened trade winds in the western Pacific Ocean near Indonesia, allowing piled-up warm water to flow toward South America.


The deeper, warmer water in the east limits the amount of nutrient-rich deep water normally surfaced by the upwelling process. Since fish can no longer access this rich food source, many of them die off. This is why these conditions are called “El Nino”, or “the Christ Child”, which is what Peruvian fisherman call the particularly bad fishing period around December. More importantly, the different water temperatures tend to change the weather of the region.


What happens to the ocean also affects the atmosphere. Tropical thunderstorms are fueled by hot, humid air over the oceans. The hotter the air, the stronger and bigger the thunderstorms. As the Pacific’s warmest water spreads eastward, the biggest thunderstorms move with it. If you look on a map, you will see that suddenly islands like Tahiti, normally tropical paradises, experience massive storms.


effects
El Nino can have impacts on weather at various locations around the globe. Off the east coast of southern Africa, drought conditions often occur. In countries such as Zimbabwe, the effects of drought can be devastating.


The clouds and rainstorms associated with warm ocean waters also shift toward the east. Thus, rains which normally would fall over the tropical rain forests of Indonesia start falling over the deserts of Peru, causing forest fires and drought in the western Pacific and flooding in South America. Moreover the Earth’s atmosphere reponds to the heating of El-Nino by producing patterns of high and low pressure which can have a profound impact on weather far away from the equatorial Pacific. For instance, higher temperatures in western Canada and the upper plains of the United States, colder temperatures in the southern United States. The east coast of southern Africa often experiences drought during El Nino.

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Scientists do not really understand how El Nino forms. It is believed that El Nino may have contributed to the 1993 Mississippi and 1995 California floods, drought conditions in South America, Africa and Australia. It is also believed that El Nino contributed to the lack of serious storms such as hurricanes in the North Atlantic which spared states like Florida from serious storm related damage.
Unfortunately not all El Nino’s are the same nor does the atmosphere always react in the same way from one El Nino to another. This is why NASA’s Earth scientists continue to take part in international efforts to understand El Nino events. Hopefully one day scientists will be able to provide sufficient warning so that we can be better prepared to deal with the damages and changes that El Nino causes in the weather.


Article courtesy of kids.earth.nasa.gov
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ULASAN PANDANGAN IKIM
UTUSAN MALAYSIA PADA 12 MAC 2010
“El Nino punca cuaca dunia bercelaru”

Jabatan Meteorologi Malaysia  (JMM)  mengucapkan  terima  kasih  kepada  IKIM
kerana  memberi  perhatian  terhadap  keadaan  cuaca  kering  semasa  dan
fenomena El Nino.


Pemantauan El Nino


Pemantauan  fenomena  El‐Nino  dilakukan  oleh  pusat  kajian  iklim  dunia  yang
dikoordinasikan  oleh  Pertubuhan  Meteorologi  Sedunia  dengan  menggunakan
pelbagai  kaedah.  Salah  satu  kaedah  yang  selalu  digunakan  ialah  melalui
pemantauan  peningkatan  suhu  permukaan  lautan  Pasifik  Tengah  di  kawasan
Khatulistiwa.  Pemantauan  suhu  permukaan  lautan  ini  adalah  lebih  berkesan
dalam  memberikan  petunjuk  awal  kejadian  fenomena  El‐Nino  berbanding
dengan pemantauan perubahan parameter lain. Pencerapan ini digunakan dalam
model  ramalan  cuaca  jangka  sederhana  dan  jangka  panjang  bagi  membuat
ramalan kemungkinan berlakunya fenomena El Nino.


Bagi episod El Nino 2009/2010, tanda‐tanda peningkatan suhu permukaan laut di
lautan  Pasifik  Tengah  telahpun  dikesan  berlaku  sejak  bulan  Jun  2009.  Nasihat
berkemungkinan berlakunya  fenomena El Nino  lemah ke  tahap sedarhana  telah
dikeluarkan  pada  bulan  September  2009.  Lazimnya  tempoh  masa  3  bulan
diperlukan dalam mengesahkan kejadian fenomena ini.

Pada masa  ini,  JMM menggunakan  output  daripada  pusat  kajian  iklim  dunia  ini
dalam memantau perkembangan El Nino.


Kesan Fenomena El Nino Di Malaysia


Fenomena  El  Nino  memberi  kesan  langsung  ke  atas  taburan  amaun  hujan  di
negara  kita.  Perkara  ini  berlaku  kerana  semasa  El  Nino,  kelompok  awan  dan
taburan  hujan  di  kawasan  tropika  beralih  dari  barat  ke  tengah  Pasifik
menyebabkan keadaan cuaca kering di Malaysia.


El Nino 2009/2010 yang sederhana kuat ini menyebabkan taburan hujan di Sabah
dan utara  Sarawak berada di bawah paras purata  sepanjang  tempoh El Nino  ini

yang  dijangkakan  sehingga Mei  2010. Di  Semenanjung,  taburan hujan  adalah  di
bawah  paras  purata  direkodkan  dari  Februari  dan  separuh  pertama  bulan Mac
2010. Setakat ini, suhu paling panas yang direkodkan bagi episod El Nino ini ialah

38.1˚C di Chuping, Perlis pada 9 Mac 2010 berbanding dengan suhu paling panas
iaitu  40.1˚C  yang  direkodkan  semasa  episod  El Nino  kuat  1997/1998  di  tempat
yang sama.

Langkah‐Langkah Persediaan Menghadapi El Nino 


Bagi episod El Nino 2009/2010, walaupun ianya dikategorikan sebagai sederhana,
namun  pelbagai  langkah  persediaan  awal  bagi  mengurangkan  impak  El  Nino
telahpun  dimulakan  sejak  bulan  Jun  2009.  JMM  telah melaksanakan  beberapa
operasi  pembenihan  awan  bagi  mengatasi  masalah  kekurangan  bekalan  air  di
kawasan  tadahan  empangan  dan  jerebu  kesan  kebakaran  hutan.  Dua  kaedah
pembenihan  awan  telah  dilaksanakan  JMM  iaitu  kaedah  “hygroscopic  flare”
dengan  menggunakan  pesawat  swasta  dan  kaedah  penyemburan  larutan
pembenihan dengan menggunakan pesawat TUDM iaitu seperti berikut:‐


(1)    Pada  13  hingga  15  Jun  2009,  operasi  pembenihan  awan  telah
dijalankan bagi menangani masalah jerebu di Selangor.
(2)    Pada  19  Jun  hingga  11  Julai  2009,   operasi  pembenihan  awan  telah
dijalankan  di  kawasan  tadahan  empangan  Pedu  dan  Muda,  Kedah
yang diperlukan bagi tujuan kawasan pertanian MADA.
(3)    Pada  24  Jun  hingga  1  Julai  2009,  JMM  dengan  kerjasama  TUDM  telah
menjalankan  operasi  pembenihan  awan  bagi  menangani
masalah kekurangan air di Kuching, Sarawak.
(4)    Pada  4  hingga  20  Ogos  2009,  JMM  dengan  kerjasama  TUDM  telah
menjalankan  operasi  pembenihan  awan  bagi  menangani
masalah kekurangan air di Wilayah Persekutuan Labuan.
(5)    Pada  10  hingga  20  Ogos  2009,  operasi  pembenihan  awan  telah
dilaksanakan bagi menangani masalah  jerebu  kesan  kebakaran hutan dan
menangani masalah kekurangan air di Kuching, Sarawak.
(6)    Pada 12 hingga 14 Mac 2010, JMM bersama‐sama dengan Kerajaan Negeri
Johor  telah melaksanakan operasi pembenihan  awan di  kawasan  tadahan
Empangan  Sembrong,  Johor  bagi  menangani  masalah  kekurangan  air  di
empangan tersebut.


Selain  daripada  itu,  JMM  telah  turut menyampaikan  beberapa  taklimat  tentang
keadaan  cuaca  dan  impak  El Nino  dalam Mesyuarat  Jawatan  Kuasa  Pengurusan
dan Bantuan Bencana di peringkat pusat dan negeri.


JMM  juga  telah memuat naik  laporan dan  tinjauan El Nino 2009/2010 di  laman
sesawangnya  untuk  rujukan  awam.  Maklumat  ini  dikemaskini  dari  semasa  ke
semasa berpandukan output daripada analisis pusat kajian iklim dunia. Pada masa
sama,  maklumat  pemantauan  kemarau  dan  Fire  Danger  Rating  System  yang
memberikan petunjuk kawasan yang berpotensi berlakunya kebakaran turut juga
dipaparkan.


Article courtesy of Utusan Malaysia

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To Humaira:

Hi Sayang,

Nmpk gayanya kena duduk dalam ofis beraircond selalu la…..tak pun kena duduk lama2 kat tesco, giant, Carrefour, atau jusco lama2 ckit time shopping tu,hehe.

From,
Gjoy

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