AsiaViews, Edition: 35/VII/December2010
Category: ENVIRONMENT
FOR decades, Javanese farmers have been faithful to titi kolo mongso (season) calculations contained in their primbon (traditional almanac). From sowing and planting seeds, treating crops with manure, to harvesting, they have followed the almanac reckoning.
However, the sky behaves more unpredictably. The seasons that normally repeat and serve as a primbon orientation this year don?t apply. Strawberry growers in Magetan, East Java, also misread the seasons. The wet season, which usually starts in October, turns out to have begun earlier. Since June, heavy rain has fallen in most regions of Indonesia.
As a result, strawberry harvests have failed. Narjo, a strawberry farmer in Cemoro Sewu village, Plaosan, said over 80 percent of strawberries decayed after being drenched by rain almost the whole day. When this season appeared normally, he could reap10 kilos of strawberries every other day. Now his harvest has slumped.
?Now I gather 2 or 3 kilos at most,? Narjo complained. The rain has also increased humidity so that it triggers plant diseases. ?As far as pests are concerned, we can still overcome them with insecticides. But if it rains, farmers are helpless.? Still undeterred, Narjo again plans to grow strawberries next year.
This year, the dry season is indeed extremely short. According to the Deputy for Climatology at the Agency for Meteorology, Climatology and Geophysics (BMKG), Soeroso Hadiyanto, this year has seen the most extreme season in the past 12 years. In 1998, after a dry, protracted drought, in subsequent months the greater part of Indonesia was soaked by torrential rain. The rainy season in 1998 and 1999 was far longer than its normal period.
Today most areas in Indonesia have entered the wet season. Extreme rain (with over 50 millimeters of daily rainfall) in the course of the recent transitional season has also decreased. In July, extreme rain occurred 125 times in all parts of Indonesia. In September, extreme rain lessened to 115 times. ?In the first 10 days of October, extreme rain only took place 14 times,? said Soeroso on Tuesday two weeks ago.
Does it mean the frequency of extreme rain will keep declining? Not quite. The various factors affecting the rainy season in Indonesia indicate signs of strengthening. Soeroso pointed to three main factors determining the black, gray or blue sky in Indonesia: El Nino-La Nina, Dipole Mode, and the sea-level temperature of Indonesia.
El Nino or the Little Child is the warming sea-level temperature along the equator of the Pacific Ocean. When the Child makes mischief, like he did in 1982, 1987, and 1997, rain clouds were drawn toward the east of the Pacific, causing long droughts in Indonesia, Australia, and the Philippines. On the other hand, if his twin, the Little Girl or La Nina, shows up, the sea-level temperature in the Pacific gets cooler, below the normal rate, and at the same time the sea-level temperature in Indonesia warms up. So the wind will blow rain clouds into Indonesian territory.
According to the Climate Prediction Center of the National Oceanic and Atmospheric Administration (NOAA), USA, La Nina appears less frequently than El Nino. The emergence of El Nino in fact is not always followed by its twin. In the past 50 years, the Little Girl came out in 1964, 1970, 1973, 1975, 1988, 1995, 1998-1999, and 2007.
Dipole Mode is more or less the same phenomenon as El Nino-La Nina occurring in the Indian Ocean. The warming or cooling of the sea-surface temperature in the Indian Ocean east of the African continent considerably affects the wet or dry season in Indonesia?s central and western regions.
Since El Nino ended in early May, gradually the sea level temperature around the equator of the Pacific Ocean has fallen below the normal rate. Weak La Nina (less than -0.5 degrees Celsius) began in mid-June and has kept rising.
The Southern Oscillation Index in August also showed the rate of +16.8 or above the normal threshold of +10, meaning the trade wind will blow in the direction of Indonesia with rain cloud. It has caused rain to come earlier in several parts of the country. ?We predict La Nina will remain until March next year,? said Widada Sulistya, Head of the Public Meteorology Center of BMKG. Even according to William Patzer from the US National Aeronautics and Space Administration, the Little Girl may stay longer because the warmth retained in the Pacific waters is already far below the normal rate.
As to how strong the Little Girl will blow rain into Indonesian territory, each meteorology agency has a prediction. Soeroso said La Nina would strengthen until November-December (see chart) and later weaken. Meanwhile, the Dipole Mode Index, though listing negative figures, has normal ranges. He forecast the peak of rain to occur in the beginning of next year. And this should be monitored. ?Rainfall can be higher than that in July and August,? said Widada. NOAA and the Japan Agency for Marine Science and Technology (JAMSTEC) foresee a stronger La Nina this year than in previous years.
Some regions should be prepared to anticipate extreme rain. Aceh, West Sumatra, Riau, Riau Islands, and part of West Kalimantan should be on red alert. Based on BMKG estimates, certain areas in the provinces are very vulnerable to floods, particularly in November and December.
Jakarta, which was inundated by major floods in February 2002, should also be alert. Some areas such as Kebayoran, Kramat Jati, Pasar Minggu and Tebet have the potential for floods. Deputy Mayor of Central Jakarta Fatahillah said his administration had earlier made various preparations. ?Rubber boats, jackets, supplies, drugs, tents and field kitchens are ready in all districts,? added Fatahillah early last month.
By: Sapto Pradityo, Nalia Rifika, Ishomuddin (Magetan)
Tempo No. 14/XI/ 01-07 December 2010
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