Head of BMKG, Dwikorita Karnawati: The La Nina Moderate Phenomenon, Preparing to Anticipate Disasters
JAKARTA - The Meteorology, Climatology and Geophysics Agency (BMKG), NOAA, JMA, and BoM Australia confirmed that the La Nina phenomenon will occur at a moderate level in line with the start of the rainy season in October - November. This has the potential to cause increased rainfall in most parts of Indonesia.
"With the moderate La Nina phenomenon, it is predicted that there will be an increase in rainfall from October to November, and will have an impact in almost all regions of Indonesia, except in Sumatra. Therefore I invite all ladies and gentlemen to prepare, because this is already in sight. , "said the Head of BMKG, Dwikorita Karnawati, Friday (9/10/2020).
Dwikorita added, historical records show that La Nina can cause an increase in the accumulated monthly rainfall in Indonesia 20 percent to 40 percent above normal, or even more.
However, the impact of La Nina is not uniform across Indonesia. In October - November 2020, it is predicted that an increase in monthly rainfall can occur in almost all regions of Indonesia except Sumatra. Furthermore, from December to February 2021, increased rainfall due to La Nina may occur in eastern Kalimantan, Sulawesi, Maluku - North Maluku and Papua.
Meanwhile, for earthquake event data, added Dwikorita, based on seismic monitoring data carried out by BMKG, since 2017 there has been a trend of increasing earthquake activity in Indonesia in number and strength.
The occurrence of earthquakes before 2017 averaged only 4000-6000 times a year, with a feeling or strength of more than 5 around 200. However, after 2017 the number of incidents increased to more than 7000 times a year. In fact, in 2018 there were 11920 earthquakes and in 2019 there were 11588 earthquakes.
"This is no longer an increase, but a significant increase. With the data and the fact that the tsunami events that occur in the world are mostly triggered by tectonic earthquakes, of course the trend of increasing earthquake events also increases the potential for tsunamis. So it is necessary to strengthen the reliability of the Mitigation System. Earthquakes and Tsunami Early Warning, considering that until now there is no technology capable of predicting when an earthquake will occur, "explained Dwikorita.
Apart from that, the facts show that tsunamis are not only triggered by tectonic earthquakes. In December 2018, there was a typical Sunda Strait tsunami event on December 22, 2018 which was caused by volcanic activity in the sea, which according to statistics, is very rare, which is as much as 5 percent of the total tsunami events in the world.
Based on this data, Dwikorita explained that mitigation and early warning of earthquakes and tsunamis as well as extreme weather and climate are urgent matters to be prepared and strengthened. Problems and gaps between the center and the regions must be immediately identified to increase effectiveness in realizing Zero Victims.
"For example, on October 6 yesterday we just carried out the IOWave 20 tsunami evacuation rehearsal which were held nationally and internationally. There it was identified that several tsunami sirens were not working, while to repair or replace no one had provided spare parts. This is a problem. technical or micro, but the impact could be big so it needs better coordination between the center and the regions, between BNPB as the coordinator and the regional head or BPBD, "said Dwikorita.
Thus, Dwikora invites all related parties to jointly formulate alternative solutions to the problems that will be identified, and in the end a joint action plan will be formulated to realize Zero Victims in facing multiple hydrometeorological disasters, earthquakes, and tsunamis.
Previously, the Coordinating Minister for Maritime Affairs Luhut Binsar Pandjaitan in the Virtual Coordination Meeting for Hydrometeorological and Earthquake-Tsunami Disaster Anticipation in 2020/2021 had appealed to all Ministries / Agencies and Local Governments to work together in responding to potential disaster information submitted by BMKG.
"I received information from the Head of BMKG that the increase in rainfall due to La Nina could be up to 40 percent. So please take this seriously. All K / L leaders, Governors, Regents must increase their vigilance, especially when we are still in a Covid-19 pandemic condition. "said Luhut.
According to the Coordinating Minister for Luhut, the technological advances currently owned by BMKG can make it easier for anyone to access early warning information issued by BMKG. Therefore, Luhut asked K / L and regional leaders to use BMKG information as a reference in policy making.
PHENOMENON La Nina
Based on the explanation from BMKG, La Nina in general can be said to be a climate phenomenon that is opposite to El Nino. If the El Nino event is associated with warming in the central and eastern tropical Pacific. So the La Nina phenomenon is an unusual cooling, where the temperature anomaly exceeds minus 0.5 degrees Celsius in the same area as El Nino.
La Nina is a fairly frequent global system anomaly with return periods ranging from 2 to 7 years. La Nina events occur when the Pacific Ocean and the atmosphere above it changes from a neutral (normal) state for a period of 2 months or more. Changes in the Pacific Ocean and the atmosphere above it occur in a cycle known as ENSO (El Nino - Southern Oscillation).
In that instant, the atmosphere and the oceans interact with each other, amplify each other, and create mutually reinforcing cycles of small changes in the ocean. If the couple (couple) between the ocean and the atmosphere has fully occurred, then ENSO is said to have formed.
MECHANISM OF THE ESTABLISHMENT OF La Nina
In brief, the mechanism for the formation of La Nina is explained as follows:
During trade winds, the warm seawater pools can reach further into the western Pacific. This includes Indonesia so that Indonesian waters are warmer than usual.
The central Pacific Ocean will be cooler than usual and the thermocline will be shallower in the east. As a result, sea water colder from the lower level rises to the surface as upwelling reinforces. Convection and cloud formation strengthened in Indonesia, along with the Walker circulation also strengthening.
MAIN IMPACT OF La Nina
In general, the main impact of the La Nina phenomenon on the weather or climate in Indonesia is the increase in rainfall. However, topographical conditions in Indonesia are different, so the impact of La Nina in Indonesia is not uniform across regions. Based on scientific studies from the history of previous events, the impact of La Nina in the form of increased rainfall occurs especially in the central and eastern parts of Indonesia.
This high rainfall will cause a series of other disasters, namely hydrometeorological disasters such as floods and landslides. (***)