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Flood in Jakarta and Its Atmosphere Conditions Analysis
21 Feb 2017 • Read : 1812 x ,

Figure 1. Rainfall on Indonesia (Jakarta in the red circle) of GSMaP Data on February 21, 2017 (03.00 to 06:00 am local time)

Torrential rains that have occurred since Tuesday, February 21, 2017 early morning is known to cause catastrophic flooding in dozens of places in Jakarta and Bekasi. The flooding caused hundreds of people in the village Cipinang Melayu, East Jakarta become refugees for days and had cut access off the city of Bekasi to Jakarta in Kalimalang. According to the Regional Disaster Management Agency (BPBD) Jakarta, until Wednesday (February 22, 2017) afternoon at 12.00, 46 RW in 21 Sub-district affected by floods in Jakarta and its surrounding areas (BBC 2017).

Center of Atmospheric Science and Technology (PSTA) LAPAN make observations of atmospheric conditions over Jakarta when the floods on the hour 3:00 to 6:00 am (20-23 UTC). Based on observations of rainfall from Global Satellite Mapping of Precipitation (GSMaP) in Figure 1, it appears that the intensity of rainfall over Jakarta is quite high at about 10-30 mm / h with an average highest peak on the hour 4:00 am (21 UTC). This indicates that heavy rain at the time of the flood event truly happened.

Figure 2. Rainfall intensity (mm / hour) over Jakarta 20 to 21 February 2017 of GPM 3IMERGHHL V03 Data.

Observations of rainfall were also performed on Global Precipitation Measurement (GPM) satellite data on 20-21 February 2017 (Figure 2). It is seen that the intensity of the rainfall in time series on the average region 106,726-106,965 lon and 6,119-6,302 lat (Jakarta and surrounding areas) are in the category of heavy (rainfall) and very heavy (rainfall) starting at 3:00 until 6:00 am on Tuesday, February 21, 2017, peaking at 04.00 am (21 UTC).

Figure 3. Sea Surface Temperature Anomalies (February 21, 2017).

The intensity of heavy rainfall, causing flooding in Jakarta, presumably because of lower condition of Pressure Sea Level (TPL) in the south and north of the island of Java, while Anomalies Sea Surface Temperature (ASPL) in the region is high, as shown in red in the seas around the islands of Java and Bali (Figure 3). Low TPL conditions has the potential to attract the mass of air in the Indian Ocean region and is believed to be passing through the area of Java and Bali, which can lead to the growth potential of lot of cloud. Thus, the growth of convective cloud caused by the mass influx of water vapor.

In addition to TPL and ASPL, observations of global climatic conditions are generally observed (both IOD and ENSO), indicating normal conditions. Even Madden Julian Oscillation (MJO) is currently in phase 7 that located around the Indian Ocean. Concluded that this flood is not due to the influence of global atmospheric conditions, but because of the influence of regional (local).

Figure 4. Himawari-8 Satellite Visualization (February 21, 2017).

Data visualization of Temperature Black Body (TBB) of Himawari-8 satellite (Figure 4) at the time of the incident shows convective clouds began to cover the area northwest of Java Island (Jakarta) from 04.00 am (21 UTC) displayed as pink above Jakarta. The convective cloud growth continues to cover the entire area of Jakarta at 06.00 am (23 UTC). This indicates that Jakarta experienced rain with a very high intensity for 2 hours.

PSTA LAPAN develops Decision Support Systems (abbreviated DSS) related to hydro-meteorological disasters early warning called Satellite Disaster Early Warning System (Sadewa). Sadewa uses Weather Research and Forecasting (WRF) model with the initiation of Global Forecast System (GFS) atmospheric data to predict the weather for 24 hours ahead.

Figure 5. Results of Prediction Model Weather Forecasting Research (WRF) when Jakarta floods on February 21, 2017.

The prediction results of Sadewa (with the initiation of the model GFS dated February 20, 2017 at 06 UTC) in Figure 5, predicted heavy rains occurred in Jakarta on February 21 at 04.00 until 06.00 am (February 20 at 21-23 UTC) indicated by the distribution of the dominant red over Jakarta. This indicates that Sadewa predicted well as an early warning of heavy rainfall, evidenced by the similarity of observation results with the Sadewa, which is satellite observation data (GSMaP and GPM) as well as the analysis of other weather conditions.

From the above analysis, it can be concluded that the flooding in Jakarta and surrounding areas on February 21, 2017 as a result of the merging of mass of water vapor from Asia (Monsoon Asia) and the Indian Ocean at the same time (simultaneously) within a relatively short time (1-2 hours) aggravated by environmental conditions, such as drainage is no longer in a condition capable of holding water in relatively large amounts.

Written by: Center of Atmospheric Science and Technology Dissemination Team - LAPAN

Cover picture source: Regional Disaster Management Agency of Jakarta

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