Meteorological Conditions in South East Asia: 14 November 1998

Meteorological Conditions in SouthEast Asia

14 November 1998

The ASEAN Fire Weather Information System (ASFWIS) a co-operation between ASEAN and the Canadian Forest Service it provides maps describing the current fire weather situation in South East Asia. This system is based upon the Canadian Forest Fire Danger Rating System (CFFDRS) (for further infomation to the CFFDRS refer to http://www.nofc.forestry.ca/fire/asean), and is currently tested on an experimental basis. Studies have shown that the CFFDRS is applicable outside of Canada. Currently it is also used in a modified form in New Zealand. According to M.Alexander (1994) the Weather Indices Fine Fuel Moisture Code (FFMC) and the Initial Spread Index (ISI) represent the fire danger in the scrublands of New Zealand. The Duff Moisture Code (DMC) is also applicable in South East Asia, because it potentially describes the moisture state of the upper peat layers in peat and peat swamp forests. All three parameters may serve as a suitable indicator of forest fire danger in South East Asia.

Early Fire Danger Warning for Central Sumatera:

According to the ASFWIS (http://www.nofc.forestry.ca/fire/asean/) for the 14 November 1998 these parameters are slightly increasing almost all over South East Asia. The highest FFMC readings are recorded for northern Thailand, with the FFMC ranging between 90-92. The readings in Indonesia indicate increasing fire danger in Central Sumatera. The ISI readings are over 16, this indicates high fire danger rating in grasslands. The ISI which is comprised of the FFMC and wind speed serves as the indicator for fire danger in grasslands. (Since the ISI is highly dependent on windspeed as input it can track down rapid fire weather changes and is reacting faster than the FFMC and DMC Index.)

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Fig.1. FFMC output of the ASFWIS

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Fig.2. DMC output of the ASFWIS

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Fig.3. ISI output of the ASFWIS

These findings are consistent with the current weather reports from Badan Meteorologi dan Geofisika (http://bmg.cbn.net.id/) which records rainy and cloudy conditions for Indonesia with temperatures between 20° C (Bandung) and 33° C (Pekanbaru and Jambi) with high relative humidity (up to 97%). An exception is Central Sumatra where the maximum temperature is the highest (Pekanbaru and Jambi) and the minimum relative humidity comparatively low (Penkanbaru 50%). The general forecast for whole Indonesia is rainy or at least cloudy.

The Meteorological Service of Singapore (http://www.gov.sg/metsin/hazed.html) reports for the South East Asian region “few hot spots over Sumatra”. It further states that the region is “generally clear of smoke haze”, The Meteorological Service states for the near future that: “rainfall in the region is expected to be near or above normal for the next few months. However it should be noted that many parts of Indonesia (Kalimantan and parts of Sumatra) would be in their traditional dry season in the next few months. As such, though extensive and prolonged smoke haze is unlikely for this period, occasional short periods (e.g. a few days) of slight to moderate haze in a more localised manner remain probable”.

The FFPCP project in Palembang (http://www.mdp.co.id/ffpcp/overview.htm) records 16 hotspots on 11 November 1998 with a detection threshold of 310 K in Sumatera (in the provinces of Sumut and Riau). The burning activities detected by the NOAA AVHRR sensor are land clearing fires. Attention must be given in these provinces of Sumatera to prevent the escape of these land-use fires into surrounding vegetation.

The IFFM/gtz Project (http://smd.mega.net.id/iffm/fdr.html) reports low fire danger based on the Keetch Byram Index used in East Kalimantan. It has to be noted that a sharpe increase of the readings occurred in the last days. The NOAA AVHRR receiving station of the project reported 41 hotspots on 23 October 1998 for Kalimantan with a detection threshold of 320 K, although the fire detection was obscured due to cloud coverage over Kalimantan. (http://smd.mega.net.id/iffm/hotspots_map.htm)

Summary: Although the current fire weather conditions do under normal conditions not favour extensive land clearing by fire or escaping wildfires, the consequences of the large wildifres of 1997-98 must been taken into consideration. These fires had caused extensive degradation of primary and secondary forests along with the spreading of “alang-alang” (Imperata cylindrica) grasslands. These grasslands facilitate the spread of uncontrolled fires over large areas. It can be predicted that in November-December with only moderate fire danger new vegetation fires will occur. The situation could create critical fire conditions in the alang-alang grasslands of the Central Sumatra with the reported high ISI readings.