METEOROLOGICAL AND GEOPHYSICAL AGENCY
Indonesian Fire Danger Rating System
Frequently Asked Questions:
- General
- How is fire danger different from fire potential or fire occurrence?
- How is fire weather different from weather?
- How is the FDRS different from Hotspots?
- Do forests around burning coal seams have higher fire danger?
- Applications
- How does an FDRS put out fires?
- How can an FDRS be used to create policy?
- How can an FDRS be used in an action plan?
- Technical details
1. General
How is fire danger different from fire potential or fire occurrence?
Fire danger is a general indicator of many factors affecting the physical aspects of fire (e.g., how easily a fire can be started, how fast it will spread, how intense it will be), our ability to control a fire if one was started, and what the impacts of that fire would be.
Fire potential is generally used in reference to the danger of fires starting or spreading. A high fire start potential indicates a high probability of fires starting. A high fire spread potential indicates that once a fire starts, it can grow to a large size.
Fire occurrence refers to the number of fires started in a given area over a certain amount of time.
How is fire weather different from weather?
Weather is the physical processes occurring in the atmosphere on time scales ranging up to several days in length. Fire weather, which is a subset of weather, includes factors that lead directly to ignition, spread, and intensity of fire. This includes temperature, humidity, wind, and precipitation, which are input into fire danger and behavior calculations. Lightning is an important fire ignition factor in mid-latitude continental forests. Other factors influence these variables of course, such as cloud cover affecting temperature, or the atmospheric pressure gradient affecting wind.
How is the FDRS different from Hotspots?
A hotspot is a fire, or other source of intense heat, that has been recorded by a satellite sensor and detected by a remote sensing algorithm. Hotspots usually indicate where a fire is detected, but is limited by false detections, cloud and smoke cover. Fire danger rating does not indicate where fires occur. It can be used to predict where there are areas with high flammability, where the physical impact a fire may be severe, and the level of difficulty to control a fire.
Do forests around burning coal seams have higher fire danger?
Coal seam fires act as ignition sources when vegetation fuels are dry.* If the area around a burning coal seam has high Fire Danger, then there is an increased risk that the coal seam will successfully start a fire because the vegetation is dry.
2. Applications
How does an FDRS put out fires?
An FDRS does not put out fires. It is a tool used by fire managers to predict areas and time periods when fire danger is high. This gives them time to prevent fires by alerting the public to be careful with fire or to restrict the use of fire for agricultural and land management purposes. It also gives them time to mobilize and position fire fighting resources before fires start. After a vegetation fire has started, they can use the information to predict the rate of spread and ease of control.
How can an FDRS be used to create policy?
An FDRS can also be used to analyze historical fire and weather data to identify important factors that are contributing to serious fire problems. For instance, such an analysis may indicate that serious fire or haze problems typically occur at a certain time of year, or in specific areas, or under particular meteorological conditions. Policy makers can use this information to set policy criteria for fire restriction and resource mobilization based on fire danger, time of year and/or location.
How can an FDRS be used in an action plan?
An FDRS can be used to identify limits of fire suppression capability based on physical fire characteristics. For instance, it can identify when hand tools or power water pumps are effective in controlling a fire, based on fire intensity criteria. Those limits of fire control can be used in an action plan to determine when and where specific fire suppression resources need to be ready or mobilized.
As part of a proactive action plan, an FDRS can also be used to identify time periods and locations when prescribed burning can be done safely based on smoke production estimates and ability to control a fire. This helps to prevent prescribed burns from being conducted under conditions that would result in negative social, economic or environmental impacts.
3. Technical details
What are the fuel complexes, and how were they selected?
The surface fuel complexes in the Indonesia FDRS are: grassland (rumput-rumputan), slash (limbah hutan), open forest (hutan terbuka), and closed forest (hutan basah). Each of these may occur on mineral or peat soils. The grasslands are open areas with mainly fine, non-woody fuels. The vegetation may be grasses, sedges, crops, ferns or other herbaceous species. This fuel complex was selected because it represents the majority of fire starts in Indonesia. These fuels burn easily, but little biomass is consumed.
Slash areas are open areas with distributed, horizontal, woody fuels. This fuel complex includes forest and shifting agricultural waste. This fuel complex was selected because it represents the majority of burned area in Indonesia. Small fuels burn easily, but after prolonged drying, large amounts of biomass may be consumed.
Open forest is made up of standing, living, broad-leaved evergreen trees where the canopy is open enough that wind can penetrate to the forest floor. This fuel complex includes plantations, logged over areas (selective logging), and secondary forest. This fuel complex was selected because it represents the greatest economic risk to Indonesia. The fire is usually carried by low biomass surface fuels on the forest floor.
Closed forest is similar in definition to open forest, but the tree and vegetation density is very high, which prevents drying of dead fuels. This fuel complex includes primary forests. This fuel complex is included because the physical properties of the stands creates low fire risk.
These surface fuel complexes may be on mineral soils, where the biomass loss is limited to the surface fuels. However, when the area is underlain by organic soils, these may dry out enough for large amounts of biomass to be consumed in ground fires. The peat fuel complex includes drained, rain-dependent organic soils. Undrained peatlands are not included because they typically remain wet for most of the dry season. While drained, tidal peatlands may become flammable, the moisture content cannot be predicted by a weather-based FDRS.
How do you map slash?
Slash is a temporary state in between growing vegetation and cleared land, so it is difficult to map. It may be mapped two ways. Both are essentially "slash potential." Vegetation types such as shifting cultivation, bush, shrubby plantations, regrowth and mixed woody vegetation areas close to settlements or roads will all probably burn after being cut. The second slash potential are concession areas that are planned for conversion to estate or plantation crops. In the current FDRS, the potential slash areas and open forest areas are combined into one fuel complex, with a slash fuel model.
What are the differences between DC and KBDI?
The Drought Code (DC) and Keetch-Byram Drought Index (KBDI) both reflect long term moisture deficit in large logs and the uppermost metre of forest floor debris and soil. The DC is derived from experimental data in a pine forest floor, while the KBDI attempts to solve the physical equations that govern moisture gain and loss.
The DC is derived from experimental data, while the KBDI attempts to solve the physical equations that govern moisture gain and loss. The DC uses 12:00 noon standard time observations of temperature and 24-hour precipitation, while the KBDI uses daily maximum temperature, 24-hour precipitation valid at 3:00 p.m., and annual precipitation.
The maximum value of the KBDI is 800 (tenths of an inch moisture deficit), or 203.2 mm. The Drought Code has an open-ended upper limit, but values generally remain below 800, as the soil holds some moisture at temperatures found on Earth's surface. Both indexes use a lower limit of zero to indicate saturation.
How can Fire Danger be interpolated?
Where no weather observations are available, fire danger is estimated using interpolated fire weather parameters (e.g., temperature, relative humidity, wind speed and precipitation amounts) from surrounding weather stations. Conditions at the interpolation point are estimated by averaging station values, favoring closer stations, and by making adjustments for differences in elevation. The accuracy of the estimated fire danger depends on the density of weather stations and on local climatic conditions.
How often does the FDRS need to be updated?
The FDRS maps are updated every day. This is necessary because weather conditions, and hence the fire danger, change on a daily basis. There are ways to update FDRS values more frequently, for example on an hourly basis, if hourly weather information is available.
What time is the FD calculated for?
The Fire Danger is normally calculated with weather observations from 12:00 noon local standard time. The noon weather information is used to estimate fire conditions at their peak in the mid to late afternoon -- about 3:00 to 5:00 p.m., at which time fine fuel moisture and test fire data was correlated with noon weather. The Keetch-Byram Drought Index is calculated at 3:00 p.m. local standard time, at which time the observed temperature approximates the daily maximum temperature.
