With the above average rainfall that our region experienced this past winter, there’s been abundant growth in grasses, brush, and trees. The dryness of vegetation – or fuel in the mind of firefighters – is one key factor that our meteorology team takes into account when they forecast wildfire risk and its potential threat to our communities.
Given that the region we serve encompasses 4,100 square miles spread over 25 cities and two counties, how do we keep tabs on the state of vegetation and how fast plants are drying out?
The answer: with a little bit of help from outer space.
To prepare our company’s daily Fire Potential Index, which categorizes the risk of wildfires in our eight operating district in three categories: normal, elevated and extreme, our meteorology team leverages data from NASA’s MODIS satellites, as well as from NOAA’s geostationary satellite. These data sources feed into the forecasting system in our Weather Center. Also feeding into our forecast system is temperature, wind and humidity data collected by the 177 weather stations SDG&E operates across the High Fire Threat Districts in our region.
The Weather Center staff issues a daily weather report with the Fire Potential Index to all the employees at SDG&E and shares the report with local public agencies as well. The Index provides a seven-day look-ahead so resources, staffing and field work can be planned accordingly, taking into consideration wildfire risk.
We recently talked to Steven Vanderburg, our principal meteorologist, to better understand how satellite data helps to enhance our situational awareness.
How does the gathering of information from the satellite work?
The NASA satellites has a camera-like sensor (spectroradiometer) that is constantly collecting high resolution images of earth in 32 spectral bands, or wavelengths (i.e. visible, infrared, etc.). The satellite transmits this data to satellite dishes (receivers) on earth. From there, the data is delivered to end users, such as SDG&E.
What type of information is received?
The information that SDG&E collects every day is called Normalized Difference Vegetation Index (NDVI). We use NDVI to monitor the greenness of the seasonal grasses across our service territory.
We only collect NDVI data for specific locations on the landscape that are entirely comprised of grasslands (i.e. Santa Ysabel, Guejito Ranch, etc.). This data is used to help calculate SDG&E’s Fire Potential Index (FPI).
Why is receiving this type of information important?
The condition of the grass is critical component of understanding day-to-day fire potential across the service territory. By monitoring the greenness of the grasses from satellite, we can better understand the potential for fire on the landscape. Dry vegetation essentially becomes fuel for fires.
In addition to the NASA satellite data, SDG&E also pulls in data from the NOAA geostationary satellite via a satellite dish on the roof of one of our facilities. How is the data from the NOAA satellite different from the data from the NASA satellites?
Besides satellite imagery, the NOAA satellite provides weather balloon data, weather station observations, doppler radar data, among other information.