Transcript Satellite Detection of Fires Over N America

Mapping of Fires Over North
America Using Satellite Data
Sean Raffuse
CAPITA, Washington University
September, 22 2001
Introduction
•
•
•
•
Motivation for study
Fire detection method
Temporal pattern of fires
Temporal and spatial distribution of fires in
North America
• Future Work
• Conclusion
Why study fires?
• Fires endanger humans and destroy property
• Fires play a major role in the transport and
conversion of nutrients in the global
biogeochemical cycle
• Fires produce smoke
– Reduced visibility
– Health concerns
• Particulate matter
• Potential toxins (Hg)
Remote Sensing of Fires
• A sensor on the
European Space
Agency’s ERS-2
satellite is used to
detect fires
– This sensor detects the
intensity of the light at 3.7
m, which is the peak
wavelength
– If an area has a high
enough intensity, the pixel
is flagged as a “fire pixel”
– Pixel resolution is ~ 1 km
Remote Sensing of Fires
• Sensing is done at night to avoid interference from the sun
• Clouds block fire signals
Here will be a diagram
of the satellite
detecting fires.
Problems
• Incomplete coverage
– Clouds preclude detection
– Fires are more prominent in the daytime
• Sensor is active at night
– Sensor does not cover entire globe every day
•False Detection
–Not all signals are from
fires
–Certain urban areas may
produce counts
•Non-periodic noise
•Low signal counts
•Large fires are counted
multiple times
California
Fires (1997-2000)
Large fires are evident
as clusters of ‘fire
pixels’
Temporal Pattern of Fires
• Seasonal
– Heavy burning
– Highly regional
– Burning season lasts a few
months
• Sporadic
– Occur during regional dry
periods
– Do not cover a large region
– Not annual in a given location
– Bad time charts – connected
Fire Zones of North America
FIRE and Norm. Diff. Veg. Index, NDVI
The ‘Northern’ zone from Alaska to Newfoundland has large fire ‘patches’, evidence of large, contiguous fires.
The ‘Northwestern’ zone (W. Canada, ID, MT, CA) is a mixture of large and small fires
The ‘Southeastern’ fire zone (TX–NC–FL) has a moderate density of uniformly distributed small fires.
The ‘Mexican’ zone over low elevation C America is the most intense fire zone, sharply separated from arid and the lush regions.
Fires are absent in arid low-vegetation areas (yellow) and over areas of heavy, moist vegetation (blue).
Seasonality of
Fire
Dec, Jan, Feb is generally
fire-free except in
Mexico, and W.
Canada
Mar, Apr, May is the
peak fire season in
Mexico and Cuba;
fires occur also in
Alberta-Manitoba and
in OK-MO region
Jun, Jul, Aug is the peak
fire season in N.
Canada, Alaska and
the NW US.
Sep, Oct, Nov is fire over
the ‘Northwest’ and
the “Southeast’
Seasonal Pattern of Fires over the North (52N-72N)
North
•
•
The number of satellite-observed fires peaks in May and July-August
The daily fire counts data shows a significant fluctuation
Seasonal Pattern of Fires over the ‘South’ (12N-30N)
South
•
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The fire count gradually increases from March through May and sharply declines by June
The daily fire counts over the entire South varies by a factor of five within a month
Seasonal Pattern of Fires over the ‘West’ (30N-52N, > 100W)
West
•
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The fire count gradually increases from March through May and sharply declines by June
The daily fire counts over the entire West varies by an order of magnitude during the fire season
Seasonal Pattern of Fires over the ‘East’ (30N-52N, < 100W)
East
•
•
About 10-100 fires are recorded from March-November.
The fire counts over the East are low compared to other regions of NAM.
Future Work
• Develop algorithm to distinguish and
eliminate false detection
• Fusion of fire data with other data
– Smoke detected by other remote sensors
– Air quality monitoring networks
– US Forest Service fire data
Data Fusion: Fire and Smoke
Conclusion
• Fires are an important mechanism of material
transport and conversion
• Smoke from fire poses a risk to visibility and
human health
• The ATSR-2 sensor on the ERS-2 satellite detects
fires via light intensity at 3.7 m
– Coverage is incomplete not 100% accurate
• Fires are seasonal and regional
– In North America, the most intense fires seasons are in
Mexico in the spring and the Northwest in the fall
• Future work will focus on improving the dataset
and integrating it with data from other sources