Ongoing work

GOES-R ABI
Sub-Pixel Fire Detection & Characterization
Fire Characterization
FRP Product
Trend Analysis

Development of the WFABBA for GOES-R ABI is multifaceted:
-Adapt the legacy algorithm to the new satellite system
-Enhance capabilities to take advantage of the improvements available from ABI
-Address user needs
By its nature as a subpixel feature, satellite observation of fire is extraordinarily sensitive to the characteristics of the sensor and recognizing this has been a fundamental part of the GOES-R WFABBA development work.

Sub-Pixel Fire Detection & Characterization

The image to the right shows GOES-R ABI nominal pixels (grid) overlaid on coincident 30m resolution ASTER image (RGB 8-3-1) acquired on 19 Oct 2002 14:21:59UTC. WF-ABBA fire pixels are marked in red (credit: Wilfrid Schroeder). This illustrates a subpixel hotspot feature appearing in multiple full-resolution pixels as an artifact of the shape of the imager response function and relative position of the subpixel feature.

The figure to the left compares a Gaussian PSF (color filled) and step function PSF (transparent), both having the same ensquared energy. This illustrates how the response from seemly similar PSF can be significantly different depending on the sub-pixel location of a thermal feature. At CIMSS, active subpixel fire product research and developing, particularly for GOES-R ABI, has focused on working with simulations and proxy fire data.

Fire Characterization

In addition to fire detection location, WFABBA provides fire characterization in the form of estimate instantaneous fire size and temperature as well as fire radiative power (FRP). To solve fire size and temperature, a modified Dozier system of two equations with two unknowns can be solved for numerically.

Modified Dozier equation terms
Term	Definition
Lx(Tx)	Radiance calculated by integrating the product of the Planck function and the response function for each spectral band x
p	Proportion of pixel on fire
Tb	Background/non-fire brightness temperature
Tt	Average instantaneous target temperature of sub-pixel fire

There are two distinct forms of FRP, FRPDEF and FRPMIR as defined below.

FRP equation terms
Term	Definition
Apixel	Area of pixel
ε	Emissivity of the fire (typically assumed to be 1)
σ	Stefan – Boltzmann constant [5.67 x 10-8 Wm-2K4]
pk	Instantaneous sub-component area on fire within the pixel where the number of sub-components ranges from 1 to n
Tk	Instantaneous temperature of the sub-component area on fire within the pixel where the number of sub-components ranges from 1 to n
B(λ,T)	The monochromatic irradiance of a blackbody at a specific temperature and wavelength
a	An empirically derived , instrument specific constant typically around 3.0 x 10-9 [Wm-2sr-1μm-1K-4]

FRP Product

The fire radiative power (FRP) product is an important fire characteristic particularly in the emissions community. FRP is the time derivative of the fire radiative energy, which is proportional to the biomass consumed by the fire and can be estimated by applying Dozier solution to FRPDEF or from radiances using FRPMIR. Shown below is a GOES-12 scene with fires over Texas and Oklahoma on 9 April 2009 at 2045 UTC The units in the figure are in MW. This product is being tested in real-time in AWIPS at NSSL.

Trend Analysis

A consistent fire database exists for the Western Hemisphere dating back to 1997. It shows nearly twice as many processed fire detects occurred in 2007 compared to 2008 or 2009. This was in part due to the increased soybean production in 2007 and decrease in 2008 and 2009. A steady downward trend since 2004 has occurred in number of processed fire detects (besides 2007). Similar analysis has been generated for North America

Algorithm Description : History : Applications : Ongoing Work : People