I’ve been searching for better ways to present the MODIS data, and in this post I’ll try a new one. I downloaded the fire outline as of midnight last night into Google Earth. I changed the color and put a heavy black border around it:
Then I downloaded the MODIS aged hot spot data after this afternoon’s first satellite pass, but before the one a little after two this afternoon:
You can see that, in the time since the fire outline was made and now, there has been some expansion. However, there are many reasons to think that this map overstates that expansion. Some of the fires that MODIS is detecting are backburns, which Cal Fire considers, and quite properly so, outside the fire area. Also, MODIS can make mistakes.
Still, it give you some idea of the fire’s direction.
I was, for the first time in several days, able to get the fire radiant power MODIS data. Here’s what that looks like:
With two notable exceptions near White Rock, most of teh detections outside last night’s official fire boundary are of relatively low intensity. I should note that the fire seems to burn at a greater intensity somewhat inside its periphery than it does at the boundaries.
By the way, here is today’s operations map:
I’ve been able to find the completed (as of 7/30) and proposed (also as of that date) dozer fire breaks in Google Earth format. Here they are on the above MODIS aged data map:
The completed fire breaks are orange, and the proposed ones are pink. Unless there are many back burns in the MODIS data, the fire break on the western part of the southern fire perimeter may have been overrun. That’s the problem with MODIS data; you can’t tell the good fire from the bad fire.
There is a higher resolution band in the VIIRS data. Here’s what it looks like now (I don’t know how old the data is, but it’s pretty recent, by the looks of it:
How to read the MODIS/VIIRS heat indications: The size of the square represents the nominal margin of error. The fire could be anywhere in the square, not just at the center. Dark red squares were detected less than six hours before the data set was created. Light red squares were detected less than twelve hours before the data set was created. Orange squares were detected less than 24 hours before the data set was created. Yellow squares were detected less than six days before the data set was created. Since the fire is now over six days old, some of the early detections have dropped off the map. MODIS makes mistakes, sometimes missing outbreaks, and sometime misplacing them outside the nominal margin of error. It is also a snapshot of the activity at the time the satellite is overhead, and will definitely miss flare ups between passes. MODIS can’t tell the difference between wildfires and intentional back burns.
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