GeoMAC Wildland Fire Support Website – IMS 10 February 2009
Posted by Rob Barber-Delach in Wildfire Data.Tags: ArcIMS Image Service
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Introduction
The term GeoMAC stands for Geospatial Multi-Agency Coordination, and as such the web site is designed for support of multi-agency wildland fire situational awareness. Participating agencies include BLM, USFS, NPS, NIFC, CA Fire, among others. I will let you visit the GeoMAC web site for the full list of agency partners and the acronmy definitions. The GeoMAC site is updated daily and therefore contains fairly current data about large wildfires being managed by the National Interagency Fire Center (NIFC).
Figure 1. GeoMAC Main Web Page.
During major wildfire flare-ups, GeoMAC can get a considerable amount of use. As case in point, during the 2007 October wildfires in California, the GeoMAC site was receiving so many hits during business hours that the interactive web map crawled to a halt, although accessing the web map services directly on the “back-end” still worked, albeit slower than normal.
Data Listing (partial)
I have listed what I feel are the most relevant data layers available from the GeoMAC web map services. In addition GeoMAC offers direct download of active and historical fire perimeters in shapefile and in Google Earth KML.
Web Map Service Data Layers
- Current Fires
- Current Fire Perimeters
- MODIS Thermal Satellite fire detects
- HMS Thermal Satellite hot spots
- Historical Fires and Fire Perimeters
Downloadable Data Layers
- Active Fire Perimeters – KML
- Active Fire Perimeters – Shapefile
Access
Figure 2. GeoMAC Interactive Web Map Page
Access to all the features of the GeoMAC web site, including the web map services is free and open to the public.
As far as the primary data layers of interest (current and historical fires and perimeters and MODIS satellite data) there is little difference between the geomac and geomac_wms web map services. Overall, it appears that the geomac_wms service has fewer base data layers. Note that Alaska fire data is presented in a separate web map service of its own (geomacak).
- Service Type: ArcIMS Image Service
- Server Address: http://www.geomac.gov
- Service Name(s): geomac, geomac_wms, geomacak
Figure 3. GeoMAC Data Download Page
The data download is via from an ftp-like web page (see figure 3). This page is accessed via the “Download Perimeters” link on the entry page (see figure 1).
Usability
While my interest in and the purpose of this blog of geospatial data sources is primarily for use of geospatial data in GIS and similar software, it is worth noting that the GeoMAC web map has minimal functionality and many data layers in the web map service are not exposed in the web map interface. The data is best used when accessed via the web map services and can easily be ingested into ArcGIS Explorer and ArcGIS Desktop. The Current Fires and Perimeters overlaid well on your own base maps (when the GeoMAC base data is turned off)
Figure 4. GeoMAC web map service overlaid in ArcGIS Explorer
Figure 5. GeoMAC web map service as displayed in ArcGIS Desktop
Data Quality
Overall data quality is good, but there are some issues to be aware of.
The Current Fires point layer is maintained by the central office and therefore is generally not a very accurate location for the active fire (see figure 6 for a random example). In this example, the point for the fire is off by almost 4 miles from the historical fire perimeter. Fire perimeters are generally accurate in part because they were developed by the field staff at the site of the fire.
Figure 6. Example of error in fire points versus fire perimeters using ArcGIS Desktop.
My other note about accuracy is regarding the thermal satellite fire/hot spot detections. The MODIS data is fairly useful, especially if current fire perimeters are not available for a given fire of interest, but the HMS data appears to have many false hits, by my assessment, so many as to make it worthless.
The base data layers provided in the web map services are somewhat useful, but you will more than likely want to display the GeoMAC fire data over your own base map data.
Update Frequency
The current fire layer is updated daily. The fire perimeter data is updated periodically with data from the field offices (generally every 1-2 days), but it is important to note that they are not received for all fires.
Metadata
FGDC compliant metadata is available for the historical data, but not for the more dynamic layers, such as Current Fires and Perimeters and the thermal satellite data.
Ratings
Accessibility Rating: Excellent
Usability Rating: Very Good
Data Quality Rating: Good
Overall Rating: Very Good
Ratings on 5-pt scale (1- Poor, 2- Fair, 3- Good, 4- Very Good, 5- Excellent)
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