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Geostationary Lightning Mapper (GLM)
GLM Engineering Design Unit
GLM Engineering Design Unit GLM Engineering Design Unit
Additional GLM images
The Geostationary Lightning Mapper is a single-channel, near-infrared optical transient detector that can detect the momentary changes in an optical scene, indicating the presence of lightning. GLM will measure total lightning activity continuously over the Americas and adjacent ocean regions with near uniform spatial resolution of approximately 10 km. GLM will provide early predictions of intensifying storms and severe weather events. It will also provide data for long-term climate studies. The instrument will aid forecasting of weather events that could affect aviation safety and efficiency. GLM is unique both in how it operates and in the information it collects. While ground-based sensors only provide cloud-to-ground lightning coverage, GLM provides total lightning activity detection with both cloud-to-ground and cloud-to-cloud coverage. Also, ground-based systems can only provide coverage over land. GLM will identify growing, active and potentially destructive thunderstorms in areas over both land and oceans.

The instrument will collect information such as the frequency and location of lightning events to detect the intensification of thunderstorms and tropical cyclones, which are often accompanied by increased lightning activity. Research and testing has demonstrated the GLM potential for improvement in tornado warning lead time and false alarm rate reduction. It is anticipated that GLM data will have immediate applications to aviation weather services, climatological studies, and severe thunderstorm forecasts and warnings. Data from the instrument will also be used to produce a long term database to track decadal changes in lightning activity. This is important due to lightning’s role in maintaining the Earth-atmosphere electrical balance.

GLM measurements

GLM measurements can provide vital information to help the operational weather, aviation, disaster preparedness, and fire communities in a number of areas:
1) Improvement in tornado and severe thunderstorm lead times and false alarm reduction
2) Early warning of lightning ground strike hazards
3) Advancements in the initialization of numerical weather prediction models through better identification of deep convection
4) Improved routing of commercial, military, and private aircraft over oceanic regions where observations of thunderstorm intensity are scarce
5) Improved ability to monitor intensification or decay of storms during radar outages, or where radar coverage is poor or scarce, such as in mountainous areas and oceanic regions
6) Better detection and short range forecasts of heavy rainfall and flash flooding
7) Ability to monitor the intensity change of tropical cyclones, which is often accompanied by increased lightning activity
8) Continuity and refinements of lightning climatology within the GOES field of view

GLM Sensor Unit
image: GLM Sensor Unit
GLM Sensor Unit (see through)
image: GLM Sensor Unit
GLM Characteristics
 •  Staring CCD imager (1372x1300 pixels)
 •  Near uniform spatial resolution 8 km nadir, 14 km edge fov
 •  Coverage up to 52 deg N lat
 •  70-90% flash detection day and night
 •  Single band 777.4 nm
 •  2 ms frame rate
 •  7.7 Mbps downlink data rate (for comparison- TRMM LIS 8 kbps)
 •  < 20 sec product latency
GLM Fact Sheet
Thumbnail image of GLM Factsheet   Click on the image to view a PDF (1,827 KB) of the
GLM Fact Sheet.
List of GLM Products:  Click here

Contractor:  Lockheed Martin Advanced Technology Center ,
Palo Alto, Calif.
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