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Global Frequency and Distribution of Lightning as Observed from Space by the Optical Transient DetectorThe Optical Transient Detector (OTD) is a space-based instrument specifically designed to detect and locate lightning discharges as it orbits the Earth. This instrument is a scientific payload on the MicroLab-1 satellite that was launched into a low-earth, 70 deg. inclination orbit in April 1995. Given the orbital trajectory of the satellite, most regions of the earth are observed by the OTD instrument more than 400 times during a one year period, and the average duration of each observation is 2 minutes. The OTD instrument optically detects lightning flashes that occur within its 1300x1300 sq km field-of-view during both day and night conditions. A statistical examination of OTD lightning data reveals that nearly 1.4 billion flashes occur annually over the entire earth. This annual flash count translates to an average of 44 +/- 5 lightning flashes (intracloud and cloud-to-ground combined) occurring around the globe every second, which is well below the traditional estimate of 100 flashes per second that was derived in 1925 from world thunder-day records. The range of uncertainty for the OTD global totals represents primarily the uncertainty (and variability) in the flash detection efficiency of the instrument. The OTD measurements have been used to construct lightning climatology maps that demonstrate the geographical and seasonal distribution of lightning activity for the globe. An analysis of this annual lightning distribution confirms that lightning occurs mainly over land areas, with an average land:ocean ratio of 10:1. A dominant Northern Hemisphere summer peak occurs in the annual cycle, and evidence is found for a tropically-driven semiannual cycle.
Document ID
20020051098
Acquisition Source
Marshall Space Flight Center
Document Type
Preprint (Draft being sent to journal)
Authors
Christian, Hugh J.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Blakeslee, Richard J.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Boccippio, Dennis J.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Boeck, William L.
(Niagara Univ. New York, NY United States)
Bucchler, Dennis E.
(Alabama Univ. Huntsville, AL United States)
Driscoll, Kevin T.
(Alabama Univ. Huntsville, AL United States)
Goodman, Steven J.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Hall, John M.
(Computer Sciences Corp. Huntsville, AL United States)
Koshak, William J.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Mach, Douglas M.
(Alabama Univ. Huntsville, AL United States)
Arnold, James E.
Date Acquired
August 20, 2013
Publication Date
January 1, 2002
Subject Category
Meteorology And Climatology
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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