Proposed project on lightning-induced electron precipitation (LEP)

Lightning produces VLF waves that propagate globally in the Earth-ionosphere waveguide as well as into the into the radiation belts, where these so-called “whistler” waves produce pitch angle scattering, leading to energetic particle precipitation above the lightning source, and in the conjugate hemisphere.

The precipitating particles in turn modify the D-region ionization locally. Researchers have used VLF transmitters to sense these transient ionospheric disturbances (called “Trimpi events”) at VLF reflection heights.

Many papers have been written documenting such events, using ground-based data.

A few studies have identified a connection between lightning and induced electron precipitation from space.

Only Gemelos et al. [2009, 2011] has attempted to do this in any kind of climatological sense, comparing electron precipitation and lightning patterns for December and August over the U.S.

logarithm of median monthly nighttime 126 keV electron fluxes from the DEMETER satellite over the U.S. averaged over 2006, 2007, 2008. Black dots show U.S. coastline.

The corresponding nighttime fluxes in the geomagnetic conjugate region. L = 2 and L = 3 contours are shown in white.

Number of nighttime lightning strokes per month, weighted by peak current from the NLDN.

Proposed Project:Delineate the month vs. longitude climatologies of different electron energy fluxes for different L-shells, and interpret in terms of space-based lightning climatologies

• Use space-based OTD-LIS lightning climatologies currently in use in ECCWES

• Use electron fluxes from DEMETER

• Science motivations: Make possible calculation of D-region electron

density/conductivity perturbations due to lightning Quantify radiation belt loss due to lightning Possibly look at other parameters such as NO

production/cooling from TIMED/SABER • DEMETER 98.23°-orbit circular near 700 km, 2004-2010

• 10:30 x 22:30 Sun-synchronous• Continuous measurements

between -65 and +65 invariant latitude

• Instrument Detecteur de Plasma (IDP)

• energetic electron fluxes, 72.9 keV to 2.35 MeV

• 4-sec time resolution and 17.8-keV energy resolution.