Numerical simulations of the region of possible sprite inception in the mesosphere above winter thunderstorms under wind shear

TL;DR

This paper uses 3D numerical simulations to identify how wind shear in winter thunderstorms influences the possible locations of sprite inception in the mesosphere, revealing that sprites can occur far from the parent lightning.

Contribution

It introduces a detailed 3D electrostatic simulation approach to study sprite inception regions in tilted winter thunderstorms affected by wind shear.

Findings

Sprites can be displaced significantly from the parent lightning due to wind shear.

Sprites occur over larger regions in tilted storms compared to non-sheared storms.

Simulation results align with observational data on sprite locations.

Abstract

Transient luminous events (TLEs) is the collective name given to mesospheric electrical breakdown phenomena occurring in conjunction with strong lightning discharges in tropospheric thunderstorms. They include elves, sprites, haloes and jets, and are characterized by short lived optical emissions, mostly of red (665 nm) and blue (337 nm) wavelengths. Sprites are caused by the brief quasi-electrostatic field induced in the mesosphere, mostly after the removal of the upper positive charge of the thundercloud by a +CG, and they have been recorded above most of the lightning activity centers on Earth. In wintertime, there are just a few areas where lightning occurs, and of those, sprites have been observed over the Sea of Japan, the British Channel, and the Mediterranean Sea. Unlike their summer counterparts, winter thunderstorms tend to have weaker updrafts and as a result, reduced vertical dimensions and compact charge structures, whose positive and negative centers are located at lower altitudes. These storms are often susceptible to significant wind shear and as a result may exhibit a tilted dipole charge structure and a lateral offset of the upper positive charge relative to the main negative charge. We present results of numerical simulations using a three-dimensional explicit formulation of the mesospheric electrostatic electrical field following a lightning discharge from a typical mid-latitude winter thunderstorm exhibiting tilt due to wind shear and evaluate the regions of possible sprite inception. Our results show, as numerous observations suggest, that sprites can be shifted a large distance from the location of the parent +CG in the direction of the shear and will occur over a larger region compared with non-sheared storms.