Abstract The present article reports on a distinct class of long-lasting overdense trail echoes occasionally detected with the 53 MHz Gadanki (13.5<InlineEquation ID="IEq1"> <EquationSource Format="TEX">$^\circ$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mrow /> <mo>∘</mo> </mmultiscripts> </math></EquationSource> </InlineEquation>N, 79.2<InlineEquation ID="IEq2"> <EquationSource Format="TEX">$^\circ$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mrow /> <mo>∘</mo> </mmultiscripts> </math></EquationSource> </InlineEquation>E) MST radar. These echoes are associated with overdense trail formation and are characterised by strong, coherent reflections persisting for several seconds, with the dominant reflecting region confined to one or two range bins. They frequently exhibit morphological irregularities that are consistent with meteoroid fragmentation. The analysed examples indicate that their evolution is strongly influenced by fragmentation-driven plasma structuring and diffusion processes. The results show that overdense echoes provide complementary information on meteor trail dynamics beyond that obtained from underdense echoes and can form over a range of altitudes in the mesosphere and lower thermosphere (MLT)-region. Overall, the observations highlight the critical roles of background winds and meteoroid fragmentation in controlling the dynamics of long-lasting overdense meteor trails. Only a small fraction (<InlineEquation ID="IEq3"> <EquationSource Format="TEX">$\sim$</EquationSource> <EquationSource Format="MATHML"><math> <mo>∼</mo> </math></EquationSource> </InlineEquation>3%) of long-duration overdense echoes undergo fragmentation. Research highlights <UnorderedList Mark="Bullet"> <ItemContent> A rare class of long-lasting specular overdense meteor trail echoes has been identified using the 53 MHz Gadanki MST radar. These events constitute a small fraction (<InlineEquation ID="IEq4"> <EquationSource Format="TEX">$\sim$</EquationSource> <EquationSource Format="MATHML"><math> <mo>∼</mo> </math></EquationSource> </InlineEquation>3%) of overdense echoes and are characterised by fragmentation, thereby extending radar meteor observations beyond the classical underdense regime. </ItemContent> <ItemContent> Case-by-case analyses of these events show that meteoroid fragmentation, rather than ambipolar diffusion alone, plays a dominant role in controlling the morphology, lifetime, and amplitude structure of these long-duration overdense echoes. </ItemContent> <ItemContent> The results further demonstrate that background neutral winds and evolving plasma structures, together with fragmentation-induced multiple scattering centres, govern the temporal evolution of overdense meteor trails. This supports the interpretation of such trails as dynamic plasma systems, rather than simple diffusing columns. </ItemContent> </UnorderedList>

Fragmentation signature in long-lasting overdense meteor trail echoes observed with the Gadanki MST radar

期刊论文
发表日期：

2026年6月25日

查看全文

K Chenna Reddy

摘要

Abstract

The present article reports on a distinct class of long-lasting overdense trail echoes occasionally detected with the 53 MHz Gadanki (13.5 $^\circ$ $^{\circ}$ N, 79.2 $^\circ$ $^{\circ}$ E) MST radar. These echoes are associated with overdense trail formation and are characterised by strong, coherent reflections persisting for several seconds, with the dominant reflecting region confined to one or two range bins. They frequently exhibit morphological irregularities that are consistent with meteoroid fragmentation. The analysed examples indicate that their evolution is strongly influenced by fragmentation-driven plasma structuring and diffusion processes. The results show that overdense echoes provide complementary information on meteor trail dynamics beyond that obtained from underdense echoes and can form over a range of altitudes in the mesosphere and lower thermosphere (MLT)-region. Overall, the observations highlight the critical roles of background winds and meteoroid fragmentation in controlling the dynamics of long-lasting overdense meteor trails. Only a small fraction ( $\sim$ $\sim$ 3%) of long-duration overdense echoes undergo fragmentation.

Research highlights

A rare class of long-lasting specular overdense meteor trail echoes has been identified using the 53 MHz Gadanki MST radar. These events constitute a small fraction ( $\sim$ $\sim$ 3%) of overdense echoes and are characterised by fragmentation, thereby extending radar meteor observations beyond the classical underdense regime.

Case-by-case analyses of these events show that meteoroid fragmentation, rather than ambipolar diffusion alone, plays a dominant role in controlling the morphology, lifetime, and amplitude structure of these long-duration overdense echoes.

The results further demonstrate that background neutral winds and evolving plasma structures, together with fragmentation-induced multiple scattering centres, govern the temporal evolution of overdense meteor trails. This supports the interpretation of such trails as dynamic plasma systems, rather than simple diffusing columns.