Statistical Observations in Support of Bow Shock Current Closure to Earth's High-Latitude Ionosphere During Non-Zero IMF By

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11320%2F25%3A10510437" target="_blank" >RIV/00216208:11320/25:10510437 - isvavai.cz</a>

Výsledek na webu

<a href="https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=-DE-tO5aig" target="_blank" >https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=-DE-tO5aig</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1029/2024JA033599" target="_blank" >10.1029/2024JA033599</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Statistical Observations in Support of Bow Shock Current Closure to Earth's High-Latitude Ionosphere During Non-Zero IMF By

Popis výsledku v původním jazyce

The bow shock current (BSC) plays an important role in supplying the magnetosphere with solar wind energy, in particular during times of low solar wind magnetosonic Mach numbers. Since the magnetic pile-up in the magnetosheath has to be maintained, the BSC cannot close locally, but must instead connect to magnetospheric current systems. However, the details of this closure remain poorly understood. For east-west interplanetary magnetic field (IMF) it has been hypothesized that the BSC partly closes to the high-latitude ionosphere, as field-aligned currents (FACs) on open field lines, but there is still no statistical evidence of this. In order to investigate this hypothesis, we use 9 years of Defense Meteorological Satellite Program (DMSP) data to construct normalized FAC maps of the northern hemisphere polar cap. We sort them according to different IMF clock angles, IMF magnitudes and magnetosonic Mach numbers. By separating opposite polarity FACs, we show that, on average, a unipolar FAC exists in the dayside polar cap when the IMF B-y not equal 0, regardless of the sign of the IMF B-z. This current flows out of (into) the ionosphere in the northern hemisphere for IMF B-y&gt;0 (&lt;0) and is thus of the correct polarity to connect to the north-south component of the BSC. Moreover, it is strongest when the BSC flows predominantly in the north-south direction. These results constitute the first statistical evidence in support of at least a partial closure of the BSC to the ionosphere during non-zero IMF B-y.

Název v anglickém jazyce

Statistical Observations in Support of Bow Shock Current Closure to Earth's High-Latitude Ionosphere During Non-Zero IMF By

Popis výsledku anglicky

The bow shock current (BSC) plays an important role in supplying the magnetosphere with solar wind energy, in particular during times of low solar wind magnetosonic Mach numbers. Since the magnetic pile-up in the magnetosheath has to be maintained, the BSC cannot close locally, but must instead connect to magnetospheric current systems. However, the details of this closure remain poorly understood. For east-west interplanetary magnetic field (IMF) it has been hypothesized that the BSC partly closes to the high-latitude ionosphere, as field-aligned currents (FACs) on open field lines, but there is still no statistical evidence of this. In order to investigate this hypothesis, we use 9 years of Defense Meteorological Satellite Program (DMSP) data to construct normalized FAC maps of the northern hemisphere polar cap. We sort them according to different IMF clock angles, IMF magnitudes and magnetosonic Mach numbers. By separating opposite polarity FACs, we show that, on average, a unipolar FAC exists in the dayside polar cap when the IMF B-y not equal 0, regardless of the sign of the IMF B-z. This current flows out of (into) the ionosphere in the northern hemisphere for IMF B-y&gt;0 (&lt;0) and is thus of the correct polarity to connect to the north-south component of the BSC. Moreover, it is strongest when the BSC flows predominantly in the north-south direction. These results constitute the first statistical evidence in support of at least a partial closure of the BSC to the ionosphere during non-zero IMF B-y.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10305 - Fluids and plasma physics (including surface physics)

Projekt

<a href="/cs/project/GA21-26463S" target="_blank" >GA21-26463S: Procesy na magnetopauze, jejich příčiny a následky</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2025

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Journal of Geophysical Research. Space Physics

ISSN

2169-9380

e-ISSN

2169-9402

Svazek periodika

130

Číslo periodika v rámci svazku

6

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

18

Strana od-do

e2024JA033599

Kód UT WoS článku

001499454500001

EID výsledku v databázi Scopus

2-s2.0-105007810765