[Magnetic reconnection]

Project work suggestion / Examensarbeten (30 hp)

Timing analysis using multi-spacecraft data

Student: you?
Supervisor: and

Goal

To develop a better method to estimate velocities using multi-spacecraft data and apply it study the distribution of scales and orientations of current sheets for the current sheets observed in the Earth's magnetosheath.

Background

Estimating scales and speeds of plasma structures is crucial for understanding of many plasma phenomena. One such plasma structure are the current sheets forming in different parts of the magnetosphere as magnetotail, magnetopause, turbulent magnetosheath and knowledge of their scale, speed and orientation from observations is important for comparisons with theories of magnetic reconnection and plasma turbulence. For true quantitative comparisons one needs to have full control of the uncertainties.

Based on data from one spacecraft, it is generally not possible decide whether an observed variation is coming from temporal or spatial changes. To resolve this ambiguity, ESA launched a multi-spacecraft Cluster mission, which consists of 4 spacecraft flying in a constellation with orbit apogee at 19 Earth radii. So, if 4 spacecraft (located in corners of a tetrahedron) observe the same plasma structure, we can assume the structure is planar and moving at a constant speed and it straightforward to compute the velocity of the structure. But what if the observed profiles are similar and not identical? How can we quantify the error?

Project

In this project we will extend the existing methods for timing analysis of multi-spacecraft to provide quantitative estimates of the error for the both the magnitude and direction of the velocity vector.

We will test the method on surrogate data wich can simulate background noise and accelerated motion of current sheets, but also on several cases of real current sheet observed by Cluster.

As the last part of the project we will apply the method to a large number of small-scale current sheets observed in magnetosheath.

The method developed will have important implication for analysis of multi-spacecraft data from the Cluster mission as well as from the future NASA MMS mission.

Plan