HAO Colloquium - Nathalia Alzate, NASA Goddard Space Flight Center

Identifying Sources of the Variable Solar Wind Through Advanced Image Processing Techniques 

The solar wind is a crucial physical link between the Sun and objects in the solar system.  It contains signatures of the physical processes that heat the corona and accelerate the wind. Remote sensing and in situ data strongly suggest that much of the density variability observed in the slow solar wind (in the form of blobs and puffs) is a tracer of solar wind formation.  However, the nature of this connection has yet to be established.  So far, identification of the source of the slow solar wind has been hampered by the complexity of plasma structures in the very low corona and data limitations in terms of noise reduction.  We are pushing the limits of current instrumental sensitivity and resolution with new state of the art image processing tools, which we apply to coronal imaging data from EUV and coronagraph instruments.  Our goal is to identify and characterize the sources of the variable slow solar wind by exploring the variability of coronal density structures over a distance range starting from the solar surface out to tens of radii and beyond.  To achieve this, we are making use of STEREO (i.e., EUVI, COR and HI) and SOHO (i.e., EIT and LASCO) data.  We will expand our study to include data from other EUV and coronagraph instruments (e.g., GOES/SUVI, SDO/AIA, etc.).

To overcome the faint signals and noise in the data, we are applying new state of the art image processing techniques to EUV and coronagraph data to identify, for the first time, the formation of solar wind plasma structures.  The application of novel image processing techniques, namely the NRGF method, the MGN technique and the DST, has revealed faint signatures in the low corona that have an impact on the structure of the extended corona, which would otherwise go unnoticed.  We are applying these techniques, and exploring others, to coronagraph and EUV data in order to properly determine the exact formation heights of ambient solar wind structures and the features in the low corona they connect to.  We started with structures previously identified in situ and traced through HI1, down through COR2 for a 10-day period in 2008 January, but will expand our study to include several different coronal configurations (e.g., pseudostreamers, active regions, etc.) in order to characterize solar wind structures low in the corona as a function of coronal magnetic complexity, which will be an essential test for theories of solar wind formation.  This work is part of the broad effort in Heliospheric physics to understand the different types of transient structures created in the solar wind as it is formed.

Date and time: 
Thursday, March 14, 2019 - 2:00pm to 3:00pm