Noise mask of magnetic field strength for the inverted full-disk vector magnetic field data

The noise mask of the magnetic field strength is a full-disk map that represents the median of the quiet-Sun magnetic field strength over the Sun's disk. The noise values at a given location are used in some versions of the disambiguation code to optimize performance.

A Noise Mask is derived from a group of FD10 full-disk magnetic field strength data observed at a specific HMI-Sun velocity. It has been demonstrated that the noise level of the measured field strength varies over the Sun's disk, and the pattern of this noise variation changes with the orbital velocity (Vr) of HMI relative to the Sun. Thus it is necessary to generate Vr-dependent noise masks. The method is described below.

Changes of instrument settings took place at several instants (tabulated below). When the settings change, the noise appears to change slightly. To reflect these changes, a noise mask needs to be generated specifically for each time period. The masks currently available in JSOC are generated using FD10 data from April-June 2012. Thus they can be used for data after 19 January 2012. Based on comprison of samples at Vr=0 over a longer interval, no significant changes in the noise mask were observed to occur between instrument reconfigurations.





Noise Mask Characteristics


Responsible scientist

JsocWiki: MagneticNoiseMask (last edited 2013-05-01 04:35:27 by localhost)