Time--Distance Helioseismology Data Analysis Pipeline for Helioseismic and Magnetic Imager onboard Solar Dynamics Observatory (SDO/HMI) and Its Initial Results

TL;DR

This paper presents a data analysis pipeline for helioseismology using SDO/HMI data, enabling routine near-real-time mapping of solar interior properties and initial results on solar flows and rotation.

Contribution

The paper introduces a comprehensive pipeline for analyzing SDO/HMI helioseismic data, including processing, measurements, inversions, and map generation, with initial results demonstrating its capabilities.

Findings

Full-disk flow maps and sunspot subsurface flows generated

Initial interior rotation and meridional flow speeds measured

Pipeline enables routine near-real-time solar interior mapping

Abstract

The Helioseismic and Magnetic Imager onboard the Solar Dynamics Observatory (SDO/HMI) provides continuous full-disk observations of solar oscillations. We develop a data-analysis pipeline based on the time-distance helioseismology method to measure acoustic travel times using HMI Doppler-shift observations, and infer solar interior properties by inverting these measurements. The pipeline is used for routine production of near-real-time full-disk maps of subsurface wave-speed perturbations and horizontal flow velocities for depths ranging from 0 to 20 Mm, every eight hours. In addition, Carrington synoptic maps for the subsurface properties are made from these full-disk maps. The pipeline can also be used for selected target areas and time periods. We explain details of the pipeline organization and procedures, including processing of the HMI Doppler observations, measurements of the travel times, inversions, and constructions of the full-disk and synoptic maps. Some initial results from the pipeline, including full-disk flow maps, sunspot subsurface flow fields, and the interior rotation and meridional flow speeds, are presented.