HMI now routinely produces vector magnetic field synoptic charts. This Nugget describes the data reduction procedures and the method chosen to resolve the 180-degree ambiguity in azimuth.
Using a combination of the magnetograms, we find signs of the beginning of the 25th cycle from both HMI and WSO by calculating the inclination angles determined from the variation in line of sight field during a disk passage.
Large-scale inflows form around emerging solar active regions in the near-surface layer and alter the global meridional flow patterns.
The HMI data-collection scheme was changed on 13 April 2016 to reduce noise in the vector magnetic field measurement. Starting at 19:24, the Stokes data series hmi.S_720s has been computed by combining filtergrams from both HMI cameras.
A realistic MHD simulation driven directly by SDO/HMI vector magnetograms reproduced a solar eruption in a non-potential flux-emerging active region.
An atypical X-shaped-ribbon flare provides evidence for 3D magnetic reconnection at a separator.
The F10.7 microwave flux shows remarkabke agreement with the unsigned magnetic flux from MDI and HMI over the past 20 years, attesting to the accuracy and significance of both.
We observed magnetoacoustic waves propagating along the magnetic field lines of a sunspot. Based on the wave periods and atmospheric characteristics, we reconstructed the magnetic field topology of the sunspot.
The HMI team has developed several Python codes that can be used to conveniently analyze its many magnetic field data products. Check it out!
The magnetic twist of a flux rope is carefully calculated for an active region model. The flux rope is close to the threshold of helical kink instability and has powered a series of eruptions.