New HMI Data Series: temporally consistent disambiguation for HARP vector magnetic field timeseries data
Abstract
The last step of the HMI pipeline removes the 180 degree ambiguity in the direction of the field transverse to the line of sight, enabling users to download physically meaningful components of the photospheric vector field. However, for the pipeline, each time is treated independently, which can lead to changes in the direction of the transverse field from one time to the next that are unphysical. These changes result in large values of the time derivative of the inferred surface magnetic field vector, and hence spurious changes in quantities such as flows and electric fields computed from it. NWRA has developed an enhanced version of the disambiguation code that includes a temporal consistency term. We compare the results of the new method to the results of the pipeline code and demonstrate the improvement in temporal stability. A new data product with the time-series disambiguation is being made available to the community through the JSOC for selected HARPS. This material is based upon work supported by NASA under award Nos. 80NSSC18K0055 and 80NSSC18K0180.
- Publication:
-
Catalyzing Solar Connections
- Pub Date:
- November 2018
- Bibcode:
- 2018csc..confE.116B