Daily Update Synoptic Maps
Daily-updated Synoptic Charts of the Photospheric Line-of-sight and Radial Magnetic Fields
Daily-updated synoptic charts are maps of the Sun produced by combining traditional Carrington charts with magnetograms observed at the time of interest.
Daily-updated synoptic chart of the photospheric line-of-sight magnetic field
There are two types of daily-updated synoptic maps. One is from the near-real-time (NRT) 720-s line-of-sight magnetograms generated at 11:00:00 UT in the very day; the other from the definitive 720-s line-of-sight magnetograms generated with a 45-day delay.
The series names are hmi.Mldailysynframe_720s_nrt (NRT) and hmi.Mldailysynframe_720s (Definitive).
The size of map is 3600x1440 with longitude in degree in x-axis and sin(latitude) in y-axis. The resolution is 0.1 degree in longitude.
Daily-updated synoptic chart of the photospheric radial magnetic field:
The radial magnetic field is converted from line-of-sight field by assuming that the field is purely radial. The series names are hmi.Mrdailysynframe_720s_nrt (NRT) and hmi.Mrdailysynframe_720s (Definitive). The size of map is 3600x1440 with longitude in degree in x-axis and Sin(latitude) in y-axis. The resolution is 0.1 degree in longitude.
Algorithm For Calculation:
The line-of-sight field maps are produced from the HMI 720-s full-disk line-of-sight magnetograms.
The radial field maps from the HMI full-disk radial magnetograms are generated from the 720s line-of-sight magnetograms by assuming the field is purely radial.
Each daily map is composed of two parts. The update part is a 120 degree wide band in longitude from a 4-hour average of the remapped magnetograms centered at the central meridian time of interest; the 120-degree updated region provides data in longitude from the left-edge towards the right. The remainder of the map comes from the standard Carrington synoptic chart(s) that makes up rest of the Carrington rotation. By making a 4-hour average of remapped magnetograms we assure that the noise matches the noise in standard Carrington synoptic charts; each pixel in a Carrington chart uses data contributed by twenty 720s magnetograms that are collected over a 4-hour interval.
The resolution is a little lower than the disk-center resolution of single HMI magnetograms. A two-dimensional Gaussian function is applied to HMI full-resolution remapped data to reduce the spatial resolution before generating synoptic maps. The width of the Gaussian is 3 pixels. The upper limit of the noise for the line-of-sight field maps is about 2.3 Mx cm^2.
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