• DailySynopticMaps

Daily Update Synoptic Maps

Daily-updated Synoptic Charts of the Photospheric Line-of-sight and the Presumed 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. Data for the most recent 120 degrees of the synoptic map are replaced with a 4-hour average of the observations taken on the day of interest. Currently the charts are updated at ~11 UT each day.

Daily-updated synoptic chart of the photospheric line-of-sight magnetic field

We produce two main types of daily-updated synoptic maps. One is created from four hours of the near-real-time (NRT) 720-s line-of-sight magnetograms observed prior to 11:00:00 UT on the day of interest. The other is computed from the definitive 720-s line-of-sight magnetograms and is generated with a delay of up to 45 days.

The size of each map is 3600x1440 with longitude in degree in x-axis and sin(latitude) in y-axis. The resolution is 0.1 degree in longitude.

Smaller 720*360 versions of the map are available with the suffix '_small'

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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