| { | |
| "bbox": { | |
| "lat_min": -90, | |
| "lat_max": 90, | |
| "lon_min": -180, | |
| "lon_max": 180 | |
| }, | |
| "width": 2880, | |
| "height": 1440, | |
| "elev_min": -32000, | |
| "elev_max": 32000, | |
| "dtype": "int16", | |
| "byte_order": "little", | |
| "row_order": "north_to_south", | |
| "col_order": "west_to_east", | |
| "reference_radius_m": 696000000, | |
| "source": "NASA SDO/HMI synoptic magnetogram CR2300 via JSOC/Stanford", | |
| "carrington_rotation": 2300, | |
| "carrington_date_start": "2025-07-19", | |
| "carrington_date_end": "2025-08-15", | |
| "rotation_period_note": "Carrington sidereal rotation 25.38 days", | |
| "value_kind": "magnetic_field", | |
| "value_unit": "gauss", | |
| "value_mapping": "elev_int16 = round(sign(B) * sqrt(|B| / 1500.0) * 30000), clipped to +/-32000; inverse (valid below ceiling): B_gauss = sign(elev) * (elev / 30000)^2 * 1500; ceiling reached at |B| ~= 1638 G; NaN/nodata -> 0", | |
| "value_mapping_rationale": "Signed sqrt compression spreads quiet-sun |B|~5G into elev~+/-700 for visible texture while active-region |B|~1000G map to elev~+/-24500 and |B|~1638G reaches the +/-32000 int16-safe ceiling. Full gradation is preserved across 5-1638 G (no early plateau). Previous bake used +/-10000 cap which clipped everything above |B|~167G to the same height, making active regions render as a flat tabletop." | |
| } |