SHARP Cylindrical-Equal-Area Data

SHARP stands for Space-weather HMI Active Region Patch. A SHARP is a DRMS series that contains (1) various space-weather quantities calculated from the photospheric vector magnetogram data and stored as FITS header keywords, and (2) 31 data segments (described in detail below), including each component of the vector magnetic field, the line-of-sight magnetic field, continuum intensity, doppler velocity, error maps and bitmaps. The data segments are not full-disk; rather, they are partial-disk, automatically-identified active region patches. SHARPs are calculated every 12 minutes. Often, there is more than one active region on the solar disk at any given time. Thus, SHARPs are indexed by two prime keys: time, T_REC, and HMI Active Region Patch Number, HARPNUM.

The hmi.sharp_720s_cea_nrt and hmi.sharp_cea_720s data have been projected and remapped to a Cylindrical Equal Area (CEA) Cartesian coordinate system centered on the tracked active region. The size of the nrt regions will evolve with time. At each time step the definitive SHARPs will enclose the maximum extent of the region during it's disk passage. The three prime vector components are Bx, By, and Bz. HARP maps of 8 additional quantities are also provided at each time step: the three estimated component errors, the line-of-sight magnetogram, a Dopplergram, the continuum intensity, a map of the active pixels, and an estimate of the confidence in the disambiguation.

SHARP全称Space-weather HMI Active Region Patch，即空间天气HMI活动区斑块。SHARP属于DRMS数据集序列，包含两类核心数据：其一为基于光球矢量磁图数据计算得到的多种空间天气参量，以FITS文件头关键字的形式存储；其二为31个数据段（详见下文），涵盖矢量磁场各分量、视向磁场、连续谱强度、多普勒速度、误差图与位图。此类数据段并非全日面覆盖数据，而是经自动识别提取的局域活动区斑块。SHARP数据集的更新周期为12分钟。任意时刻日面上往往存在多个活动区，因此SHARP数据集通过两个主关键字进行索引：观测时间T_REC与HMI活动区斑块编号HARPNUM。

hmi.sharp_720s_cea_nrt与hmi.sharp_cea_720s数据集已完成投影与重映射，被转换至以追踪得到的活动区为中心的圆柱等面积（Cylindrical Equal Area, CEA）笛卡尔坐标系下。近实时活动区的空间尺寸会随时间动态演化。在每个时间步长中，标准SHARP数据会覆盖该活动区在其日面过境期间的全部最大活动范围。矢量磁场的三个主分量分别为Bx、By与Bz。每个时间步长还附带8项额外参量的HARP图像：三个分量的估算误差、视向磁图、多普勒图、连续谱强度图、活动像素分布图以及消歧义置信度估算结果。

搜集汇总

背景与挑战

背景概述

该数据集是太阳动力学天文台（SDO）HMI仪器提供的SHARP（空间天气HMI活动区补丁）数据，专注于太阳活动区的矢量磁场和空间天气参数监测。数据以圆柱等积投影坐标系统重映射，包含31个数据段，如磁场分量、多普勒速度、误差图等，每12分钟更新一次，时间跨度从2010年5月开始，适用于太阳物理研究和空间天气预报。