We derive the nonthermal velocities (NTVs) in the transition region of an active region using the Si iv 1393.78 Å line observed by the Interface Region Imaging Spectrograph and compare them with the line-of-sight photospheric magnetic fields obtained by the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory. The active region consists of two strong field regions with opposite polarity, separated by a weak field corridor that widened as the active region evolved. The means of the NTV distributions in strong field regions (weak field corridors) range between ∼18–20 (16–18) km s⁻¹, albeit the NTV maps show a much larger range. In addition, we identify a narrow lane in the middle of the corridor with significantly reduced NTV. The NTVs do not show a strong center-to-limb variation, albeit they show somewhat larger values near the disk center. The NTVs are well correlated with redshifts as well as line intensities. The results obtained here and those presented in our companion paper on Doppler shifts suggest two populations of plasma in the active region emitting in Si iv. The first population exists in the strong field regions and extends partway into the weak field corridor between them. We attribute this plasma to spicules heated to ∼0.1 MK (often called type II spicules). They have a range of inclinations relative to vertical. The second population exists in the center of the corridor, is relatively faint, and has smaller velocities, likely horizontal. These results provide further insights into the heating of the transition region.

我们使用界面区域成像光谱仪观察到的 Si iv 1393.78 Å 线推导出活动区域过渡区域的非热速度 (NTV)，并将它们与由日震和磁成像仪获得的视线光球磁场进行比较在太阳动力学天文台上。活动区由两个极性相反的强场区组成，由一个弱场走廊隔开，随着活动区的发展而变宽。强场区（弱场走廊）中 NTV 分布的均值范围在 ∼18-20 (16-18) km s ^{−1 之间}，尽管 NTV 地图显示的范围要大得多。此外，我们在走廊中间确定了一条狭窄的车道，其 NTV 显着降低。NTVs 没有表现出强烈的中心到肢体的变化，尽管它们在磁盘中心附近显示出更大的值。NTV 与红移以及线强度密切相关。这里获得的结果以及我们关于多普勒频移的配套论文中提出的结果表明，在 Si iv 中发射的有源区域中有两个等离子体群. 第一个种群存在于强场区域，并延伸到它们之间的弱场走廊中。我们将这种等离子体归因于加热到 0.1 MK 的针状体（通常称为 II 型针状体）。它们相对于垂直方向具有一定的倾角范围。第二个种群存在于走廊的中心，相对微弱，速度较小，可能是水平的。这些结果提供了对过渡区加热的进一步见解。