Upflows in a Decaying Active Region and its Potential Contribution to the Solar Wind

Plasma upflows with a Doppler shift exceeding 20 km/s at active region (AR) boundaries are considered potential sources of nascent slow solar wind.  These upflows are often located at the footpoints of large-scale fan-like loops, showing temperature-dependent Doppler shifts from the transition region to the lower corona. In this study, we identified two upflow regions in the vicinity of an active region by analyzing the blueshifts of the Fe XII 195 line observed by Hinode/EIS. Context images for the two regions were obtained by the High Resolution Imager (HRI) telescope of the Extreme Ultraviolet Imager (EUI) on board the Solar Orbiter. The region to the west of the AR appears as typical fan-like loops, while the eastern upflow region is near AR moss, revealing moss-like features but with lower intensity from the upper transition region into the corona. Free from the potential contamination of fan-like loops, the east region provides unique insights into the flow properties from the chromosphere into the corona and the coupling between the atmospheric layers in the upflow region. Carefully addressing the point spread function issue with the SPectral Imaging of the Coronal Environment (SPICE), we derive the Doppler shifts of Ne VIII, emitted by cooler plasma compared to Fe XII, in these two regions. The fan-like loops in the west show downflows (redshifts) of approximately 20 km/s, whereas the eastern region shows upflows (blueshifts) from 20 to 30 km/s. This suggests the actual upflows might develop in the upper transition region (~0.6 MK), challenging the typical conclusion of a coronal upflow (> 1 MK), which is affected by downflows in fan-like loops.  Observations from the Interface Region Imaging Spectrograph (IRIS) satellite confirm the coronal upflows influence the velocity field in the lower transition region (Si IV). However, the critical transition temperature from a net redshift into a blueshift is still unclear due to the lack of temperature coverage. Combined with potential field extrapolations, we confirm the driver of the major upflow component might be persistent reconnections between over-pressure AR loops and ambient low-pressure field lines. However, the small-scale dynamics in upflows by observed HRIEUV, e.g., dynamic fibrils and jetlet, may still contribute passively to the upflow plasma in the coupled atmosphere. Preliminary differential emission measure (DEM) analysis reveals a photospheric abundance in both upflow regions, which is compared to the in-situ solar wind measurements when the Solar Orbiter was predicted to connect to the west upflow region by the Connectivity tool.