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Abstract The radial evolution of interplanetary coronal mass ejections (ICMEs) is dependent on their interaction with the ambient medium, which causes ICME erosion and affects their geoefficiency. Here, an ICME front boundary, which separates the confined ejecta from the mixed, interacted sheath–ejecta plasma upstream, is analyzed in a multipoint study examining the ICME at 1 au on 2020 April 20. A bifurcated current sheet, highly filamented currents, and a two-sided jet were observed at the boundary. The two-sided jet, which was recorded for the first time for a magnetic shear angle <40°, implies multiple (patchy) reconnection sites associated with the ICME erosion. The reconnection exhaust exhibited fine structure, including multistep magnetic field rotation and localized structures that were measured only by separate Cluster spacecraft with the mission inter-spacecraft separation of 0.4–1.6R_E. The mixed plasma upstream of the boundary with a precursor at 0.8 au lacked coherency at 1 au and exhibited substantial variations of southward magnetic fields over radial (transverse) distances of 41–237R_E(114R_E). This incoherence demonstrates the need for continuous (sub)second-resolution plasma and field measurements at multiple locations in the solar wind to adequately address the spatiotemporal structure of ICMEs and to produce accurate space weather predictions. 

Abstract We present observations and modeling results of the propagation and impact at Earth of a high-latitude, extended filament channel eruption that commenced on 2015 July 9. The coronal mass ejection (CME) that resulted from the filament eruption was associated with a moderate disturbance at Earth. This event could be classified as a so-called “problem storm” because it lacked the usual solar signatures that are characteristic of large, energetic, Earth-directed CMEs that often result in significant geoeffective impacts. We use solar observations to constrain the initial parameters and therefore to model the propagation of the 2015 July 9 eruption from the solar corona up to Earth using 3D magnetohydrodynamic heliospheric simulations with three different configurations of the modeled CME. We find the best match between observed and modeled arrival at Earth for the simulation run that features a toroidal flux rope structure of the CME ejecta, but caution that different approaches may be more or less useful depending on the CME–observer geometry when evaluating the space weather impact of eruptions that are extreme in terms of their large size and high degree of asymmetry. We discuss our results in the context of both advancing our understanding of the physics of CME evolution and future improvements to space weather forecasting. 

Millions of in situ ocean temperature profiles have been collected historically using various instrument types with varying sensor accuracy and then assembled into global databases. These are essential to our current understanding of the changing state of the oceans, sea level, Earth’s climate, marine ecosystems and fisheries, and for constraining model projections of future change that underpin mitigation and adaptation solutions. Profiles distributed shortly after collection are also widely used in operational applications such as real-time monitoring and forecasting of the ocean state and weather prediction. Before use in scientific or societal service applications, quality control (QC) procedures need to be applied to flag and ultimately remove erroneous data. Automatic QC (AQC) checks are vital to the timeliness of operational applications and for reducing the volume of dubious data which later require QC processing by a human for delayed mode applications. Despite the large suite of evolving AQC checks developed by institutions worldwide, the most effective set of AQC checks was not known. We have developed a framework to assess the performance of AQC checks, under the auspices of the International Quality Controlled Ocean Database (IQuOD) project. The IQuOD-AQC framework is an open-source collaborative software infrastructure built in Python (available from https://github.com/IQuOD ). Sixty AQC checks have been implemented in this framework. Their performance was benchmarked against three reference datasets which contained a spectrum of instrument types and error modes flagged in their profiles. One of these (a subset of the Quality-controlled Ocean Temperature Archive (QuOTA) dataset that had been manually inspected for quality issues by its creators) was also used to identify optimal sets of AQC checks. Results suggest that the AQC checks are effective for most historical data, but less so in the case of data from Mechanical Bathythermographs (MBTs), and much less effective for Argo data. The optimal AQC sets will be applied to generate quality flags for the next release of the IQuOD dataset. This will further elevate the quality and historical value of millions of temperature profile data which have already been improved by IQuOD intelligent metadata and observational uncertainty information ( https://doi.org/10.7289/v51r6nsf ). 

Streamer-blowout coronal mass ejections (SBO-CMEs) are the dominant CME population during solar minimum. Although they are typically slow and lack clear low-coronal signatures, they can cause geomagnetic storms. With the aid of extrapolated coronal fields and remote observations of the off-limb low corona, we study the initiation of an SBO-CME preceded by consecutive CME eruptions consistent with a multi-stage sympathetic breakout scenario. From inner-heliospheric Parker Solar Probe (PSP) observations, it is evident that the SBO-CME is interacting with the heliospheric magnetic field and plasma sheet structures draped about the CME flux rope. We estimate that 18 ± 11% of the CME’s azimuthal magnetic flux has been eroded through magnetic reconnection and that this erosion began after a heliospheric distance of ∼0.35 AU from the Sun was reached. This observational study has important implications for understanding the initiation of SBO-CMEs and their interaction with the heliospheric surroundings.