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Type II radio bursts arise due to shocks typically driven by coronal mass ejections (CMEs). When these shocks propagate outward from the Sun, their associated radio emissions drift down in frequency as excited particles emit at the local plasma frequency, creating the usual type II patterns. In this work, we use dynamic spectra from the Wind/WAVES Thermal Noise Receiver (TNR) to identify type II radio emissions in the kilometric wavelength range (kmTIIs, f < 300 kHz ) between 1 January 2000 and 31 December 2012, i.e., over a solar cycle. We identified 134 kmTII events and compiled various characteristics for each of them. The finding of 45 kmTII events not reported by the official Wind/WAVES catalog (based on RAD1 and RAD2 data) is particularly important. We search for associations with interplanetary structures and analyze their main characteristics to reveal distinctive attributes that may correlate with the occurrence of kmTII emission. We find that the fraction of interplanetary coronal mass ejections (ICMEs) classified as magnetic clouds (MCs) that are associated with kmTIIs is roughly similar to that of MCs not associated with kmTIIs. Conversely, the fraction of ICMEs with bidirectional electrons is significantly larger for those ICMEs associated with kmTIIs (74% vs. 48%). Likewise, on average, ICMEs associated with kmTIIs are 23% faster. The disturbance storm time (Dst) mean value is almost twice as large for kmTII-associated ICMEs, indicating that they tend to produce intense geomagnetic storms. In addition, the proportion of ICMEs producing moderate to intense geomagnetic storms is twice as large for the kmTII-associated ICMEs. After this investigation, TNR data proved to be valuable not only as complementary data for the analysis of kmTII events but also for forecasting the arrival of shocks at Earth. [ABSTRACT FROM AUTHOR]

We study an extreme ultraviolet (EUV) confined ejection observed on 9 May 2012 in Active Region (AR) NOAA 11476. For the analysis we use observations in multiple wavelengths (EUV, X-rays, Hα, and magnetograms) from a variety of ground- and space-based instruments. The magnetic configuration showed two rotating bipoles within the following polarity of the AR. This evolution was present some tens of hours before the studied event and continued thereafter. During this period, the magnetic flux of both bipoles continuously decreased. A mini-filament with a length of ≈30″ lay along the photospheric inversion line of the largest bipole. The mini-filament was observed to erupt, accompanied by an M4.7 flare (SOL20120509T12:23:00). This injected dense material as well as twist along closed loops in the form of a very broad ejection whose morphology resembled that of typical Hα surges. We conclude that the flare and eruption can be explained as due to two reconnection processes, one occurring below the erupting mini-filament, and another above it. This second process injects the mini-filament plasma within the reconnected closed loops linking the main AR polarities. By analyzing the magnetic topology using a force-free model of the coronal field, we identify the location of quasi-separatix layers, where reconnection is prone to occur, and present a detailed interpretation of the chromospheric and coronal eruption observations. In particular, this event, in contrast to what has been proposed in several models explaining surges and/or jets, is not produced by magnetic flux emergence, but by magnetic flux cancellation accompanied by the rotation of the bipoles. In fact, the conjunction of these two processes, flux cancellation and bipole rotations, is at the origin of a series of events, homologous to the event we analyze in this article, which occurred in AR 11476 from 8 to 10 May 2012. [ABSTRACT FROM AUTHOR]