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The turbulent foreshock region upstream of the quasi- parallel bow shock is dominated by waves and reflected particles that interact with each other and create a large number of different foreshock phenomena. Plasma structures with enhanced magnetic field (Short Large Amplitude Magnetic Structures or SLAMS), and density spikes, named plasmoids, are frequently observed. Based on our previous results, we have found that there is a category of events exhibiting both magnetic field and density enhancements simultaneously and we introduce the term “mixed structure” for them. Using measurements of the Magnetospheric Multiscale Spacecraft (MMS) and OMNI solar wind database, we try to explore the origin of these structures, their occurrence rate and properties in association with the foreshock boundary. Moreover, we attempt to trace and observe their interaction with the bow shock, using multi-spacecraft analysis by simultaneous measurements of Cluster, THEMIS, GEOTAIL and MMS and discuss their evolution., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

Spontaneous Hot Flow Anomalies (sHFAs) are a kind of foreshock transients. Unlike hot flow anomalies, they are formed in the foreshock region without a clear upstream discontinuity. Nevertheless, the features and their influence on the magnetospheric system are the same for these two types of discontinuities. Previous studies revealed that HFA and sHFA preferentially occur under radial IMF conditions. However, our preliminary investigation shows that sHFA rarely occurs during long-lasting radial IMF events. In this study, we will completely check the characteristics of various parameters in the foreshock under different IMF cone angle conditions to reveal the candidate mechanism for this disagreement., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)