On 20 December 2015, three THEMIS spacecrafts detected a nightside magnetotail reconnection event at about 04:36 UT. The spacecrafts (P5, P4, and P3) had their footprints located over North America in the near vicinity of the Gillam ground magnetometer station in Canada. Multipoint observations, both in space and from the ground, allow for an examination of the spatiotemporal characteristics of the disturbance on the ground and the associated physical drivers in the magnetosphere and ionosphere. This study shows that the geomagnetic field dB/dt localization observed at Gillam ground magnetometer site was caused by an isolated substorm onset near that location driven by a nightside magnetotail reconnection event detected by three THEMIS spacecrafts that were located near the central plasma sheet. This event represents the first observation of ground dB/dt localization that is directly linked to nightside magnetotail fast flow bursts and reconnection event.

A document by Dean Thomas. Click on the document to view its contents.

Groups of pelagic dolphins and whales (order cetacea) regularly strand on beaches throughout the world and are referred to as mass stranding events (MSEs). MSEs have been observed for centuries, however the underlying causes remain unclear. We investigated possible connections between MSEs in Cape Cod Massachusetts, USA, and regional wind and ocean currents. The seasonal MSE distribution is strongly correlated to both wind and ocean current strengths, and correlation is maximized when MSEs are compared to environmental data one month in the past. Furthermore, a superposed epoch analysis (a Chree analysis) indicates significant shifts in ocean current strength for months surrounding MSEs. These results may indicate that atmospheric and oceanic effects are possible underlying factors influencing MSEs. These factors could generate environments conducive for prey assemblages that attract cetaceans, or perhaps by driving seasonal production of prey species.