Our high microseisms are, I think, typically produced by storm waves and their reflections off of the nearby coast or, less often, from the global microseism generating regions near Greenland or the Aleutian islands. We can distinguish between these by matching the wave periods in global maps to the microseismic peak frequency that we detect, and by the propagation direction. When the dominant microseism is from our coast, it affects the two arms about equally, when it is from the Aleutian island region it travels down the X-arm and there is little relative motion along the Y-arm, and when, like today, it is from the region near Greenland, it travels along the Y-arm and there is little relative motion between the stations on the X-arm. I wonder if the lack of relative motion along one of the arms could be used to improve our performance during these periods...  The figure shows today's spectra from our 5 stations and the phase delays between the corner and out-stations, as well as maps estimating the wave height and wave period for today.

Wave models: https://mag.ncep.noaa.gov/model-guidance-model-parameter.php?group=Model%20Guidance&model=GEFS-WAVE&area=ATL-PAC&ps=area