MIMIC (Morphed Integrated Microwave Imagery at CIMSS)
It is probably an artifact of the morphing algorithm. The algorithm
blends in a new "base image" every hour, and if there is a long time
gap between actual microwave data, then the animation will repeat
small-scale advection in the same feature until the next update occurs,
creating a "pulsing" artifact.
The MIMIC morphing algorithm needs to define a center of rotation for the resulting animation, and so the algorithm's center moves directly between microwave-defined center locations. This path will veer slightly from the official storm track record (from NHC and JTWC), for several reasons. First, midlevel eye shown in the microwave imagery is sometimes offset from the surface-level storm center described by the official record. Second, the temporal resolutions of the two sources (1-12 hours for MIMIC and 6-12 hours for the official track) are different, so a position on one track has to be compared against the interpolated version of the other track. Third, every track (MIMIC, NHC, JTWC, etc.) is affected by navigation error, either in microwave imagery or geostationary satellite imagery, and they affect each track differently.
MIMIC and MIMIC-IR have a simple parallax correction algorithm. The position of the microwave imagery is shifted on the assumption that the observed structures are uniformly 10 km high. This creates an overcorrection for low-lying features, particularly coastlines, but minimizes the position error on the eyewall, which is the most important feature.