These graphs show the seasonal component, which is also referred to as the seasonality of a time series. This is the part of the variations in a time series representing intra-year fluctuations that are more or less stable year after year with respect to timing, direction and magnitude.
The seasonal component may also include calendar-related systematic effects that are not regular in their annual timing or are caused by variations in the calendar from year to year.
The seasonality values in this graph are calculated in regular intervals, where an algorithm fills the dates based on the pattern of displacement. Displacement can be seen in the graphs as part of the Number Of Anomalies layers.