On several occasions, Lively Data or our other items on the Aviso website, have echoed the ocean seasons : the alternation of the seasons is the main cause of changes in sea level during a year.
It's a simple phenomenon : surface temperature increases as a result of solar radiation, the heat propagates in-depth and while it warms up, there's a water's dilatation. Conversely, if the surface temperature drops, there's water's contraction. This is called steric effect.

We can observe a difference of about 20 cm to 30 cm in the sea level between the seasons in the Mediterranean Sea, where this phenomenon is amplified by the characteristics of this semi-enclosed sea. This amplitude in sea level anomalies can be revealed on a time serie (year 2004, on the left) at a point of Western Mediterranean (6°E, 40°N) : minimum end of March (-16 cm) and maxima end of October (+14 cm).
Using the LAS, this seasonal amplitude can also be revealed by representating and comparing the minimum (for the period between mid-March and mid-May) and maximum (for the period between mid-September and mid-November ) of sea level anomalies of each grid point (maps below).