Tick length for time interval

Hello all,
is there a way to set the length of the tick that defines the intervals in time axis?
e.g. in the plot i want to make the tick smaller not to overlap with 31 or make it plot inside the plot?

thanks in advance

Have a look at the following MAP parameters:

They control tick length in plots. The long ones seem to be the secondary ticks as their default value is 6.6p (see Cookbook, Automatic GMT settings)

thank you @KristofKoch the MAP_TICK_LENGTH_SECONDARY is the correct option!