Context : The effect of metallicity on the granulation activity in stars , and hence on the convective motions in general , is still poorly understood .
Available spectroscopic parameters from the updated APOGEE- Kepler catalog , coupled with high-precision photometric observations from NASA ’ s Kepler mission spanning more than four years of observation , make oscillating red giant stars in open clusters crucial testbeds .

Aims : We aim to determine the role of metallicity on the stellar granulation activity by discriminating its effect from that of different stellar properties such as surface gravity , mass , and temperature .
We analyze 60 known red giant stars belonging to the open clusters NGC 6791 , NGC 6819 , and NGC 6811 , spanning a metallicity range from [ Fe/H ] \simeq - 0.09 to 0.32 .
The parameters describing the granulation activity of these stars and their frequency of maximum oscillation power , \nu _ { \mathrm { max } } , are studied while taking into account different masses , metallicities , and stellar evolutionary stages .
We derive new scaling relations for the granulation activity , re-calibrate existing ones , and identify the best scaling relations from the available set of observations .

Methods : We adopted the Bayesian code D iamonds for the analysis of the background signal in the Fourier spectra of the stars .
We performed a Bayesian parameter estimation and model comparison to test the different model hypotheses proposed in this work and in the literature .

Results : Metallicity causes a statistically significant change in the amplitude of the granulation activity , with a dependency stronger than that induced by both stellar mass and surface gravity .
We also find that the metallicity has a significant impact on the corresponding time scales of the phenomenon .
The effect of metallicity on the time scale is stronger than that of mass .

Conclusions : A higher metallicity increases the amplitude of granulation and meso-granulation signals and slows down their characteristic time scales toward longer periods .
The trend in amplitude is in qualitative agreement with predictions from existing 3D hydrodynamical simulations of stellar atmospheres from main sequence to red giant stars .
We confirm that the granulation activity is not sensitive to changes in the stellar core and that it only depends on the atmospheric parameters of stars .