While the velocity fluctuations of supergranulation dominate the spectrum of solar convection at the solar surface , very little is known about the fluctuations in other physical quantities like temperature or density at supergranulation scale .
Using SDO/HMI observations , we characterize the intensity contrast of solar supergranulation at the solar surface .
We identify the positions of { \sim } 10 ^ { 4 } outflow and inflow regions at supergranulation scales , from which we construct average flow maps and co-aligned intensity and magnetic field maps .
In the average outflow center , the maximum intensity contrast is ( 7.8 \pm 0.6 ) \times 10 ^ { -4 } ( there is no corresponding feature in the line-of-sight magnetic field ) .
This corresponds to a temperature perturbation of about 1.1 \pm 0.1 K , in agreement with previous studies .
We discover an east-west anisotropy , with a slightly deeper intensity minimum east of the outflow center .
The evolution is asymmetric in time : the intensity excess is larger 8 hours before the reference time ( the time of maximum outflow ) , while it has almost disappeared 8 hours after the reference time .
In the average inflow region , the intensity contrast mostly follows the magnetic field distribution , except for an east-west anisotropic component that dominates 8 hours before the reference time .
We suggest that the east-west anisotropy in the intensity is related to the wave-like properties of supergranulation .