Gas convection is observed in the solar photosphere as the granulation , i.e. , having highly time-dependent cellular patterns , consisting of numerous bright cells called granules and dark surrounding-channels called intergranular lanes .
Many efforts have been made to characterize the granulation , which may be used as an energy source for various types of dynamical phenomena .
Although the horizontal gas flow dynamics in intergranular lanes may play a vital role , but they are poorly understood .
This is because the Doppler signals can be obtained only at the solar limb , where the signals are severely degraded by a foreshortening effect .
To reduce such a degradation , we use Hinode ’ s spectroscopic data , which are free from a seeing-induced image degradation , and improve its image quality by correcting for straylight in the instruments .
The dataset continuously covers from the solar disk to the limb , providing a multidirectional line-of-sight ( LOS ) diagnosis against the granulation .
The obtained LOS flow-field variation across the disk indicates a horizontal flow speed of 1.8-2.4 km/s .
We also derive the spatial distribution of the horizontal flow speed , which is 1.6 km/s in granules and 1.8 km/s in intergranular lanes , and where the maximum speed is inside intergranular lanes .
This result newly suggests the following sequence of horizontal flow : A hot rising gas parcel is strongly accelerated from the granular center , even beyond the transition from the granules to the intergranular lanes , resulting in the fastest speed inside the intergranular lanes , and the gas may also experience decelerations in the intergranular lane .