SOLAR MESOGRANULE LIFETIME MEASUREMENTS

We present a study in which the solar lifetime of mesocells (4-10 arcs ec) was determined from a lon,a time sequence (6h 40min) obtained at t he Pic du Midi Observatory. The mesocell detection was performed by lo cal correlation tracking, using various spatial and temporal windows. The histograms derived from the visual measurements reveal that mesosc ale lifetime is between 10 min and 160 min, with peaked distributions around 30-40 min. The indirect method for lifetime estimation using a correlation coefficient, gives a mesocale lifetime from 16 to 185 min depending on the temporal window and the methods used. The proper moti ons of the long-living mesocells are found to be random with respect t o the super-ganule flows, with the peak distribution of horizontal vel ocities at 0.5 km/s. The results of this mesocell lifetime determinati on method are smaller by a factor of 2 to 5 with respect to the previo us results. This difference could be attributed to the mesocell defini tion, the method of measurement or the different location of the mesoc ell field of view in the supergranular network.