FIGURE 3 (A) Temporalcharacteristicofthevelocityvariationsofthreeglaciersalongtheircentral fl owlines.Thevelocityofthe79Nglacierat-30to-53 km alongthecentral fl owline.0 intheX axisindicatesthegrounding line positionof79NglacierasshowninFigure 1, andthenegative valuespointtothe directionofinternalextensionoftheicesheet. (Ai) Thevelocityof79Nglacierat-110to-30 kmalongthecentral fl owline. (Aii) Thevelocityofthe79N glacier at 53 to 67 km along the central fl ow line. (B) The velocity of ZI glacier at -30 to 5 km along the central fl ow line (Bi) The velocity of ZI glacier at -140 to -30 km along the central fl ow line. (C) The velocity of SG glacier along the central fl ow