Desarrollo de la Antártica

EL DESARROLLO DE J.A A.1IJTÁRTlCA balance in these ice shelves may be kept in a steady condition. Thu5\ it may be considerable tlhat the income of ice for ice shelves comprising vhe snow accumulation, the inflow from the continental ice sheet and the production of ice by freeZÍ<ng sea water at the bottom of lihe ice shelves is balanced with the outgoing of ice consisting of the ca1ving into icebergs and the melting 10ss at the 'Oot– tom of ice shelves in summer. According to Barkov (197 1 1), each of the income and outgoing of ice of Antarctic ice she1ves is about 1.4 x 10 12 tonjyear in total. TABLE 4 CHARACTERISTICS OF TYPICAL ANTARCTIC ICE SHELVES. (AFTER BARKOV, 1971) Ice shelf Area (km") Ross 525xloa Filchner 41111xloa Amery 39xloa Shackleton 37xl0' e. Ice Core Drillz'ng Flow velo- Inflow (x l015jyear) dty at ed- ge Snow (mjyear) accumulation) (Ice stream) 1240± 50 92+24 166±51 1260+100 78+23 204+61 900+135 11+ 4 19+ 8 700+ 50 27+ 6 37+12 Outflow I (x JOl. gmj year) 256+56 175+79 18+ 6 52+26 The deep drilling of Antarctic ice síheet down to 2,164 m in depth was completed at Byrd Station in 1968. This drilling program succeeded in retuming the who1e ice core samp1es from the surface of ice sheet down to the ibed rook surfaée, and has revealed ew sygnifiaant 'data iOJl physical and ,dhemical propertiesl of the ice sheet ice from the surface to the bottom. Obvious1y, the physica1 properties of the deep ice sheet ice sudh. as density, tem¡>erature, heat conductivity, crystal structure, air cavities, deavage cracks, ete., are essentially important in understand– ing dynamics and thermodynamics of the Antarctic ice sheet. In addition, vhe isotope ana1yses of these ice core samples couId indicate the climate variation during the past 80,t/.O{) years. Recent knowledge of the isotope ratios sudh as 0 18 j016 and H2jW as dependent on temperature enab1e us to estimate the atmospheric temperature when the ice samples concemed feIl in Antarctica as 88