North Greenland Glacier Velocities and Calf Ice Production

Abstract

Average vclocitics ofNonh Grecnlancl glaciers whieh reach thc sea have becn determined by comparison of acrial photographs taken bctween 1947 and 1978.Glacicrs draining thc northcm margin of thc Inland lee have floating frontal portions up to 50 km In length.whose integrity is mainrained by the confining effcct of scmi-pcrmanent fjord icc: their measured fotward velocitics range from about 100111 10 more than 980 m per year.SmalJer glaciers draining indcpendcnt iee caps havc movcments of generally lcss than 50 m per ycar, but occasionally as mueh as 150-200111.Total calf ice production front thc tuajor glacier out lets ofthe Inland Ice in North Greenland is estimated at slightly under 3.5 km' annually.Most fjords havc a sernipermanent icc cover which melts completcly only at rare intervals (> 30 years): accompanying break-up and dispersal of floating glacier tongues releascs Iarge tabular icebergs resembling ice islands.sornc of which may reach the Arctic Ocean.