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<br />},M 1110-2--1406 <br />5 Ian 60 <br /> <br />where: <br />Jf <br />T: <br /> <br />i~ the snmvlnelt rate in inehcs per day. <br />is the difference bctweelL the air templ'ralure measured at 10 feet and the snow surface <br />tempcrattTe, in of. <br />T; is the difference between the dewpoint temperature measured at 10 feet and the snow <br />surface temperature, in of. <br />is the w::nd speed at 50 :feet a,bove the SIlO\V, ill miles per hour. <br />is the ObSCITCd or estimated insolation (solar radiation on horizontal surface) in langleys. <br />is the observed or cstimntcll avcrngc SIlOW surface albedo. <br />is the bLsin shortwave radiation melt faelor. Jt depends upon the average exposure of <br />the open llfcas to short,vavc radiation in comparison with an unshiclded horizontal <br />surface. <br />F is an estimated average basin forest CiLIlOpy ('oyer, effective in shading the area from <br />solar radia,tion, expressed as a decimal fraction. <br />r; is the diff,~rence between the cloud base temperaturn and snow surface temperature, in <br />OF. It is estimated from upper air temperalures or by lapse rates from surface station, <br />preferably on a snow-free si te. <br />is the estimated cloud covC'r, expressed us a del'imal fraction. <br />is the hasin convection-condensat.ion mdt. factor, as opfincd above. It dqwnds on t.he <br />relative exposure of the area to wind. <br />As pointed out in paragraph 3-08, melt coefficients represent mean snowmelt. rates in inches <br />per day. For equations 22 and 23 (which do !lot invoh-e solar radiation directly), snowmelt for <br />~ubperiods less than a day may be ohtained by applying mean values of air temperat.ure and wi_nd <br />for the particular subperiod, and dividing the computed melt by the number of subperiods per day, <br /> <br />v <br />!, <br />a <br />k' <br /> <br />N <br />k <br /> <br />16 <br /> <br />e <br /> <br />e <br /> <br />e <br />