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<br />r <br /> <br />REPORT DOCUMENTATION PAGE I Form,4pplovfJrJ <br /> O~'B No 070...0'88 <br />P.clt:'IJPO'l"'ll....,_b'~ItOlllitclc>'>ot"*""'.hDn.........ledlO._.' 1'IOu'j)et_".WICIuOonQ_~""'~"'~""'oOnl. ""~''''\InlIdll'IoOl/IC>",.Il'I_'''ll'"'' <br />"'."'~lt'4dNl_...:l~"G''lClf~t'Ie~OI'''~ &.t>cIOO/II/""''''''lIll'dol\Ql~..b;Ir-'IKl"".t'Dl.nv_',*,ol'''''~oOnr;jl",Io}rm'T.on <br />ncluI,loN;I'uggo.IllO".Icf'~",,"bur-,loW.ohngIon ~0<lquI._1 s..-el. OIo_.,.for'"IQtm'Ioon~"(JI'I._R~, '~l~Je""oono....H.",...y_Sulll204. .o.rllnglOi'lVA <br />222O:H3O:!:,.""lIIl....OOad"'~_~P__~Rfl)OI1lO1C14-0'NlJ,WIl'*'glorlDC205OJ <br />1. AGENCY USE ONLY ('--SI.nkJ I ~. REPORT 0... rE I J. REPORT TYPE AND DATES COVERED <br /> June 1996 Final <br />4. TITLE AND SUBTITlE 5. FUNDING NUMBERS <br />Snow Accumulation Algorithm for <br />the WSR~88D Radar, Version 1 PR <br />6. AUTHOR(S) <br />Arlin B. Super and Edmond W. Holroyd, III <br />1. PERFORMING ORGANlZAllON NAME(S) AND ADORESS(ES) 8. PERFORMING ORGANIZATION <br />Bureau of Reclamation REPORT NUMBER <br />Technical Servic(. Center R-96-04 <br />Denver CO 8022.') <br />9. SPONSORING./MONITORlNG AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORINQJMONITORING <br />Bun-au of Reclamation AGENCY REPORT NUMBER <br />Denver Federal Center llIBR <br />PO Box 25007 <br />Dt'nver CO 80225.0007 <br />11. SUPPl.EMENTARY NOn:S <br />Hard copy available at the Technical Service Center, Denver, Colorado <br />12.. DISTRIBUnONlAVAlLA81UTY STATEMENT 12b. DISTRIBUTION CODE <br />Available from the National Technical Information Service, <br />Operations Division, 5285 Port Royal Road, Springfield, Virginia 22161 <br />13. ABSTRACT (M..imum 200 -rrora.) <br />This annual Bureau of Reclamation report describes the initial year of a 3-year effort to develop n Snow <br />Accumulation Algorithm for the new network of WSR-88D (NEXRAD) radars. Snowfall mt'asurements were <br />made during the 1995-96 winter/spring within range ofWSR-88Ds at Albany, NY, Cleveland, OH, and Denver, <br />CO. Observations of S (snow water equivalent) from the latter two locations were related to Z. (effective <br />reflecti\'ity factor) measurements to determine "best fit" a and P coefficients for the commonly-used equation <br />Z.=aSl1. Recommended a and p values are 318 and 1.5 for Cleveland and 155 and 1.6 for Denver. <br />Observations near Lake Erie revealed a significant range effect. The Cleveland radar underestimated snowfall <br />beyond about 60 km. Radar-estimated snowfall amounts were about 85, 61, 31, and 22 percent of gage <br />observations Ilt 61, 87,115, and 146 km. respectively. A scheme should be developed to use the vertical profile of <br />Z, to adjust for mid. and far-range snowfall underestimates by WSR-88Ds. <br />Initial Snow Accumulation Algorithm code is described and prcFoented. The code development borrow!> from the <br />current NEXRAD rainfall algorithm but makes several important modifications, including an advection scheme, <br />because snowflakes can be transporWd tens of kilometers from the lowest tilt radar beam to the ground. <br />14. SUBJECT TERMS- -radar! NEXRAD/ WSR.88D! snow! snowfalV precipitation 15. NUMBER OF PAGES <br /> 133 <br /> 16. PRICE CODE <br />17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION HI. SECURITY CLASSIFICATION 20. LIMITATION OF ABSTRACT <br />OF REPORT OF THIS PAGE OF ABSTRACT <br />UL UL UL UL <br /> <br />NSN 754o.<ll-280-SSOO <br /> <br />St.nd.lrd Form 298 (Rev. 2-891 <br />""~_""Af<tSlSI".2n'1' <br />211--102 <br />