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<br />APPENDIX A EXCEllPTS FROM CAPABILITY STATEMENTS REGARIIING <br />WINTER PROGRAMS <br /> <br />Weather Modification Association (2005) <br /> <br />"Winter Preel/Ji/alion Augmenlalion <br /> <br />The capability to increase prl!t:ipilalion from winler/ime orographic cloud systems has <br />noli' been demonstrated sIKces.\fulfl' in mmwrou.\' "links in rhe dUlin" research experiment.5. <br />The emili/ion. growlh (lnd fallout of seeding-induced {and enhanced} ice parrides hare been <br />documented in several f1lOwlIainous regions of the It.estern U. S Enhanced precipitation rales in <br />seeded cloud regiolls hm'l! been mNI,'iIlreJ in the range of hllndndths to > I Inm per hOllr. <br />Allhough conducted over smaller temporal and spatial scale.f, research results tend 10 be <br />C01/si.5ten/ with l!\.tliuations of randomb!d experimenls and II .wbs/unrja/ and growing !lumber 0/ <br />operational programs where 5% - 15% im'rea.w.'s in ,w:a.wl1al precipitalion JUH'e been <br />consistemly reported. Similar resulls han:' been found in bolh comil1('l1lal and L'oaslal regions, <br />wilh the polential jor enhanced precipitation in coastal re;!.ions appearin;!. to be Kreater in <br />L'onvecliw.' cloud rt.'gimes. The (:onsistent range of indicated e.ffc(:ts in many regions suggests <br />fairly widespread tran.yerabilil)' oflhe e.~timated results. <br /> <br />Technological adl'(lnces hm'e aided winter precipitalion allgmt:'nlation programs. Fi.nt- <br />acting si/l'er iodide ice nuclei, ,'..ith higher aClidl)' at warmer lemperatllres. hare increased the <br />capability to augment precipitalion in shallow orographic cloud systems. Numaical modeling <br />has imprOl'l'(lthe understanding of almospheric Inlt/sport processes and allowed simulation of <br />the meleorological and microphysical processes inm/wd in cloud seeding. Improvements in <br />compuler and communications sySlems haw resulted in a steady improwme11l in remolely <br />controlled c:/oud (ice) nuclei generalors (CNG '.~), which permit impro\'ed placemenl ofeNG's in <br />remote mounlaimms locations. <br /> <br />lVinlerlime snoufall 11111:mentation programs can use (I combination of aircraji and <br />ground-based dispersing systems. Allhough sil\'Cr iodide I.:ompolllul~ (Ire still Ihe most <br />('ommonly lIsed glClciogenic (causing Ihe jormation of ice) seeding agems, dry ice is used in some <br />warmer (but still supercooled) cloud si/ualions. Liquid propane also shows some promise lIS a <br />seeding llxenl It'hen dispensers ('111/ be posilioned abo\'C the freezing le,'el on Ihe upwind slope.\' <br />of mountains at 10catiofJ.{ lIdequalely filr upwind 10 allow growlh und fallow of precipitation <br />wilhin the intended targelarea.... Dr)' ice and liquid propane expand the window of opporlunify <br />for seeding m't:'r Ihat of si/wr iodide. since Ihey ('1lI1 produce ice pal'l ides at tempt.'ratures as <br />warm as _0.50 C. For ejfe(.tiw precipillllion augmenlttlion. seeding melhods and guidelines need <br />to he adapled to regional meteorological and topographical situatiollS. <br /> <br />AllhollXh tradilimwl stlllistical method~ continue to be used 10 evalllllle bolh randomi=ed <br />and non-randomi=ed wintertimt! predpilaliofl augmentalion programs, Ilrt' resulls of similar <br />programs are al.m being pooled objectively in order 10 obtain more rohUSI t!stimll/es of seeding <br />efficacy. Objecliw emlulIlions of non-randomi=ed operational programs ('onlinlle to be a <br />dt[ticlllt challenge. Some nell' method'! 0/ emluation using the trace chemkal and physical <br />