Laserfiche WebLink
<br />I <br />I <br /> <br />I <br />I <br /> <br />The new VPR correction uses the clearance C (meters) between the beam cenler and the ground. <br />In effect. the coefficient a becomes dependent on this C and is now tcnned ac. The new snow <br />precipil:.nion rate, S. then becomes: <br /> <br />S = (7..,!ac)**(I/p) <br /> <br />(4) <br /> <br />I <br />I <br /> <br />If a correction factor Fe is defined as the nuio corrected/uncorrected. or <br />Fe = (alae).'( liP), <br /> <br />(5) <br /> <br />then (4) may be expressed as: <br /> <br />S = Fe . (Z/a).'( liP) <br /> <br />(6) <br /> <br />I <br />I <br /> <br />The a versus C profile is a linear least squares filln 21 data points from four sites: Minneapolis. <br />Alhany, Denver, and Cleveland. This fit is expressed by equation (7) and portrayed in ligure 4. <br /> <br />ac = cxp (-0.0004092687' C + 5.225943), or <br />In (ae) = -0.0004092687 . C + 5.225943. <br /> <br />(7) <br /> <br />I <br />I <br />I <br />I <br /> <br />From equation (7), it is evident that ac decreases with increasing clearance C. This means thaI in <br />equation (7) and the VPR. a larger Fe will he applied (yielding a greater S) not only if data are <br /> <br />,~ <br /> <br />~ ..t~r <br />+ <br />Il"'~ + <br /> <br />J ~ <br /> <br />IlHO+ <br /> <br />1. -+IlW'l..... <br />~ - + <br />+llfNX <br />+~+ <br /> <br />+ <br /> <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />" <br /> <br />. <br /> <br />~ <br /> <br />lOOl '!iXI l'OOO <br />,""-0 <br /> <br />- <br /> <br />- <br /> <br />Figure 4.-Relation between 0 and beam <br />clearance for several radars (colored <br />curves). Data sources include sheltered <br />gauges and snow boards. Black line is linear <br />least squares fit to the exponential relationship <br />(oc. equalion 7). VPR used for the previous <br />range correction (FR) included for reference <br />(KMPX-vert). <br /> <br />17 <br />