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Title: Vertical Motions in Orographic Cloud Systems over the Payette River Basin Part 1: Recovery of Vertical Motions and their Uncertainty from Airborne Doppler Radial Velocity Measurements.
Vertical motions over the complex terrain of Idaho’s Payette River Basin were observed by the Wyoming Cloud Radar (WCR) during 23 flights of the Wyoming King Air during the SNOWIE field campaign. The WCR measured radial velocity, V_r, which includes the reflectivity-weighted terminal velocity of hydrometeors (V_t), vertical air velocity (w), horizontal wind contributions as a result of aircraft attitude deviations, and aircraft motion. Aircraft motion was removed through standard processing. To retrieve vertical radial velocity (W), V_r was corrected using rawinsonde data and aircraft attitude measurements. w was then calculated by subtracting the mean W, (W ̅), at a given height along a flight leg long enough for W ̅ to equal the mean reflectivity weighted terminal velocity, (V_t ) ̅, at that height. The accuracy of the w and (V_t ) ̅ retrievals were dependent on satisfying assumptions along a given flight leg that the winds at a given altitude above/below the aircraft did not vary, the vertical air motions at a given altitude sum to 0 m s-1, and (V_t ) ̅ at a given altitude did not vary. The uncertainty in the w retrieval associated with each assumption is evaluated. Case studies and a project more » wide summary show that this methodology can provide estimates of w that closely match gust probe measurements of w at the aircraft level. Flight legs with little variation in equivalent reflectivity factor at a given height and large horizontal echo extent were associated with the least retrieval uncertainty. The greatest uncertainty occurred in regions with isolated convective turrets or at altitudes where split cloud layers were present. « less
Rapp, Anita
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Journal of applied meteorology and climatology
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National Science Foundation
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