Method of Solving Moist Thermodynamic Equations in NTU-Purdue Non-Hydrostatic Model and Tests on 2D Moist Mountain Waves

A moving frame of reference technique is proposed so that the retrievalof cross-beam wind components is feasible from observations by singleDoppler Radar without sacrificing data resolution.In this algorithm,thereflectivity fields observed by consecutive radar scans are used to find amoving Lagrangian coordinate on which the reflectivity measurements areas stationary as possible.After interpolating all the observational data tothis optimal moving frame,and assuming the wind field is steady state withinseveral radar scans,one can formulate a cost function which contains thefollowing weak constraints:(1)reflectivity is preserved;(2)a geometricrelationship between radial velocity Vr and the Cartesian components u,v,w;(3)mass conservation;and(4)weak vertical vorticity.By minimizingthis cost function,the unobserved cross-beam wind component can be recovered.Applying this algorithm to a simulated,idealized Rankine vortex circulation,it is found that with an appropriate scan strategy,that is,a sufficientnumber of radar scans(＞2),separated by a short enough period oftime(～3 minutes),low level circulation can be successfully retrieved usingdata detected by single Doppler radar.This technique is robust in compensatingfor observational errors,and,in a qualitative sense,works well whenonly reflectivity measurements are available.

並列關鍵字

Nonhydrostatic Numerical Model ； Moist Mountain Waves ； Moist Thermodynamics

國際替代計量

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