radvert4 −− compute vertical particle velocity, divergence, vertical wind, and hydrometeor terminal velocity for Candis radar data file
radvert4 wp div wi wt u v
Radvert4 expects a three−dimensional, synthesized Candis radar data file produced by radcart5, on the standard input. This file is transferred to the standard output with the addition of certain fields. The added fields are the vertical particle velocity, the horizontal divergence, the vertical wind, the particle terminal velocity, and the x and y wind components. Various ambient profiles are added as well. The above fields are added to the variable slice section, whereas the ambient density, pressure, and scale height profiles are added to the static slice. Though normally only one variable slice occurs per file, radvert4 will treat an arbitrary number.
The command line arguments are the desired names of the vertical particle velocity, divergence, vertical wind, particle terminal velocity, and x and y wind fields. These must not exist in the input file. The names of the density, pressure, and scale height fields are internally specified.
Normally the divergence is calculated using centered differences. However, if missing data would prevent the centered difference calculation of the divergence at some point, off−centered differences are tried. A column correction is always done on the divergence such that the vertical integral of divergence times density equals zero.
The vertical wind is calculated by integrating the mass continuity equation down from cloud top. The vertical wind is assumed to be zero at cloud top.
The particle terminal velocity is estimated using the procedure of Jorgensen, LeMone, and Jou (1970): Monthly Weather Review, Vol. 119, pp 2608-2637. This procedure is only valid for the deep tropics and must be modified for other locales. The particle terminal velocity is taken as negative, reflecting the downward motion of particles.
The particle vertical velocity is computed as the sum of the vertical wind and the particle terminal velocity.
The horizontal wind components are computed according to the equations u = ux0 + gx*wp and v = uy0 + gy*wp, where ux0, uy0, gx, and gy are fields generated by radcart5 and wp is the particle vertical velocity.
Units of velocity are m/s, while distance is measured in km. Density is measured in kg/m^3, while pressure is measured in kpa.
Radvert4 doesn’t do extensive checking on the size and dimensions of input fields. If these take on unexpected values, trouble could result.
Bugs occasionally act like hydrometeors.