Two itcsrativc mt+hods are driscribcd for obtaining horizontal winds from the pressure-height field by means of higher-order grostrophic approximations for the purposc of improving up011 thcl geostrophic wind. The convergence propert,ies of the iterative. mtxthods are discussed; nnd in :t simplcx theoretical case, one of the methods is found to diverge with strong cyclonic motion. Both iter:ttivc mcthods were applied to analyzed 500-mb. height charts and over most of thr map convergd in a few scans to wind values somewhere between the geostrophic wind and the wind obtairlrd from the balance rqnation. Howe~ve~r i n a few locations continued iteration led t o increasing differences betwecn successively computed winds: i.c.., the methods appc,ared to diverge. In fact, wind values in adjacent areas gradually tended to be corrnptcd. This lack of convergtance, occurring mainly in areas of negative vorticity and additionally i n t,he case of mrthod I1 in are'as of strong cyclonic vorticity, was associated with the development of excessive horizontal wind divergence, which after three. or four iterations sometimes exceeded the relative vorticity.Stream functions were computed by rtlaxing the. relative vorticity of the winds obtained by methods I and 11, generally after one itcration. These \?-ere compared to thv stream function obtained by solving t,hcl balance equation and no significant differences were noted. 13arotropic fortac:tsts prepurcd from the stream functions derived from the two methods are essentially the same as forecasts with the, stro:rtn fullction obtaintd from t,he balance equation.
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