螺旋度（Helicity）.doc

螺旋度（Helicity） Horizontal spiral GS file: reinit clear Prefix.1=u; prefix.2=v Pi=3.1415926 sdfopen f:\hyx\data\ncep\uwnd.2003.nc sdfopen f:\hyx\data\ncep\vwnd.2003.nc Levstr=850700600500400300 set lon 80 110 set lat 30 50 set time 06z20jul define cr=uwnd ************************************************************************************************** I=1 While (i=9) J=1 While (j=13) Uave.i.j=0.0 Vave.i.j=0.0 K=1 While (k=5) set, LEV,subwrd (levstr, K) undefine fld define fld=uwnd.1 q, defval, FLD,32+j,48+i Nwval=subwrd (result, 3) Uave.i.j=uave.i.j+nwval undefine fld define fld=vwnd.2 q, defval, FLD,32+j,48+i Nwval=subwrd (result, 3) Vave.i.j=vave.i.j+nwval * say nwval=nwval vave.i.j=vave.i.j K=k+1 Endwhile Uave.i.j=uave.i.j/5 Vave.i.j=vave.i.j/5 If (vave.i.j, =0) Qq.i.j=math_atan (math_abs (vave.i.j/uave.i.j)) Else If (uave.i.j0) Qq.i.j=0 Endif If (uave.i.j0) Qq.i.j=pi Endif If (uave.i.j=0) Say chaos has arrised! Endif Endif If (uave.i.j=0 vave.i.j=0); qq.i.j=qq.i.j-40.0; endif; If (uave.i.j0 vave.i.j=0); qq.i.j=180-40.0-qq.i.j; endif; If (uave.i.j=0 vave.i.j=0); qq.i.j=180-40.0+qq.i.j; endif; If (uave.i.j0 vave.i.j=0); qq.i.j=270-40.0+qq.i.j; endif; * if (uave.i.j=0 vave.i.j=0); qq.i.j=qq.i.j-40.0*3.1415926/180.0; endif; * if (uave.i.j0 vave.i.j=0); qq.i.j= (180-40.0) *3.1415926/180.0-qq.i.j; endif; * if (uave.i.j=0 vave.i.j=0); qq.i.j= (180-40.0) *3.1415926/180.0+qq.i.j; endif; * if (uave.i.j0 vave.i.j=0); qq.i.j= (270-40.0) *3.1415926/180.0+qq.i.j; endif; Uave.i.j=math_sqrt (uave.i.j*uave.i.j+vave.i.j*vave.i.j) *math_cos (qq.i.j*3.1415926/180.0) *0.75 Vave.i.j=math_sqrt (uave.i.j*uave.i.j+vave.i.j*vave.i.j) *math_sin (qq.i.j*3.1415926/180.0) *0.75 * uave. I.j = math _ sqrt (uave.i.j * uave.i.j + vave.i.j * vave.i.j) * math _ cos (qq.i.j) * 0.75 * vave.i.j = math _ sqrt (uave.i.j * uave.i.j + vave.i.j * vave.i.j) * math _ sin (qq.i.j) * 0.75 J = j + 1 Endwhile I = I + 1 Endwhile * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *