4 SUBROUTINE ustarhb(knon, u, v, cd_m, ustar)
31 REAL zxt, zxq, zxu, zxv, zxmod, taux, tauy
41 zx_alf2 = 1.0 - zx_alf1
42 zxu = u(i, 1)*zx_alf1 + u(i, 2)*zx_alf2
43 zxv = v(i, 1)*zx_alf1 + v(i, 2)*zx_alf2
44 zxmod = 1.0 + sqrt(zxu**2+zxv**2)
45 taux = zxu*zxmod*cd_m(i)
46 tauy = zxv*zxmod*cd_m(i)
47 ustar(i) = sqrt(taux**2+tauy**2)
subroutine ustarhb(knon, u, v, cd_m, ustar)