_RL zref
& zref = 10.000 d0 ,
aln = log(ht/zref)
_RL zref, zwd, zth
& zref, zwd, zth,
WRITE(iUnit,*) 'BlkF: zref =',zref
zref = 10.0 _d 0
zwd = zref
zth = zref
czol = zref*xkar*gravity
rdn=xkar/(log(zref/zice))
zwln = LOG(zwd/zref)
ztln = LOG(zth/zref)