_RL ztln ! = log(zth/zref)
ztln = LOG(ht/zref)
rh = rhn/(exf_one + rhn*(ztln-psixh)/karman)
re = ren/(exf_one + ren*(ztln-psixh)/karman)
rh(i,j)= rhn/( exf_one + rhn*(ztln-psixh)/karman )
re(i,j)= ren/( exf_one + ren*(ztln-psixh)/karman )
ztln = LOG(zth/zref)
rh = rhn/(1. _d 0 + rhn*(ztln-psixh)/xkar)
re = ren/(1. _d 0 + ren*(ztln-psixh)/xkar)