ttas=tta+gamma_blk*zref
pt=p0*(1-gamma_blk*cheaphgrid(i,j,bi,bj)/ttas)
ttas = tta+gamma_blk*(zref-ht)
t0 = ttas*(1. _d 0 + humid_fac*q)
_RL rd,re,rh,tta,ttas,toa,ttt