Fix land-mask creation and use transparent land overlay

se region/y=30S:30N/x=60W:20E

let ocean_mask = if LSM[d=3, l=@max] == 0 then 1

let ocean_mask = if LSM[d=3, l=@max] eq 0 then 1

let taux = IEWS[d=1] * LSM[gxy = IEWS[d=1]@asn]

let tauy = INSS[d=2] * LSM[gxy = INSS[d=2]@asn]

let taux = IEWS[d=1] * ocean_mask

let tauy = INSS[d=2] * ocean_mask

let taux_seasonal_cycle = taux[gt=month_gregorian@mod]

let tauy_seasonal_cycle = tauy[gt=month_gregorian@mod]

! plot mean wind stress

se viewp upper

vector/yskip=2/title="mean wind stress" taux[l=@ave], tauy[l=@ave]

go fland

go land

! plot wind stress anomalies (w.r.t. seasonal cycle) for a given day

set viewp lower

vector/length=3e-2/title="wind stress an. May 1982"/t="15-Mar-1982" taux_deseasoned, tauy_deseasoned

go fland

go land

frame/file="example_08_ERAIN_SFC12_MM_deseasoned_Tropical_Atlantic_wind_stress.png"