def igrf(
time: datetime,
glat: Union[np.ndarray, float],
glon: Union[np.ndarray, float],
alt_km: Union[np.ndarray, float],
isv: int = 0,
itype: int = 1,
model: int = 12,
) -> xarray.Dataset:
"""
date: datetime.date or decimal year yyyy.dddd
glat, glon: geographic Latitude, Longitude
alt_km: altitude [km] above sea level for itype==1
isv: 0 for main geomagnetic field
itype: 1: altitude is above sea level
"""
# decimal year
if isinstance(time, (str, date, datetime)):
yeardec = sciencedates.datetime2yeardec(time)
elif isinstance(time, float): # assume decimal year
yeardec = time
else:
raise TypeError(f"unknown time format {type(time)}")
colat, elon = latlon2colat(glat, glon)
assert colat.size == elon.size == 1
alt_km = np.atleast_1d(alt_km)
Bnorth = np.empty(alt_km.size)
Beast = np.empty_like(Bnorth)
Bvert = np.empty_like(Bnorth)
Btotal = np.empty_like(Bnorth)
for i, a in enumerate(alt_km):
if model == 12:
Bnorth[i], Beast[i], Bvert[i], Btotal[i] = igrf12fort.igrf12syn(
isv, yeardec, itype, a, colat, elon)
elif model == 11:
Bnorth[i], Beast[i], Bvert[i], Btotal[i] = igrf11fort.igrf11syn(
isv, yeardec, itype, a, colat, elon)
else:
raise ValueError(f"unknown IGRF model {model}")
# %% assemble output
mag = xarray.Dataset(
{
"north": ("alt_km", Bnorth),
"east": ("alt_km", Beast),
"down": ("alt_km", Bvert),
"total": ("alt_km", Btotal)
},
coords={"alt_km": alt_km},
)
decl, incl = mag_vector2incl_decl(mag.north, mag.east, mag.down)
mag["incl"] = ("alt_km", incl)
mag["decl"] = ("alt_km", decl)
return mag
def gridigrf12(
t: datetime,
glat: Union[np.ndarray, float],
glon: Union[np.ndarray, float],
alt_km: Union[np.ndarray, float],
isv: int = 0,
itype: int = 1,
) -> xarray.Dataset:
glat = np.atleast_1d(glat)
glon = np.atleast_1d(glon)
yeardec = sciencedates.datetime2yeardec(t)
colat, elon = latlon2colat(glat.ravel(), glon.ravel())
x = np.empty(colat.size)
y = np.empty_like(x)
z = np.empty_like(x)
f = np.empty_like(x)
for i, (clt, eln) in enumerate(zip(colat, elon)):
x[i], y[i], z[i], f[i] = igrf12fort.igrf12syn(isv, yeardec, itype,
alt_km, clt, eln)
# %% assemble output
if glat.ndim == 2 and glon.ndim == 2: # assume meshgrid
coords = {"glat": glat[:, 0], "glon": glon[0, :]}
elif glat.ndim == 1 and glon.ndim == 1:
coords = {"glat": glat, "glon": glon}
else:
raise ValueError(f"glat/glon shapes: {glat.shape} {glon.shape}")
mag = xarray.Dataset(coords=coords, attrs={"time": t, "isv": isv})
mag["north"] = (("glat", "glon"), x.reshape(glat.shape))
mag["east"] = (("glat", "glon"), y.reshape(glat.shape))
mag["down"] = (("glat", "glon"), z.reshape(glat.shape))
mag["total"] = (("glat", "glon"), f.reshape(glat.shape))
decl, incl = mag_vector2incl_decl(mag.north, mag.east, mag.down)
mag["incl"] = (("glat", "glon"), incl)
mag["decl"] = (("glat", "glon"), decl)
return mag