def _igrf_interpolate(time, notilt1967=True):
# get time as decimal year, note that epoch is completely arbitrary
years = datetime64_as_years(time)
if notilt1967 and np.abs(years - 1967.0) < 0.0006:
# OpenGGCM special no-tilt hack
# g10, g11, h11 = np.linalg.norm(IGRF[0, 1:]), 0.0, 0.0
g10, g11, h11 = -30554.00, 0.0, 0.0
else:
g10 = np.interp(years, _IGRF[:, 0], _IGRF[:, 1])
g11 = np.interp(years, _IGRF[:, 0], _IGRF[:, 2])
h11 = np.interp(years, _IGRF[:, 0], _IGRF[:, 3])
return g10, g11, h11
def _igrf_interpolate(time, notilt1967=True):
# get time as decimal year, note that epoch is completely arbitrary
years = datetime64_as_years(time)
if notilt1967 and np.abs(years - 1967.0) < 0.0006:
# OpenGGCM special no-tilt hack
# g10, g11, h11 = np.linalg.norm(IGRF[0, 1:]), 0.0, 0.0
g10, g11, h11 = -30554.00, 0.0, 0.0
else:
g10 = np.interp(years, _IGRF[:, 0], _IGRF[:, 1])
g11 = np.interp(years, _IGRF[:, 0], _IGRF[:, 2])
h11 = np.interp(years, _IGRF[:, 0], _IGRF[:, 3])
return g10, g11, h11
def __init__(self, time='1967-01-01', dip_tilt=None, dip_gsm=None, rdim=3,
notilt1967=True):
"""Construct Cotr instance
Args:
time (datetime-like): A specific date and time for the
transformations (sets earth's geographic and dipole
orientations)
rdim (int): Dimensionality of rotation matrices
dip_tilt (float): if given, override the dipole tilt angle
(mu in degrees, positive points north pole sunward)
dip_gsm (float): if given, override the dipole gse->gsm
angle (psi in degrees, positive points north pole
duskward)
notilt1967 (bool): if True, then all transforms (except
<->mhd transforms) are set to the identity. This is
the special OpenGGCM no-dipole-tilt-time.
"""
self._emat_cache = dict()
self._xform_cache = dict()
# exact UT time of interest
time = as_datetime64(time)
self.time = time
# dimension of rotation matrices (3 or 4), use 4 to support
# translations
self.rdim = rdim
# modified julian date is days from 00:00UT on 17 Nov 1858
mjd0 = as_datetime64('1858-11-17T00:00:00.0')
mjd_td = as_timedelta(time.astype(mjd0.dtype) - mjd0)
self.mjd = mjd_td.total_seconds() // (24 * 3600)
# ut is hours from midnight
dt = as_datetime(time)
day = as_datetime64("{0:04d}-{1:02d}-{2:02d}"
"".format(dt.year, dt.month, dt.day))
secs = as_timedelta(time - day.astype(time.dtype)).total_seconds()
self.ut = secs / 3600.0
# julian centuries (36525 days) since 1 Jan 2000 (epoch 2000)
self.t0 = (self.mjd - 51544.5) / 36525.0
# interpolated IGRF
g10, g11, h11 = _igrf_interpolate(self.time, notilt1967=notilt1967)
self.g10 = g10
self.g11 = g11
self.h11 = h11
self._disable_mag_crds = dip_tilt is not None or dip_gsm is not None
years = datetime64_as_years(time)
notilt = notilt1967 and np.abs(years - 1967.0) < 0.0006
if self._disable_mag_crds or notilt:
dip_tilt = 0.0 if dip_tilt is None else dip_tilt
dip_gsm = 0.0 if dip_gsm is None else dip_gsm
self._cached_sun_ecliptic_longitude = None
self._cached_q_g = None
self._cached_q_e = None
self._cached_dip_geolon_rad = None
self._cached_dip_geolat_rad = None
self._cached_dip_tilt = dip_tilt
self._cached_dip_gsm = dip_gsm
# hack the cache to set all geocentric transforms to the identity
# except GSE -> MHD
if notilt:
eye = np.eye(self.rdim)
# matrices 3, 4, and 6 are missing so that gse, gsm, sm, mhd
# transformations still do something (from dip_tilt and dip_gsm)
for i in (1, 2, 5):
self._emat_cache[-i] = eye
self._emat_cache[i] = eye
def __init__(self,
time='1967-01-01',
dip_tilt=None,
dip_gsm=None,
rdim=3,
notilt1967=True):
"""Construct Cotr instance
Args:
time (datetime-like): A specific date and time for the
transformations (sets earth's geographic and dipole
orientations)
rdim (int): Dimensionality of rotation matrices
dip_tilt (float): if given, override the dipole tilt angle
(mu in degrees, positive points north pole sunward)
dip_gsm (float): if given, override the dipole gse->gsm
angle (psi in degrees, positive points north pole
duskward)
notilt1967 (bool): if True, then all transforms (except
<->mhd transforms) are set to the identity if time is
Jan 1 1967. This is the special OpenGGCM
no-dipole-tilt-time.
"""
self._emat_cache = dict()
self._xform_cache = dict()
# exact UT time of interest
time = as_datetime64(time)
self.time = time
# dimension of rotation matrices (3 or 4), use 4 to support
# translations
self.rdim = rdim
# modified julian date is days from 00:00UT on 17 Nov 1858
mjd0 = as_datetime64('1858-11-17T00:00:00.0')
mjd_td = as_timedelta(time.astype(mjd0.dtype) - mjd0)
self.mjd = mjd_td.total_seconds() // (24 * 3600)
# ut is hours from midnight
dt = as_datetime(time)
day = as_datetime64("{0:04d}-{1:02d}-{2:02d}"
"".format(dt.year, dt.month, dt.day))
secs = as_timedelta(time - day.astype(time.dtype)).total_seconds()
self.ut = secs / 3600.0
# julian centuries (36525 days) since 1 Jan 2000 (epoch 2000)
self.t0 = (self.mjd - 51544.5) / 36525.0
# interpolated IGRF
g10, g11, h11 = _igrf_interpolate(self.time, notilt1967=notilt1967)
self.g10 = g10
self.g11 = g11
self.h11 = h11
self._disable_mag_crds = dip_tilt is not None or dip_gsm is not None
years = datetime64_as_years(time)
notilt = notilt1967 and np.abs(years - 1967.0) < 0.0006
# do i really want the self._disable_mag_crds part of this? what
# if i want dip_gsm set by the time, and dip_tilt set by hand...
# would anyone ever want that? is it really more natural to say that
# if you specify dip_tilt or dip_gsm then both ignore the time?
if self._disable_mag_crds or notilt:
dip_tilt = 0.0 if dip_tilt is None else dip_tilt
dip_gsm = 0.0 if dip_gsm is None else dip_gsm
self._cached_sun_ecliptic_longitude = None
self._cached_q_g = None
self._cached_q_e = None
self._cached_dip_geolon_rad = None
self._cached_dip_geolat_rad = None
self._cached_dip_tilt = dip_tilt
self._cached_dip_gsm = dip_gsm
# hack the cache to set all geocentric transforms to the identity
# except GSE -> MHD
if notilt:
eye = np.eye(self.rdim)
# matrices 3, 4, and 6 are missing so that gse, gsm, sm, mhd
# transformations still do something (from dip_tilt and dip_gsm)
for i in (1, 2, 5):
self._emat_cache[-i] = eye
self._emat_cache[i] = eye
