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# -*- coding: utf-8 -*- |
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from __future__ import division, print_function, absolute_import |
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import os |
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import warnings |
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import datetime as dt |
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import numpy as np |
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from . import helpers |
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# below try..catch required for autodoc to work on readthedocs |
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try: |
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from . import fortranapex as fa |
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except: |
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print("ERROR: fortranapex module could not be imported. apexpy probably" |
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" won't work") |
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# make sure invalid warnings are always shown |
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warnings.filterwarnings('always', message='.*set to -9999 where*', |
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module='apexpy.apex') |
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class ApexHeightError(ValueError): |
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pass |
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class Apex(object): |
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"""Performs coordinate conversions, field-line mapping and base vector |
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calculations. |
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Parameters |
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========== |
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date : float, :class:`dt.date`, or :class:`dt.datetime`, optional |
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Determines which IGRF coefficients are used in conversions. Uses |
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current date as default. If float, use decimal year. |
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refh : float, optional |
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Reference height in km for apex coordinates (the field lines are mapped |
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to this height) |
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datafile : str, optional |
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Path to custom coefficient file |
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Attributes |
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========== |
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year : float |
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Decimal year used for the IGRF model |
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refh : float |
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Reference height in km for apex coordinates |
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datafile : str |
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Path to coefficient file |
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Notes |
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===== |
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The calculations use IGRF-12 with coefficients from 1900 to 2020 [1]_. |
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References |
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========== |
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.. [1] Thébault, E. et al. (2015), International Geomagnetic Reference |
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Field: the 12th generation, Earth, Planets and Space, 67(1), 79, |
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:doi:`10.1186/s40623-015-0228-9`. |
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""" |
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def __init__(self, date=None, refh=0, datafile=None): |
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if datafile is None: |
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datafile = os.path.join(os.path.dirname(__file__), 'apexsh.dat') |
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self.RE = 6371.009 # mean Earth radius |
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self.set_refh(refh) # reference height |
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if date is None: |
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self.year = helpers.toYearFraction(dt.datetime.now()) |
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else: |
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try: |
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# convert date/datetime object to decimal year |
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self.year = helpers.toYearFraction(date) |
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except: |
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# failed so date is probably int/float, use directly |
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self.year = date |
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if not os.path.isfile(datafile): |
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raise IOError('Datafile does not exist: {}'.format(datafile)) |
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self.datafile = datafile |
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self.set_epoch(self.year) |
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# vectorize fortran functions |
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self._geo2qd = np.frompyfunc( |
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lambda glat, glon, height: fa.apxg2q(glat, (glon + 180) % 360 - 180, |
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height, 0)[:2], 3, 2) |
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self._geo2apex = np.frompyfunc( |
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lambda glat, glon, height: fa.apxg2all(glat, (glon + 180) % 360 - |
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180, height, self.refh, |
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0)[2:4], 3, 2) |
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self._geo2apexall = np.frompyfunc( |
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lambda glat, glon, height: fa.apxg2all(glat, (glon + 180) % 360 - |
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180, height, self.refh, |
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1), 3, 14) |
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self._qd2geo = np.frompyfunc( |
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lambda qlat, qlon, height, precision: fa.apxq2g(qlat, (qlon + 180) |
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% 360 - 180, height, |
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precision), 4, 3) |
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self._basevec = np.frompyfunc( |
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lambda glat, glon, height: fa.apxg2q(glat, (glon + 180) % 360 - 180, |
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height, 1)[2:4], 3, 2) |
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# vectorize other nonvectorized functions |
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self._apex2qd = np.frompyfunc(self._apex2qd_nonvectorized, 3, 2) |
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self._qd2apex = np.frompyfunc(self._qd2apex_nonvectorized, 3, 2) |
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def convert(self, lat, lon, source, dest, height=0, datetime=None, |
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precision=1e-10, ssheight=50*6371): |
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"""Converts between geodetic, modified apex, quasi-dipole and MLT. |
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Parameters |
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========== |
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lat : array_like |
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Latitude |
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lon : array_like |
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Longitude/MLT |
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source : {'geo', 'apex', 'qd', 'mlt'} |
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Input coordinate system |
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dest : {'geo', 'apex', 'qd', 'mlt'} |
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Output coordinate system |
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height : array_like, optional |
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Altitude in km |
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datetime : :class:`datetime.datetime` |
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Date and time for MLT conversions (required for MLT conversions) |
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precision : float, optional |
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Precision of output (degrees) when converting to geo. A negative |
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value of this argument produces a low-precision calculation of |
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geodetic lat/lon based only on their spherical harmonic |
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representation. |
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A positive value causes the underlying Fortran routine to iterate |
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until feeding the output geo lat/lon into geo2qd (APXG2Q) reproduces |
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the input QD lat/lon to within the specified precision (all |
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coordinates being converted to geo are converted to QD first and |
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passed through APXG2Q). |
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ssheight : float, optional |
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Altitude in km to use for converting the subsolar point from |
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geographic to magnetic coordinates. A high altitude is used |
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to ensure the subsolar point is mapped to high latitudes, which |
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prevents the South-Atlantic Anomaly (SAA) from influencing the MLT. |
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Returns |
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======= |
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lat : ndarray or float |
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Converted latitude (if converting to MLT, output latitude is apex) |
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lat : ndarray or float |
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Converted longitude/MLT |
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""" |
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if datetime is None and ('mlt' in [source, dest]): |
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raise ValueError('datetime must be given for MLT calculations') |
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lat = helpers.checklat(lat) |
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if source == dest: |
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return lat, lon |
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# from geo |
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elif source == 'geo' and dest == 'apex': |
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lat, lon = self.geo2apex(lat, lon, height) |
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elif source == 'geo' and dest == 'qd': |
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lat, lon = self.geo2qd(lat, lon, height) |
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elif source == 'geo' and dest == 'mlt': |
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lat, lon = self.geo2apex(lat, lon, height) |
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lon = self.mlon2mlt(lon, datetime, ssheight=ssheight) |
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# from apex |
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elif source == 'apex' and dest == 'geo': |
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lat, lon, _ = self.apex2geo(lat, lon, height, precision=precision) |
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elif source == 'apex' and dest == 'qd': |
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lat, lon = self.apex2qd(lat, lon, height=height) |
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elif source == 'apex' and dest == 'mlt': |
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lon = self.mlon2mlt(lon, datetime, ssheight=ssheight) |
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# from qd |
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elif source == 'qd' and dest == 'geo': |
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lat, lon, _ = self.qd2geo(lat, lon, height, precision=precision) |
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elif source == 'qd' and dest == 'apex': |
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lat, lon = self.qd2apex(lat, lon, height=height) |
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elif source == 'qd' and dest == 'mlt': |
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lat, lon = self.qd2apex(lat, lon, height=height) |
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lon = self.mlon2mlt(lon, datetime, ssheight=ssheight) |
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# from mlt (input latitude assumed apex) |
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elif source == 'mlt' and dest == 'geo': |
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lon = self.mlt2mlon(lon, datetime, ssheight=ssheight) |
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lat, lon, _ = self.apex2geo(lat, lon, height, precision=precision) |
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elif source == 'mlt' and dest == 'apex': |
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lon = self.mlt2mlon(lon, datetime, ssheight=ssheight) |
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elif source == 'mlt' and dest == 'qd': |
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lon = self.mlt2mlon(lon, datetime, ssheight=ssheight) |
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lat, lon = self.apex2qd(lat, lon, height=height) |
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# no other transformations are implemented |
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else: |
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estr = 'Unknown coordinate transformation: ' |
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estr += '{} -> {}'.format(source, dest) |
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raise NotImplementedError(estr) |
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return lat, lon |
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def geo2apex(self, glat, glon, height): |
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"""Converts geodetic to modified apex coordinates. |
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Parameters |
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========== |
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glat : array_like |
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Geodetic latitude |
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glon : array_like |
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Geodetic longitude |
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height : array_like |
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Altitude in km |
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Returns |
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======= |
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alat : ndarray or float |
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Modified apex latitude |
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alon : ndarray or float |
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Modified apex longitude |
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""" |
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glat = helpers.checklat(glat, name='glat') |
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alat, alon = self._geo2apex(glat, glon, height) |
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if np.any(np.float64(alat) == -9999): |
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warnings.warn('Apex latitude set to -9999 where undefined ' |
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'(apex height may be < reference height)') |
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# if array is returned, dtype is object, so convert to float |
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return np.float64(alat), np.float64(alon) |
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def apex2geo(self, alat, alon, height, precision=1e-10): |
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"""Converts modified apex to geodetic coordinates. |
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Parameters |
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========== |
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alat : array_like |
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Modified apex latitude |
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alon : array_like |
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Modified apex longitude |
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height : array_like |
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Altitude in km |
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precision : float, optional |
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Precision of output (degrees). A negative value of this argument |
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produces a low-precision calculation of geodetic lat/lon based only |
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on their spherical harmonic representation. A positive value causes |
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the underlying Fortran routine to iterate until feeding the output |
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geo lat/lon into geo2qd (APXG2Q) reproduces the input QD lat/lon to |
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within the specified precision. |
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Returns |
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======= |
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glat : ndarray or float |
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Geodetic latitude |
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glon : ndarray or float |
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Geodetic longitude |
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error : ndarray or float |
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The angular difference (degrees) between the input QD coordinates |
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and the qlat/qlon produced by feeding the output glat and glon |
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into geo2qd (APXG2Q) |
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""" |
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alat = helpers.checklat(alat, name='alat') |
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qlat, qlon = self.apex2qd(alat, alon, height=height) |
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glat, glon, error = self.qd2geo(qlat, qlon, height, precision=precision) |
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return glat, glon, error |
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def geo2qd(self, glat, glon, height): |
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"""Converts geodetic to quasi-dipole coordinates. |
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Parameters |
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========== |
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glat : array_like |
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Geodetic latitude |
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glon : array_like |
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Geodetic longitude |
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height : array_like |
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Altitude in km |
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Returns |
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======= |
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qlat : ndarray or float |
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Quasi-dipole latitude |
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qlon : ndarray or float |
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Quasi-dipole longitude |
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""" |
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glat = helpers.checklat(glat, name='glat') |
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qlat, qlon = self._geo2qd(glat, glon, height) |
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# if array is returned, dtype is object, so convert to float |
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return np.float64(qlat), np.float64(qlon) |
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304
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def qd2geo(self, qlat, qlon, height, precision=1e-10): |
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"""Converts quasi-dipole to geodetic coordinates. |
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306
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307
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Parameters |
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308
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========== |
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309
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qlat : array_like |
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310
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Quasi-dipole latitude |
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311
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qlon : array_like |
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312
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Quasi-dipole longitude |
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313
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height : array_like |
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314
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Altitude in km |
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315
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precision : float, optional |
|
316
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|
|
Precision of output (degrees). A negative value of this argument |
|
317
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|
|
produces a low-precision calculation of geodetic lat/lon based only |
|
318
|
|
|
on their spherical harmonic representation. A positive value causes |
|
319
|
|
|
the underlying Fortran routine to iterate until feeding the output |
|
320
|
|
|
geo lat/lon into geo2qd (APXG2Q) reproduces the input QD lat/lon to |
|
321
|
|
|
within the specified precision. |
|
322
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|
323
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Returns |
|
324
|
|
|
======= |
|
325
|
|
|
glat : ndarray or float |
|
326
|
|
|
Geodetic latitude |
|
327
|
|
|
glon : ndarray or float |
|
328
|
|
|
Geodetic longitude |
|
329
|
|
|
error : ndarray or float |
|
330
|
|
|
The angular difference (degrees) between the input QD coordinates |
|
331
|
|
|
and the qlat/qlon produced by feeding the output glat and glon |
|
332
|
|
|
into geo2qd (APXG2Q) |
|
333
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334
|
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""" |
|
335
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336
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qlat = helpers.checklat(qlat, name='qlat') |
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337
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338
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glat, glon, error = self._qd2geo(qlat, qlon, height, precision) |
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339
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340
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# if array is returned, dtype is object, so convert to float |
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341
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return np.float64(glat), np.float64(glon), np.float64(error) |
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342
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343
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View Code Duplication |
def _apex2qd_nonvectorized(self, alat, alon, height): |
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344
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"""Convert from apex to quasi-dipole (not-vectorised) |
|
345
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346
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Parameters |
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347
|
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----------- |
|
348
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|
alat : (float) |
|
349
|
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|
Apex latitude in degrees |
|
350
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|
alon : (float) |
|
351
|
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|
Apex longitude in degrees |
|
352
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height : (float) |
|
353
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|
Height in km |
|
354
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|
|
355
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Returns |
|
356
|
|
|
--------- |
|
357
|
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|
qlat : (float) |
|
358
|
|
|
Quasi-dipole latitude in degrees |
|
359
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|
|
qlon : (float) |
|
360
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|
Quasi-diplole longitude in degrees |
|
361
|
|
|
""" |
|
362
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|
363
|
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|
alat = helpers.checklat(alat, name='alat') |
|
364
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|
365
|
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# convert modified apex to quasi-dipole: |
|
366
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|
qlon = alon |
|
367
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|
|
368
|
|
|
# apex height |
|
369
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|
|
hA = self.get_apex(alat) |
|
370
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|
|
371
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if hA < height: |
|
372
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|
|
if np.isclose(hA, height, rtol=0, atol=1e-5): |
|
373
|
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|
# allow for values that are close |
|
374
|
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|
hA = height |
|
375
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|
else: |
|
376
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|
estr = 'height {:.3g} is > apex height '.format(np.max(height)) |
|
377
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|
estr += '{:.3g} for alat {:.3g}'.format(hA, alat) |
|
378
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|
|
raise ApexHeightError(estr) |
|
379
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|
380
|
|
|
qlat = np.sign(alat) * np.degrees(np.arccos(np.sqrt((self.RE + height) / |
|
381
|
|
|
(self.RE + hA)))) |
|
382
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|
383
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|
|
return qlat, qlon |
|
384
|
|
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|
385
|
|
|
def apex2qd(self, alat, alon, height): |
|
386
|
|
|
"""Converts modified apex to quasi-dipole coordinates. |
|
387
|
|
|
|
|
388
|
|
|
Parameters |
|
389
|
|
|
========== |
|
390
|
|
|
alat : array_like |
|
391
|
|
|
Modified apex latitude |
|
392
|
|
|
alon : array_like |
|
393
|
|
|
Modified apex longitude |
|
394
|
|
|
height : array_like |
|
395
|
|
|
Altitude in km |
|
396
|
|
|
|
|
397
|
|
|
Returns |
|
398
|
|
|
======= |
|
399
|
|
|
qlat : ndarray or float |
|
400
|
|
|
Quasi-dipole latitude |
|
401
|
|
|
qlon : ndarray or float |
|
402
|
|
|
Quasi-dipole longitude |
|
403
|
|
|
|
|
404
|
|
|
Raises |
|
405
|
|
|
====== |
|
406
|
|
|
ApexHeightError |
|
407
|
|
|
if `height` > apex height |
|
408
|
|
|
|
|
409
|
|
|
""" |
|
410
|
|
|
|
|
411
|
|
|
qlat, qlon = self._apex2qd(alat, alon, height) |
|
412
|
|
|
|
|
413
|
|
|
# if array is returned, the dtype is object, so convert to float |
|
414
|
|
|
return np.float64(qlat), np.float64(qlon) |
|
415
|
|
|
|
|
416
|
|
View Code Duplication |
def _qd2apex_nonvectorized(self, qlat, qlon, height): |
|
|
|
|
|
|
417
|
|
|
|
|
418
|
|
|
qlat = helpers.checklat(qlat, name='qlat') |
|
419
|
|
|
|
|
420
|
|
|
alon = qlon |
|
421
|
|
|
hA = self.get_apex(qlat, height) # apex height |
|
422
|
|
|
|
|
423
|
|
|
if hA < self.refh: |
|
424
|
|
|
if np.isclose(hA, self.refh, rtol=0, atol=1e-5): |
|
425
|
|
|
# allow for values that are close |
|
426
|
|
|
hA = self.refh |
|
427
|
|
|
else: |
|
428
|
|
|
estr = 'apex height ({:.3g}) is < reference height '.format(hA) |
|
429
|
|
|
estr += '({:.3g}) for qlat {:.3g}'.format(self.refh, qlat) |
|
430
|
|
|
raise ApexHeightError(estr) |
|
431
|
|
|
|
|
432
|
|
|
alat = np.sign(qlat) * np.degrees(np.arccos(np.sqrt((self.RE + |
|
433
|
|
|
self.refh) / |
|
434
|
|
|
(self.RE + hA)))) |
|
435
|
|
|
|
|
436
|
|
|
return alat, alon |
|
437
|
|
|
|
|
438
|
|
|
def qd2apex(self, qlat, qlon, height): |
|
439
|
|
|
"""Converts quasi-dipole to modified apex coordinates. |
|
440
|
|
|
|
|
441
|
|
|
Parameters |
|
442
|
|
|
========== |
|
443
|
|
|
qlat : array_like |
|
444
|
|
|
Quasi-dipole latitude |
|
445
|
|
|
qlon : array_like |
|
446
|
|
|
Quasi-dipole longitude |
|
447
|
|
|
height : array_like |
|
448
|
|
|
Altitude in km |
|
449
|
|
|
|
|
450
|
|
|
Returns |
|
451
|
|
|
======= |
|
452
|
|
|
alat : ndarray or float |
|
453
|
|
|
Modified apex latitude |
|
454
|
|
|
alon : ndarray or float |
|
455
|
|
|
Modified apex longitude |
|
456
|
|
|
|
|
457
|
|
|
Raises |
|
458
|
|
|
====== |
|
459
|
|
|
ApexHeightError |
|
460
|
|
|
if apex height < reference height |
|
461
|
|
|
|
|
462
|
|
|
""" |
|
463
|
|
|
|
|
464
|
|
|
alat, alon = self._qd2apex(qlat, qlon, height) |
|
465
|
|
|
|
|
466
|
|
|
# if array is returned, the dtype is object, so convert to float |
|
467
|
|
|
return np.float64(alat), np.float64(alon) |
|
468
|
|
|
|
|
469
|
|
|
def mlon2mlt(self, mlon, datetime, ssheight=50*6371): |
|
470
|
|
|
"""Computes the magnetic local time at the specified magnetic longitude |
|
471
|
|
|
and UT. |
|
472
|
|
|
|
|
473
|
|
|
Parameters |
|
474
|
|
|
========== |
|
475
|
|
|
mlon : array_like |
|
476
|
|
|
Magnetic longitude (apex and quasi-dipole longitude are always |
|
477
|
|
|
equal) |
|
478
|
|
|
datetime : :class:`datetime.datetime` |
|
479
|
|
|
Date and time |
|
480
|
|
|
ssheight : float, optional |
|
481
|
|
|
Altitude in km to use for converting the subsolar point from |
|
482
|
|
|
geographic to magnetic coordinates. A high altitude is used |
|
483
|
|
|
to ensure the subsolar point is mapped to high latitudes, which |
|
484
|
|
|
prevents the South-Atlantic Anomaly (SAA) from influencing the MLT. |
|
485
|
|
|
|
|
486
|
|
|
Returns |
|
487
|
|
|
======= |
|
488
|
|
|
mlt : ndarray or float |
|
489
|
|
|
Magnetic local time [0, 24) |
|
490
|
|
|
|
|
491
|
|
|
Notes |
|
492
|
|
|
===== |
|
493
|
|
|
To compute the MLT, we find the apex longitude of the subsolar point at |
|
494
|
|
|
the given time. Then the MLT of the given point will be computed from |
|
495
|
|
|
the separation in magnetic longitude from this point (1 hour = 15 |
|
496
|
|
|
degrees). |
|
497
|
|
|
|
|
498
|
|
|
""" |
|
499
|
|
|
ssglat, ssglon = helpers.subsol(datetime) |
|
500
|
|
|
ssalat, ssalon = self.geo2apex(ssglat, ssglon, ssheight) |
|
501
|
|
|
|
|
502
|
|
|
# np.float64 will ensure lists are converted to arrays |
|
503
|
|
|
return (180 + np.float64(mlon) - ssalon)/15 % 24 |
|
504
|
|
|
|
|
505
|
|
|
def mlt2mlon(self, mlt, datetime, ssheight=50*6371): |
|
506
|
|
|
"""Computes the magnetic longitude at the specified magnetic local time |
|
507
|
|
|
and UT. |
|
508
|
|
|
|
|
509
|
|
|
Parameters |
|
510
|
|
|
========== |
|
511
|
|
|
mlt : array_like |
|
512
|
|
|
Magnetic local time |
|
513
|
|
|
datetime : :class:`datetime.datetime` |
|
514
|
|
|
Date and time |
|
515
|
|
|
ssheight : float, optional |
|
516
|
|
|
Altitude in km to use for converting the subsolar point from |
|
517
|
|
|
geographic to magnetic coordinates. A high altitude is used |
|
518
|
|
|
to ensure the subsolar point is mapped to high latitudes, which |
|
519
|
|
|
prevents the South-Atlantic Anomaly (SAA) from influencing the MLT. |
|
520
|
|
|
|
|
521
|
|
|
Returns |
|
522
|
|
|
======= |
|
523
|
|
|
mlon : ndarray or float |
|
524
|
|
|
Magnetic longitude [0, 360) (apex and quasi-dipole longitude are |
|
525
|
|
|
always equal) |
|
526
|
|
|
|
|
527
|
|
|
Notes |
|
528
|
|
|
===== |
|
529
|
|
|
To compute the magnetic longitude, we find the apex longitude of the |
|
530
|
|
|
subsolar point at the given time. Then the magnetic longitude of the |
|
531
|
|
|
given point will be computed from the separation in magnetic local time |
|
532
|
|
|
from this point (1 hour = 15 degrees). |
|
533
|
|
|
""" |
|
534
|
|
|
|
|
535
|
|
|
ssglat, ssglon = helpers.subsol(datetime) |
|
536
|
|
|
ssalat, ssalon = self.geo2apex(ssglat, ssglon, ssheight) |
|
537
|
|
|
|
|
538
|
|
|
# np.float64 will ensure lists are converted to arrays |
|
539
|
|
|
return (15*np.float64(mlt) - 180 + ssalon + 360) % 360 |
|
540
|
|
|
|
|
541
|
|
|
def map_to_height(self, glat, glon, height, newheight, conjugate=False, |
|
542
|
|
|
precision=1e-10): |
|
543
|
|
|
"""Performs mapping of points along the magnetic field to the closest |
|
544
|
|
|
or conjugate hemisphere. |
|
545
|
|
|
|
|
546
|
|
|
Parameters |
|
547
|
|
|
========== |
|
548
|
|
|
glat : array_like |
|
549
|
|
|
Geodetic latitude |
|
550
|
|
|
glon : array_like |
|
551
|
|
|
Geodetic longitude |
|
552
|
|
|
height : array_like |
|
553
|
|
|
Source altitude in km |
|
554
|
|
|
newheight : array_like |
|
555
|
|
|
Destination altitude in km |
|
556
|
|
|
conjugate : bool, optional |
|
557
|
|
|
Map to `newheight` in the conjugate hemisphere instead of the |
|
558
|
|
|
closest hemisphere |
|
559
|
|
|
precision : float, optional |
|
560
|
|
|
Precision of output (degrees). A negative value of this argument |
|
561
|
|
|
produces a low-precision calculation of geodetic lat/lon based only |
|
562
|
|
|
on their spherical harmonic representation. A positive value causes |
|
563
|
|
|
the underlying Fortran routine to iterate until feeding the output |
|
564
|
|
|
geo lat/lon into geo2qd (APXG2Q) reproduces the input QD lat/lon to |
|
565
|
|
|
within the specified precision. |
|
566
|
|
|
|
|
567
|
|
|
Returns |
|
568
|
|
|
======= |
|
569
|
|
|
newglat : ndarray or float |
|
570
|
|
|
Geodetic latitude of mapped point |
|
571
|
|
|
newglon : ndarray or float |
|
572
|
|
|
Geodetic longitude of mapped point |
|
573
|
|
|
error : ndarray or float |
|
574
|
|
|
The angular difference (degrees) between the input QD coordinates |
|
575
|
|
|
and the qlat/qlon produced by feeding the output glat and glon |
|
576
|
|
|
into geo2qd (APXG2Q) |
|
577
|
|
|
|
|
578
|
|
|
Notes |
|
579
|
|
|
===== |
|
580
|
|
|
The mapping is done by converting glat/glon/height to modified apex |
|
581
|
|
|
lat/lon, and converting back to geographic using newheight (if |
|
582
|
|
|
conjugate, use negative apex latitude when converting back) |
|
583
|
|
|
|
|
584
|
|
|
""" |
|
585
|
|
|
|
|
586
|
|
|
alat, alon = self.geo2apex(glat, glon, height) |
|
587
|
|
|
if conjugate: |
|
588
|
|
|
alat = -alat |
|
589
|
|
|
try: |
|
590
|
|
|
newglat, newglon, error = self.apex2geo(alat, alon, newheight, |
|
591
|
|
|
precision=precision) |
|
592
|
|
|
except ApexHeightError: |
|
593
|
|
|
raise ApexHeightError("newheight is > apex height") |
|
594
|
|
|
|
|
595
|
|
|
return newglat, newglon, error |
|
596
|
|
|
|
|
597
|
|
|
def _map_EV_to_height(self, alat, alon, height, newheight, X, EV): |
|
598
|
|
|
|
|
599
|
|
|
# make sure X is array of correct shape |
|
600
|
|
|
if(not (np.ndim(X) == 1 and np.size(X) == 3) and |
|
601
|
|
|
not (np.ndim(X) == 2 and np.shape(X)[0] == 3)): |
|
602
|
|
|
# raise ValueError because if passing e.g. a (6,) ndarray the |
|
603
|
|
|
# reshape below will work even though the input is invalid |
|
604
|
|
|
raise ValueError(EV + ' must be (3, N) or (3,) ndarray') |
|
605
|
|
|
X = np.reshape(X, (3, np.size(X)//3)) |
|
606
|
|
|
|
|
607
|
|
|
_, _, _, _, _, _, d1, d2, _, e1, e2, _ = self.basevectors_apex(alat, \ |
|
608
|
|
|
alon, height, coords='apex') |
|
609
|
|
|
|
|
610
|
|
|
if EV == 'E': |
|
611
|
|
|
v1 = e1 |
|
612
|
|
|
v2 = e2 |
|
613
|
|
|
else: |
|
614
|
|
|
v1 = d1 |
|
615
|
|
|
v2 = d2 |
|
616
|
|
|
|
|
617
|
|
|
# make sure v1 and v2 have shape (3, N) |
|
618
|
|
|
v1 = np.reshape(v1, (3, v1.size//3)) |
|
619
|
|
|
v2 = np.reshape(v2, (3, v2.size//3)) |
|
620
|
|
|
|
|
621
|
|
|
X1 = np.sum(X*v1, axis=0) # E dot e1 or V dot d1 |
|
622
|
|
|
X2 = np.sum(X*v2, axis=0) # E dot e2 or V dot d2 |
|
623
|
|
|
|
|
624
|
|
|
_, _, _, _, _, _, d1, d2, _, e1, e2, _ = self.basevectors_apex(alat, \ |
|
625
|
|
|
alon, newheight, coords='apex') |
|
626
|
|
|
|
|
627
|
|
|
if EV == 'E': |
|
628
|
|
|
v1 = d1 |
|
629
|
|
|
v2 = d2 |
|
630
|
|
|
else: |
|
631
|
|
|
v1 = e1 |
|
632
|
|
|
v2 = e2 |
|
633
|
|
|
|
|
634
|
|
|
# make sure v1 and v2 have shape (3, N) |
|
635
|
|
|
v1 = np.reshape(v1, (3, v1.size//3)) |
|
636
|
|
|
v2 = np.reshape(v2, (3, v2.size//3)) |
|
637
|
|
|
|
|
638
|
|
|
X_mapped = X1[np.newaxis, :]*v1 + X2[np.newaxis, :]*v2 |
|
639
|
|
|
|
|
640
|
|
|
return np.squeeze(X_mapped) |
|
641
|
|
|
|
|
642
|
|
|
def map_E_to_height(self, alat, alon, height, newheight, E): |
|
643
|
|
|
"""Performs mapping of electric field along the magnetic field. |
|
644
|
|
|
|
|
645
|
|
|
It is assumed that the electric field is perpendicular to B. |
|
646
|
|
|
|
|
647
|
|
|
Parameters |
|
648
|
|
|
========== |
|
649
|
|
|
alat : (N,) array_like or float |
|
650
|
|
|
Modified apex latitude |
|
651
|
|
|
alon : (N,) array_like or float |
|
652
|
|
|
Modified apex longitude |
|
653
|
|
|
height : (N,) array_like or float |
|
654
|
|
|
Source altitude in km |
|
655
|
|
|
newheight : (N,) array_like or float |
|
656
|
|
|
Destination altitude in km |
|
657
|
|
|
E : (3,) or (3, N) array_like |
|
658
|
|
|
Electric field (at `alat`, `alon`, `height`) in geodetic east, |
|
659
|
|
|
north, and up components |
|
660
|
|
|
|
|
661
|
|
|
Returns |
|
662
|
|
|
======= |
|
663
|
|
|
E : (3, N) or (3,) ndarray |
|
664
|
|
|
The electric field at `newheight` (geodetic east, north, and up |
|
665
|
|
|
components) |
|
666
|
|
|
|
|
667
|
|
|
""" |
|
668
|
|
|
|
|
669
|
|
|
return self._map_EV_to_height(alat, alon, height, newheight, E, 'E') |
|
670
|
|
|
|
|
671
|
|
|
def map_V_to_height(self, alat, alon, height, newheight, V): |
|
672
|
|
|
"""Performs mapping of electric drift velocity along the magnetic field. |
|
673
|
|
|
|
|
674
|
|
|
It is assumed that the electric field is perpendicular to B. |
|
675
|
|
|
|
|
676
|
|
|
Parameters |
|
677
|
|
|
========== |
|
678
|
|
|
alat : (N,) array_like or float |
|
679
|
|
|
Modified apex latitude |
|
680
|
|
|
alon : (N,) array_like or float |
|
681
|
|
|
Modified apex longitude |
|
682
|
|
|
height : (N,) array_like or float |
|
683
|
|
|
Source altitude in km |
|
684
|
|
|
newheight : (N,) array_like or float |
|
685
|
|
|
Destination altitude in km |
|
686
|
|
|
V : (3,) or (3, N) array_like |
|
687
|
|
|
Electric drift velocity (at `alat`, `alon`, `height`) in geodetic |
|
688
|
|
|
east, north, and up components |
|
689
|
|
|
|
|
690
|
|
|
Returns |
|
691
|
|
|
======= |
|
692
|
|
|
V : (3, N) or (3,) ndarray |
|
693
|
|
|
The electric drift velocity at `newheight` (geodetic east, north, |
|
694
|
|
|
and up components) |
|
695
|
|
|
|
|
696
|
|
|
""" |
|
697
|
|
|
|
|
698
|
|
|
return self._map_EV_to_height(alat, alon, height, newheight, V, 'V') |
|
699
|
|
|
|
|
700
|
|
|
def basevectors_qd(self, lat, lon, height, coords='geo', precision=1e-10): |
|
701
|
|
|
"""Returns quasi-dipole base vectors f1 and f2 at the specified |
|
702
|
|
|
coordinates. |
|
703
|
|
|
|
|
704
|
|
|
The vectors are described by Richmond [1995] [2]_ and |
|
705
|
|
|
Emmert et al. [2010] [3]_. The vector components are geodetic east and |
|
706
|
|
|
north. |
|
707
|
|
|
|
|
708
|
|
|
Parameters |
|
709
|
|
|
========== |
|
710
|
|
|
lat : (N,) array_like or float |
|
711
|
|
|
Latitude |
|
712
|
|
|
lon : (N,) array_like or float |
|
713
|
|
|
Longitude |
|
714
|
|
|
height : (N,) array_like or float |
|
715
|
|
|
Altitude in km |
|
716
|
|
|
coords : {'geo', 'apex', 'qd'}, optional |
|
717
|
|
|
Input coordinate system |
|
718
|
|
|
precision : float, optional |
|
719
|
|
|
Precision of output (degrees) when converting to geo. A negative |
|
720
|
|
|
value of this argument produces a low-precision calculation of |
|
721
|
|
|
geodetic lat/lon based only on their spherical harmonic |
|
722
|
|
|
representation. |
|
723
|
|
|
A positive value causes the underlying Fortran routine to iterate |
|
724
|
|
|
until feeding the output geo lat/lon into geo2qd (APXG2Q) reproduces |
|
725
|
|
|
the input QD lat/lon to within the specified precision (all |
|
726
|
|
|
coordinates being converted to geo are converted to QD first and |
|
727
|
|
|
passed through APXG2Q). |
|
728
|
|
|
|
|
729
|
|
|
Returns |
|
730
|
|
|
======= |
|
731
|
|
|
f1 : (2, N) or (2,) ndarray |
|
732
|
|
|
f2 : (2, N) or (2,) ndarray |
|
733
|
|
|
|
|
734
|
|
|
References |
|
735
|
|
|
========== |
|
736
|
|
|
.. [2] Richmond, A. D. (1995), Ionospheric Electrodynamics Using |
|
737
|
|
|
Magnetic Apex Coordinates, Journal of geomagnetism and |
|
738
|
|
|
geoelectricity, 47(2), 191–212, :doi:`10.5636/jgg.47.191`. |
|
739
|
|
|
|
|
740
|
|
|
.. [3] Emmert, J. T., A. D. Richmond, and D. P. Drob (2010), |
|
741
|
|
|
A computationally compact representation of Magnetic-Apex |
|
742
|
|
|
and Quasi-Dipole coordinates with smooth base vectors, |
|
743
|
|
|
J. Geophys. Res., 115(A8), A08322, :doi:`10.1029/2010JA015326`. |
|
744
|
|
|
|
|
745
|
|
|
""" |
|
746
|
|
|
|
|
747
|
|
|
glat, glon = self.convert(lat, lon, coords, 'geo', height=height, |
|
748
|
|
|
precision=precision) |
|
749
|
|
|
|
|
750
|
|
|
f1, f2 = self._basevec(glat, glon, height) |
|
751
|
|
|
|
|
752
|
|
|
# if inputs are not scalar, each vector is an array of arrays, |
|
753
|
|
|
# so reshape to a single array |
|
754
|
|
|
if f1.dtype == object: |
|
755
|
|
|
f1 = np.vstack(f1).T |
|
756
|
|
|
f2 = np.vstack(f2).T |
|
757
|
|
|
|
|
758
|
|
|
return f1, f2 |
|
759
|
|
|
|
|
760
|
|
|
def basevectors_apex(self, lat, lon, height, coords='geo', precision=1e-10): |
|
761
|
|
|
"""Returns base vectors in quasi-dipole and apex coordinates. |
|
762
|
|
|
|
|
763
|
|
|
The vectors are described by Richmond [1995] [4]_ and |
|
764
|
|
|
Emmert et al. [2010] [5]_. The vector components are geodetic east, |
|
765
|
|
|
north, and up (only east and north for `f1` and `f2`). |
|
766
|
|
|
|
|
767
|
|
|
Parameters |
|
768
|
|
|
========== |
|
769
|
|
|
lat, lon : (N,) array_like or float |
|
770
|
|
|
Latitude |
|
771
|
|
|
lat : (N,) array_like or float |
|
772
|
|
|
Longitude |
|
773
|
|
|
height : (N,) array_like or float |
|
774
|
|
|
Altitude in km |
|
775
|
|
|
coords : {'geo', 'apex', 'qd'}, optional |
|
776
|
|
|
Input coordinate system |
|
777
|
|
|
return_all : bool, optional |
|
778
|
|
|
Will also return f3, g1, g2, and g3, and f1 and f2 have 3 components |
|
779
|
|
|
(the last component is zero). Requires `lat`, `lon`, and `height` |
|
780
|
|
|
to be broadcast to 1D (at least one of the parameters must be 1D |
|
781
|
|
|
and the other two parameters must be 1D or 0D). |
|
782
|
|
|
precision : float, optional |
|
783
|
|
|
Precision of output (degrees) when converting to geo. A negative |
|
784
|
|
|
value of this argument produces a low-precision calculation of |
|
785
|
|
|
geodetic lat/lon based only on their spherical harmonic |
|
786
|
|
|
representation. |
|
787
|
|
|
A positive value causes the underlying Fortran routine to iterate |
|
788
|
|
|
until feeding the output geo lat/lon into geo2qd (APXG2Q) reproduces |
|
789
|
|
|
the input QD lat/lon to within the specified precision (all |
|
790
|
|
|
coordinates being converted to geo are converted to QD first and |
|
791
|
|
|
passed through APXG2Q). |
|
792
|
|
|
|
|
793
|
|
|
Returns |
|
794
|
|
|
======= |
|
795
|
|
|
f1, f2 : (2, N) or (2,) ndarray |
|
796
|
|
|
f3, g1, g2, g3, d1, d2, d3, e1, e2, e3 : (3, N) or (3,) ndarray |
|
797
|
|
|
|
|
798
|
|
|
Note |
|
799
|
|
|
==== |
|
800
|
|
|
`f3`, `g1`, `g2`, and `g3` are not part of the Fortran code |
|
801
|
|
|
by Emmert et al. [2010] [5]_. They are calculated by this |
|
802
|
|
|
Python library according to the following equations in |
|
803
|
|
|
Richmond [1995] [4]_: |
|
804
|
|
|
|
|
805
|
|
|
* `g1`: Eqn. 6.3 |
|
806
|
|
|
* `g2`: Eqn. 6.4 |
|
807
|
|
|
* `g3`: Eqn. 6.5 |
|
808
|
|
|
* `f3`: Eqn. 6.8 |
|
809
|
|
|
|
|
810
|
|
|
References |
|
811
|
|
|
========== |
|
812
|
|
|
|
|
813
|
|
|
.. [4] Richmond, A. D. (1995), Ionospheric Electrodynamics Using |
|
814
|
|
|
Magnetic Apex Coordinates, Journal of geomagnetism and |
|
815
|
|
|
geoelectricity, 47(2), 191–212, :doi:`10.5636/jgg.47.191`. |
|
816
|
|
|
|
|
817
|
|
|
.. [5] Emmert, J. T., A. D. Richmond, and D. P. Drob (2010), |
|
818
|
|
|
A computationally compact representation of Magnetic-Apex |
|
819
|
|
|
and Quasi-Dipole coordinates with smooth base vectors, |
|
820
|
|
|
J. Geophys. Res., 115(A8), A08322, :doi:`10.1029/2010JA015326`. |
|
821
|
|
|
|
|
822
|
|
|
""" |
|
823
|
|
|
|
|
824
|
|
|
glat, glon = self.convert(lat, lon, coords, 'geo', height=height, |
|
825
|
|
|
precision=precision) |
|
826
|
|
|
|
|
827
|
|
|
returnvals = self._geo2apexall(glat, glon, height) |
|
828
|
|
|
qlat = np.float64(returnvals[0]) |
|
829
|
|
|
alat = np.float64(returnvals[2]) |
|
830
|
|
|
f1, f2 = returnvals[4:6] |
|
831
|
|
|
d1, d2, d3 = returnvals[7:10] |
|
832
|
|
|
e1, e2, e3 = returnvals[11:14] |
|
833
|
|
|
|
|
834
|
|
|
# if inputs are not scalar, each vector is an array of arrays, |
|
835
|
|
|
# so reshape to a single array |
|
836
|
|
|
if f1.dtype == object: |
|
837
|
|
|
f1 = np.vstack(f1).T |
|
838
|
|
|
f2 = np.vstack(f2).T |
|
839
|
|
|
d1 = np.vstack(d1).T |
|
840
|
|
|
d2 = np.vstack(d2).T |
|
841
|
|
|
d3 = np.vstack(d3).T |
|
842
|
|
|
e1 = np.vstack(e1).T |
|
843
|
|
|
e2 = np.vstack(e2).T |
|
844
|
|
|
e3 = np.vstack(e3).T |
|
845
|
|
|
|
|
846
|
|
|
# make sure arrays are 2D |
|
847
|
|
|
f1 = f1.reshape((2, f1.size//2)) |
|
848
|
|
|
f2 = f2.reshape((2, f2.size//2)) |
|
849
|
|
|
d1 = d1.reshape((3, d1.size//3)) |
|
850
|
|
|
d2 = d2.reshape((3, d2.size//3)) |
|
851
|
|
|
d3 = d3.reshape((3, d3.size//3)) |
|
852
|
|
|
e1 = e1.reshape((3, e1.size//3)) |
|
853
|
|
|
e2 = e2.reshape((3, e2.size//3)) |
|
854
|
|
|
e3 = e3.reshape((3, e3.size//3)) |
|
855
|
|
|
|
|
856
|
|
|
# compute f3, g1, g2, g3 |
|
857
|
|
|
F1 = np.vstack((f1, np.zeros_like(f1[0]))) |
|
858
|
|
|
F2 = np.vstack((f2, np.zeros_like(f2[0]))) |
|
859
|
|
|
F = np.cross(F1.T, F2.T).T[-1] |
|
860
|
|
|
cosI = helpers.getcosIm(alat) |
|
861
|
|
|
k = np.array([0, 0, 1], dtype=np.float64).reshape((3, 1)) |
|
862
|
|
|
g1 = ((self.RE + np.float64(height)) / (self.RE + self.refh))**(3/2) \ |
|
863
|
|
|
* d1 / F |
|
864
|
|
|
g2 = -1.0 / (2.0 * F * np.tan(np.radians(qlat))) * \ |
|
865
|
|
|
(k + ((self.RE + np.float64(height)) / (self.RE + self.refh)) |
|
866
|
|
|
* d2 / cosI) |
|
867
|
|
|
g3 = k*F |
|
868
|
|
|
f3 = np.cross(g1.T, g2.T).T |
|
869
|
|
|
|
|
870
|
|
|
if np.any(alat == -9999): |
|
871
|
|
|
warnings.warn(('Base vectors g, d, e, and f3 set to -9999 where ' |
|
872
|
|
|
'apex latitude is undefined (apex height may be < ' |
|
873
|
|
|
'reference height)')) |
|
874
|
|
|
f3 = np.where(alat == -9999, -9999, f3) |
|
875
|
|
|
g1 = np.where(alat == -9999, -9999, g1) |
|
876
|
|
|
g2 = np.where(alat == -9999, -9999, g2) |
|
877
|
|
|
g3 = np.where(alat == -9999, -9999, g3) |
|
878
|
|
|
d1 = np.where(alat == -9999, -9999, d1) |
|
879
|
|
|
d2 = np.where(alat == -9999, -9999, d2) |
|
880
|
|
|
d3 = np.where(alat == -9999, -9999, d3) |
|
881
|
|
|
e1 = np.where(alat == -9999, -9999, e1) |
|
882
|
|
|
e2 = np.where(alat == -9999, -9999, e2) |
|
883
|
|
|
e3 = np.where(alat == -9999, -9999, e3) |
|
884
|
|
|
|
|
885
|
|
|
return tuple(np.squeeze(x) for x in |
|
886
|
|
|
[f1, f2, f3, g1, g2, g3, d1, d2, d3, e1, e2, e3]) |
|
887
|
|
|
|
|
888
|
|
|
def get_apex(self, lat, height=None): |
|
889
|
|
|
""" Calculate apex height |
|
890
|
|
|
|
|
891
|
|
|
Parameters |
|
892
|
|
|
----------- |
|
893
|
|
|
lat : (float) |
|
894
|
|
|
Latitude in degrees |
|
895
|
|
|
height : (float or NoneType) |
|
896
|
|
|
Height above the surface of the earth in km or NoneType to use |
|
897
|
|
|
reference height (default=None) |
|
898
|
|
|
|
|
899
|
|
|
Returns |
|
900
|
|
|
---------- |
|
901
|
|
|
apex_height : (float) |
|
902
|
|
|
Height of the field line apex in km |
|
903
|
|
|
""" |
|
904
|
|
|
lat = helpers.checklat(lat, name='alat') |
|
905
|
|
|
if height is None: |
|
906
|
|
|
height = self.refh |
|
907
|
|
|
|
|
908
|
|
|
cos_lat_squared = np.cos(np.radians(lat))**2 |
|
909
|
|
|
apex_height = (self.RE + height) / cos_lat_squared - self.RE |
|
910
|
|
|
|
|
911
|
|
|
return apex_height |
|
912
|
|
|
|
|
913
|
|
|
def set_epoch(self, year): |
|
914
|
|
|
"""Updates the epoch for all subsequent conversions. |
|
915
|
|
|
|
|
916
|
|
|
Parameters |
|
917
|
|
|
========== |
|
918
|
|
|
year : float |
|
919
|
|
|
Decimal year |
|
920
|
|
|
|
|
921
|
|
|
""" |
|
922
|
|
|
|
|
923
|
|
|
fa.loadapxsh(self.datafile, np.float(year)) |
|
924
|
|
|
self.year = year |
|
925
|
|
|
|
|
926
|
|
|
def set_refh(self, refh): |
|
927
|
|
|
"""Updates the apex reference height for all subsequent conversions. |
|
928
|
|
|
|
|
929
|
|
|
Parameters |
|
930
|
|
|
========== |
|
931
|
|
|
refh : float |
|
932
|
|
|
Apex reference height in km |
|
933
|
|
|
|
|
934
|
|
|
Notes |
|
935
|
|
|
===== |
|
936
|
|
|
The reference height is the height to which field lines will be mapped, |
|
937
|
|
|
and is only relevant for conversions involving apex (not quasi-dipole). |
|
938
|
|
|
|
|
939
|
|
|
""" |
|
940
|
|
|
|
|
941
|
|
|
self.refh = refh |
|
942
|
|
|
|
aburrell /
apexpy
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