def Bfield(gc_points, time=5.0e9):
'''
Get Bfield value in nT.
Parameters
----------
gc_points : (3,) or (n,3) ndarray
Point(s) at which to evaluate the B field. Must be given in
geocentric ITRS. Unit: meter
time : float, optional. default = some time in 2017.
MJD seconds single timestep for the simulation.
Returns
-------
Bfield : (3,) or (n,3) ndarray
B-field vectors (in nT?)
'''
llr = geocentric_to_geodetic(gc_points)
lon = np.rad2deg(llr[..., 0])
lat = np.rad2deg(llr[..., 1])
height = (llr[..., 2].mean() - R_earth) / 1000. # to km
year = yearfrac_from_mjds(time)
if hasattr(lon, "__len__"):
B_xyz = np.zeros((len(lon), 3))
emm = EMM.WMM(date=year, lon=lon[0], lat=lat[0], h=height)
for i, (lo, la) in enumerate(zip(lon, lat)):
emm.lon = lo
emm.lat = la
B_xyz[i] = emm.getXYZ()
return B_xyz
else:
emm = EMM.WMM(date=year, lon=lon, lat=lat, h=height)
return emm.getXYZ()
def getBarray(pointing, time, position, height_array):
az, el = PosTools.getAzEl(pointing, time, position)
lonlat = PosTools.getLonLatStation(az, el, pos=position)
los_dir = [lonlat['m0']['value'], lonlat['m1']['value']]
lat = los_dir[1]
lon = los_dir[0]
itrfdir = [
np.cos(lat) * np.cos(lon),
np.cos(lat) * np.sin(lon),
np.sin(lat)
]
pp, am = PosTools.getPPsimpleAngle(height=height_array,
mPosition=position,
direction=itrfdir)
year, month, day, myfrac = PosTools.obtain_observation_year_month_day_fraction(
time)
dayofyear = date(year, month, day).timetuple().tm_yday
emm = EMM.WMM(date=year + float(dayofyear) / 365.)
BField = emm.getProjectedFieldArray(np.degrees(pp[:, 0]),
np.degrees(pp[:, 1]), pp[:, 2] / 1e3,
los_dir)
return pp, am, BField
def getBarray(pointing, time, position, height_array):
pp, am = getPParray(pointing, time, position, height_array)
year, month, day, myfrac = PosTools.obtain_observation_year_month_day_fraction(
time)
dayofyear = date(year, month, day).timetuple().tm_yday
emm = EMM.WMM(date=year + float(dayofyear) / 365.)
BField = emm.getProjectedFieldArray(np.degrees(pp[:, 0]),
np.degrees(pp[:, 1]), pp[:, 2] / 1e3,
los_dir)
return pp, am, BField
def getRM(MS=None,
server="ftp://cddis.gsfc.nasa.gov/gnss/products/ionex/",
prefix='codg',
ionexPath="IONEXdata/",
earth_rot=0,
timerange=0,
use_azel = False,ha_limit=-1000,use_filter=None,
**kwargs):
'''optional arguments are:
radec or pointing : [ra,dec] in radians, or if use_azel =True, az + el in radians,
timestep in s, timerange = [start, end]in MJD seconds,
otherwise use start_time/end_time (casa timestring,eg. 2012/11/21/12:00:00 or 56252.5d NEEDS PYRAP) ,
stat_names = list of strings per station,
stat_positions = list of length 3 numpy arrays, containing station_position in ITRF meters.
useEMM = boolean, use EMM for Earth magnetic field, otherwise WMM cooefficients will be used.
out_file = string, if given the data points will be written to a text file.
use_mean = True if you only want report for mean of station positions
use_filter =standard deviation,or list of standard deviations (time,long, lat) to gaussian filter TEC data
TIME_OFFSET = float, offset time at start and end to ensure all needed values are calculated,
Returns the (timegrid,timestep,TEC) where TEC is a dictionary containing 1 enumpyarray per station in stat_names.
If stat_names is not given, the station names will either be extracted from the MS or st1...stN '''
#print ('earth_rot', earth_rot)
#print ('timerange ', timerange)
#print ('use_azel ', use_azel)
stat_names=[]
useEMM=False
use_mean = False
myobject = ''
timestep=60
pointing=[0.,0.5*np.pi]
out_file=''
stat_pos=[PosTools.posCS002]
use_proxy = False
#stat_names=['LOFAR_CS002']
if not (MS is None):
(timerange,timestep,pointing,stat_names,stat_pos)=PosTools.getMSinfo(MS);
for key in kwargs.keys():
if key=='use_mean':
use_mean = kwargs[key]
stat_pos_mean = False
if key=='radec' or key=='pointing':
pointing = kwargs[key]
if key=='object':
myobject = kwargs[key]
#out_file = 'RMextract_report_' + myobject
if key=='start_time':
start_time=kwargs[key]
time_in_sec = False
if key=='end_time':
end_time=kwargs[key]
time_in_sec = False
if key=='timestep':
timestep=kwargs[key]
if key=='stat_names':
stat_names=kwargs[key]
if key=='out_file':
out_file=kwargs[key]
if key=='TIME_OFFSET':
TIME_OFFSET=kwargs[key]
if key=='stat_positions':
stat_pos=kwargs[key]
if not stat_names:
stat_names =['st%d'%(i+1) for i in range(len(stat_pos))]
if key=='useEMM':
useEMM=kwargs[key]
if key=="proxy_server": #Check to see if user wants to use a proxy for downloading IONEX files.
use_proxy = True
proxy_server=kwargs["proxy_server"]
proxy_type=kwargs["proxy_type"]
proxy_port=kwargs["proxy_port"]
proxy_user=kwargs["proxy_user"]
proxy_pass=kwargs["proxy_pass"]
if timerange != 0:
start_time = timerange[0]
end_time = timerange[1]
time_in_sec = True
reference_time = start_time
timerange[0] = start_time - timestep
timerange[1] = end_time + timestep
str_start_time=PosTools.obtain_observation_year_month_day_hms(reference_time)
else:
timerange,str_start_time,reference_time=PosTools.get_time_range(start_time,end_time,timestep,time_in_sec,0)
if str_start_time==-1:
return
if useEMM:
#print ("USING EMM for EarthMagnetic Field")
emm=EMM.EMM()
else:
emm=EMM.WMM()
times,timerange=PosTools.getIONEXtimerange(timerange,timestep)
if len(times[-1])==0 or times[-1][-1]<timerange[1]:
timestmp=list(times[-1])
timestmp.append(timerange[1]) #add one extra step to make sure you have a value for all times in the MS in case timestep hase been changed
times[-1]=np.array(timestmp)
timegrid=np.array([])
TECs={};
Bs={}
Bpars={}
air_mass={};
RMs={};
azimuth={};
elevation={};
flags={}
if len(out_file) and len(myobject):
out_file = out_file + '_' + myobject
else:
if len(myobject):
out_file = 'RMextract_report_' + myobject
# print header section of report
if len(out_file):
if os.path.exists(out_file):
os.remove(out_file)
log = open(out_file, 'a')
log.write ('Observing %s\n' % myobject)
if not (MS is None):
log.write ('Using measurement set %s\n' % MS)
if use_azel:
log.write ('observing at a fixed azimuth and elevation \n')
log.write ('station_positions %s \n' % stat_pos)
log.write ('\n')
for st in stat_names:
azimuth[st] = []
elevation[st] = []
air_mass[st] = []
Bs[st]=[]
Bpars[st]=[]
RMs[st]=[]
TECs[st]=[]
air_mass[st]=[]
flags[st]=[]
for time_array in times:
#get RM per timeslot
starttime=time_array[0]
#print ("getting ionexfile for",starttime)
date_parms = PosTools.obtain_observation_year_month_day_fraction(starttime)
dayofyear = date(date_parms[0],date_parms[1],date_parms[2]).timetuple().tm_yday
emm.date=date_parms[0]+float(dayofyear)/365.
#get relevant ionex file
if not use_proxy:
if not "http" in server: #ftp server use ftplib
ionexf=ionex.getIONEXfile(time=date_parms,server=server,prefix=prefix,outpath=ionexPath)
else:
ionexf=ionex.get_urllib_IONEXfile(time=date_parms,server=server,prefix=prefix,outpath=ionexPath)
else:
ionexf=ionex.get_urllib_IONEXfile(time=date_parms,server=server,prefix=prefix,outpath=ionexPath,proxy_server=proxy_server,proxy_type=proxy_type,proxy_port=proxy_port,proxy_user=proxy_user,proxy_pass=proxy_pass)
assert (ionexf!=-1),"error getting ionex data"
tecinfo=ionex.readTEC(ionexf,use_filter=use_filter)
if use_mean:
if not stat_pos_mean:
stn_mean = stat_pos.mean(0)
stat_pos = []
stat_pos.append(stn_mean)
stat_pos_mean = True
#print ('stat_pos.mean', stn_mean)
for station,position in zip(stat_names,stat_pos):
#print ('generating data for station ', station)
for time in time_array:
result = PosTools.obtain_observation_year_month_day_fraction(time)
part_of_day= result[3] * 24
if use_azel:
az = pointing[0]
el = pointing[1]
flags[station].append(1)
else:
az,el = PosTools.getAzEl(pointing,time,position,ha_limit)
if az==-1 and el==-1:
return
if az==999 and el==999:
#outsite hadec range
air_mass[station].append(-999)
azimuth[station].append(-999)
elevation[station].append(-999)
Bs[station].append([-999,-999,-999])
Bpars[station].append(-999)
RMs[station].append(-999)
TECs[station].append(-999) #sTEC value
flags[station].append(0)
continue
flags[station].append(1)
latpp,lonpp,height,lon,lat,am1=PosTools.getlonlatheight(az,el,position)
if latpp==-1 and lonpp==-1 and height==-1:
return
#get VTEC from IONEX interpolation
vTEC=ionex.getTECinterpol(time=part_of_day,lat=latpp,lon=lonpp,tecinfo=tecinfo,apply_earth_rotation=earth_rot)
TECs[station].append(vTEC*am1) #STEC value
emm.lon = lonpp
emm.lat = latpp
emm.h= ION_HEIGHT / 1.0e3
Bpar=-1*emm.getProjectedField(lon,lat)# minus sign since the radiation is towards the Earth
BField=emm.getXYZ()
Bs[station].append(BField)
air_mass[station].append(am1)
azimuth[station].append(az)
elevation[station].append(el)
Bpars[station].append(Bpar)
#calculate RM constant comes from VtEC in TECU,B in nT, RM = 2.62
RMs[station].append((Bpar*vTEC*am1)*2.62e-6)
if use_mean:
break
timegrid=np.concatenate((timegrid,time_array));
for st in stat_names:
air_mass[station] = np.array(air_mass[st])
azimuth[station] = np.array(azimuth[st])
elevation[station] = np.array(elevation[st])
TECs[st]=np.array(TECs[st])
Bs[st]=np.array(Bs[st])
Bpars[st]=np.array(Bpars[st])
RMs[st]=np.array(RMs[st])
flags[st]=np.array(flags[st])
if use_mean:
break
big_dict={}
big_dict['STEC']=TECs
big_dict['Bpar']=Bpars
big_dict['BField']=Bs
big_dict['AirMass']=air_mass
big_dict['elev']=elevation
big_dict['azimuth']=azimuth
big_dict['RM']=RMs
big_dict['times']=timegrid
big_dict['timestep']=timestep
big_dict['station_names'] = stat_names
big_dict['stat_pos'] = stat_pos
big_dict['flags'] = flags
big_dict['reference_time'] = reference_time
# finish writing computed data to report
if len(out_file):
time_range=[big_dict['times'][0],big_dict['times'][-1]]
log.write ('start and end times %s %s \n' % (time_range[0], time_range[1]))
log.write ('reference time for rel_time=0: year month day hr min sec %s %s %s %s %s %s \n' % str_start_time)
if use_azel:
log.write ('observing at azimuth and elevation %s %s \n' % (pointing[0], pointing[1]))
else:
log.write ('observation direction %s %s \n' % (pointing[0], pointing[1]))
log.write ('\n')
k = 0
for key in big_dict['station_names']:
seq_no = 0
if use_mean:
log.write ('data for station mean position at %s\n' % (stat_pos[k]))
else:
log.write ('data for station %s at position %s\n' % (key, stat_pos[k]))
log.write ('seq rel_time time_width El Az STEC RM (rad/m2) VTEC factor \n')
for i in range (timegrid.shape[0]):
el = big_dict['elev'][key][i]
if el < 0 :
ok = 1
stec = 0.0
rm = 0.0
vtec_factor = 1.0
else:
ok = 0
stec =big_dict['STEC'][key][i]
rm = big_dict['RM'][key][i]
vtec_factor = 1.0 / big_dict['AirMass'][key][i]
az = big_dict['azimuth'][key][i]
rel_time = timegrid[i] - reference_time
if i == 0:
time_width = reference_time - timegrid[i]
else:
time_width = timegrid[i] - timegrid[i-1]
log.write("%s : %s %s %s %s %s %s %s %s\n" % (seq_no, ok, rel_time, time_width, el, az, stec, rm, vtec_factor))
seq_no = seq_no + 1
k = k + 1
if use_mean:
break
log.write (' \n')
log.close()
print ('****** finished ionosphere predictions report: ', out_file)
else:
print ('*********** finished ionosphere predictions ***************')
return big_dict