An example of custom local SHC model evaluation¶
In [1]:
# load data from VirES server
from viresclient import SwarmRequest
request = SwarmRequest("https://staging.viresdisc.vires.services/openows")
request.set_collection("SW_OPER_MAGA_LR_1B")
request.set_products(
measurements=['B_NEC'],
auxiliaries=['QDLat'],
sampling_step="PT1S"
)
data = request.get_between(
start_time="2014-01-01T00:00:00Z",
end_time="2014-01-02T00:00:00Z"
).as_xarray()
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Can't download new leap second table Can't find leap second table. Using one built into code. Last leap second in built in table is on Jan 01 2017.
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In [2]:
# extract times, coordinates and other data
from numpy import asarray, datetime64, stack
NS2DAYS = 1.0/(24*60*60*1e9) # nano seconds to days scale factor
# time as MJD2000
times = (
asarray(data["Timestamp"], dtype="M8[ns]") - datetime64('2000')
).astype('int64') * NS2DAYS
# spherical coordinates
coords = stack((
data["Latitude"].values, # latitude in deg
data["Longitude"].values, # latitude in deg
data["Radius"].values*1e-3, # radius in km
), axis=1)
# measurements
b_nec_measured = data["B_NEC"].values
# quasi-dipole latitudes
qdlats = data["QDLat"].values
In [3]:
# load model and evaluate the model
from eoxmagmod import load_model_shc
from eoxmagmod.data import CHAOS6_CORE_LATEST as CUSTOM_SHC_FILE
custom_model = load_model_shc(CUSTOM_SHC_FILE)
b_nec_model = custom_model.eval(times, coords, scale=[1, 1, -1]) # note the reversed radial component
In [5]:
# display residuals
from matplotlib.pyplot import figure, subplot, show
b_nec_res = b_nec_measured - b_nec_model
fig = figure(figsize=(12, 6), dpi=100)
ax = subplot(111)
ax.plot(qdlats, b_nec_res[..., 2])
ax.grid()
ax.set_xlabel('QD Latitude / deg')
ax.set_ylabel('B_C residual / nT')
show()
