113 lines
4.3 KiB
Python
113 lines
4.3 KiB
Python
import astropy.units as unit
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import numpy as np
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from astropy.coordinates import EarthLocation, AltAz
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from astropy.coordinates import get_sun
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from astropy.time import TimeISO
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from input.natural_constants import *
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class TimeYearDayTimeCustom(TimeISO):
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"""
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day-of-year as "<DOY>".
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The day-of-year (DOY) goes from 001 to 365 (366 in leap years).
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The allowed subformat is:
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- 'doy': day of year
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"""
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name = 'doy' # unique format name
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subfmts = (('doy',
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'%j',
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'{yday:03d}'),
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('doy',
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'%j',
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'{yday:03d}'),
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('doy',
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'%j',
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'{yday:03d}'))
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def sun_angles_astropy(lat, lon, h, utc): # get current sun elevation and azimuth through astropy
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loc = EarthLocation(lat=lat*unit.deg, lon=lon*unit.deg, height=h*unit.m)
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ref = AltAz(obstime=utc, location=loc)
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sun_pos = get_sun(utc).transform_to(ref)
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az = sun_pos.az.degree
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elv = sun_pos.alt.degree
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return az, elv
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def sun_angles_analytical(lat, lon, utc): # get current sun elevation and azimuth through several equations (see [xx])
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if np.abs(lat) == 90: # handling collapse of longitudes at poles by
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lat = np.sign(lat) * 89.999999 # expanding one point to a very small circle
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else:
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pass
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jd = utc.jd
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jc = (jd - 2451545) / 36525
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gml = (280.46646 + jc * (36000.76983 + jc * 0.0003032)) % 360
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gma = 357.52911 + jc * (35999.05029 - 0.0001537 * jc)
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eeo = 0.016708634 - jc * (0.000042037 + 0.0000001267 * jc)
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sec = np.sin(np.deg2rad(gma)) * (1.914602 - jc * (0.004817 + 0.000014 * jc)) + np.sin(np.deg2rad(2 * gma)) * (
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0.019993 - 0.000101 * jc) + np.sin(np.deg2rad(3 * gma)) * 0.000289
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stl = gml + sec
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sal = stl - 0.00569 - 0.00478 * np.sin(np.deg2rad(125.04 - 1934.136 * jc))
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moe = 23 + (26 + (21.448 - jc * (46.815 + jc * (0.00059 - jc * 0.001813))) / 60) / 60
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oc = moe + 0.00256 * np.cos(np.deg2rad(125.04 - 1934.136 * jc))
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sd = np.rad2deg(np.arcsin(np.sin(np.deg2rad(oc)) * np.sin(np.deg2rad(sal)))) # radian
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var_y = np.tan(np.deg2rad(oc / 2)) ** 2
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eot = 4 * np.rad2deg(
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var_y * np.sin(2 * np.deg2rad(gml)) - 2 * eeo * np.sin(np.deg2rad(gma)) + 4 * eeo * var_y * np.sin(
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np.deg2rad(gma)) * np.cos(2 * np.deg2rad(gml)) - 0.5 * var_y ** 2 * np.sin(
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4 * np.deg2rad(gml)) - 1.25 * eeo ** 2 * np.sin(2 * np.deg2rad(gma)))
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tst = (((jd - 0.5) % 1) * 1440 + eot + 4 * lon) % 1440
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if tst / 4 < 0:
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ha = tst / 4 + 180
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else:
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ha = tst / 4 - 180
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sza = np.rad2deg(np.arccos(
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np.sin(np.deg2rad(lat)) * np.sin(np.deg2rad(sd)) + np.cos(np.deg2rad(lat)) * np.cos(np.deg2rad(sd)) * np.cos(
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np.deg2rad(ha))))
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sea = 90 - sza
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if ha > 0:
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saa = (np.rad2deg(np.arccos(((np.sin(np.deg2rad(lat)) * np.cos(np.deg2rad(sza))) - np.sin(np.deg2rad(sd))) / (
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np.cos(np.deg2rad(lat)) * np.sin(np.deg2rad(sza))))) + 180) % 360
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else:
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saa = (540 - np.rad2deg(np.arccos(
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((np.sin(np.deg2rad(lat)) * np.cos(np.deg2rad(sza))) - np.sin(np.deg2rad(sd))) / (
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np.cos(np.deg2rad(lat)) * np.sin(np.deg2rad(sza)))))) % 360
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return saa, sea # Azimuth, Elevation
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def AirMass(p_air, p_0, ELV, h): # get atmospheric air mass over balloon
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ELV_rad = np.deg2rad(ELV) # convert ELV from degree to radian
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Dip = np.arccos(R_E / (R_E + h)) # geometric "dip" in radian
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if ELV_rad >= -Dip and ELV_rad < 0:
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res = p_air/p_0 * (1 + ELV_rad/Dip) - 70 * ELV_rad/Dip
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else:
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res = (p_air/p_0) * ((1229 + (614 * np.sin(ELV_rad)) ** 2) ** (1/2) - 614 * np.sin(ELV_rad))
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return res
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def tau(ELV, h, p_air): # get atmospheric transmissivity as function of balloon altitude and sun elevation
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if ELV >= -(180 / np.pi * np.arccos(R_E / (R_E + h))):
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tau_atm = 0.5 * (
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np.exp(-0.65 * AirMass(p_air, p_0, ELV, h)) + np.exp(-0.095 * AirMass(p_air, p_0, ELV, h)))
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tau_atmIR = 1.716 - 0.5 * (np.exp(-0.65 * p_air / p_0) + np.exp(-0.095 * p_air / p_0))
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else:
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tau_atm = 0
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tau_atmIR = 0
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return tau_atm, tau_atmIR
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