atten_slant_annex1

pycraf.atm.atten_slant_annex1(elevation, obs_alt, atm_layers_dict, do_tebb=True, t_bg=<Quantity 2.73 K>, max_arc_length=<Quantity 180. deg>, max_path_length=<Quantity 1000. km>)

Path attenuation for a slant path through full atmosphere according to ITU-R P.676-11 Eq (17-20).

Parameters:

elevationQuantity, scalar

(Apparent) elevation of source as seen from observer [deg]

obs_altQuantity, scalar

Height of observer above sea-level [km]

atm_layers_cachedict

Pre-computed physical parameters for each atmopheric layer as returned by the atm_layers function.

do_tebbbool, optional

Whether to calculate the equivalent blackbody brightness temperature of the (full) Earth’s atmosphere. (default: True)

If you’re only interested in path attenuation, you can switch this off for (somewhat) improved computing speed. Note, that the result will only be meaningful if the propagation path ends in space.

t_bgQuantity, scalar, optional

Background temperature, i.e. temperature just after the outermost layer (default: 2.73 K)

This is needed for accurate t_ebb calculation, usually this is the temperature of the CMB (if Earth-Space path), but at lower frequencies, Galactic foreground contribution might play a role.

max_path_lengthQuantity, scalar

Maximal length of path before stopping iteration [km]

(default: 1000 km; useful for terrestrial paths)

max_arc_lengthQuantity, scalar

Maximal arc-length (true angular distance between observer and source/ target) of path before stopping iteration [deg]

(default: 180 deg; useful for terrestrial paths)

Returns:

total_attenQuantity

Total attenuation along path [dB]

RefractionQuantity

Offset with respect to a hypothetical straight path, i.e., the correction between real and apparent source elevation [deg]

t_ebb (K)Quantity

Equivalent black body temperature of the atmosphere (accounting for any outside contribution, e.g., from CMB) [K]

Will be all-NaN if not a space path, or do_tebb == False.