ITU-R Atmospheric Attenuation Calculator

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Height above sea level [ITU-R P.1511] —
Surface mean temperature [ITU-R P.1510] —
Surface pressure [ITU-R P.835] —
Standard surface temperature [ITU-R P.835] —
Standard water vapour density [ITU-R P.835] —
Water vapour density (p) [ITU-R P.836] —
Total water vapour content (p) [ITU-R P.836] —
Rain attenuation probability [ITU-R P.618] —
Rain percentage probability [ITU-R P.837] —
Rainfall rate exceeded for (p) [ITU-R P.837] —
0 °C isotherm height [ITU-R P.839] —
Rain height [ITU-R P.839] —
Columnar content of reduced liquid water content (p) [ITU-R P.840] —
Zenith water vapour attenuation (p) [ITU-R P.676] —
Attenuation (dB)
Total atmospheric attenuation [ITU-R P.618] —
Gaseous attenuation [ITU-R P.676] —
Cloud attenuation [ITU-R P.840] —
Rain attenuation [ITU-R P.618] —
Scintillation attenuation [ITU-R P.618] —

ITU-R Recommendations implemented

The following ITU-R Recommendations are implemented in ITU-Rpy

ITU-R P.453-13: The radio refractive index: its formula and refractivity data
ITU-R P.530-17: Propagation data and prediction methods required for the design of terrestrial line-of-sight systems
ITU-R P.618-13: Propagation data and prediction methods required for the design of Earth-space telecommunication systems
ITU-R P.676-12: Attenuation by atmospheric gases
ITU-R P.835-6: Reference Standard Atmospheres
ITU-R P.836-6: Water vapour: surface density and total columnar content
ITU-R P.837-7: Characteristics of precipitation for propagation modelling
ITU-R P.838-3: Specific attenuation model for rain for use in prediction methods
ITU-R P.839-4: Rain height model for prediction methods
ITU-R P.840-8: Attenuation due to clouds and fog
ITU-R P.1144-10: Interpolation methods for the geophysical properties used to compute propagation effects
ITU-R P.1510-1: Mean surface temperature
ITU-R P.1511-2: Topography for Earth-to-space propagation modelling
ITU-R P.1623-1: Prediction method of fade dynamics on Earth-space paths
ITU-R P.1853-1: Tropospheric attenuation time series synthesis

Valid ranges for each ITU-R Recommendation

ITU-R Recommendation Primary Purpose Key Parameters Valid Range(s)
ITU-R P.453-13 Radio refractivity and refractive index Latitude, longitude, height Latitude: −90° to +90°
Longitude: −180° to +180°
Height: 0–100 km
ITU-R P.530-17 Terrestrial line-of-sight propagation Frequency, path length, antenna heights, time percentage Frequency: ~1–86 GHz
Path length: up to ~100 km
Time percentage: 0.001–50%
ITU-R P.618-13 Earth–space propagation Frequency, elevation angle, antenna diameter, time percentage Frequency: 1–55 GHz
Elevation: 0–90°
Antenna diameter: > 0 m
Time percentage: 0.001–50%
ITU-R P.676-12 Atmospheric gas attenuation Frequency, pressure, temperature, water vapour density Frequency: ~1–350 GHz
Surface pressure: ~300–1100 hPa
Temperature: −50 to +50 °C
ITU-R P.835-6 Reference standard atmospheres Altitude Altitude: 0–100 km
ITU-R P.836-6 Water vapour density and content Latitude, longitude Latitude: −90° to +90°
Longitude: −180° to +180°
ITU-R P.837-7 Precipitation characteristics Latitude, longitude, time percentage Latitude: −90° to +90°
Longitude: −180° to +180°
Time percentage: 0.001–50%
ITU-R P.838-3 Rain specific attenuation Frequency, polarization, rain rate Frequency: 1–1000 GHz
Rain rate: 0–300 mm/h
ITU-R P.839-4 Rain height model Latitude, longitude Latitude: −90° to +90°
Longitude: −180° to +180°
ITU-R P.840-8 Cloud and fog attenuation Frequency, cloud liquid water Frequency: 1–200 GHz
ITU-R P.1144-10 Interpolation of geophysical data Latitude, longitude Latitude: −90° to +90°
Longitude: −180° to +180°
ITU-R P.1510-1 Mean surface temperature Latitude, longitude Latitude: −90° to +90°
Longitude: −180° to +180°
ITU-R P.1511-2 Topography for Earth-to-space propagation Latitude, longitude Latitude: −90° to +90°
Longitude: −180° to +180°
ITU-R P.1623-1 Fade dynamics (Earth–space) Time percentage, frequency Time percentage: 0.001–50%
Frequency: ≤55 GHz
ITU-R P.1853-1 Tropospheric attenuation time-series synthesis Frequency, elevation angle, time percentage Frequency: ≤55 GHz
Elevation: 0–90°
Time percentage: 0.001–50%

Typical Accuracy / Uncertainty

Propagation Effect ITU-R Recommendation Typical Accuracy / Uncertainty Applicability Notes
Total atmospheric attenuation ITU-R P.618 ±20–30% (long-term statistics) Combined effect of gases, rain, clouds, and scintillation; accuracy depends on dominance of rain attenuation
Gaseous attenuation ITU-R P.676 ±5–10% High accuracy due to spectroscopic basis; uncertainty increases near absorption lines
Cloud attenuation ITU-R P.840 ±20–30% Dominated by uncertainty in cloud liquid water content; regional variability significant
Rain attenuation ITU-R P.618 ±25–40% Largest source of uncertainty; strongly dependent on local rain rate statistics (P.837)
Scintillation attenuation ITU-R P.618 ±30–50% Valid mainly for small antennas and low elevations; short-term variability dominates error 
@misc{iturpy-2017,
      title={ITU-Rpy: A python implementation of the ITU-R P. Recommendations to compute atmospheric
	     attenuation in slant and horizontal paths.},
      author={Inigo del Portillo},
      year={2017},
      publisher={GitHub},
      howpublished={\url{https://github.com/inigodelportillo/ITU-Rpy/}}
}