Atmosphere

The Atmosphere settings cover the following options:

• Ionosphere Settings
• Troposphere Settings

The settings which apply for both Ionosphere and Troposphere are the atmospheric attenuation.

Parameter	Description
Atmospheric attenuation	Atmospheric attenuation of satellite signals in [dB].

Ionosphere

Parameter	Description
Import Model from File	Imports model parameters from a RINEX navigation message file. If the header contains ionospheric correction entries for multiple GNSS systems only one model is imported. This example shows GPS and BEIDOU ionospheric parameters for the Klobuchar model. Only the first parameters (GPS) will be imported. Note: the read parameters are sorted internally by their GNSS system (satflag) and can differ from the order in the RINEX file.
Ionosphere Model	Determines which computational model is used by the simulation. Klobuchar NeQuick
Model Input	Specifies the user input type of Ionosphere parameters: Solar Activitiy: model parameters are automatically determined based on the chosen number of sunspots. Alternatively, one can also choose between pre-defined activity levels (low, medium or high). Model Parameters: allows for directly editing the corresponding model parameters chosen in the Ionosphere Model combobox.

See Ionosphere models for a detailed list of utilized models.

Solar Activity

Ionospheric activity largely depends on the ionization of the Earth's atmosphere, which in turn is depending on the number of sunspots. Higher solar activity leads to a higher sunspot number and thus higher ionization of the atmosphere.

Users can either select pre-defined activity levels or directly insert the number of sunspots, which is used to automatically determine suitable parameters for the utilized ionospheric models. The ionospheric delays are then simulated according to the chosen model.

Model Parameters

The Ionosphere model parameters can be set here. Depending on the selected model, only one table is available:

Parameter	Description
Klobuchar Parameters	Ionosphere parameters for the Klobuchar Ionosphere Model: : hold the Klobuchar coefficients. : hold the Klobuchar coefficients.
NeQuick Parameters	Ionosphere parameters for the NeQuick Ionosphere Model: a0 - a2: the effective ionisation level 1st-3rd order parameters. SF1 - SF5: the ionospheric disturbance flags for region 1-5.

See Ionosphere models for a detailed list of utilized models.

Noise

Parameter	Description
Apply Noise	Determines, whether AWGN is applied to ionosphere-based delays.
Noise σ [m]	The standard deviation of the normal distribution.

Troposphere

Parameter	Description
Set Parameters manually	If enabled, parameters for the chosen troposphere model can be set manually. Otherwise a fixed internal model is used.
Troposphere Model	Available models are: Hopfield Galileo Reference GPT2w

See Troposphere models for a detailed list of utilized models.

Hopfield

Parameter	Description
Temperature [°C]	Temperature
Atmospheric Pressure [mbar]	Air pressure
Humidity [%]	Relative Humidity
Heigth Polytropic Layer Wet [km]	Height of polytropic wet layer

Galileo Reference

Parameter	Description
Temperature [°C]	Temperature
Atmospheric Pressure [mbar]	Air pressure
Humidity [%]	Relative Humidity

GPT2w

Parameter	Description
Temperature [°C]	Temperature
Atmospheric Pressure [mbar]	Air pressure
Humidity [%]	Relative Humidity
Grid Cell Size [° x °]	Grid cell size in [°] of the grid file. Supported values are [1°, 5°]

Noise

Parameter	Description
Apply Noise	Determines, whether AWGN is applied to troposphere-based delays.
Noise σ [m]	The standard deviation of the normal distribution.