How can I determine tropospheric dealy at give location (latitude, longitude, height) from VMF?
How can I access VMF using python?
You can get the answers to the above questions at VMF Data Server (https://vmf.geo.tuwien.ac.at/products.html). As far as I know, there are only Fortran and Matlab versions available, and python is not supported.
Shanker KC The Vienna Mapping Function (VMF) is a mathematical model that is used to calculate the delay of satellite signals due to the Earth's atmosphere. The inputs to the VMF model are the latitude, longitude, and height above sea level of the satellite receiver, the elevation angle of the satellite, and the temperature, pressure, and humidity at the satellite receiver. The outputs of the VMF model are the total atmospheric delay, the dry component of the delay, and the wet component of the delay
Shanker KC To use the VMF model to calculate the tropospheric delay, you would need to input the appropriate values for the latitude, longitude, and height of the satellite receiver, as well as the elevation angle of the satellite and the temperature, pressure, and humidity at the satellite receiver. You can then use the outputs of the VMF model to calculate the total atmospheric delay, which includes both the dry and wet components of the delay. The dry component of the delay is due to the refraction of the satellite signal by the Earth's atmosphere, while the wet component is due to the absorption of the signal by water vapor in the atmosphere
Shanker KC There are a few different ways that you can access the Vienna Mapping Function (VMF) using Python. One option is to use the PyVMF library, which is a Python wrapper for the VMF model developed by the Technical University of Vienna. To use PyVMF, you will need to install the library and then import it into your Python script
Here is an example of how you can use PyVMF to calculate the tropospheric delay at a given location:
import pyvmf
# Set the latitude, longitude, and height of the satellite receiver
latitude = 48.210033
longitude = 16.363449
height = 200
# Set the elevation angle of the satellite
elevation = 30
# Set the temperature, pressure, and humidity at the satellite receiver
temperature = 20
pressure = 1013
humidity = 50
# Calculate the tropospheric delay using the VMF model
delay = pyvmf.vmf1_map(latitude, longitude, height, temperature, pressure, humidity, elevation)
print(delay)
Another option is to use the pygeodesy library, which includes an implementation of the VMF model. To use the VMF model from pygeodesy, you will need to install the library and then import it into your Python script. Here is an example of how you can use pygeodesy to calculate the tropospheric delay at a given location:
import pygeodesy
# Set the latitude, longitude, and height of the satellite receiver
latitude = 48.210033
longitude = 16.363449
height = 200
# Set the elevation angle of the satellite
elevation = 30
# Set the temperature, pressure, and humidity at the satellite receiver
temperature = 20
pressure = 1013
humidity = 50
# Calculate the tropospheric delay using the VMF model
delay = pygeodesy.vmf1(latitude, longitude, height, temperature, pressure, humidity, elevation)
print(delay)
Shanker KC The Vienna Mapping Function (VMF) is a mathematical model that represents the mapping between the zenith hydrostatic delay and the entire zenith delay of the Earth's atmosphere (zenith hydrostatic delay plus zenith wet delay).
The geographical location of the site (latitude, longitude, and elevation above sea level) and the day of the year are fed into the VMF.
The overall zenith delay of the atmosphere at the location, including the zenith hydrostatic delay and the zenith wet delay, is the output of the VMF. Subtract the zenith hydrostatic delay from the overall zenith delay to obtain the tropospheric delay from the VMF output.
The VMF is commonly used in geodetic and geophysical applications such as GPS location and satellite altimetry to compensate for the effects of the Earth's atmosphere on distance and height measurements.
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