The Kp-Index and Why it Matters to Drone Pilots

It all begins with a solar wind moving at one million miles per hour

In a world filled with growing technology and intelligent machines, the Sun plays an important part in the success or failure of drone flight. Solar wind or particle radiation continuously affect all electronics on a near-daily basis, especially high precision drones using a Geographical Positioning System (GPS). The Kp-index is a necessary factor for flight.

The planetary magnetic index, or Kp-index (K meaning Kennziffer or ‘code number’ in German, and P meaning planetary), has been available for some time now. Thanks to Julius Bartels and his dedication to geophysics, we have the 3hr Kp-index for all your magnetic interference needs. Julius Bartels was born on August 17th, 1899 in Magdeburg, Germany. He is known for his introduction and development of the 3hr Kp-index in 1938. His ability to showcase particle radiation data of the Sun in a user friendly and efficient manner, first using musical scales, paved the way for many industries.

Image for post
Source: GFZ German Research Centre for Geosciences (Unaltered Image) License: Creative Commons — Attribution 4.0 International — CC BY 4.0

Solar Wind and the Ionosphere

A geomagnetic storm or solar wind is a disturbance sent from the Sun to the atmosphere that surrounds the Earth. We also know this field as the Ionosphere; an important layer that allows for high-frequency radio waves to travel smoothly with minimal disturbance. Magnetically charged particles are highly affected in this region of space.

“Mankind will discover objects in space sent to us by the watchers..”

– Nostradamus

The Sun is a powerful force within our solar system, constantly bubbling and churning out solar charged energy toward all those in its path. When these bubbles of radiation are powerful enough, they will venture out into space at a speed beyond one million miles per hour, penetrating the atmosphere surrounding our planet. When solar wind disturbs the ionosphere, we will get GPS errors.

Global Positioning System (GPS)

The Global Positioning System (GPS) is a primary method of determining a precise location on Earth using the multiple satellites floating in space. Remote or Drone pilots with high-frequency GPS capability rely heavily on GPS to keep the aircraft behaving the way it should. If the aircraft doesn’t know where it is in relation to the Earth’s surface, we end up with errors and erratic behavior. The level of error can vary.

  • Calm Day: 1 Meter
  • Highly Disturbed Day: 10+ Meters

In order to limit the number of errors received, the GPS system will use different models based on accuracies during a normal or a ‘quiet’ atmosphere. This is information collected and analyzed over years of study. Without these models, the GPS system has nothing to compare ‘normal’ to. The ‘quiet’ models are used to compensate in order to find a true current position and speed.

GPS uses a connection to multiple satellites to triangulate coordinates or the current position of the receiver (drone) in relation to the ground. Using the satellites available in space, it broadcasts radio signals in relation to the sphere below. It then compares the current position and speed to other satellites broadcasting to the same receiver. This process tells the drone its current position, which is then used in coordination with commands received from the remote pilot. A general rule of thumb for many drone or remote pilots is to gain a connection with a minimum of four satellites. If a pilot is able to connect to more, this may benefit the accuracy and decrease the level of error. Basically, three to triangulate position and a fourth to calculate timing and other important measurements.

There are many applications and tools available in order to get a current forecast on weather, satellite connection availability, and the current Kp-index all wrapped up in one view. One example is the UAV Forecast application. A choice in the number of satellites to the general consumer or user is not available. You simply get what is available at that moment in space based on your geographical location. It is up to the user to know whether the amount of available connections is worth the level of risk for flight.

The Kp-Index

The Kp-index is a scale of geomagnetic storm activity within a 3hr window. In order to produce a Kp-index, many observatories around the world are monitoring Sun activities day and night. There are (13) thirteen magnetic observatories around the globe. These observatories are in New Zealand, Australia, US, Germany, UK, Sweden, Denmark, and Canada. Some regions have more than one observatory. Through the careful collaboration of the 13 observatories, an accurate Kp-index is born and available just about anywhere with an internet connection. Due to the distance between Earth and the Sun, magnetic particles emitted from the Sun take an average of two to four days to reach Earth. Space between allows for an accurate prediction of impacts.

There are many resources on the web to find the current Kp-index. Two of these resources include the National Oceanic and Atmospheric Administration (NOAA) and the GFZ German Research Center for Geosciences (GFZ). The Kp-index is viewed in 3hr prediction windows for 24hrs, and impacts are based on a scale of 0 to 9.

  • 1 equals calm or ‘quiet’ conditions
  • 4 and above equals severe impacts

Based on this scale, many drone or remote pilots will not fly if the Kp-index reaches 4. Severe impacts increase the level of error and lead to risky flying. The drone will not have an accurate location or continuous GPS lock to allow the pilot to maintain control and change direction on command. With a high disturbance, the GPS radio frequency are disrupted and the satellites will lose the critical lock necessary for intelligent flight.

Image for post
Source: GFZ German Research Centre for Geosciences (Unaltered Image) License: Creative Commons — Attribution 4.0 International — CC BY 4.0

The image above is the Kp-index from the GFZ German Research Center for Geosciences. In order for the predictions to be used on a real-time global scale, the timeframe used for the Kp-index prediction is on Coordinated Universal Time (UTC). Depending on a user’s location, we can make accurate predictions and plan for any location around the globe. For instance, the Kp-index above indicates severe impacts will occur between the hours of 0000 and 1500 UTC (including all yellow for discussion purposes).

From 1500 to the 2400 mark, impacts begin to improve. Using Central time as an example, we would add 6 hours to this window. This means that on 7 Feb 2021, from 2100 to 0600 hours local Central time, impacts were less severe and this would have been a window of consideration for flight. However, based on this example, these are night hours for a location in the Central time zone. The next window of opportunity may be a better choice. Consider the Kp-index for the next day since the severe impacts appear to decrease. There may have been a window of opportunity in the early morning hours of 8 Feb 2021.

The Kp-Index Matters (a lot) to a Drone Pilot

A pilot must understand and consider the magnetic field impacts prior to each flight. Without GPS risk management and Kp-index considerations, the pilot is open to GPS error, satellite lock loss, flight emergencies, or even injury to people, animals, or structures. The continuous data collection of the 13 observatories and the brilliant mind of Julius Bartel, make safe flight easier. And just like that, the normal churn of the Sun has a major impact on drone piloting. Remote pilots care because they have to. Drones can be expensive and intelligent, but even the drone has limited capabilities. Nobody wants to be involved in an air emergency, especially from negligence. The tools are available and the Kp-index prediction is free!

Thanks for reading!

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