Geoscientist Heather Reese studies the Earth’s surface. A year ago she acquired a new tool for her toolbox. “That’s when I began using drones. And now I’m sold.”
Heather reese has been a senior lecturer at the Department of Earth Sciences since April of last year. She is studying Sweden’s mountains through remote sensing, using satellites and drones. With this method she can examine a landscape, phenomenon or object without coming into contact with it.
“I want to combine the drone and satellite data to look at alpine vegetation, among other things.”
Reese displays an image of a landscape on her computer screen. It actually is a composite of 400 drone photos that overlap each other 80 per cent, providing an overview. She turns and twists the landscape, and the image becomes three-dimensional. Vegetation shows up as several green shades and various formations emerge. You can distinguish clumps of trees, hills and people walking on a trail. Zooming in provides a resolution down to an area of only seven millimetres. Differences in height, shrubs and cracks in the peat – everything is visible in the detailed image on the computer.
the drone images cover an area of about 15,000 square metres on the border between Sweden and Finland, one hour’s drive from Karesuando. Heather went there for field studies in the autumn along with researchers and students from the Department of Earth Sciences. They mapped the area, much of which consists of what are known as “palsas”. The word palsa, which comes from the Sámi language and northern Finnish dialects, means a mound in the bog with a core of ice.
Palsas are small hillocks or plateau-shaped ridges in subarctic marshes. They form when the water found in the peat freezes. Additional layers of peat and ice form during the winter, causing the height of the palsa to keep increasing, especially when continuously frozen ground, permafrost, reaches the mineral soil beneath the peat. Within the palsa ice lenses form, and the ground rises several metres above the surrounding bog.
“Many people do not know about the phenomenon. The area visible here in the photo is an interesting place with many palsas permeated with permafrost and covered with peat,” says Reese, pointing to the green mounds in the landscape.
palsas had been widespread in northern Sweden until the 1960s. As the climate changed, many palsas thawed, sank and simply collapsed, while methane and carbon dioxide leaked out into the surroundings.
When a palsa collapses, water-filled pools form on the surface of the palsa or along its edges.
Reese points to a small pool in the green landscape.
“This small lake formed in 2018. It is an edge of a palsa that has collapsed. We can make use of remote sensing data in this way to study vegetation and water as well as formations in the landscape such as palsas. When we have remote sensing data that goes back in time, such as aerial photographs from the 1960s, we can record what changes have taken place. This palsa has shrunk a lot since the 1960s.”
on the table next to the computer is the drone Reese uses in the research: a DJI Phantom, purchased for SEK 18,000. In addition to the original camera, a special camera has been mounted on it.
“The special camera has an infrared sensor that can record not only red, green and blue light, but also near-infrared wavelengths. This means it provides more detailed information and can identify different types of vegetation on the ground.”
Despite its small size, the drone contains features similar to those in a satellite.
“But drones provide greater flexibility when we are collecting data. The other important difference is that the drones we researchers use fly much lower, at a height of no more than 120 metres according to flight restrictions. To fly higher, you need to apply for a permit. We get very detailed pictures, but we cannot cover areas as large as with a satellite.”
reese, who comes from New York state, received her Master’s degree in remote sensing and geographic information systems (GIS) in the United States and had already begun research in the field in 1990. During nearly three decades as a researcher, she has seen major changes in the research field. And followed how the tools have evolved.
“When I started, I could work with only a small part of a satellite image at a time. Now I can process many at the same time. Computing power has increased enormously.”
Changes interest Reese. Whether it is about palsas or the treeline. Or vegetation. She wants to know more about “greening”, the growth of shrubbery in the alpine world, and what is called “browning”, which also is now occurring there.
“A recent Norwegian study done with remote sensing shows that in several places in Norway where snow cover has declined, vegetation has frozen and died.”
An important research project currently under way is Reese’s mapping of Sweden’s mountains using satellite data. The project, which receives funding from the Swedish National Space Board, uses satellite images to make time series. European satellites have been taking photos every other day in northern Sweden since 2015.
“This makes it possible to monitor the seasons. That was interesting to monitor last summer when temperatures were so high that the snow cover melted faster than usual. When snow and ice disappeared, vegetation reappeared in a week. It went incredibly fast!”
during the previous century, the development of remote sensing took a giant leap forward. And today, when satellites and drones are commonplace, great advances are being made.
How old is the research field of remote sensing?
“You might say it started with a man in a hot air balloon in 1858 who took pictures of Paris, and then a man in an airplane,” says Reese.
Research using remote sensing
When it became possible for people to fly, remote sensing also emerged. Remote sensing was primarily developed by the military. For example, remote sensing was used during World War I to spy on the enemy and estimate its military strength. But military technology for remote sensing has often passed into civilian applications in many fields, such as geology, geography and urban planning.
Remote sensing has two components. One is a platform, which can be a drone, an airplane or a satellite. The other is a sensor. This can be an optical sensor (such as a camera), a laser scanner or radar. The data, which has geographic coordinates, can be inserted into a geographic information system (GIS) for further analysis.
... drones, which have revolutionised many different areas. How do you use drones in your field, what are the benefits and what does the future hold?
Head of the Fish Management Department, Swedish Agency for Marine and Water Management.
”Drones are used to find illegal eel fish traps. So far we have carried out pilot efforts in Skåne County to learn how to use drones and become acquainted with their limitations. The advantage of the drones is that they make searches more effective. With drones we can cover large areas in a short time, and if we locate any equipment, we can go out with a boat to pick it up. Searching with a boat takes much longer. However, weather conditions and visibility in the water limit the possibility of using drones. Next we will be applying for permits in more counties to expand the areas in which we may use drones, starting with a larger portion of the east coast than just Skåne County. Generally, we see great opportunities for developing the use of drones in fisheries inspection and enforcement.”
Command teacher at the Swedish Civil Contingencies Agency (MSB), Unit for Professional Development.
”Since 2014 we have been using drones to train officers in the municipality rescue service at MSB’s school in Revinge. Drones are used in combination with the pilot in response management, which is to provide support for better decision-making in final exercises.
The main advantage of the drones is that you can quickly get a different perspective on an accident with a drone in the air. You can see the extent of the accident, alternative roadways, the spread of smoke or hazardous substance. And with the right sensor and analysis of data, you can make calculations and use them to forecast expected outcomes. We are not using drones in operations today, but we have done a study on how they could be used in our reinforcement resources. Personally, I am convinced that we will be using drones more than we do now.”
CEO and cofounder at Inkonova AB, a company that manufactures drones that can fly, swim and climb.
”Commercially, aerial robots (drones) are used for survey, mapping and inspection, filmography and photography and to a lesser extent delivery and mechanical engagements. Industries include oil & gas, mining, agriculture, land surveys, utilities and infrastructure.
As we progress in areas like battery, sensor, control, swarm control, propulsion, autonomous navigation technology, we’ll see more penetration of drones’ into different industries and our everyday lives and it will follow the trend of robotics in general; as force of automation and risk aversion.
As with technology in general, its developed for good but can be used for bad, but overall I see it as positive force as long as we collectively regulate it towards the good.”
Is: Senior lecturer at the Department of Earth Sciences
Current research projects: Mapping of Sweden’s mountains using satellite data, and operational mapping of alpine vegetation types in the new National Land Cover Map.