US: A group of researchers including scientists from the US Department of Energy”s Lawrence Berkeley National Laboratory (Berkeley Lab) developed a new approach that combines several remote-sensing tools to study the Arctic landscape — above and below ground — in high resolution and over large spatial scales.
They use ground-penetrating radar, electrical resistance tomography, electromagnetic data and LiDAR airborne measurements. Together, these tools allow the scientists to see the different layers of the terrestrial ecosystem, including the surface topography, the active layer that seasonally freezes and thaws and the deeper permafrost layer. The research was recently published online in the journal Hydrogeology.
Their research is one of the first papers published in association with a new Department of Energy project called the Next-Generation Ecosystem Experiment (NGEE-Arctic), which seeks to gain a predictive understanding of the Arctic terrestrial ecosystem”s feedback to climate. The NGEE-Arctic project is collaboration among scientists and engineers at Oak Ridge National Laboratory, Los Alamos National Laboratory, Brookhaven National Laboratory, Berkeley Lab and the University of Alaska Fairbanks.
“By combining surface geophysical and airborne remote-sensing methods, we have a new window that allows us to study permafrost systems like never before,” said Susan Hubbard, a geophysicist in Berkeley Lab”s Earth Sciences Division who leads the Lab”s participation in the NGEE-Arctic collaboration.
The scientists tested their system on a plot of land near Barrow, Alaska, that measures about 500 meters long and 40 meters wide. Hubbard and her team conducted their first field campaign at the site last fall when the system was freezing up. They”ve since returned several times to conduct more research.
To characterise the land surface, they used data from a remote sensing device called LiDAR, which is short for Light Detection and Ranging. The device was mounted on a Cessna aircraft. It uses light to measure the microtopography, which controls water drainage in the Barrow region.
The scientists use data from airborne LiDAR, surface geophysical measurements and point measurements to explore the complex relationships between different layers of permafrost soil.
The scientists also used three tools to explore the hidden world below the surface. Ground-penetrating radar was pulled from one end of the plot to the other. They set up a string of electrodes at different locations to conduct electrical resistance tomography measurements. Electromagnetic data was collected along more than a dozen lines that spanned the length of the plot. The scientists also collected point measurements of temperature, moisture, and other properties at several locations to verify the data from the remote-sensing tools.
These geophysical measurements, coupled with the point measurements, allowed the scientists to see how the different layers of the permafrost system vary spatially, including the topography, the active layer, and the deeper permafrost. They could also see how these layers relate to each other.
These new vantages will enable the team to learn much more about how permafrost systems change over time — and what this means for trapped carbon.
Source: Science Daily