Instrument training at RPG Radiometer Physics, Meckenheim, Germany
Heather Guy
Heather Guy
Two of the flagship instruments that will be part of the Automated Unit for Remote Observations and Research of the Atmosphere (AURORA) are currently being built by RPG Radiometer Physics: specialists in microwave remote sensing who are based in Meckenheim, Germany.
The vertically pointing cloud radar will be our gold-mine for information when it comes to understanding clouds over Greenland and how they impact the energy budget of the ice-sheet. This will be the only instrument that can “see” through multiple layers of thick cloud, providing information on cloud height and thickness as well as detailed information about small scale variability inside clouds, which is related to how cloud particles form and mix with the surrounding air. The second instrument from RPG – the microwave radiometer – measures the ambient microwave emissions of the atmosphere. This microwave signature is related to the temperature and humidity profile of the atmosphere and the amount of liquid water. Knowing how much liquid water is in the atmosphere is critical because even small amounts can have large impacts on the radiation balance at the surface. Understanding the vertical profile of temperature and humidity will help us to understand how energy is transported down through the atmosphere to the ice sheet surface.
Michael, Heather and Sarah excited to be at RPG!
Operating these instruments and interpreting the data requires specialist knowledge, and so the GAMB2LE team were invited to Meckenheim to visit the factory and receive training from the manufacturers prior to the instrument’s delivery. We came armed with questions and were rewarded by four long and intensive days of learning. We practised physically installing both instruments, learnt about the software operation, viewed the assembly lines in the factory, and filled notebooks with the theory and equations of microwave remote sensing.
Both instruments need calibrating with reference points of accurately known temperatures. For the cold temperature reference point, we use liquid nitrogen, that has a well characterised boiling point of -195.8°C. This means we need to understand how to handle liquid nitrogen to perform the instrument calibrations – a particularly exciting component of the training!
Understanding the complete measurement chain from the design and build of the physical hardware, to software and data collection limitations, to how the raw signals are converted to useful atmospheric variables, was especially rewarding. We now have a much fuller understanding of the capabilities, limitations, and uncertainties of the measurements from both instruments that we hope to propagate forward into our data products.
Hopefully we can still remember it all when the instruments arrive in December!
Sarah and Heather practicing installing the Microwave Radiometer.
Heather filling the radar calibration target with liquid nitrogen.