A Swiss funnel in Tibet: WSL device verifies satellite measurements

The renowned science journal Nature Scientific Data recently published interim results of a project [1] with which I am very closely connected as a WSL employee.

I remember very well the day when Prof. Bob Su from the University of Twente (Netherlands) called me in 2015. He wanted to use an L-band radiometer for a project in Tibet. In fact I had developed such an instrument together with the GAMMA REMOTE SENSING company (Gümligen BE) [2]. At that time the device was available for tests on the premises of the WSL. The employees jokingly used to call it “funnel” because of its peculiar appearance just like a funnel.

But what did Professor Su want to do with it on the Tibetan plateau?

The microwave emissions from soil, vegetation and snow indicate how much water they contain. This information is important to better understand the global water cycle and to improve the reliability of weather forecasts. To this end, the European Space Agency (ESA) is carrying out a long-term satellite mission called “Soil Moisture and Ocean Salinity” (SMOS). One of the goals of the SMOS mission is to measure the soil-water content on a global scale. In order to correctly interpret the data recorded by satellite, ground-based comparative measurements are an important aid. Thus, the ESA commissioned the international research group of Prof. Su [3] to carry out such measurements on the Tibetan plateau.

During the development work at GAMMA and at the WSL I established good contacts and occasional cooperation with the ESA. I was familiar with both the technical and the scientific side of the project that had just been launched, thus I was not surprised to get the research group’s request.

I quickly realized that the transport and commissioning of this large apparatus to Tibet would be a challenge. So I linked my collaboration to this condition: The professionals involved had to learn how to operate the “funnel” in Birmensdorf and they needed to know how to dismantle it by themselves for its transport all the way to Tibet.

In November 2015 we organized a radiometer workshop at the WSL. Together with Donghai Zheng and Prof. Yijian Zeng from the University of Twente, Dr. Jun Wen of the Chinese Academy of Sciences also joined us. For three days the three scientists immersed themselves in the basics of radiometry and learned how to handle the research device. On the last day, they then dismantled the “funnel” into its components for the airfreight transport.