Can we measure evaporation using commercial microwave links?

The aim of this study is to investigate whether it is feasible to obtain evaporation estimates from commercial microwave links, which are normally used for telecommunication. These commercial microwave links are already used to monitor path-averaged precipitation by determining the rain-induced attenuation along the link path. The signal transmitted by these microwave links is also perturbed by turbulence during dry periods, which consists of diffraction of the emitted beam by turbulent eddies. This is known as the scintillation effect and special microwave links, called scintillometers, have been designed to measure the full spectral range of the signal intensity fluctuations caused by the scintillation effect and link these fluctuations to the turbulent heat fluxes. However, commercial microwave links are usually sampled at too low temporal resolution to directly capture all the relevant scintillation fluctuations (typically between 0.1 – 100 s). Currently, the links are most often sampled at a temporal resolution of 15 minutes with a recording of the minimum and maximum values, while more recently also “active” forms of sampling with possible intervals up to 1 s have been set up. We intend to investigate what kind of sampling is required to obtain the structure parameter of the refractive index, C_nn, from commercial microwave link data. We will use high resolution sampling rates, which we resample to mimic various commercial sampling strategies. Subsequently, we aim to compute evaporation through deriving the structure parameters for temperature, C_tt, and humidity, C_qq, through a combination with auxiliary data. For this research, we will use data from a dual-beam scintillometer setup, a RPG-MWSC 160 GHz and a Large-Aperture Scintillometer with a 15 cm diameter over a 850 m path over the Ruisdael Observatory at Cabauw, the Netherlands. Additionally, we will install a Nokia Flexihopper 38 GHz, formerly part of a telecom network in the Netherlands, serving as our commercial microwave link. On the measurement site, many other relevant meteorological measurements for studying evaporation (e.g. temperature, humidity, turbulence and energy fluxes) are performed, which we will use as auxiliary and reference data. During this poster session, we would like to present our research plans and invite fellow session participants to join the discussion and give feedback on our ideas.