Accurate rainfall detection and estimation are essential for many research and operational applications. Traditional rainfall detection and estimation techniques have achieved considerable success but with limitations. Thus, in this study, the relationships between the gauge (point measurement) and the microwave links (MWL) rainfall (line measurement), and the MWL to the satellite observations (area-wide measurement) are investigated for (area-wide) rainfall detection and rain rate retrieval. More precisely, we investigate if the combination of MWL with Meteosat Second Generation (MSG) satellite signals could improve rainfall detection and rainfall rate estimates. The investigated procedure includes an initial evaluation of the MWL rainfall estimates using gauge measurements, followed by a joint analysis of the rainfall estimates with the satellite signals by means of a conceptual model in which clouds with high cloud top optical thickness and large particle sizes have high rainfall probabilities and intensities. The analysis produced empirical thresholds that were used to test the capability of the MSG satellite data to detect rainfall on the MWL. The results from Kenya, during the “long rains” of 2013, 2014, and 2018 show convincing performance and reveal the potential of MWL and MSG data for area-wide rainfall detection.

Abstract. We propose a new technique that overcomes the obstacles of the existing methods for monitoring near-surface water vapour, by estimating humidity from data collected through existing wireless communication networks.Weather conditions and atmospheric phenomena affect the electromagnetic channel, causing attenuations to the radio signals. Thus, wireless communication networks are in effect built-in environmental monitoring facilities. The wireless microwave links, used in these networks, are widely deployed by cellular providers for backhaul communication between base stations, a few tens of meters above ground level. As a result, if all available measurements are used, the proposed method can provide moisture observations with high spatial resolution and potentially high temporal resolution. Further, the implementation cost is minimal, since the data used are already collected and saved by the cellular operators. In addition -many of these links are installed in areas where access is difficult such as orographic terrain and complex topography. As such, our method enables measurements in places that have been hard to measure in the past, or have never been measured before. The technique is restricted to weather conditions which exclude rain, fog or clouds along the propagation path. Strong winds that may cause movement of the link transmitter or receiver (or both) may also interfere with the ability to conduct accurate measurements.We present results from real-data measurements taken from two microwave links used in a backhaul cellular network that show convincing correlation to surface station humidity measurements. The measurements were taken daily in two sites, one in northern Israel (28 measurements), the other

[1] Here we show the potential for dense fog monitoring using existing measurements from wireless communication systems. Communication networks widely deploy commercial microwave links across the terrain at ground level. Operating at frequencies of tens of gigahertz, they are affected by fog and are, practically, an existing, sensor network, spatially distributed worldwide, which can provide crucial information about fog concentration and visibility. The goal of this paper is to show the feasibility for fog identification and intensity estimation. A method is proposed and is demonstrated by two cases of heavy fog that took place in Israel. During these events, fog covered wide areas (tens of kilometers) and caused severe decrease in visibility, dropping as low as several tens of meters. Liquid water content and visibility values were estimated using measurements from tens of microwave links deployed in the observed area for each event. Each of the links provided a single measurement which was taken simultaneously across all of the links in the system. The values were found to be in the range of 0.5-0.8 gr/m 3 , high concentration values that match the maximum value range observed in field measurements carried out for prior studies in different test areas in the world. The visibility ranges calculated, between 30 and 70 m, fit the visibility assessments from the specialized measuring equipment operating in the observed area at the same time. These results point to the strong potential of the proposed technique.Citation: David, N., P. Alpert, and H. Messer (2013), The potential of commercial microwave networks to monitor dense fog-feasibility study,

Severe visibility limitations resulting from fog may lead to acute transportation accidents and high losses of property and lives. Thus, reliable monitoring facilities are of extreme importance. Nevertheless, current monitoring instruments suffer from low spatial resolution, high costs, or lack of precision at near-surface levels. It has, however, recently been shown that the commercial microwave links that form the infrastructure of cellular communication networks can provide crucial information regarding the appearance of dense fog and its intensity. Typical microwave systems currently in operation make use of frequencies between 6 and 40 GHz and, thus, can only monitor heavy fog. However, there is a growing demand for high data rates and expanded bandwidth in modern mobile radio networks. As a result, higher frequencies (e.g., around 80 GHz) are being implemented in order to fulfill these increased requirements. Notably, the attenuation induced as a result of fog at a given intensity increases as operating frequency rises, allowing, for the first time, the possibility of using this system to monitor typical fog intensities, at high resolution and low cost. Here, a theoretical simulation is presented in which simulated fog patches are introduced into an area where a network of links is deployed. Two-dimensional maps are generated utilizing the simulated microwave network to represent sensitivity thresholds for fog detection at three different frequencies: 20, 38, and 80 GHz. Real-data measurements of fog are also demonstrated using 38-GHz band links. The results indicate the vast future potential of commercial microwave links as an opportunistic system for monitoring fog.

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