The future of Earth observation in hydrology

Abstract

Abstract. In just the past 5 years, the field of Earth observation has progressed beyond the offerings of conventional space-agency-based platforms to include a plethora of sensing opportunities afforded by CubeSats, unmanned aerial vehicles (UAVs), and smartphone technologies that are being embraced by both for-profit companies and individual researchers. Over the previous decades, space agency efforts have brought forth well-known and immensely useful satellites such as the Landsat series and the Gravity Research and Climate Experiment (GRACE) system, with costs typically of the order of 1 billion dollars per satellite and with concept-to-launch timelines of the order of 2 decades (for new missions). More recently, the proliferation of smartphones has helped to miniaturize sensors and energy requirements, facilitating advances in the use of CubeSats that can be launched by the dozens, while providing ultra-high (3-5 m) resolution sensing of the Earth on a daily basis. Startup companies that did not exist a decade ago now operate more satellites in orbit than any space agency, and at costs that are a mere fraction of traditional satellite missions.With these advances come new space-borne measurements, such as real-time high-definition video for tracking air pollution, storm-cell development, flood propagation, precipitation monitoring, or even for constructing digital surfaces using structure-from-motion techniques. Closer to the surface, measurements from small unmanned drones and tethered balloons have mapped snow depths, floods, and estimated evaporation at sub-metre resolutions, pushing back on spatio-temporal constraints and delivering new process insights. At ground level, precipitation has been measured using signal attenuation between antennae mounted on cell phone towers, while the proliferation of mobile devices has enabled citizen scientists to catalogue photos of environmental conditions, estimate daily average temperatures from battery state, and sense other hydrologically important variables such as channel depths using commercially available wireless devices. Global internet access is being pursued via highaltitude balloons, solar planes, and hundreds of planned satellite launches, providing a means to exploit the "internet of things" as an entirely new measurement domain. Such globalPublished by Copernicus Publications on behalf of the European Geosciences Union. The future of Earth observation in hydrology access will enable real-time collection of data from billions of smartphones or from remote research platforms. This future will produce petabytes of data that can only be accessed via cloud storage and will require new analytical approaches to interpret. The extent to which today's hydrologic models can usefully ingest such massive data volumes is unclear. Nor is it clear whether this deluge of data will be usefully exploited, either because the measurements are superfluous, inconsistent, not accurate enough, or simply because we lack the capacity to process and analyse them. What is apparen...

Spatial assessment of the performance of multiple high‐resolution satellite‐based precipitation data sets over the Middle East

“…With advances in space science and hydrological remote sensing instruments and retrieval techniques (McCabe et al ., ), many remotely sensed precipitation products have been made publicly available for research community, mostly from the late 1970s onwards. These multiple remotely sensed data sets employ different retrieval schemes, merging estimates from microwave, infrared, and sounder data from an international constellation of precipitation‐related satellites (Adler et al ., ; Huffman et al ., ).…”

Similarities and Improvements of GPM Dual-Frequency Precipitation Radar (DPR) upon TRMM Precipitation Radar (PR) in Global Precipitation Rate Estimation, Type Classification and Vertical Profiling

“…Other efforts such as the constructing constellation of various instruments and platforms can make a great contribution as well. NASA's Jet Propulsion Laboratory's (JPL's) new mission, RainCube, takes advantages of a number of CubeSat satellites and pairs of low-cost Ka band radar system to achieve a more frequent earth observation with higher temporal and spatial resolution [78,79]. Allamano et al have explored the use of mobile video and imagery to capture and analyze precipitation events, showing that crowd-source projects have a promising future in earth observation [79,80].…”

Tracking Dynamic Northern Surface Water Changes with High-Frequency Planet CubeSat Imagery

“…2017, 9, 1306 3 of 22 about cross-sensor calibration, image quality, geolocation accuracy, and data availability have limited the advent of CubeSat-based hydrological research. Despite the strong potential of frequent, highresolution CubeSat imagery to transform hydrological remote sensing, such data remain generally untested and unproven within the hydrologic community [27].…”

“…Owing to their small size and low cost, CubeSat imagers can overcome the tradeoff between high spatial and high temporal resolution by deploying them in a multi-satellite constellation. This approach relies on both satellite mass production and declining launch costs, making CubeSats comparatively affordable for commercial satellite companies to launch and operate [27]. A notable example is Planet (formally known as Planet Labs; http://planet.com), a company that has successfully built and launched 281 CubeSats since 2013.…”