Environmental Electronic Sensing Systems

Although environmental measurement instrumentation has been utilized by human civilizations for thousands of years, the use of electronics to conduct measurements closely parallels the development of electrical theory from the 19th century to the present. Environmental electronic sensing systems have been created to automate measurement tasks that are difficult for humans to repeat in a precise and synchronous fashion or to measure phenomena that cannot be manually observed at scales ranging from the microscopic to the planetary. The collection and recording of data at regular timesteps enable inputs to mathematical models that provide predictions and forecasts of environmental processes; moreover, these models can be used to better understand planetary systems. Data measurements conducted at different scales can be subjected to statistical or scaling analysis to provide gridded data sets for application of mathematical models. Point measurements made at a single geographic location provide calibration or validation for satellite remote sensing data products. Measurements made by different sensors can be utilized along with sensor fusion algorithms to calculate indexes or gridded data sets. The sources in this article have been selected to provide an overview of the sensors and associated sensing systems that measure components of the environment on or near the surface of the Earth. Each first-level heading demarcates different environmental components. The final section of the article provides a selection of references pertaining to the engineering of sensor networks that are used to obtain areal measurements of environmental processes. Each section contains a series of subsections that divide the literature according to the type of sensor or measurement. An emphasis is placed on the selection of references that provide insight into the measurement physics of the sensor and the environmental physics of the phenomena being measured. Moreover, references are selected that provide schematic diagrams and engineering design considerations suitable for replication and development of new sensors. Papers on sensor calibration and error analysis as well as case studies are included for operational use and field deployment applications. Due to the numerous papers that have been published on environmental sensing systems, it is not possible to cite all available literature pertaining to a certain type of sensor. To close gaps in the literature and to provide ideas for students, instrument developers, engineers, and environmental scientists, overview papers are also provided in this article. These overview papers often present ideas in a succinct fashion and the associated sensor mathematics, design, and signal processing are provided in a manner to enhance pedagogical value.