The term “remote sensing” sounds decidedly hi-tech and at first glance many people assume it has something to do with complex production processes, the truth is that these small, smart pieces of tech are being used across the globe in a number of highly practical applications, that are changing the way we live every day.
Remote sensing essentially means “measured from a distance”, and in many cases these remarkable sensors change the way we see, measure and interpret the world around us. We’ve gathered together some of the more important ways in which remote sensor technology is affecting the everyday lives of millions of people across the world.
Oil spills pose a significant threat to marine and human life. Detecting oil spills via remote sensors dramatically improves response times, and ultimately reduces the hazardous consequences. Currently the Scanning Laser Environmental Airborne Fluorosensor (SLEAF) is the most comprehensive remote oil spill sensing system in use. The system utilises the unique way in which certain aromatic hydrocarbon compounds in petroleum oils absorb laser-induced UV light, becoming electronically excited. This excitation then releases a fluorescence emission, largely within the visible spectrum. These specially designed sensors can then “see” and record the fluorescent data overlaid by geo-referenced maps, giving scientists detailed data on the nature and extent of an oil spill.
Safe Air Travel
Other satellite-mounted remote sensors allow scientists to monitor dust and ash from volcanic eruptions, which are hazardous for aircraft. With more detailed, current information about hazards in their flight-path, pilots can better assess risks and make informed decisions before taking off. This is increasingly important as the volume of worldwide air traffic continues to increase.
Studying the Biome
Light Detection and Ranging (LiDAR), is a high-precision sensor that is used to gather important 3D surface information. One of the most crucial abilities of these types of sensors is that they can measure the height and canopy of surface vegetation and forests from an “aerial platform” – usually a satellite. The information gathered in this way assists with everything from tracking deforestation, to predicting the growth and success of crops, and measuring alien vegetation infestations.
Satellite-derived drought indicators, such as the Evaporative Stress Index (ESI) is a promising development in predicting what scientists call “flash droughts” – fast developing meteorological conditions. This innovative drought index uses remote sensor technology to depict changes in the amount of water vapour released by vegetation. Decreases in soil moisture in the root zone can reduce the amount of water released through transpiration, and so a decrease in water evaporation by the plant indicates dry root conditions, long before any visible sign of decline is seen.
Where to Position a Solar Panel
Global Horizontal Irradiance (GHI) is the total amount of shortwave radiation received from above by a surface horizontal to the ground. This data is particularly useful to anyone installing a solar panel, or larger photovoltaic installation, as it includes both Direct Normal Irradiance (DNI) data and Diffuse Horizontal Irradiance (DIF) data and shows the rate of total incoming solar energy at the Earth’s surface in watts per square kilometer. The Global Horizontal Irradiance (GHI) map is developed using highly specialised remote sensors that measure solar surface radiation indirectly, via reflections on the Earth’s surface.
Monitoring Healthy Vegetation
The global food supply is being monitored with satellite imagery and the Normalized Difference Vegetation Index (NDVI) where near-infrared radiation sensors are tracking healthy vegetation in agriculture. Healthy vegetation reflects green light and absorbs red and blue light. Healthy plants, as we know, are green to the eye – this indicates high levels of chlorophyll, which reflects more light in the green and near infrared spectrum compared to other wavelengths emitted by barren and arid regions of the Earth’s surface.
Earth's Shifting Gravity
GRACE stands for Gravity Recovery and Climate Experiment, and is a recently completed mission conducted by NASA. The mission consisted of two satellites in the same orbit approximately 220 kilometres apart. When the leading satellite increased its speed, it meant a greater gravitational pull. When the leading satellite slowed down, it meant less gravitational pull. These pulls in gravity were measured using microwave pulses from one satellite to the other, and have resulted in the most accurate “map” of the Earth’s gravitational field to date. By sensing minute changes in the Earth’s gravitational field the data has revealed how water, ice and solid earth masses move on or near Earth's surface due to changes in how water is constantly being redistributed around the planet. The mission revealed deep insights about climate change, rising sea levels and ocean topography.
The variety of remote sensing technologies is astounding, and today we can mount remote sensors that can track and measure everything from UV light and wind speed, to temperature, radiation, humidity and even changes in colour. Tracking and monitoring the environment around us – both on a macroscopic scale such as the satellite-based examples we explored here, or on a more localised scale such as the sensors distributed by Xemote, increases our understanding and control of the environment, enabling better, swifter and more informed decisions.