Earthobservation

Earth observation is the collection, analysis, and interpretation of information about the Earth's surface, atmosphere, and oceans using remote sensing technologies. This includes data gathered from satellites, aircraft, and ground-based sensors, often integrated with in situ measurements, weather observations, and geospatial information systems to monitor change over time.

Sensors used in Earth observation include optical imaging in visible and near-infrared bands, multispectral and hyperspectral sensors, and radar instruments such as synthetic aperture radar (SAR). Lidar and altimeters measure surface elevation and height. Data are produced by national space agencies and international programs, such as Landsat (USGS/NASA), Sentinel under the Copernicus program (ESA), and NASA MODIS, as well as commercial satellite and air-borne campaigns.

Applications span environmental monitoring, agriculture, forestry, water resources, urban planning, disaster management, climate research, and public health. Open access to many datasets has accelerated research and decision making; examples include Landsat data and Copernicus Open Access Hub, which provide long-term archives for free or low-cost use.

Benefits are balanced by challenges, including limitations from cloud cover in optical data, varying spatial and temporal resolutions, processing demands, data volume, and privacy concerns. The field has evolved with higher-resolution sensors, more frequent revisits, and advances in machine learning for image interpretation, while governance emphasizes international collaboration and standardized data formats.