Airborne and satellite based imaging sensors.   Airborne based sensors Airborne sensors collected data of the atmosphere, land, and ocean from multi-level platforms, each of which has its own unique advantages. Medium altitude (greater than 10 km) aircraft allow scientists to ride along with the sensors and monitor their performance in real-time. Whereas, high altitude (greater than 20 km) aircraft provide a wider perspective view of the earth scene below, which closely replicates the behaviour of space based sensors, as it is above the majority of the atmosphere. Click HERE and explore the following link and find out more about Airborne sensors Satellite based sensors The majority of the early satellite sensors obtained data for meteorological purposes, however recently earth resources satellite sensors have been developed with the main objective to map and monitor land cover. Presently there is more than 12 orbiting satellites of various sorts, (eg. ERS and RADARSAT) which supply data which is vital for increasing our awareness of Earth's atmosphere, oceans, ice and snow, and land. ERS satellites ERS-1 and ERS-2 are the first and second European Remote-Sensing Satellites. As they orbit the Earth in under 2 hours, within 35 days they have covered almost every corner of the earth's surface at least once. One of the main applications of the satellites is to almost constantly monitor the sea surface. The ERS data for oceanography is particularly important for the monitoring El Niño. For additional information on the ERS satellites click HERE RADARSAT RADARSAT is a sophisticated Earth observation satellite that provides large amounts of up-to-date data that operates no matter what the weather conditions are. RADARSAT also imparts useful information to commercial and scientific users, particularly within in the fields of cartography, forestry, ice studies and coastal monitoring. RADARSAT is an important and reliable source of environmental and resource information, and has provided one of the first routine surveillance of the entire Arctic region. such information is potentially useful to many people, especially government agencies with ice reconnaissance and mapping mandates and North American and European shipping companies. RADARSAT also facilitates the mapping and planning of land use and aid in the monitoring of disasters such as oil spills, floods and earthquakes. To find out more about these satellites click HERE