### Glossary

Aerial photograph: a photograph of the Earth using a photo camera installed on an airplane. This photography can be done perpendicular or obliquely to the surface of the earth.

Albedo: is a number that can express the ratio between reflected and incident light for a particular object. If this object absorb the entire light, then the albedo is 0, or if can reflect the entire amount of light, then the albedo is equal to 1.

Altimeter: a device for measuring the altitude of a platform above a local datum.

Altitude: in remote sensing is the height of a satellite above the Earth surface; in geography altitude is a value, usually express in meters, above a medium sea level.

Azimuth: the distance measured in a clockwise direction from the north and expressed in degrees.

Boundaries: polylines or polygons indicating the limits between two different administrative units. A boundary can describe even a separation of two water masses, relief units, etc.

Buffer: a constant distance defined by user around a point/line/polygon. The resulting shape of this spatial analysis function will be a polygon.

Calibration: a technique of comparing and adjusting the values received from a sensor with values derived from the ground measurements. A calibration can be done for global and local products.

Climate: the average weather conditions recording in a time interval for a specific area.

Coverage map: the footprint coverage of a sensor projected on the earth surface.

El Nino: an irregular phenomenon that appears in the Pacific Ocean, which consist in a rise of sea surface temperature.

Hyperspectral imaging: a simultaneous acquisition of images for the same area, in many spectral bands.

Layer: a spatial dataset containing one theme or single feature type (roads, rivers, lakes, forest etc. Using the same projection different layers can be connected and analyzed.

Map Projection: a representation on a plan surface (2 dimensions) of a curved body like the earth (with 3 dimensions), using mathematical equations.

Map scale: indicates the relation between a distance measured on the earth and the corresponding value on the map.

Multispectral: two or more images at different wavelength for the same area.

Near real time data: data that are available for use at a short time after a process has been started.

Orbit: a path that describes the rotation of a satellite around the Earth, under the influence of gravitational or other forces. http://www.esa.int/eduspace.

Radiance: the entire amount of light emitted from a particular area in a specific direction. When this quantity is a response at some wavelength or frequency, became spectral radiance.

Real time data: data that are transmitted immediately from the satellite to a station on the ground.

Reflectance: a ratio between radiance energy, which come from an object, and the incident energy on it. At a specific wavelength became spectral reflectance.

Registration: is a process of matching points from an image to the corresponding points on the earth surface.

Resolution: for an image represents the minimum size of detail or the smallest feature than can be identified.

SST: Sea Surface Temperature.

Universal Transverse Mercator (UTM): a rectangular coordinate system derived from Mercator projection. The UTM divides the world into 60 zones of 6 degrees longitudes. The starting point is the 180-degree meridian taken from west to east. The advantage of this system is derived from the capacity to calculate more easily a distance between two points using Pythagorean theorem.

Smoothing: an average value generated from all the surrounding pixels, which replace the original data, in order to create a better transition between every cell. This method induced a generalization of the information for the entire image.

Swath width: the width measured on the ground, covered by a sensor in the along-track direction.

Wavelength: a distance measured between two wave crests.

Z value: the elevation value for a specific point at X/Y location. Underwater Z values are expressed like negative data bellow sea level.