@prefix cpm: . @prefix dc: . @prefix dcat: . @prefix dce: . @prefix dct: . @prefix grg: . @prefix iop: . @prefix ns0: . @prefix ns1: . @prefix owl: . @prefix pav: . @prefix prov: . @prefix puv: . @prefix qudt: . @prefix rdf: . @prefix rdfs: . @prefix reg: . @prefix semapv: . @prefix skos: . @prefix sssom: . @prefix void: . skos:member . skos:altLabel "GLAS" , "GLAS"@en ; skos:broader , ; skos:definition "A laser-ranging (lidar) instrument designed to perform continuous global observations of clouds, atmospheric properties and ice-sheet topography, used for short-term climate and weather prediction. The instrument includes a laser system, a telescope, a Global Positioning System (GPS) and Stellar Reference System (SRS), the latter composed of a star tracker and a Laser Reference System (LRS). The laser transmits two pulses at 40 Hz of visible green light (1064 nm) and infrared light (532 nm) towards the Earth's surface, the return signals of which are detected by the telescope and recorded along the laser pointing vector. The time interval taken by the laser pulse to make a round trip from the instrument to the Earth's surface and back, can be converted into distance; this series of altimeter measurements, together with positional measurements and calibrations carried out by the various instrument components, can be assembled to determine surface topography as well as temporal changes in surface topography. The instruments samples along-track (nadir only view) at intervals of 170m within an instantaneous field of view (IFOV) of 66m. The vertical resolution is 10cm at the surface, and 200m at cloud top. Flown on ICESat. http://www.wmo-sat.info/oscar/instruments/view/155"@en ; skos:inScheme ; skos:notation "SDN:L22::TOOL1079" ; skos:note "accepted"@en ; skos:prefLabel "Geoscience Laser Altimeter System"@en . skos:narrower . skos:narrower . skos:narrower . skos:narrower .