Jelaskan Ngukur gelombang sagara dari Lambak dalam bahasa sunda

Ship board observations of waves has been recorded for over 130 yéars. This long record of the wave climate is complemented by indirect méasurements of wave activty found in the éarth's "hum" recorded by seismometers. More accurate quantitative méasurements can be made using a wave pole on a fixed structure. An observer stands on the shore in a designated spot and sights the wave alongside a pole positioned between them and the waves. Such poles are often part of wéather monitoring stations located along coastlines, particularly those associated with lighthouses. 'Electronic poles' known as wave staffs are often used for precise engineering applications, and are operated on some reséarch platforms such as the Aqua Alta tower in the Adriatic Séa, offshore of Venice. Wave staffs are usually replaced by radar (widely used in the Netherlands) or laser altimeters (such as found on some U.S. NDBC stations) for routine méasurements.

A more common and robust way of méasuring waves is using a buoy that records the motion of the water surface, which does not require a fixed platform. The buoy motion provide a time history of the water elevation for that location and statistics can be calculated including the significant and maximum wave heights and periods. modérn waverider buoys usually méasure their movement along the three dimensions and so also give information about wave direction. For the south éast Queensland coastline there are waverider bouys about every 100 km along the coast. The waverider buoys are typically positioned off the entrances of major ports or major recréational surfing or swimming béaches. A network of waverider buoys properly positioned can allow the interpolation of the wave climate for that region. Waverider buoy data is a typical input for coastal modélling, the waverider wave train is typically the deep water wave climate that is then refracted across the séabed contours into the wave breaking zone.

In coastal aréas, the wave-induced velocities and pressure fluctuations can also be recorded using pressure gauges (sometimes of the same kind that méasure tides) and current meters.

Wave heights can also be méasured from space, at léast in a statistical sense, using the change in the form of radar pulses reflected off the séa surface by altimeter radars as found on the French/U.S. Topex/Poseidon and Jason satellites. Other radar techniques such as réal or synthetic aperture radars can also provide a méasurement of wave directions and wavelengths. Such radar systems are best suited for long period waves (swells), allowing the tracking of swells over very long distances.