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Hurricanes: Science and Society
Glossary - G
G
gale warning
A warning of 1-minute sustained surface winds in the range 34 kt (39 mph or 63 km/hr) to 47 kt (54 mph or 87 km/hr) inclusive, either predicted or occurring and not directly associated with tropical cyclones. Source NOAA-NHC.
genesis
The early development of a tropical cyclone.
GFDL model
National Weather Service (NWS) Geophysical Fluid Dynamics Laboratory model Source: NOAA-NWS
global model
Another global model used by NCEP is the Global Ocean Model. The ocean model forecasts seasonal changes in oceanic variables, such as sea surface temperature and ocean currents. The ocean model is coupled with an atmospheric model to help determine how forecasted changes in oceanic variables, such as sea surface temperature, will affect the atmosphere. This model tandem is not used to give detailed daily forecasts for the ocean or the atmosphere like some of the other models. Instead it is mainly used to help forecast seasonal or yearly variations of the ocean and the atmosphere. The ocean model coupled with the atmospheric model is used to forecast events such as an El Niño warming event in the Pacific Ocean and in long range seasonal outlooks. Source: NOAA-NWS SRH
Global Positioning System (GPS)
A navigation system based on a constellation of 24 low earth-orbiting satellites having highly accurate clocks and the computational capacity to triangulate positions near the surface of the earth. Developed by the U.S. Department of Defense, the system has the capability of determining position to an accuracy of 30–100 m. If systems at two locations are used with long integration times, positions may be determined within millimeters of a known reference position. Source: (c) 1999, American Meteorological Society. Used with permission.
GOES
Geostationary Operational Environmental Satellite: Applies to both the satellites themselves and to the overall system of geostationary observations used by the United States. The current operational series of GOES satellites were preceded by the ATS and SMS satellites, with GOES-1 being launched on 16 October 1975. The early GOES (1 through 7) were spin- stabilized spacecraft, while the latest GOES are three-axis stabilized. Two GOES satellites are normally in operation, one at 75° W longitude and the other at 135° W longitude. Before launch, GOES satellites are given a letter designation (e.g., GOES-J) that is changed to a number designation (e.g., GOES-9) when the satellite becomes operational. The current generation of GOES satellites supports separate imager and sounder systems, SEM and DCS. The imager is a five-channel scanning radiometer with a 1-km resolution visible channel, along with slightly lower resolution images in the midinfrared, water vapor, and thermal IR bands. The sounder has 18 thermal infrared bands and a low-resolution visible band. Source: (c) 1999, American Meteorological Society. Used with permission.
gravitational force
The force of attraction between all masses in the universe including the attraction of the mass of the earth for bodies near its surface
greenhouse warming
The heating effect exerted by the atmosphere upon the earth because certain trace gases in the atmosphere (water vapor, carbon dioxide, etc.) absorb and reemit infrared radiation. Most of the sunlight incident on the earth is transmitted through the atmosphere and absorbed at the surface of the Earth. The annual mean surface temperature of Earth is 15°C, which is .33°C higher as a result of the greenhouse effect than the mean temperature resulting from radiative equilibrium of a blackbody at the mean distance of the earth from the sun. The term greenhouse effect is something of a misnomer. It is an analogy to the trapping of heat by the glass panes of a greenhouse, which let sunlight in. In the atmosphere, however, heat is trapped radiatively, while in an actual greenhouse, heat is mechanically prevented from escaping (via convection) by the glass enclosure. Source: Glossary of Meteorology. (c)American Meteorological Society. Reprinted with permission.
grid
A set of points arranged in an orderly fashion on which specified variables are analyzed or predicted. Various forms of horizontal and vertical grids, each with particular characteristics, have been devised for use in numerical weather prediction. Source: (c) 1999, American Meteorological Society. Used with permission.
ground-truth
Any measurement of an observed quantity that can be used to validate or verify a new (often remote sensing) measurement or technique. Source: (c) 1999, American Meteorological Society. Used with permission.
Gulf Stream
Warm water current extending from the Gulf of Mexico and Florida up the U.S. east coast then east/northeast to Iceland and Norway.
gustiness
A brief sudden increase in wind speed. Generally the duration is less than 20 seconds and the fluctuation greater than 10 mph. Source: NOAA-NWS ERH
gyre
Oceanic current systems of planetary scale driven by the global wind system. Source: NOAA-NWS