Satellite Imagery Meteorology 101 Lab 9 December 1, 2009.
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Satellite Imagery Meteorology 101 Lab 9 December 1, 2009
Satellites October 4, 1957 – Russia launched Sputnik 1, the first satellite in history –As a result, space science boomed in America as it led Americans to fear that the Soviets would launch missiles containing nuclear weapons. 1959 – Scientists at the Space Science and Engineering Center (SSEC) at UW- Madison conducted pioneering meteorological satellite research, revealing the vast benefits of meteorological satellites. http://burro.astr.cwru.edu/stu/a dvanced/20th_soviet_sputnik. html
Evolution Until Today First weather satellite lasted 79 days Now many years Two distinct types of weather satellites –GOES - Geostationary Operational Environmental Satellites -POES - Polar Operational Environmental Satellites (also referred to as “LEO” – Low Earth Orbit) They are defined by their orbital characteristics There are also many other satellites in orbit, some of which are not functioning and those are referred to as “space debris”.
Geostationary Vs. Polar Orbiting http://cimss.ssec.wisc.edu/satmet/modules/sat_basics/images/orbits.jpg
GOES GOES: Geostationary Operational Environmental Satellites Orbit as fast as the earth spins Maintain constant altitudes (~36,000 km, or 22,300 miles) and momentum over a single point, always over the equator Imagery is obtained approximately every 15 minutes unless there happens to be an important meteorological phenomenon worth higher temporal resolution Generally has poor spatial resolution- sees large fixed area and covers polar regions poorly. But, good for viewing large scale meteorological phenomena (cyclones, hurricanes, etc.) at lower and middle latitudes
GOES GOES- EAST (GOES- 12) GOES- WEST (GOES – 11)
POES POES: Polar Operational Environmental Satellites Rotates around the earth from pole to pole Significantly closer to the Earth than geostationary satellites (879 km above the surface) Sees the entire planet twice in a 24 hour period Lower altitude gives it a good spatial resolution: Very high resolution images of the atmosphere and Earth Poor temporal resolution: Over any point on Earth, the satellite only captures two images per day! Best resolution over the poles
POES More then a few in orbit currently Two examples are TERRA and AQUA Have different viewing instruments on them One example is MODIS: Moderate Resolution Imaging Spectroradiometer Acquires data in 36 spectral bands (groups of wavelengths) As a result, MODIS can create a true color visible image, which can: –Show changes in vegetation during fall/spring –Show smoke plumes, dust plumes, etc.
Example MODIS image http://modis.gsfc.nasa.gov/gallery/individual.php?db_date=2009-11-13
Types of Satellite Imagery VISIBLE Measures visible light (solar radiation, 0.6 m) which is reflected back to the satellite by cloud tops, land, and sea surfaces. Thus, visible images can only be seen during daylight hours! Dark areas: Regions where small amounts of visible light are reflected back to space, such as forests and oceans Light areas: Regions where large amounts of visible light are reflected back to space, such as snow or clouds
Visible Pros/Cons Pros: –Seeing basic cloud patterns and storm systems –Monitoring snow cover – Shows nice shadows of taller clouds (has a 3-D look to it) Cons: –Only useful during the daylight hours –Difficult to distinguish low clouds from high clouds since all clouds have a similar albedo (reflect a similar amount of light) –Hard to distinguish snow from clouds in winter
Types of Satellite Imagery WATER VAPOR (WV) Displays infrared radiation emitted by the water vapor (6.5 to 6.7 m) in the atmosphere Bright, white shades represent radiation from a moist layer or cloud in the upper troposphere Dark, grey or black shades represent radiation from the Earth or a dry layer in the middle troposphere
Types of Satellite Imagery INFRARED (IR) Displays infrared radiation (10 to 12 m) emitted directly by cloud tops, land, or ocean surfaces Wavelength of IR depends solely on the temperature of the object emitting the radiation Cooler temperatures (like high cloud tops) are shown as light gray, or white tones Warmer temperatures (low clouds, ocean/lake surfaces) are shown dark gray Advantage: You can always see the IR satellite image