Lecture 6 1014 METR 1111

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Lecture 6 (10/14)METR 1111

• Satellites
• Doing Something Different

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What are satellites?

• Satellite Any object that orbits around another
  object
• (Youve got to like these intensive definitions)

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What can satellites do?

• Man-made satellites are designed to carry out a
  wide range of tasks
• Take images, relay signals, etc
• First introduced over 40 years ago with the
  Russian satellite Sputnik
• Currently, over 8000 satellites orbiting Earth
• Most are not much bigger than a softball, but
  some are the size of a small car.

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4 Main Types of Satellites

• Geosynchronous Orbiting stays over same spot on
  earth (rotates at same speed as land under it)
• Polar Orbiting pole to pole orbit
• Low Earth Orbiting very low orbit
• Elliptical Orbiting elongated pole to pole
  orbit

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Geosynchronous Orbiting

• Geosynchronous a satellite in an equatorial or
  near equatorial orbit
• Has the same angular velocity of the earth
• Geostationary satellite - a type of
  geosynchronous satellite that is in a west to
  east orbit at an altitude of 35,786 km above the
  equator.
• Why can it only be at this altitude?

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Geostationary Satellites

• Ans At this altitude it encircles the earth once
  every 24 hours, making its speed in orbit
  synchronous (or in sync) with earths rotation
• Balance between gravitational force pulling it
  towards Earth and centripetal force away from it
• Stays over same geographic area 24/7
• Examples GOES East and West take images of
  clouds from space from same vantage point.

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GOES

• GOES Geostationary Operational Environmental
  Satellite
• Observes the atmosphere in different wavelengths
• Visible captures visible light (useless at
  night but valuable during day)
• Infrared captures emitted long and short wave
  radiation
• Water Vapor Just an infrared detector thats
  extra-sensitive to water vapor

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Current GOES Images

• http//www.rap.ucar.edu/weather/satellite/

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Polar Orbiting Satellites

• Polar-Orbiting Satellite a satellite with an
  orbit that lies in a plane passing through the
  center of the earth that traverses polar
  latitudes.
• POES (Polar-Orbiting
• Operational Environmental
• Satellite)

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More on POES

• Polar orbiting satellites orbit earth in a couple
  hours.
• They cover the entire earth with data breaks
  between paths
• 2 or 3 polar orbiting
• satellites can work
• together to minimize
• data breaks.

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Another Interesting Satellite

• TRMM Tropical Rainfall Measuring Mission
• First satellite to carry a weather radar
• Main web site http//trmm.gsfc.nasa.gov/
• Images http//trmm.gsfc.nasa.gov/images_dir/hurri
  cane.html
• Animations http//trmm.gsfc.nasa.gov/images_dir/a
  nim_hurricane.html

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Satellite derived winds

• can track a clouds movement and get approx.
  winds at an estimated height.
• Not as reliable as rawinsondes but it gives us
  more observations
• http//cimss.ssec.wisc.edu/tropic/real-time/europe
  /winds/winds.html

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Satellite Derived Indices

• Great for forecasting severe weather and
  precipitation
• Based on soundings that GOES makes
• Not as accurate as rawinsondes, but again, it
  helps fill data voids and gives big picture
• http//orbit-net.nesdis.noaa.gov/goes/soundings/ht
  ml/fields.html

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Satellite-Derived Soundings

• Gives you soundings every hour instead of every
  12 hours
• http//orbit-net.nesdis.noaa.gov/goes/soundings/sk
  ewt/html/

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For next time

• Read Ch 9 Hurricanes - REAL WEATHER! (Im
  wishing for something interesting)
• Homework 6 is posted
• Reminder Your grade is affected by your
  attendance. This is my one call to make sure you
  turn in anything you have not given me yet