4.3

• Atmospheric Waves and Air Dispersion Model

  ES 131 – Atmospheric Physics
• Instructor


  ENGR. ROTSEN B. LABISORES
• Global Observation and Air Dispersion Model

  • Learning Outcomes
  • Identify the required observations and the use of remote sensing
  • Explain the observations from the remote platforms
  • Describe Air Dispersion Model and Air pollution
  • Explain the dispersion equations, the indoor air pollution, and human exposure and risk from air pollutants
• Ground observation

  Instruments placed in the Earth's surface (e.g., synoptic station, buoy, upper air, etc.)
• Remote sensing


  Instruments placed onboard the satellites and utilizes specific band from electromagnetic (EM) spectrum for measurement
• Weather satellites


  Satellites orbiting the Earth that obey the same orbital mechanics as planets orbiting the Sun

  
• Balancing forces on weather satellites

  Gravity force (fG) balances centrifugal force (fC)

  
• Weather satellite orbits


  • Polar-orbiting
  • Geostationary

  
• Polar-orbiting satellites


  Low-Earth-orbit (LEO) satellites

  
• Sun-synchronous satellites


  Polar-orbiting satellites designed to observe the same local solar times on every orbit

  
• Geostationary satellites


  High Earth orbit over the equator, matching Earth's rotation

  
• Geostationary satellites


  • Appear parked over a fixed point on the equator
  • Take a series of photographs of the same location
  • Disadvantages include larger magnification needed, need for satellites at different longitudes, potential interruption during nights near the equinoxes, and difficulty in polar regions
  • Lifetimes are limited due to limited propellant storage and high-speed damage

  
• Polar-orbiting weather satellites


  • Placed in low Earth orbit at 700 to 850 km altitude, with short orbital periods of 98 to 102 minutes, and inclinations of 98.5° to 99.0°
  • Maintain sun-synchronous orbit through combination of low Earth orbit altitude and inclination greater than 90°

  
• Satellite imager


  Instrument system that digitally photographs clouds, atmosphere, and Earth's surface

  
• Satellite imager capabilities


  • Identify and locate weather patterns
  • Track cloud motions to infer winds at cloud top level
• Visible channel


  Shows what you could see in space, with daytime cloud tops appearing white due to sunlight reflection
• Infrared channel


  Uses long wavelengths to see through the atmosphere to the surface or highest cloud top, mostly seeing emissions from Earth or clouds
• Water vapor channel


  Selects a wavelength not in a window, allowing water in the atmosphere to absorb radiation and show average conditions over a thick layer in the upper troposphere
• Image interpretation


  • Refer to Figure 16 for examples