Remote Sensing
Allie Marquardt Collow
Met Analysis – December 3, 2012
Remote Sensing
Homework #6
• Be sure to
kink the
isobars
around fronts!
• Don’t forget to
complete the
COMET
Module on
Weather
Radar for next
week!
Met Analysis Fall 2012
You may hand in your hurricane tracking charts
today or next week
Remote Sensing
Types of Radiation
Longwave Radiation: Energy that
is emitted by the Earth
proportional to the temperature4.
Can be absorbed by greenhouse
gases.
Met Analysis Fall 2012
Shortwave Radiation:
Energy that is emitted by
the Sun, which enters
Earth’s atmosphere. Can
be reflected by clouds
and aerosols.
Remote Sensing
Satellites
• Can be used to measure radiation in different wavelengths
• Can also be used for soundings, measuring emissions in
different wavelengths, and interpreting them as layer
temperatures or humidity
• Active Sensor – Emits radiation that is reflected by a target,
such as a cloud, which is then detected by the satellite.
Examples are radar and lidar.
• Passive Sensor – Detects radiation that is reflected or
emitted from Earth
Met Analysis Fall 2012
Remote Sensing
Comparison of Different Orbits
Geostationary Orbit
• Limited to its field of view
• Gives a constant view of
a location, enabling
diurnal studies
Met Analysis Fall 2012
Polar Orbit
• Can see the entire globe
twice in one day,
including the poles
• Will give you temporal
gaps between successive
data points for a location
Remote Sensing
Geostationary Satellites
• Orbits with same period as Earth (located at the equator)
• Gives you a constant view over its field of view
• One geostationary satellite cannot give you information for
the whole globe
• Examples:
GOES uses an
GOES
GERB (Meteosat-8)
imager to give us a
picture of the
atmosphere using
visible, shortwave,
Nasa.gov
and infrared
Esa.gov
radiation.
Also has a sounder that can give us the
temperature and moisture profile, surface and
cloud top properties, and ozone distribution.
Met Analysis Fall 2012
GERB uses a scanning
radiometer to give us
the amount of
shortwave radiation
reflected and longwave
radiation emitted from
Earth.
Remote Sensing
The A-Train
• Polar orbiting satellites that are referred to as the afternoon
constellation because they pass over the equator at 1:30 pm
local time, within minutes of each other
• Consists of 8 satellites that contain numerous instruments
including MODIS, CERES, and a cloud camera
• CloudSat = a cloud radar on a satellite
• CALIPSO = a lidar on a satellite
Met Analysis Fall 2012
Atrain.nasa.gov
Remote Sensing
A-Train, the afternoon constellation
Met Analysis Fall 2012
Remote Sensing
Sun-Synchronous Satellites
• http://earthobservatory.nasa.gov/Features/OrbitsCatalog/imag
es/sun-synchronous_orbit.h264.mov
• Pass over at the same local time each day
Met Analysis Fall 2012
Nasa.gov
Remote Sensing
GPS
• http://www.nasa.gov/mov/255363main_134_GPS_Work.mov
• GPS satellites give you a signal with the exact time and
location of the satellite
Met Analysis Fall 2012
Gps.gov
Remote Sensing
GRACE
• GRACE uses GPS to determine gravity by measuring how the
distance between two satellites changes
• When the first satellite encounters a region with stronger
gravity, it starts to move faster, increasing its distance from
the other satellite
Csr.utexas.edu/grace
Met Analysis Fall 2012
Remote Sensing
COSMIC
• http://www.cosmic.ucar.edu/index.html
• Stands for Constellation Observing System for Meteorology
Ionosphere and Climate
• Contains 6 satellites, 5 of which are operational, in a low
Earth orbit that use GPS signals to get temperature and
moisture profiles of the atmosphere
Met Analysis Fall 2012
Cosmic.ucar.edu
Remote Sensing
MODIS
• MODIS stands for Moderate Resolution Imaging
Spectroradiometer
• Aboard Aqua (passes over the equator in the afternoon) and
Terra (passes over the equator in the morning)
• Views the entire Earth every 1 to 2 days
• The optical system aboard MODIS contains a two-mirror offaxis afocal telescope that directs energy to four different
refractive assemblies (Visible, Near IR, SW/MW IR, LW IR)
• http://modis.gsfc.nasa.gov/about/media/modis_sm.mov
• http://modis.gsfc.nasa.gov/gallery/
Met Analysis Fall 2012
Remote Sensing
Visible Satellite
• A visible satellite image shows reflected shortwave radiation
at a wavelength of 0.52 to 0.75 micrometers
• Only available during daytime hours
• Clouds appear white, while the land and ocean appears gray
or black
• Can distinguish between land and ocean
• Loops can show snow cover
Met Analysis Fall 2012
Smoke from wildfires
http://synoptic.envsci.rutgers.edu/site/sat/sat.php
Remote Sensing
Infrared Satellite
• An infrared satellite image shows radiation emitted from the surface
and atmosphere at a wavelength of 10.2 to 11.2 micrometers
• Can be used during the night, unlike the visible channel
• Lighter colors (white) represent colder temperatures, such as a cloud
top
• Darker colors (black) represent warmer temperatures, such as the
surface
• Can give you land and sea surface temperatures
Met Analysis Fall 2012
Remote Sensing
What are the advantages and
disadvantages of the visible
and infrared channels?
Met Analysis Fall 2012