Microwave Remote Sensing of Hurricanes

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Microwave Remote Sensing of Hurricanes Tropical
Meteorology

• Tyler Adams and Megan Leigh

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Abstract

• Remote sensing is a major contributor to the
  prediction and forecasting of hurricanes. By use
  of satellite imagery we can look at the key
  ingredients in hurricane formation as well as
  growth and sustainability. A disturbance of the
  African coast, Sea surface temperatures, and
  moisture levels seen in the water vapor loops are
  important components that remote sensing allows
  us to see. At different stages of the Hurricane
  lifespan, we use different types of remote
  sensing, including both passive and active
  sensors. Examples this project will detail
  include, SAR, SeaWinds, TRMM.

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Outline

• Introduction to Hurricanes
• Why is RS of Hurricanes important?
• History of Microwave Remote Sensors
• Scatterometers
• SAR
• Microwave radiometer
• Rain radar (TRMM)

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• HurricaneA tropical cyclone with 1-min average
  surface (10 m) winds in excess of 32 m s-1 (64
  knots) in the Western Hemisphere (North Atlantic
  Ocean, Caribbean Sea, Gulf of Mexico, and in the
  eastern and central North Pacific east of the
  date line).

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Why is RS of hurricanes important?
http//www.aoml.noaa.gov/general/WWW000/text/Pop_D
ead.html
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Why is RS of hurricanes important?
http//www.sip.ucar.edu/pdf/01_Hurricane_Forecasti
ng_the_State_of_the_Art.1.pdf
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Why is RS of hurricanes important?

• Little was known about hurricanes before remote
  sensing.
• Hurricanes such as the 1900 Galveston hurricane
  killed many because people had no idea there was
  a storm coming
• As technology improved, ships radar systems (as
  explained later) sent information back to the US,
  but that still wasnt enough warning and wasnt
  reliable.
• Hurricane related deaths have drastically
  declined in the last 100 years.

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The 1st Radars

• AN/APQ-13 radars were a ground scanning radar
  developed by Bell, Western Electric, and MIT as
  an improved model of the airborne H2X radar. They
  were used on B-29's during World War II in the
  Pacific theater for high altitude area bombing,
  search and navigation.

The AN/APS-2F radar began as a military aircraft
radar. Some of the USA's first weather radars
were modified APS-2F radars.
The AN/CPS-9 radar, the first radar specifically
designed for meteorological use, was unveiled by
the Air Weather Service in 1954.
WSR-57 radars were the USA's main weather
surveillance radar for over 35 years. The
National Weather Service operated a network of
this model radar across the country, watching for
severe weather.
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Old School Style

• Hurricane Alice
• Formed
• Dec. 1954
• Dissipated
• Jan 1955

Image of PPI scope of SPS-6 radar on the USS
MIDWAY showing rare January hurricane northeast
of British Virgin Islands. This was hurricane
Alice.
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How is MRS useful?

• Varied frequencies can measure different
  variables
• 1.) Low frequencies (lt14 GHz) can measure at the
  surface because they are not absorbed by clouds
  and rain
• 2.) Higher frequencies (20-35 GHz) are absorbed
  by clouds and rain, thus allowing us to measure
  them
• 3.) At a 22GHz frequency, we can measure the
  amount water vapor in the atmosphere

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Scatterometers

• Tells us the ocean vector winds
• Operate on polar orbiting satellites
• Measures the amount of backscatter received
• Backscatter depends on ocean surface roughness
• Rough surface backscatters more energy
• Smooth surface absorbs more energy
• Provide wind speed and direction
• Direction based on multiple beams (Ex. QuikSCAT
  operates two beams, 6º apart)

SeaWinds launched 1999
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QuikSCAT

• Launched June 19, 1999
• Altitude 800 kilometers
• Sun-synchronus
• One pas every 101 minutes
• Platform for SeaWinds

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QuikSCAT
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Products of Scatterometers

• Specialized microwave radar that measures
  near-surface wind speed and direction under all
  weather and cloud conditions over Earth's oceans.

• Launched on QuikSCAT in 1999
• Covers 90 of the Earths oceans (non-ice
  surfaces) regardless of cloud cover
• Provides wind speed/direction at 25-Km resolution
• 1,800-kilometer swath during each orbit
• Low frequencies (13.4 GHz)
• http//winds.jpl.nasa.gov/

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SeaWinds map of wind flow in the Gulf of Mexico
and the Atlantic during Hurricane Floyd
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(No Transcript)
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Synthetic Aperture Radar (SAR)

• Similar to scatterometers by relying on ocean
  surface roughness to calculate wind speeds
• Provide better, higher resolutions
• Due to observations coming from only one angle,
  wind direction is difficult to measure
• Very little effects even from very thick cloud
  cover
• http//earth.esa.int/ers/eeo4.128/
• http//southport.jpl.nasa.gov/desc/imagingradarv3.
  html

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ASAR (Advanced SAR)

• Aboard ENVISAT
• High Resolution 30 meters
• Scan SAR
• Use of several beams to provide a larger image
• Excellent for Measuring Boundary Layer Rolls
• Possible to measure ocean currents as well as
  smaller atmospheric events
• http//envisat.esa.int/handbooks/asar/CNTR5-2.htm

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ASAR/MERIS
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Special Sensor Microwave Imagers (SMM/I)

• Operate at higher frequencies (19-85 GHz), both
  horizontal and vertical polarizations
• The 22 GHz frequency operates only vertically
  (water vapor)
• Sun-synchronous orbits
• Flew onboard the Defense Meteorological Satellite
  Program (DMSP)

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SMM/I
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Advanced Microwave Scanning Radiometer

• Onboard Aqua Satellite
• Measure Frequencies ranging from 6 to 89 GHz
• Primary purpose is to measure precipitation
  rates, water vapor, moisture, SST, etc.
• Secondary purpose is to measure sea surface winds
• Resolution varies by frequency 5-55 km
• Swath nearly 1,500 km wide

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AMSR
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Stepped-Frequency Microwave Radiometer (SFMR)
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Stepped-Frequency Microwave Radiometer (SFMR)

• Measurement of Surface Winds Precip. Rates
  within a Tropical Cyclone (4.6-7.2 GHz)
• Measures Sea Brightness Temperature
• Useful in measuring the Wind Radii (eye)
  expansion or contraction

http//www.403wg.afrc.af.mil/library/factsheets/fa
ctsheet.asp?id8314
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Tropical Rainfall Measuring Mission (TRMM)

• Precipitation Radar (PR)
• TRMM Microwave Imager (TMI)
• Visible and InfraRed Scanner (VIRS)
• Cloud and Earth Radiant Energry Sensor (CERES)
• Lightning Imaging Sensor (LIS)

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Precipitation Radar (PR)

• Provides a 3-D look at rainfall within a storm
  system
• Detects precipitation up to 20 km high
• Can decipher rain echos up to .25 km high
• Horizontal Swath of 250 km and resolution of 3
  miles

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TRMM Microwave Imager (TMI)

• Passive Microwave Instrument
• Similar to SMM/I with a frequency to acquire an
  improved observation of heavy rainfall
• Higher resolution due to lower altitude
• Rainfall rates are more accurate over water than
  land

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PR TMI at Work

• http//trmm.gsfc.nasa.gov/trmm_rain/Events/ATLA/AT
  LA.2007-9-28T0327Z________LORENZO.qt

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Visible InfraRed Scanner

• Uses both Visible and Infrared radiation to
  create images
• Based on observed temperatures cloud tops are
  determined
• Useful in the tropics where there are many
  thunderstorms
• Wider swath than the other instruments
• 833 km wide compared to 247 km (PR)
• Higher resolution 2.4 km

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VIRS to PR Comparison
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Conclusions

• Within the last 20 years, Remote sensing of
  hurricanes and tropical storms has improved
  drastically, thereby improving forecasting and
  warnings.

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Future work
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References

• http//www.terrapub.co.jp/journals/JO/pdf/5801/580
  10137.pdf
• http//ams.allenpress.com/perlserv/?requestget
• abstractdoi10.11752F1520-0426(2002)0193C20493
  AEOWVOB3E2.0.CO3B2ct1
• http//ams.allenpress.com/perlserv/?requestget-ab
  stractdoi10.11752F1520-0426(1998)0153C08093AT
  TRMMT3E2.0.CO3B2
• http//earth.esa.int/ers/eeo4.128/
• http//cat.inist.fr/?aModeleafficheNcpsidt17549
  790
• http//ieeexplore.ieee.org/iel5/6913/18663/0086049
  0.pdf
• http//adsabs.harvard.edu/abs/2001AGUFMOS31A0386F