The Effect of Aerosols on the Climate

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The Effect of Aerosols on the Climate

• By
• Hugh Alvarado
• Student Researchers Juan Rodrigez, Irving
  Andino, Johan Toloza
• Faculty Mentors Dr. James Frost1, Dr. Elizabeth
  Rudolph2, and
• Mr. Ryan Hutchinson3   
• 1LaGuardia Community College 31-10 Thomson
  Avenue, Long Island City, New York 11101  
• 2City College New York, New York  
• 3Medgar Evers College 1150 Carroll Street,
  Brooklyn, NY 11225  
• of the City University of New York

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Abstract

• Aerosols in our atmosphere can affect our climate
  both directly and indirectly.
• The direct effect can cause climate forcing by
  absorbing and reflecting sunlight, therefore,
  cooling the atmosphere. While the indirect
  effect modifies cloud properties.
• With the help of the handheld Polarimeter in
  conjunction  with the automated CIMEL sun
  photometer, we can effectively determine the
  optical depth and size of aerosol particles. 

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Introduction

• What are Aerosols?
• Aerosols are tiny solid or liquid particles
  suspended in the air. These are often seen by the
  naked eye as smoke, haze and dust. Some occur
  naturally, originating from volcanoes, dust
  storms, forest and grassland fires, living
  vegetation, and sea spray.
• However, a greater percentage of aerosol
  particles originate from Human activities, such
  as the burning of fossil fuels and the alteration
  of the natural surface cover.

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Aerosols Properties

• However, the problem with aerosols is that they
  have a great variety of properties, which makes
  them difficult to identify, locate, and classify.
• Aerosols divide into, Troposheric and
  Stratospheric aerosols.
• Aerosols differ in size, chemical composition,
  and lifetime.

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Types of Aerosols

• Troposperic Aerosols
• Aerosols located in the troposphere, these are
  mainly anthropogenic.
• This type of aerosol varies in size and chemical
  composition, according to the region where it is
  located.
• Have a direct effect on the climate.

• Stratospheric Aerosol
• Aerosols located in the higher zone of the lower
  atmosphere.
• This type of aerosols affect the properties of
  clouds.
• Have an indirect effect on the climate.

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Climatic Effect of Aerosols(Problem)
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Tropospheric and Stratospheric Aerosols
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Methodology

• In this project we used a Hand-Held Polarimeter
  to measure the refractive index, optical depth,
  and particle size (radius) of aerosols. To test
  the accuracy of our data, we compared the data
  obtained from the Polarimeter, with data obtained
  from a CIMEL sun photometer.
• The data is collected by aiming the Polarimeter
  toward the sun at different angles. At the same
  time, we rotated the Polarimeter to determine the
  Imax and Imin values. Finally, we analyzed the
  data obtained using IDL (computer program) to
  determine the optical depth and size of the
  particles.

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Polarimeter
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Results

• Data
• Comparison of data taken at the same place on
  different days (and under varying weather
  conditions). These charts represent the values
  for the data acquired on July 11, 2005 and July
  12, 2005.
• Blue color filter used

• 05_07_12 clear
• Angle    Imax   Imin
• 30        165     152
• 40        144     118
• 50        125      90
• 60        111      73
• 70        105      60
• 80        106      55
• 90        119      61

• 05_07_11  cloudy
• Angle    Imax   Imin
• 30        161     153
• 40        115     105
• 50        92       73
• 60        79       73
• 70        72       42
• 80        72       36
• 90        89       61

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Data

• After analyzing the data obtained from both days,
  we discovered that the aerosol particles from
  July 12, 2005, have greater radii and optical
  depth than the particles from July 11, 2005.

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Discussion

• Although ideally we would be able to clear the
  atmosphere of harmful aerosols, such an option is
  unavailable.
• However, there are solutions to depress the
  presence of aerosols in the atmosphere. Laws can
  be enacted by the major industrial countries
  around the world to limit aerosol ejection by
  reducing the use of fuels, energy, and the
  production of waste. Implementing laws that
  regulate the use of raw materials and require the
  use of renewable resources will give scientist
  more time to analyze aerosols and develop methods
  to clear them from our atmosphere before aerosols
  reach dangerously high levels.

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Conclusion

• After analyzing the data collected with the
  Polarimeter, we can concur that aerosols can
  change in size and optical depth in a matter of
  hours if not seconds. Similarly, we hypothesized
  that aerosols modify the properties of clouds. By
  comparing the amount of energy measured on July
  11th with the measurements taken on July 12th ,
  we concluded that less energy reaches the earth
  on cloudy days, than it does on clear days.

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Future Work

• To collect data using instruments that analyze
  chemical composition, refractive index, and
  optical depth of aerosols.
• Investigate the purpose of sulfur in the
  aerosols.
• Continue gathering data to develop weather
  models.

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Acknowledgements

• Dr. Rudolph, Dr. Frost
• Juan Rodrigez, Irving Andino, Johan Toloza
• NASA Sharp

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Bibliography

• Dr. James Frost. Aerosol Project at La Guardia.
  Online. La Guardia Community College.
  http//www.cis.lagcc.cuny.edu/frost/html/
• Center for Atmospheric Sciences. Online. NASA and
  NOAA. http//cas.hamptonu.edu/research/topics/5-6a
  ersols.html