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

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. 

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.

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.

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.

Climatic Effect of Aerosols(Problem)

Tropospheric and Stratospheric Aerosols

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.

Polarimeter

Results

05_07_11  cloudyAngle    Imax   Imin30        161     15340        115     10550        92       7360        79       7370        72       4280        72       3690        89       61

05_07_12 clearAngle    Imax   Imin30        165     15240        144     11850        125      9060        111      7370        105      6080        106      5590        119      61

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

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.

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.

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.

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.

Acknowledgements

Dr. Rudolph, Dr. Frost

Juan Rodrigez, Irving Andino, Johan Toloza

NASA Sharp

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/5-6aersols.html