1997: Radiative Forcing of the Earth's Climate

Background

Earth's climate is driven by energy from the sun. Understanding the balance between the incoming solar radiation and the outgoing thermal radiation is key to being able to accurately specify the forcing. There are two basic parts to understanding the energy climate. The first is that the earth's orbit around the sun determines how much energy it receives. The second is the way the energy received from the sun is reflected or re-radiated in order for the earth to maintain an energy balance.

Scientific Questions

• What information can be derived from measurements of atmospheric extinction and/or polarization? (e.g. sun photometer, hand-held polarimeter)
• How do model energy fluxes at the top of the atmosphere compare to data from satellites?

Learning Outcomes

Students will understand and construct simple electronic circuits. These circuits will be incorporated into measuring instruments. Students will test, calibrate, and characterize the instruments. Particular emphasis will be placed on assessing the stability and reproducibility of the measurements. They will develop research and Internet skills through finding background information, related Web sites, and through the development of material for the ICP Web page. Once the instruments have been built and tested, students will measurements following the HAZE-SPAN protocols. Students will collect and analyze data as well as compare their measurements to other sun photometer measurements.

Data will be plotted and analyzed. Spreadsheet skills will be developed.

To provide the overall scientific motivation for the project, students will compare modeled and measured fluxes. This will teach the students basic data comparison skills, as well as provide an introduction into what factors affect the radiation balance (e.g. clouds, aerosols, water vapor).

Science and Math

This project addresses the planetary energy balance. The approach is to examine the modes of energy transfer in the earth atmosphere system with an emphasis on radiative processes. Specific science concepts that will be addressed include: radiation, electromagnetic spectrum, aerosols, scattering, absorption, extinction, polarization, energy flux, albedo, blackbody radiation, ideal gas law. Students will use sine functions and natural logarithms to analyze data.

These concepts will be applied to the real world. How do different gases and aerosols affect polarization and atmospheric extinction? How are the long wave flux and short wave flux at the top of the atmosphere affected by aerosols and clouds?

Roles

Andre Cassell: Andre will build and characterize the VHS-I sunphotometer. He will keep a log of what he does and learns to get up to speed at GISS: textbooks, articles, Web sites, conversations with scientists, students, and faculty. This log will serve as a basis for the Web materials that will be developed by Brendan.

Brendan Curran: Brendan will work with Barbara to complete work on the content of the Orbital Eccentricity of the Earth exercise. He will story board this exercise for Bruce Naples to put on the Web. He will build and characterize the VHS-I sunphotometer. He will compare the results of to the GISS MFRSR using the Internet.

Ely Duenas: Ely will use ERBE and ISCCP data to investigate the radiation balance in several versions of the GISS GCM. She will work with Maricela and Mitch Fox on converting his workshop material into a Web-based exercise on the planetary energy balance.

James Frost: Jim will test several versions of the hand-held photo polarimeter. He will check to see how reproducible results are for each design. The testing protocols will be put on the sun photometer Web site.

Maricela Reyes: Maricela will use ERBE and ISCCP data to investigate the radiation balance in several versions of the GISS GCM. She will work with Ely and Mitch Fox on converting his workshop material into a Web-based exercise on the planetary energy balance.

School-based Activity

At Bronx Science, construction of the sunphotometer will be offered as a project option in the Electronics class. Honors physics students will use the sun photometers constructed over the summer to collect data and compare to the GISS MFRSR. They will coordinate the Weather Club and add atmospheric extinction to the weather database. Students could then correlate atmospheric extinction to other meteorological parameters.

Improved designs will be used at LaGuardia in the "Build a Photopolarimeter Class." Students at LaGuardia will work on improving the electronic designs of the sun photometer.