EARTH SYSTEM SCIENCE STUDENT PERFORMANCE AT THE INTRODUCTORY LEVEL WITH THE CLARK ATLANTA UNIVERSITY

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EARTH SYSTEM SCIENCE STUDENT PERFORMANCE AT THE
INTRODUCTORY LEVEL WITH THE CLARK ATLANTA
UNIVERSITY ENERGY BALANCE MODULE
Randal L. N. Mandock Earth System Science
Program, Department of Physics, Clark Atlanta
University, Atlanta, GA 30314 Presented at the
"Infusing Quantitative Literacy into Introductory
Geoscience Courses" Workshop, Carleton College,
Northridge, Minnesota, 26-28 June 2006
STUDENT EVALUATION OF MODULE Student evaluation
of the energy balance module consisted of
circling the level of agreement with each of 10
statements about the student's experience with
the project and the module. Student answers to
eight of these statements are tallied in Table 1.
The statements are listed here.
INTRODUCTION The Earth System Science Program
(ESSP) at Clark Atlanta University is developing
an instructional module to study energy balance
at the land and water surfaces. A graphical user
interface (GUI) has been developed which is used
to model each of the components (net radiation,
sensible and latent heat fluxes, ground heat
flux, storage, anthropogenic, and residual)
involved in the partitioning of energy at the
air/land and air/water interfaces. The GUI
consists of a graphical model in the form of an
energy balance diagram (e.g., Figure 1). The
energy balance equation for an "ideal" land
surface may be represented in the following
form Q HS HL HG Q (also written as RN)
represents the net transfer of radiation through
the atmosphere, HS represents the atmospheric
flux of "sensible" heat, HL represents the
atmospheric flux of water vapor (also referred to
as "latent" heat), and HG represents the heat
flux through the ground.

• The training I received in lecture and laboratory
  adequately prepared me to complete the energy
  balance project.
• As a result of completing the project, I now
  understand evaporation and other atmospheric
  energy fluxes better than I did before.
• I learned about solar radiation, temperature,
  wind, and other meteorological sensors during
  completion of the project.
• The energy balance module helped me learn about
  energy fluxes and partitioning of energy at the
  land surface.
• The energy balance module's graphical interface
  was easy to use.
• The energy balance module's graphical interface
  was well designed.
• The instructions accompanying the energy balance
  module adequately explained how to use the module
  to solve energy balance problems.
• The energy balance module really helped me
  understand difficult concepts that I encountered
  in the project.

Figure 5. Air temperature.
Figure 10. Scenario prior to energy flux
estimation.
Figure 1. Energy balance diagram.
DESCRIPTION OF GUI The GUI graphically models
energy balance components. An energy balance
diagram consists of the following Sky elements
sun, moon, clouds Line or box representing
air/surface interface Arrows to indicate
magnitude and direction of fluxes The module
includes 8 model scenarios which vary
by Climate or microclimate Day and
night Cloudiness and sunshine Windy and calm
conditions Land or water surface Freezing and
nonfreezing temperatures
Figure 6. Soil temperature.
Table 1. Frequency of student responses to module
evaluation statements.
STUDENT PERFORMANCE ON MODULE TESTS Student
performance with the module was assessed by
10-question preliminary and post tests. The
questions were the same on each test and are
listed here. Histograms of results are plotted in
Figures 12 and 13.
Figure 11. Scenario after estimation of energy
fluxes.

• Heat is transferred from (circle answer) (a)
  cold to warm regions, (b) warm to cold regions,
  (c) cold to cold regions, (d) warm to warm
  regions.
• Describe what is meant by energy balance at the
  atmosphere/earth interface.
• Describe the flux of net radiation.
• Describe sensible heat flux.
• Describe latent heat flux.
• Describe ground heat flux.
• What source of energy normally drives the
  earth/atmosphere system during daylight hours?
• Write the energy balance equation for a moist,
  bare ground surface.
• Draw a typical energy balance diagram for a
  moist, bare ground surface on a sunny afternoon.
• Draw a typical energy balance diagram for a
  short, weed-covered surface late on a humid night.

Figure 2. Graphical user interface.
EXPLANATION OF PROJECT The module was tested in a
project assigned in the freshman Physics 104
"Introduction to Earth System Science" course
during Spring and Fall semesters 2005 and Spring
semester 2006. The first part of the project used
one year of archived data from the AEMN to
illustrate how variations in solar zenith angle
influence air temperature, the soil temperature
profile, and evapotranspiration. In the second
part of the project the students used daytime and
nighttime 15-minute averaged surface weather data
to infer the directions of net radiation and
sensible, latent and ground heat fluxes for
clear-sky, ideal land-surface conditions. Ideal
land-surface conditions are approximated at most
of the AEMN sites by either bare soil or short
grass canopies on relatively flat ground. Links
to NWS and Unisys weather were provided to aid in
identification of days with clear-sky conditions.
The purpose for verification that the solar
radiation sensor measured zero at night is to
illustrate the importance of identification of
systematic error and its subsequent use in
correcting real-time and archived measurements.
ENVIRONMENTAL DATA Module applications include
not only theoretical elements but measured data.
Figure 3 shows one of the more than 60 surface
meteorological stations of the Georgia Automated
Environmental Monitoring Network (AEMN). Surface
wind speed and direction Air temperature Relative
humidity Atmospheric pressure Insolation Rainfall
rate Subsurface temperature profile
Figure 7. Evapotranspiration.

• PROJECT ENERGY BALANCE AT AEMN SITES
• Goals
• Student will infer energy fluxes for one AEMN
  surface meteorology site
• Student will explore day and night scenarios
  for uniform ground cover
• Student will explore consequences of the
  earth-sun relationships
• Method
• Student goes to AEMN web site at
  http//www.griffin.peachnet.edu/bae/
• Student clicks on assigned station location on
  map of Georgia
• Student clicks on "Graph Daily Data" (Figures
  5-8)
• Student is to explain the peak in July and dip
  in January for
• Air temperature
• Soil temperature at all depths
• Evapotranspiration
• Solar radiation
• Student prints out "Current Conditions" for
  assigned site (Figure 9)
• Student runs the Energy Balance Module for
  current conditions (Figure 10)
• Student is to estimate the magnitude and
  direction of these fluxes (Figure 11)
• Net radiation flux
• Sensible heat flux

Figure 3. AEMN station at Bledsoe Farm.
Figure 8. Insolation (downwelling solar
radiation).
STUDENT PROFILE Nearly all of the 317
participating undergraduate students enrolled in
the course for the three semesters consisted of
liberal arts and education majors.
Figure 12. Fall 2005 post test scores.
Figure 13. Spring 2006 post test scores.
CONCLUSION Given that the mean score for the
module preliminary examinations in the Spring
2006 semester was 8.3 for the 110 students
tested, the results shown in Figures 12 and 13
promote confidence that use of the module is an
effective way to teach energy balance to
non-science university students. The student
evaluation results support this conclusion as
well.
ACKNOWLEDGEMENTS Support for this project was
provided by National Oceanic and Atmospheric
Administration (NOAA) Environmental
Entrepreneurship Program Grant NA030AR4810132,
and Universities Space Research Association
(USRA) Earth System Science Education for the
21st Century Grant NNG04GA82G. Corresponding
author Randal L. N. Mandock (rmandock_at_netzero.net
).
Figure 4. AEMN stations in Georgia.
Figure 9. AEMN "Current Conditions" web page.