Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
EARTH SYSTEM SCIENCE STUDENT PERFORMANCE AT THE INTRODUCTORY LEVEL WITH THE CLARK ATLANTA UNIVERSITY ENERGY BALANCE MODULE Randal L. N. Mandock STUDENT EVALUATION OF MODULE 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 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, anthropomorphic, 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 1. The training I received in lecture and laboratory adequately prepared me to complete the energy balance project. 2. As a result of completing the project, I now understand evaporation and other atmospheric energy fluxes better than I did before. 3. I learned about solar radiation, temperature, wind, and other meteorological sensors during completion of the project. 4. The energy balance module helped me learn about energy fluxes and partitioning of energy at the land surface. 5. The energy balance module's graphical interface was easy to use. 6. The energy balance module's graphical interface was well designed. 7. The instructions accompanying the energy balance module adequately explained how to use the module to solve energy balance problems. 8. The energy balance module really helped me understand difficult concepts that I encountered in the project. Figure 5. Air temperature. 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. Figure 10. Scenario prior to energy flux estimation. Figure 1. Energy balance diagram. Question Strongly Agree Disagree Strongly No No Number Agree Disagree Comment Answer 1 39 52 2 0 3 2 2 23 70 2 1 2 0 3 14 53 5 0 4 22 4 23 63 2 0 4 6 5 22 58 7 0 5 6 6 30 55 2 0 4 7 7 26 55 1 0 10 6 8 16 47 4 0 8 23 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 Figure 6. Soil temperature. Table 1. Frequency of student responses to module evaluation statements. The module includes 8 model scenarios which vary by: STUDENT PERFORMANCE ON MODULE TESTS EXPLANATION OF PROJECT 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). 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 landsurface 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. Figure 7. Evapotranspiration. Figure 3. AEMN station at Bledsoe Farm. 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 Figure 8. Insolation (downwelling solar radiation). 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: STUDENT PROFILE Nearly all of the 317 undergraduate students enrolled in the course for the three semesters consisted of liberal arts and education majors. 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 Latent heat flux Ground heat flux • Student verifies that solar radiation is zero at night ACKNOWLEDGEMENTS Figure 4. AEMN stations in Georgia. Figure 9. AEMN "Current Conditions" web page. 1. 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. 2. Describe what is meant by energy balance at the atmosphere/earth interface. 3. Describe the flux of net radiation. 4. Describe sensible heat flux. 5. Describe latent heat flux. 6. Describe ground heat flux. 7. What source of energy normally drives the earth/atmosphere system during daylight hours? 8. Write the energy balance equation for a moist, bare ground surface. 9. Draw a typical energy balance diagram for a moist, bare ground surface on a sunny afternoon. 10. Draw a typical energy balance diagram for a short, weed-covered surface late on a humid night. 12 10 8 6 4 Fall 2005 P ost Mean = 66% Median = 70% S td. Dev. = 23% 2 0 0 20 40 60 Test Score 80 100 Figure 12. Fall 2005 post test scores. Frequency of Occurrence ENVIRONMENTAL DATA Surface wind speed and direction Air temperature Relative humidity Atmospheric pressure Insolation Rainfall rate Subsurface temperature profile 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. Figure 2. Graphical user interface. Frequency of Occurrence Climate or microclimate Day and night Cloudiness and sunshine Windy and calm conditions Land or water surface Freezing and nonfreezing temperatures 25 20 S pr ing 2006 P ost Test Mean = 54% , Median = 55% S td. Dev. = 19% 15 10 5 0 0 20 40 60 80 Test Score (%) 100 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. 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 ([email protected]).