John A. Dutton e-Education Institute

Land Surface Processes Modeling Tool Available Online for Students, Professionals

10 June 2001

The Penn State e-Education Institute announces the release of SimSphere, a unique land surface processes modeling tool available online. The SimSphere package, created by Penn State meteorology professor Toby N. Carlson, consists of an interactive model written in Java, a 13-chapter student workbook, and a users' guide. The package is designed for undergraduates, graduate students, and professionals in disciplines such as meteorology, geography, landscape architecture, and civil engineering.

Carlson's soil/vegetation/atmosphere/transfer (SVAT) model simulates interactions among soil, plant, and atmospheric systems and the transfer of energy, momentum, and water through the systems. The graphical interface includes pull-down menus that allow users to set parameters such as location, type of vegetation, surface soil moisture, and amount of rainfall. Each simulation produces a graph of one or more parameters plotted over time. The graphs can be animated to show how the vertical profiles of temperature, humidity, wind velocity, and wind direction vary over time.

The student workbook, also developed by Carlson, introduces simple concepts such as how variations in sun angle, terrain slope, and season affect the energy balance on the Earth's surface and how wind, soil moisture, and relative humidity affect the surface microclimate. More complex topics include plant turbulent energy exchanges, plant water stress, photosynthesis, and ozone deposition. The explanations include only a few simplified equations. Students can use the model to answer sets of questions at the end of each workbook chapter. First, the workbook provides step-by-step instructions for running specific SVAT simulations. Next, students are encouraged to experiment with different scenarios or create their own. Each chapter includes suggestions for background reading.

The development of the SimSphere package was a group effort. Carlson originally created the model in Fortran. Rob Gillies and David A. J. Ripley rewrote the model in C, and Tim Summers of Penn State's Education Technology Services (ETS) later turned it into a Java application. Jason Meyer and Martin Gutowski of the e-Education Institute brought the Java code from beta level to release level and created the SimSphere web site. A detailed software user's guide, developed by Karen Peters of ETS, is included with the online package.

The software and instructional materials reside on the e-Education Institute's website: Users have the option of running the model as an applet from a web browser or downloading the model to a Microsoft Windows-based personal computer and running it as a stand-alone application.