David B. Miller - US grants

This award provides funds to the Psychology Department at the University of Connecticut to purchase equipment which will help improve the introductory psychology sequence at the University. The school has already funded a pilot program (tested in General Psychology 1) which provided some student computer stations, one network file server and one instructor's station. The pilot program extended control over stimulus presentation, data collection and data analysis. New programs were written and existing programs modified to increase the range and complexity of the experiments which formed the core of the labs. This award will allow the program to be expanded to give all students the opportunity to participate in the Computer Assisted Laboratory for Introductory Psychology. It will also enhance the pilot software and develop new software to enrich the understanding of experimentation and increase the level of computer literacy of primarily freshman and sophomore students. The grantee is matching this award with non-Federal sources.

As part of the CASES-99 program (Cooperative Atmosphere-Surface Exchange Study-1999), the PI, in collaboration with Dr. Jielun Sun of the University of Colorado, will employ hot film anemometers to measure the contribution of the smallest resolvable turbulent eddies to the vertical fluxes of heat and momentum. In stable, nocturnal conditions which are the focus of the CASES program, turbulent eddies near the ground are so small as to be undetectable by traditional observing means, such as sonic anemometers. In addition to evaluating the importance of the small and previously unobserved eddies, the investigators will study the relative importance of radiative and sensible heat fluxes in the energy balance of the boundary layer and determine the extent to which the Monin-Obukov similarity theory, developed for convective boundary layers, may have application in the stable boundary layer. The phenomenon of turbulence intermittency will also be studied, using data from an instrumented tower, lidars, radar wind profilers, and aircraft.

Turbulence in the canopy roughness sublayer (CRSL) is the primary driving force of the exchange processes between terrestrial ecosystems and the atmosphere. These exchanges are vital components in global carbon and water cycles and climate change research. Previous studies of short crops have shown that the aeroelasticity of plants has a significant impact on CRSL turbulence structure. The aeroelasticity of trees, however, has not been formally considered in most turbulence models of CRSL, including state of the art large-eddy simulation models (LES). This is largely due to a lack of field experiments to quantify the elastic properties of trees and their complex damped sway behaviors, which differ from those in short crops. Improved understanding and modeling of the aerodynamic interactions between forest canopies and CRSL turbulence are also significant in order to investigate the multifaceted effects of winds on the structure and function of terrestrial forest ecosystems and their responses to and interactions with future climate change.

Intellectual merit: This collaborative project is an interdisciplinary effort built upon the experimental and numerical modeling expertise of forest ecologists and micrometeorologists at the University of Connecticut, East Carolina University and Louisiana State University. The research consists of a novel but labor intensive field experiment campaign over a period of 1.5 years at an established AmeriFlux forest site at Howland, Maine, and a computationally intensive modeling component to incorporate tree sway motion physics into a current LES. The investigators will develop improved numerical models of tree-sway and their coupling with the LES. The overall goal is to improve understanding and modeling of the mechanisms underlying the aerodynamic interactions between CRSL turbulence structures and tree sway motions in and above forest canopies.

The field campaign will measure the sway motions and the elastic and aerodynamic properties of a large array of trees and turbulence wind fields simultaneously. These measurements will be used to quantify the temporal and spatial characteristics of tree-sway motions and their aerodynamic interactions with coherent gusts in a forest canopy. The coupled LES-tree-sway-model will be used to quantify the influences of tree sway motions on airflow in and above a forest over a range of atmospheric conditions.

In addition, the PIs will conduct systematic investigations, using the coupled LES-tree-sway-model, to quantify the effects and the relative significances of atmospheric boundary layer height and stability, external horizontal pressure gradient force, canopy morphology and elastic properties of trees, on the characteristics of tree-sway motions and CRSL coherent structures and their interactions. The PIs will carry out a thorough and comprehensive set of analyses of field measurements and LES outputs to create both qualitative and quantitative descriptions of the spatial and temporal characteristics of the tree-sway motions and canopy-scale coherent structures, including their relations and interactions.

Broader impacts: This collaborative project will integrate teaching and research at multiple levels of education. To cultivate and nurture the pursuit of science at the grass roots, the PIs will carry out an education program specifically designed to engage primary school children with interactive instructions on how basic data are collected, analyzed and shared, and demonstrations of the linkages between weather, climate and forested ecosystems. This outreach via family public education program will excite future generations about scientific understanding of the world, and will utilize some of the knowledge, instruments and models applied in the research portion of this project.

This project will provide support to graduate students who will receive formal training in multiple research areas (micrometeorology, boundary-layer meteorology, forest meteorology, forest ecology), learn and practice important field measurement and numerical modeling and data analysis techniques.

Research results from this project will be used to develop undergraduate and graduate course modules in micrometeorology, forest meteorology and forest ecology at both universities, and made available through a project web site.