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Welcome!

by David Medvigy — last modified 2007-09-24 14:54

David Medvigy

Contact Information:
medvigy AT post.harvard.edu

Introduction

I am a postdoc working in the lab of Prof. Paul Moorcroft at Harvard University. I am interested in the processes governing the terrestrial carbon cycle, the response of vegetation to climate change, and the role of vegetation in controlling land-atmosphere fluxes. In order to better understand these processes, I have been developing a coupled, ecosystem-atmosphere model. You could click here to download my CV.

My Research

Atmospheric inversions have suggested that temperate North America is acting as a net sink of carbon dioxide, taking up as much as one quarter of human emissions from fossil fuel combustion. However, the biological mechanisms underlying this sink are still highly uncertain, in part because these processes span a vast range of spatiotemporal scales. In terms of observations, individual datasets are typically sensitive to only a subset of the relevant scales. On the other hand, it is possible for models to continuously span the whole range of scales. You could see an illustration of this by clicking here.

One of my main projects has involved using multiple observational datasets to define and constrain a model that appropriately scales from seconds to centuries and from the leaf-level to continent-sized regions. The Ecosystem Demography Model, ED, has formed the basis of my vegetation model. ED incorporates a size- and age-structured approximation that allows it to naturally capture the range of spatial scales of interest. To date, I have used measurements from eddy flux towers and from forest inventories to constrain my model. Including inventories in the optimization was critical because of the information they provided on small spatial scale variability. (To get an idea of this variability, click here to see a satellite image of Harvard Forest.) I have coupled the constrained ED model to the Regional Atmospheric Modeling System (RAMS) and in the near future I will be using aircraft measurements of atmospheric carbon dioxide concentrations from the COBRA campaign to constrain the coupled ED-RAMS model. These observations will allow not only sensitivity to ecosystem processes, but also to representations of atmospheric boundary layer evolution.

Currently I am using the constrained model in several applications investigating ways in which the atmosphere affects vegetation dynamics, e.g. through CO2 fertilization and through climate variability and change, and the subsequent feedback of vegetation on the atmosphere. Much of my efforts in the near future will be focused on continuing these projects.

Publications

D. Medvigy, S.C. Wofsy, J.W. Munger, D.Y. Hollinger and P.R. Moorcroft (2006) Mechanistic scaling of ecosystem function and dynamics in space and time: the Ecosystem Demography model. (In prep)

D. Medvigy (2006) The state of the regional carbon cycle: results from a constrained coupled ecosystem-atmosphere model. Ph.D. thesis, Harvard University.

D. Medvigy, P.R. Moorcroft, R. Avissar and R.L. Walko (2005) Mass Conservation and Atmospheric Dynamics in the Regional Atmospheric Modeling System (RAMS). Environmental Fluid Mechanics 5:109-134.

A. Alavi-Harati, D. Medvigy et al. (2002) Radiative Decay Width Measurements of Neutral Kaon Excitations Using the Primakoff Effect. Phys. Rev. Lett 89:072001

Presentations

EPS Day 2005: The Role of Terrestrial Ecosystem Processes in Determining Patterns of Terrestrial Carbon Fluxes and Atmospheric CO2 Concentrations: Results From a Regional-Scale Coupled Atmosphere-Ecosystem Model

AGU Fall 2004: A Regional Scale Coupled Atmosphere-Ecosystem Model: Formulation and Results

AGU Fall 2003: Atmospheric signatures of terrestrial ecosystem processes

Moorcroft Lab

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