Michael Dowd

Department of Mathematics and Statistics
Dalhousie University
6316 Coburg Road, PO Box 15000
Halifax, Nova Scotia
Canada B3H 4R2

email: mdowd@mathstat.dal.ca
Telephone: (902) 494-1048
Fax : (902) 494-5130
Office: Chase Building, Room 116

Course Websites - see my Teaching Homepage

Research Interests

My research interests are in Environmental Modelling and Statistics for the Marine Sciences. They include:

Statistical Data Assimilation :
I have an ongoing research interest in data assimilation, i.e. combining nonlinear dynamical models with available observations to produce optimal estimates of the time evolving system state. This involves linking statistical estimation theory to the problem of fitting oceanographic models (governed by time and space dependent partial differential equations) to observations. My recent research involves statistical approaches for the data assimilation problem. These rely on the nonlinear, nonGaussian state space model and use Monte Carlo based methods. These ideas have been applied to marine ecological prediction, considering both the complex dynamical behaviour of population models, as well as the high dimensionality found in practical applications.

Stochastic Marine Ecosystem Modelling :
Another research area I have is in the development of mathematical models for lower trophic levels of marine ecosystems. Currently, I am considering stochastic versions of such ecological models, as well as Bayesian approachs to combining them with new types of observational data. This work has largely been focused on development and application of differential equation based box models of coastal ecosystems to assess environmental effects of shellfish aquaculture, but also food web models and spatial ecology.

Data Analysis Methods for Marine Environmental Observations :
I also have a general interest in the development and application of statistical analysis techniques for marine environmental data sets, especially satellite imagery. These have incuded spatial analysis of spaceborne synthetic aperture radar data for high resolution ocean winds and waves, and ocean color data for for biogeochemical models. Studies have also been undertaken into trend detection using monitoring time series of plankton, as well as looking at analysis of high resolution marine animal movement data and its link to behaviour.

Recent Students and Post-Docs

Joey Hartling (MSc Statistics): Statistical Software for State Space Models (Fall 2012 - present)
Sarah Ambrose (BSc Honours): Robustifying the Kalman Filter (Fall 2012 - present)
Greg Britten (MSc Biology): Marine food web analysis (Winter 2012 - present)
Paul Mattern (PhD Statistics): Parameter estimation for large scale ocean biogeochemical models (January 2009 - present)
Jessica Wong (MSc Statistics): Particle MCMC for estimating parameters in a dynamic predator prey model (Sept 2011 - present)
Jon Briggs (PhD Statistics, Univ Auckland, New Zealand): Data Assimilation with Sequential Monte Carlo (completed Fall 2011)
Greg Britten (BSc Honours): Modeling ecosystem stability and ecological interactions (completed Winter 2011)
Joe Boutilier (BSc Honours) Sensitivity analysis of the parameters in a modified random walk model for marine animal movement (completed Spring 2009)
Scott Wile (MSc Statistics): Parameter estimation and model selection for nonlinear time series (completed Fall 2008)
Rick Danielson (Post-Doctoral Fellow): Estimation of high resolution marine winds fields from RADARSAT synthetic aperture radar (2004-2008)
Paul Mattern (MSc, Univ Lubeck, Germany): Ensemble based data assimilation for a physical-biological model near Bermuda (completed Spring 2008)
Elizabete Almeida (MSc Statistics): Analysis of ocean biogeochemical time series using a cyclical state space model (completed Spring 2008)
Maud Guarracino (Post-Doctoral Fellow): Coupled biological-physical modelling of lower trophic level coastal ecosystems (2004-2008)
Jill Falkenberg (BSc Honours): Time dependent value at risk models for financial portfolios using a Kalman filter (completed Spring 2007)
Laura MacKenzie (MSc Statistics): Nonlinear time series analysis using a Monte Carlo Smooother (completed summer 2006)
Sam Stewart (BSc Honours): Spatial analysis of Radarsat synthetic aperture ocean imagery for wind estimation (completed winter 2006)
Chris Jones (MSc Statistics): State space models for bio-optical oceanic time series (completed winter 2006).
Sean Smith (MSc Statistics): Options pricing and stochastic volatility models for financial time series using particle filters (completed Winter 2006).
Talia Beech (MSc Statistics): Statistical tools for selection of Marine Protected Areas based on satellite imagery (completed Winter 2006)
Cathy French (BSc Honours): Nonlinear time series models for temperature prediction (completed winter 2005)

Publications

Refereed Journal Publications:

Mattern JP, Fennel K, Dowd M. 2012. Estimating time-dependent parameters for a biological ocean model using an emulator approach. Journal of Marine Systems. 96-97, 32-48.

Guarracino M, Dowd M, Sheng J, Cullen JJ. 2011. Development of a coupled biological-physical model for prediction in a coastal inlet. Continental Shelf Research. 31(16): 1713-1727.

Dowd M and Joy R. 2011. Estimating behavioural parameters in animal movement models using a state augmented particle filter. Ecology. 92:568-575

Dowd M. 2011. Parameter estimation for nonlinear stochastic dynamic systems with application to ocean biogeochemistry. Environmetrics. 22(4):501-515

Mattern JP, Fennel K, Dowd M. 2010. Introduction and Assessment of Measures for Quantitative Model-Data Comparison Using Satellite Images. Remote Sensing. 2(3), 794-818; doi:10.3390/rs2030794

Mattern JP, Dowd M, Fennel, K. 2010. Sequential Data Assimilation Applied to a Physical-Biological Model for the Bermuda Atlantic Time Series Station Journal of Marine Systems. 79: 144-156 doi.10.1016/j.jmarsys.2009.08.004

Almeida EA, Dowd M, Flemming J, Li WKW. 2009. State Space Model Extraction of Trends and Seasonal Variablity in Ocean Monitoring Data. Limnology and Oceanography: Methods 7:883-847.

Zhai L., T. Platt, C. Tang, M. Dowd, S. Sathyendranath, M.-H. Forget. 2008. Estimation of phytoplankton loss rate by remote sensing, Geophys. Res. Lett., 35, L23606, doi:10.1029/2008GL035666.

Beech T, Dowd M, Field C, Hatcher B, Andrefouet. 2008. A stochastic approach to marine reserve design: incorporating data uncertainty. Ecological Informatics 3:(4-5):321-333

Coll M, Palomera I, Tudela S, Dowd M. 2008. Food web dynamics in the South Catalan Sea ecosystem (NW Mediterranean) for the period 1978-2003. Ecological Modelling 217:95-116

Danielson RE, Dowd M, Ritchie H. 2008. Objective analysis of marine winds with the benefit of Radarsat-1 synthetic aperture radar: a nonlinear regression framework. Journal of Geophysical Research 113, C05019, doi:10.1029/2007JC004413

Ikeda T, Dowd M, Martin JL. 2008. Application of functional data analysis for investigating seasonal progression and interannual variability in plankton. Estuarine Coastal and Shelf Science . 78:445-455.

Dowd M. 2007. A Discussion on "Parameter Estimation for Differential Equations: A Generalized Smoothing Approach" by JO Ramsay, G Hooker, D Campbell, and J Cao. Journal of the Royal Statistical Society Series B 69(5):778-779.

Dowd M. 2007. Bayesian statistical data assimilation for ecosystem models using Markov chain Monte Carlo. Journal of Marine Systems 68:439-456.

Cranford PJ, Strain PM, Dowd M, Hargrave BT, Grant J, Archambault M-C. 2007. Influence of Mussel Aquaculture on Nitrogen Dynamics in a Nutrient Enriched Coastal Embayment. Marine Ecology Progress Series 347:61-78.

Grant J, Curran KJ, Guyondet TL, Guglielmo T, Bacher C, Koutitonsky V and Dowd M. 2007. A box model for carrying capacity for suspensed mussel aquaculture in Grand-Entree, Iles-de-la-Madeline, Quebec. Ecological Modelling . 100(1-2):193-206.

Losa, S.N., A. Vezina, D. Wright, Y. Lu, K. Thompson, and M. Dowd. 2006. 3D ecosystem modelling in the North Atlantic: relative impacts of physical and biological parameterizations. Journal of Marine Systems . 61: 230-245.

Dowd, M. 2006. A sequential Monte Carlo approach to marine ecological prediction. Environmetrics. 17:435-455.

Wong, M.C., Barbeau, M.A., M. Dowd and K. Richard. 2006. Behavioural mechanisms underlying observed functional responses of sea stars Asteris vulgaris preying on juvenille sea scallops Placopecten magellanicus. Marine Ecology Progress Series . 317:75-86

Dowd, M. 2005. A biophysical coastal ecosystem model for assessing environmental effects of marine bivalve aquaculture. Ecological Modelling . 183(2-3):323-346.

Greenberg, D.A., J.A. Shore, F.H. Page, and M. Dowd. 2005. A finite element circulation model for embayments with drying intertidal areas with application to the Quoddy region of the Bay of Fundy. Ocean Modelling 10(1-2):211-231.

Dowd, M., J.L. Martin, M.M. LeGresley, A. Hanke and F.H. Page. 2004. A statistical method for the robust detection of interannual changes in plankton abundance: Analysis of 1988-1999 monitoring data from the Bay of Fundy, Canada. Journal of Plankton Research . 26(5):509-523.

Dowd, M. 2003. Seston dynamics in a tidal embayment with shellfish aquaculture: a model study using tracer equations. Estuarine, Coastal and Shelf Science . 57(3):523-537.

Dowd, M. and R. Meyer. 2003. A Bayesian approach to the ecosystem inverse problem. Ecological Modelling . 168:39-55.

Dowd, M., J.L. Martin, M.M. LeGresley, A. Hanke and F.H. Page. 2003. Interannual variability in a plankton time series. Environmetrics . 14(1):73-86

Perrie, W., E. Dunlap, P.W. Vachon, B. Toulany, and M. Dowd. 2002. Marine winds from remotely sensed measurements. Canadian Journal of Remote Sensing . 28:450-465.

Thompson, K.R., Dowd, M., Y. Shen, D. Greenberg. 2002. Probabilistic characterization of tidal mixing in a coastal embayment: a Markov chain approach. Continental Shelf Research . 22:1603-1614

Dowd, M., P.W. Vachon, F.W. Dobson and R.B. Olsen. 2001. Ocean wave extraction from RADARSAT synthetic aperture radar inter-look image cross-spectra. IEEE Transactions on Geoscience and Remote Sensing . 39(1):21-37.

Thompson, K.R., M. Dowd, Y. Lu., and B. Smith. 2000. Oceanographic data assimilation and regression analysis. Environmetrics . 11:183-196.

Dowd, M. and K.R. Thompson. 1999. "Errata for 'Forecasting coastal circulation using an approximate Kalman filter based on dynamical modes' ". Continental Shelf Research . 19:573-574.

Dowd, M. 1998. On the estimation of circulation from density observations in coastal and continental shelf regions. Continental Shelf Research . 18:991-1014.

Dowd, M. and K.R. Thompson. 1998. Forecasting coastal circulation using an approximate Kalman filter based on dynamical modes. Continental Shelf Research . 17: 1715-1735.

Dowd, M. 1997. On predicting the growth of cultured bivalves. Ecological Modelling . 104:113-131.

Dowd, M. and K.R. Thompson. 1996. Extraction of tidal streams from a ship-borne acoustic Doppler current profiler using a statistical-dynamical model. Journal of Geophysical Research . 101: 8943-8956.

Other Refereed Contributions:

Dowd, M. 2011. Dynamic Modeling. In: Encyclopedia of Environmetrics.

Chamberlain J, Weise AM, Dowd M, and Grant J. 2006. Modelling approaches to assess the potential effects of shellfish aquaculture on the marine environment . DFO Can. Sci. Advis. Sec Res. Doc. 2006/032. CSAS Research Document available online here

Wildish, D., M. Dowd, T. Sutherland, and C. Levings. 2004. Near Field Organic enrichment from Marine Finfish Aquaculture. In: Volume III: A Scientific Review of the Potential Environmental Effects of Aquaculture in Aquatic Ecosystems. Canadian Technical Report of Fisheries and Aquatic Sciences 2450. p. 1-42.

Cranford, P., M. Dowd, J. Grant., B. Hargrave, and S. McGladdery. 2003. Ecosystem Level Effects of Marine Bivalve Aquaculture. In: Volume I: A Scientific Review of the Potential Environmental Effects of Aquaculture in Aquatic Ecosystems. Canadian Technical Report of Fisheries and Aquatic Sciences 2450. p. 51-84.

Dowd, M., F. Page, and R. Losier. 2002. Time Series Analysis of Temperature, Salinity, Chlorophyll and Oxygen data from Tracadie Bay, PEI. Canadian Technical Report of Fisheries and Aquatic Sciences 2441. 86pp.

Dowd, M., F. Page, R. Losier, P. McCurdy, G. Budgen. 2001. Physical oceanography of Tracadie Bay, P.E.I.: Analysis of sea level, current, wind and drifter data. Canadian Technical Report of Fisheries and Aquatic Sciences 2347. 80pp.

Singh, R., M. -I. Buzeta, M. Dowd, J.L. Martin, M. LeGresley. 2000. Ecological Overview of Musquash Estuary: A Proposed Marine Protected Area. Canadian Manuscript Report of Fisheries and Aquatic Sciences 2538. 39pp.