Fish Market, Santarem, Para, Brazil

SCOTT MILLER

Department of Earth System Science
University of California at Irvine
(949) 824-6174
(949) 824-3874 (fax)
sdmiller@uci.edu

Ph.D. Engineering, University of California at Irvine (1998)
M.S. Engineering, University of California at Irvine (1994)
B.S. Mechanical Engineering, State University of New York at Buffalo (1991)





RESEARCH

My interest is in using micrometeorology to address outstanding questions of exchange between the atmosphere and land or water surfaces. Four projects, both continuing and new, demonstrate the use of direct flux measurements to address important science questions: 1) the flux of dimethylsulfide, acetone and carbon dioxide over the open ocean and the relative importance of air- and water-side resistance to gas exchange; 2) the effect of selective logging on carbon dioxide, water vapor and energy exchange above a tropical rainforest; 3) the physics of momentum and energy exchange above deep ocean waves; and 4) the role of carbon dioxide evasion from rivers in the Amazon basin in the regional carbon budget. This broad range of topics has required collaborations with physical and chemical oceanographers, ecologists, hydrologists, and meteorologists. The measurements have been made using commercially available instruments in novel configurations, and, more recently, incorporating new trace gas measurements. A short overview and highlights of these projects are given below.
   

DIRECT MEASUREMENTS OF CARBON DIOXIDE, DIMETHYLSULFIDE, AND ACETONE OVER THE OCEAN BY EDDY COVARIANCE (Fall 2004-Fall 2007)

Collaborator: Eric Saltzman, UC Irvine

This project involves the direct measurement of air-sea gas fluxes of carbon dioxide, dimethylsulfide, and acetone. These gases are important in terms of their impact on atmospheric chemistry and climate: carbon dioxide as a greenhouse gas, dimethylsulfide as a precursor of atmospheric sulfate aerosols, and acetone as a precursor for tropospheric HOx. By simultaneously measuring the air-sea gas flux and the air-sea concentration gradient of these gases, an estimate of the gas transfer coefficient, or piston velocity will be obtained. These three gases cover a wide range of solubilities, and a comparison of their gas transfer coefficients under various conditions will provide insight into the mechanism of air-sea exchange. Fluxes will be measured aboard ship using the eddy correlation technique, employing an infrared gas analyzer (IRGA) for carbon dioxide, and an atmospheric pressure chemical ionization mass spectrometer (API/CIMS) for dimethylsulfide and acetone. Two Pacific cruises are proposed, on which gas fluxes will be measured over a wide range of biogeochemical, oceanographic, and atmospheric conditions, including both coastal and open ocean.

Photo taken from May 2004 Cruise on the R/V Wecoma where the API CIMS was deployed to measure DMS and Acetone flux. (photo Murat Aydin)


This photo was taken from the top of the 64 m eddy flux tower at km 83 of the Tapajos National Forest, Para, Brazil. Fast response wind speed was measured using and ultrasonic anemometer, carbon dioxide and water vapor using both open- and closed-path InfraRed Gas Analyzers (IRGAs). Radiation sensors are also shown. This entire package was mounted to a winch-driven carriage that was used to lower the instruments for servicing. (photo Marcy Litvak)

THE EFFECT OF SELECTIVE LOGGING ON CO2 AND H2O EXCHANGE ABOVE A PRIMARY TROPICAL RAINFOREST IN THE BRAZILIAN AMAZON (1998-2005)

Collaborators: Mike Goulden, UC Irvine
Humberto Rocha and Helber Freitas, University of Sao Paulo

This project is part of LBA (Large-Scale Biosphere-Atmosphere Experiment in Amazonia).   We've been measuring fluxes continuously (about 60 MBytes per day of data) from a 65 m tall tower in the Tapajos National Forest, Para, Brazil, since June 2000, when the forest was still intact (primary).  We measured fluxes for a full year before, in September 2001, the forest was selectively logged.  We reported the pre-logging state of the forest physiology, water, energy, and carbon balance in 3 papers in the LBA Special Issue of Ecological Applications:

1. Miller et al. (2004): Biometric and Micrometeorological Measurements of Tropical Forest Carbon Balance
2. Goulden et al. (2004): Physiological Controls on Tropical Forest CO2 Exchange
3. Rocha et al. (2004): Seasonality of water and heat fluxes over a tropical forest in eastern Amazonia

Our equipment remained in place during the logging, and we are monitoring how the removal of the trees has affected the CO2 and H2O exchange.  Our  team includes researchers from USP (Sao Paulo, Brazil) with whom we collaborate closely.  For more information, including data and conference presentations, go to http://www.ess.uci.edu/~lba.

TURBULENCE STRUCTURE IN THE SURFACE LAYER OVER DEEP OCEAN WAVES (1994-2000)

Collaborators: Carl Friehe , Mechanical Engineering, UC Irvine
Tihomir Hristov, Johns Hopkins University
Jim Edson, Woods Hole Oceanographic Institution

The unique research platform R/P FLIP was used for 30 days in April-May 1995 off of Monterey, California, to study the interactions of the wind and upper ocean in the Marine Boundary Layer (MBL) experiment, Phase II. The physics of the energy exchanges between the air and ocean are not well understood and require specific experiments to obtain parameterizations of the complex processes for use in computer models of weather forecasting, climate studies, ocean wave prediction and upper-ocean thermal structure.  We measured profiles of wind and wind turbulence in the first 20 meters of the atmosphere over the ocean, including 5 levels of ultrasonic anemometers.  Such vertical resolution of turbulence is rarely measured over land, let alone over the deep ocean, due to logistical difficulties.  Our approach, combined with the wide range of wind and waves we measured during MBL, provided a truly unique data set.  I was involved in all phases of the project, including planning, building equipment, data processing and presentation, and paper writing.  For more information, go to http://wave.eng.uci.edu.    

The unique research platform R/P FLIP. (photo Carl Friehe)


A typical Amazon river boat was used to mount the equipment. The boat was about 20 meters long. This photo was taken on the Amazon, which is relatively brown and muddy compared to the Tapajos River. (photo Ricleicia Reis)

CARBON DIOXIDE AND WATER VAPOR FLUX FROM THE AMAZON RIVER (Summer 2004)

Collaborators: Helber Freitas and Humberto Rocha, Unversity of Sao Paulo
Mike Goulden and Ed Read, UC Irvine

Recent reports suggest that gas evasion of carbon dioxide from the Amazon river and its tributaries to the atmosphere may play an important role in the regional carbon budget. These gas transfer rates were estimated using air-water concentration gradients and gas transfer coefficients (piston velocities) derived from floating chamber measurements. Chamber techniques have inherent uncertainties due to their effect on the near-surface air turbulence. The micrometeorological technique of eddy covariance is attractive since it is a direct measurement of gas exchange and samples over a much larger area. In August 2004, we mounted equipment on a small riverboat to measure CO2 and H2O fluxes from the rivers and lakes near Santarem, Para. The motion of the boat was recorded using an inertial measurement package combined with a GPS receiver, and subtracted from the measured winds. We experimented with both thin-wall Teflon tubing and headspace equilibrators to measure the concentration of CO2 in the water continuously. Our sampling strategy included both under-way measurements and stationary (moored) 24-hour measurements on the Amazon and Tapajos rivers, and lakes connected to these rivers. CO2 concentration in the Amazon river and a connected lake was 3000-5000 ppm, much higher than the Tapajos river and a connected lake (range 400-1200 ppm). The signal-to-noise ratio was therefore greater for fluxes measured above the Amazon. Preliminary calculations indicate fluxes of order 1-2 micromoles/m2/s over the Amazon and 0.6-1 micromoles/m2/s over the Tapajos, and the calculated gas transfer velocity agrees with existing ocean-based parameterizations.

Curriculum Vitae (PDF)
Research Statement (PDF)

CONTACT

Scott Miller
Department of Earth System Science
University of California, Irvine
Irvine, CA 92697-3100
(949) 824-6174
(949) 824-3874 (fax)
sdmiller@uci.edu

Last Updated: March 15, 2005