Cooperative Institute for Research in Environmental Sciences

R. Michael Hardesty

Research Interests

Lidar remote sensing of the atmosphere; Doppler laser radar; atmospheric propagation; signal processing of Doppler lidar returns, tropospheric aerosols.

Current Research Projects: Characterizing the boundary layer for greenhouse gas emission measurement

Our work focuses on the application of Doppler lidar to characterize the boundary layer in topdown measurement of greenhouse gas emissions from large-area sources. The lidar investigation is one aspect of a multi-year research effort, the Indiana Flux Study (INFLUX), aimed at improving emissions-estimate methodologies at the urban scale. As part of INFLUX, an observational network—including periodic aircraft-based estimates of greenhouse gases and meteorological parameters, in-situ tower-based measurements of carbon dioxide, methane, and carbon monoxide, eddy covariance and radiative flux observations, and a compact scanning Doppler—has been deployed in the Indianapolis urban region. We are using data from these sources to evaluate measurement methodologies and for inverse-modeling studies to estimate the urban area flux.
Information on boundary layer mixing, wind structure, turbulence, and thickness is a key requirement for both top-down emissions estimation and inverse modeling of emissions. During the past decade, we have employed our research High Resolution Doppler Lidar (HRDL) to develop and test Doppler lidar techniques from surface, ship, and airborne platforms for boundary layer investigations. For INFLUX, we are evaluating the effectiveness of a commercial Doppler lidar for continuous measurement of boundary layer wind and aerosol properties. The commercial instrument, which employs components used in the telecommunications industry, operates at significantly lower pulse energy but a higher pulse repetition rate than our well-characterized HRDL system. Because the commercial lidar is designed for continuous operation, it is a good candidate for extended observation of the boundary layer; however, the lower pulse energy makes it susceptible to signal dropouts under low-aerosol conditions.

We have operated the lidar at a site northeast of downtown Indianapolis since April 2013. Since then, the instrument has operated continuously to provide measurements of wind speed and direction, aerosol backscatter signal intensity, and horizontal and vertical velocity variance. We use these observations to investigate nocturnal and seasonal variability in boundary layer mixing, depth, and structure. We also analyze the lidar measurements in combination with numerical models and aircraft observations of greenhouse gas concentrations for comparisons of the flux estimates with those computed from emissions inventories and to assess the feasibility of advanced modeling and measurement techniques for general application to urban areas. The next step in the research is to extend the methodologies developed during INFLUX to more complicated urban areas such as Los Angeles or Paris.

Publications

Click here for a complete list of published works »