One Year of Doppler Lidar Observations Characterizing Boundary Layer Wind, Turbulence, and Aerosol Structure During the Indianapolis Flux Experiment

Friday, 19 December 2014: 8:30 AM
Robert Michael Hardesty1, Alan Brewer2, Paul B Shepson3, Maria Obiminda L Cambaliza4, Olivia Elizabeth Salmon4, Alexie M. F. Heimburger4, Kenneth J Davis5, Thomas Lauvaux5, Laura E McGowan5, Natasha L Miles6, Scott Richardson5, Daniel P Sarmiento5, Anna Karion2, Colm Sweeney1, Laura T Iraci7, Patrick W Hillyard8, James Robert Podolske7, Kevin R Gurney9, Igor N Razlivanov9, Yang Song9, Jocelyn C Turnbull10, James R Whetstone11, Antonio Possolo11 and Kuldeep Prasad11, (1)Cooperative Institute for Research in Environmental Sciences, Boulder, CO, United States, (2)NOAA, Earth System Research Laboratory, Boulder, CO, United States, (3)Purdue Univ, West Lafayette, IN, United States, (4)Purdue University, West Lafayette, IN, United States, (5)Pennsylvania State University Main Campus, University Park, PA, United States, (6)Penn State Univ, University Park, PA, United States, (7)NASA Ames Research Center, Moffett Field, CA, United States, (8)Bay Area Environmental Research Institute Moffett Field, Moffett Field, CA, United States, (9)Arizona State University, Tempe, AZ, United States, (10)GNS Science / Rafter Radiocarbon, Lower Hutt, New Zealand, (11)National Institute of Standards and Technology Gaithersburg, Gaithersburg, MD, United States
The Indianapolis Flux Experiment (INFLUX) is aimed at improving methods for estimation of greenhouse gas emissions at urban scales. INFLUX observational components include several-times-per-month aircraft measurements of gas concentrations and meteorological parameters, as well as a number of towers observing CO2, CH4, and CO and a single continuously operating Doppler lidar to estimate wind, turbulence and aerosol structure in the boundary layer. The observations are used to develop top-down emissions estimates from the aircraft measurements and as input to inversion models. The Doppler lidar provides information on boundary layer structure for both the aircraft and inversion studies.

A commercial Doppler lidar characterized by low pulse energy and high pulse repetition rate has operated for well over a year at a site NE of downtown Indianapolis. The lidar produces profiles of horizontal wind speed, vertical velocity variance, and aerosol structure two to three times per hour. These data are then used to investigate boundary layer mixing and thickness and horizontal transport as inputs for the flux calculations. During its one year deployment the lidar generally operated reliably with few outages. Comparisons with aircraft spirals over the site and with the NOAA High Resolution research Doppler lidar deployed to Indianapolis for one month during May, 2014, were used to assess the performance of the INFLUX lidar. Measurements agreed quite well when aerosol loading was sufficient for lidar observations throughout the boundary layer. However, low aerosol loading during some periods limited the range of the lidar and precluded characterization of the full boundary layer.

We present an overall assessment of the commercial Doppler lidar for providing the needed information on boundary layer structure for emission estimations, and show variability of the boundary layer observations over diurnal, seasonal, and annual cycles. Recommendations on system design changes to obtain data under a more complete range of atmosphere conditions are suggested.