David D. Turner, Ph.D. | |
VitaEducation
Dr. Turner is a professor in the Atmospheric and Oceanic Sciences (AOS) Department, with close ties to the high-spectral-resolution group of the Space Science and Engineering Center (SSEC) at the University of Wisconsin - Madison. Dr. Turner is intricately involved with the U.S. Department of Energy's Atmospheric Radiation Measurement (ARM) program as both a member of the science team and the infrastructure, and is currently the chair of the ARM Climate Research Facility (ACRF) Science Board. The goal of the ARM program is to improve the treatment of radiative transfer, especially with respect to clouds, in global climate models. To accomplish this goal, ARM has established several long-term climate research facilities with a wide variety of in-situ and remote sensors to gather the datasets needed to develop improved parameterizations for global climate models and to evaluate them. Dr. Turner's research interests are centered around three of the state-of-the-art remote sensors that ARM has helped to develop for its climate research facilities. These instruments are the Raman lidar, the Atmospheric Emitted Radiance Interferometer (AERI), and the microwave radiometer. He has worked extensively with the datasets from these instruments, collaborating with scientists from the NASA/Langley Research Center, University of Cologne in Germany, Sandia National Laboratories, Pacific Northwest National Laboratory, and Atmospheric and Environmental Research Inc., to name a few. His ARM infrastructure responsibilities include serving as both the Raman lidar and AERI instrument mentor, serving as the chair of the Radiative Processes Working Group (one of the four main working groups within the ARM science team), and serving as a co-chair of a focus group that is improving remote sensing observations of clouds with low optical depths. Dr. Turner's research interests cover a fairly broad spectrum. These research efforts were/are funded by grants from the DOE ARM program, with some support from the National Science Foundation. He has focused considerable attention on improving water vapor observations in clear-sky and cloudy-sky scenes, both in the total column amount and the distribution in the vertical, in order to improve infrared radiative transfer models, especially in spectral regions that are important for mid-tropospheric radiative heating. He helped develop a suite of automated algorithms to retrieve water vapor and aerosol profiles from the Raman lidar, has investigated the diurnal, seasonal, and yearly variability in these data, and is using these data to investigate the turbulent structure of the boundary layer. He is focusing on the radiative impacts of clouds that contain less than 100 g/m2 of liquid water, and is working to improve the accuracy of the microphysical property retrievals for these clouds. At the same time, he is investigating ways to remotely determine the entrainment rate in these thin liquid water clouds using the AERI and Raman lidar. These thin liquid water clouds occur fairly often in the mid-latitudes and occur very frequently in the Arctic. Thus, many of these clouds in the Arctic are mixed-phase clouds, and thus he is working to understand the lifecycle of these clouds and how the number and shape of the ice crystals affects the clouds' lifetime. He has developed a retrieval method for mixed-phase Arctic clouds that utilizes observations in the infrared in both the 8-13 um and the 16-25 um windows. The utilization of these windows (especially the latter) for cloud research require improvements in water vapor observations and infrared radiative transfer (improvements in the absorption line parameters and water vapor continuum), which brings his research full-circle... |