Micropulse Differential Absorption Lidar (DIAL) for Thermodynamic Profiling in the Lower Troposphere

The importance of thermodynamic profiling for improved weather forecasting, atmospheric science, and climate studies has been identified and repeatedly reaffirmed by a number of reports and peer reviewed articles over the past decade [e.g. 1-5]. However, observational gaps remain with respect to thermodynamic profiling in the lower troposphere. In an effort to address these observational gaps, researchers at Montana State University (MSU) and the National Center for Atmospheric Research (NCAR) are actively developing diode-laser based lidar instrumentation for thermodynamic profiling in the lower troposphere. Diode-laser based lidar systems allow for the development of multiple lidar instruments based on a common instrument architecture, leveraging broad spectral coverage and modularity

Researchers at MSU and NCAR have developed and validated an eye-safe field-deployable and autonomous diode-laser based micro-pulse DIAL (MPD) for water vapor profiling in the lower troposphere [6,7]. Based on this instrument design, construction of a network of five MPD instruments for water vapor profiling was recently finished. The MPD network completed its first deployment at the Department of Energy’s (DOE’s) Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site. The first part of this presentation will focus on the development and data products of this MPD network.

Additional measurement capabilities are also being developed. In particular, temperature profiling in the lower troposphere using a differential absorption measurement of oxygen (O₂) is under study with the development of an integrated MPD instrument that allows for simultaneous retrievals of water vapor, aerosol backscatter, and temperature profiles. The temperature retrieval is based on a recently developed perturbative retrieval technique [8] that takes into account the Doppler broadening of the molecularly scattered signal. The second part of the talk will focus on the development of the temperature profiling with and initial demonstration of temperature retrievals based on data collected at the ARM SGP site.

References

1. National Research Council (U.S.). Committee on Developing Mesoscale Meteorological Observational Capabilities to Meet Multiple National Needs., Observing weather and climate from the ground up : a nationwide network of networks (National Academies Press, Washington, D.C., 2009), pp. xvi, 234 p.

2. National Research Council (U.S.). Committee on Progress and Priorities of U.S. Weather Research and Research-to-Operations Activities., When weather matters : science and services to meet critical societal needs (National Academies Press, Washington, D.C., 2010), pp. xvi, 181 p.

3. R. M. Hoff, R. M. Hardesty, T. W. F. Carr, A. B. S. Koch, S. Crewell, D. Cimini, D. Turner, W. Feltz, B. Demoz, V. Wulfmeyer, D. Sisterson, T. Ackerman, F. Fabry, and K. Knupp, "Thermodynamic Profiling Technologies Workshop report to the National Science Foundation and the National Weather Service," NCAR Tech. Note NCAR/TN-4881STR (2012).

4. National Academies of Sciences, Engineering, and Medicine. 2018. The Future of Atmospheric Boundary Layer Observing, Understanding, and Modeling: Proceedings of a Workshop. Washington, DC: The National Academies Press. https://doi.org/10.17226/25138.

5. V. Wulfmeyer, R. M. Hardesty, D. D. Turner, A. Behrendt, M. P. Cadeddu, P. Di Girolamo, P. Schlussel, J. Van Baelen, and F. Zus, "A review of the remote sensing of lower tropospheric thermodynamic profiles and its indispensable role for the understanding and the simulation of water and energy cycles," Rev Geophys 53, 819-895 (2015).
6. 
   S. M. Spuler, K. S. Repasky, B. Morley, D. Moen, M. Hayman, and A. R. Nehrir, "Field-deployable diode-laser-based differential absorption lidar (DIAL) for profiling water vapor," Atmos Meas Tech 8, 1073-1087 (2015).

7. Weckwerth, T.M., K.J. Weber, D.D. Turner, and S.M. Spuler, 2016: Validation of a Water Vapor Micropulse Differential Absorption Lidar (DIAL).J. Atmos. Oceanic Technol.,33, 2353–2372, https://doi.org/10.1175/JTECH-D-16-0119.1

8. Bunn, Catharine E., Kevin S. Repasky, Matthew Hayman, Robert A. Stillwell, and Scott M. Spuler. "Perturbative solution to the two-component atmosphere DIAL equation for improving the accuracy of the retrieved absorption coefficient." Applied optics 57, no. 16 (2018): 4440-4450.