Dr R. Chawn Harlow

Chawn manages the Atmospheric Radiation Research Group which uses data from the FAAM BAe146 aircraft for various radiative transfer and remote sensing applications.

Areas of expertise

  • Airborne retrievals of millimetre wave surface emissivities and effective temperature.
  • Microwave emission modelling particularly of snow packs.
  • Lambertian and specular surface interaction.
  • Clear air microwave radiative transfer.

Publications by Chawn

Current activities

Chawn's research is on the microwave emissivity of snow covered surfaces in order to promote satellite data assimilation in remote Polar Regions. He is currently engaged in the analysis of airborne and ground data obtained during the CLPX-II campaign during Feb 2008 on the North Slope of Alaska. He is using his techniques for retrieval of surface emissivity using data from the  FAAM BAe 146 research aircraft to validate surface emission models such as MEMLS and DMRT. This effort is the first to attempt to validate such models on the 100-200 GHz frequency range. One of the most important findings to date of this work is that the surface emission on the 183 GHz channels is highly diffuse, nearly Lambertian, in nature. This work will have an impact on how assimilation of AMSU-B data will be assimilated over Polar Regions in the future.

Chawn is planning future snow and sea ice campaigns to extend these findings to other seasons and geographic locations.

Chawn also works closely with Tom Emery in Tom's efforts to retrieve atmospheric profile and surface information using PC radiative transfer of the hyperspectral measurements made by  IASI and ARIES. Their focus has been on data acquired over snow covered land and sea ice during the CLPX-II campaign.

Career background

Chawn graduated from high school in Lakeview, Oregon, in June 1987. He received the B.Sc. degree in physics and astronomy; the M.Sc. degree in physics; and the Ph.D. degree in hydrology, with a minor in atmospheric science, from the University of Arizona, Tucson, in 1992, 1994, and 2003, respectively, where his dissertation was titled "Remote and in situ measurement of soil moisture and vegetation water content."

Since February 2005, he has been a Radiation Research Scientist with the Observational Based Research at the Met Office based in Exeter. The majority of his work focuses on snow and sea-ice emissivities in the Advanced Microwave Sounding Unit wavelengths in order to improve retrievals of atmospheric profiles of temperature and humidity. He also serves as a Mission Scientist and MARSS Operator on the  FAAM BAe-146.

External recognition

In February 2010, Chawn received the L. G. Groves Memorial Prize for Meteorological Observations for his contribution to the planning and implementation of the CLPX-II campaign.

Last updated: 8 April 2014