Articles | Volume 16, issue 7
Atmos. Chem. Phys., 16, 4743–4756, 2016
Atmos. Chem. Phys., 16, 4743–4756, 2016

Research article 15 Apr 2016

Research article | 15 Apr 2016

Microwave signatures of ice hydrometeors from ground-based observations above Summit, Greenland

Claire Pettersen1, Ralf Bennartz1,2, Mark S. Kulie1, Aronne J. Merrelli1, Matthew D. Shupe3, and David D. Turner4 Claire Pettersen et al.
  • 1Space Science and Engineering Center, Madison, Wisconsin, USA
  • 2Vanderbilt University, Nashville, Tennessee, USA
  • 3Cooperative Institute for Research in Environmental Science, University of Colorado and NOAA – Earth System Research Laboratory, Boulder, Colorado, USA
  • 4National Severe Storms Laboratory, Norman, Oklahoma, USA

Abstract. Multi-instrument, ground-based measurements provide unique and comprehensive data sets of the atmosphere for a specific location over long periods of time and resulting data compliment past and existing global satellite observations. This paper explores the effect of ice hydrometeors on ground-based, high-frequency passive microwave measurements and attempts to isolate an ice signature for summer seasons at Summit, Greenland, from 2010 to 2013. Data from a combination of passive microwave, cloud radar, radiosonde, and ceilometer were examined to isolate the ice signature at microwave wavelengths. By limiting the study to a cloud liquid water path of 40 g m−2 or less, the cloud radar can identify cases where the precipitation was dominated by ice. These cases were examined using liquid water and gas microwave absorption models, and brightness temperatures were calculated for the high-frequency microwave channels: 90, 150, and 225 GHz. By comparing the measured brightness temperatures from the microwave radiometers and the calculated brightness temperature using only gas and liquid contributions, any residual brightness temperature difference is due to emission and scattering of microwave radiation from the ice hydrometeors in the column. The ice signature in the 90, 150, and 225 GHz channels for the Summit Station summer months was isolated. This measured ice signature was then compared to an equivalent brightness temperature difference calculated with a radiative transfer model including microwave single-scattering properties for several ice habits. Initial model results compare well against the 4 years of summer season isolated ice signature in the high-frequency microwave channels.

Short summary
We examined four summers of data from a ground-based atmospheric science instrument suite at Summit Station, Greenland, to isolate the signature of the ice precipitation. By using a combination of instruments with different specialities, we identified a passive microwave signature of the ice precipitation. This ice signature compares well to models using synthetic data characteristic of the site.
Final-revised paper