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Title: Absorption Properties of Supercooled Liquid Water between 31 and 225 GHz: Evaluation of Absorption Models Using Ground-Based Observations

Microwave radiometers (MWR) are commonly used to quantify the amount of supercooled liquid water (SLW) in clouds; however, the accuracy of the SLW retrievals is limited by the poor knowledge of the SLW dielectric properties at microwave frequencies. Six liquid water permittivity models were compared with ground-based MWR observations between 31 and 225 GHz from sites in Greenland, the German Alps, and a low-mountain site; average cloud temperatures of observed thin cloud layers range from 0° to –33°C. A recently published method to derive ratios of liquid water opacity from different frequencies was employed in this analysis. These ratios are independent of liquid water path and equal to the ratio of αL at those frequencies that can be directly compared with the permittivity model predictions. The observed opacity ratios from all sites show highly consistent results that are generally within the range of model predictions; however, none of the models are able to approximate the observations over the entire frequency and temperature range. Findings in earlier published studies were used to select one specific model as a reference model for αL at 90 GHz; together with the observed opacity ratios, the temperature dependence of αL at 31.4, 52.28, 150, andmore » 225 GHz was derived. The results reveal that two models fit the opacity ratio data better than the other four models, with one of the two models fitting the data better for frequencies below 90 GHz and the other for higher frequencies. Furthermore, these findings are relevant for SLW retrievals and radiative transfer in the 31–225-GHz frequency region.« less
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [3] ;  [4]
  1. Univ. of Cologne, Cologne (Germany)
  2. Argonne National Lab. (ANL), Argonne, IL (United States)
  3. NOAA/National Severe Storms Lab., Norman, OK (United States)
  4. Academiz Sinica Institute of Astronomy and Astrophysics, Taipei (Taiwan)
Publication Date:
Grant/Contract Number:
AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Journal of Applied Meteorology and Climatology
Additional Journal Information:
Journal Volume: 53; Journal Issue: 4; Journal ID: ISSN 1558-8424
Publisher:
American Meteorological Society
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
German Science Foundation; National Science Foundation (NSF); USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; 54 ENVIRONMENTAL SCIENCES; Absorption; Cloud microphysics; Cloud retrieval; Cloud water/phase; Radiative transfer; Microwave observations
OSTI Identifier:
1396302

Kneifel, Stefan, Redl, Stephanie, Orlandi, Emiliano, Lohnert, Ulrich, Cadeddu, Maria P., Turner, David D., and Chen, Ming -Tang. Absorption Properties of Supercooled Liquid Water between 31 and 225 GHz: Evaluation of Absorption Models Using Ground-Based Observations. United States: N. p., Web. doi:10.1175/JAMC-D-13-0214.1.
Kneifel, Stefan, Redl, Stephanie, Orlandi, Emiliano, Lohnert, Ulrich, Cadeddu, Maria P., Turner, David D., & Chen, Ming -Tang. Absorption Properties of Supercooled Liquid Water between 31 and 225 GHz: Evaluation of Absorption Models Using Ground-Based Observations. United States. doi:10.1175/JAMC-D-13-0214.1.
Kneifel, Stefan, Redl, Stephanie, Orlandi, Emiliano, Lohnert, Ulrich, Cadeddu, Maria P., Turner, David D., and Chen, Ming -Tang. 2014. "Absorption Properties of Supercooled Liquid Water between 31 and 225 GHz: Evaluation of Absorption Models Using Ground-Based Observations". United States. doi:10.1175/JAMC-D-13-0214.1. https://www.osti.gov/servlets/purl/1396302.
@article{osti_1396302,
title = {Absorption Properties of Supercooled Liquid Water between 31 and 225 GHz: Evaluation of Absorption Models Using Ground-Based Observations},
author = {Kneifel, Stefan and Redl, Stephanie and Orlandi, Emiliano and Lohnert, Ulrich and Cadeddu, Maria P. and Turner, David D. and Chen, Ming -Tang},
abstractNote = {Microwave radiometers (MWR) are commonly used to quantify the amount of supercooled liquid water (SLW) in clouds; however, the accuracy of the SLW retrievals is limited by the poor knowledge of the SLW dielectric properties at microwave frequencies. Six liquid water permittivity models were compared with ground-based MWR observations between 31 and 225 GHz from sites in Greenland, the German Alps, and a low-mountain site; average cloud temperatures of observed thin cloud layers range from 0° to –33°C. A recently published method to derive ratios of liquid water opacity from different frequencies was employed in this analysis. These ratios are independent of liquid water path and equal to the ratio of αL at those frequencies that can be directly compared with the permittivity model predictions. The observed opacity ratios from all sites show highly consistent results that are generally within the range of model predictions; however, none of the models are able to approximate the observations over the entire frequency and temperature range. Findings in earlier published studies were used to select one specific model as a reference model for αL at 90 GHz; together with the observed opacity ratios, the temperature dependence of αL at 31.4, 52.28, 150, and 225 GHz was derived. The results reveal that two models fit the opacity ratio data better than the other four models, with one of the two models fitting the data better for frequencies below 90 GHz and the other for higher frequencies. Furthermore, these findings are relevant for SLW retrievals and radiative transfer in the 31–225-GHz frequency region.},
doi = {10.1175/JAMC-D-13-0214.1},
journal = {Journal of Applied Meteorology and Climatology},
number = 4,
volume = 53,
place = {United States},
year = {2014},
month = {4}
}