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On the forward modeling of radar Doppler spectrum width from LES: Implications for model evaluation.

https://arctichealth.org/en/permalink/ahliterature296035
Source
J Geophys Res Atmos. 2018 Jul 27; 123(14):7444-7461
Publication Type
Journal Article
Date
Jul-27-2018
Author
Y-S Chen
J Verlinde
E E Clothiaux
A S Ackerman
A M Fridlind
M Chamecki
P Kollias
M P Kirkpatrick
B-C Chen
G Yu
A Avramov
Author Affiliation
Department of Meteorology and Atmospheric Science, The Pennsylvania State University, University Park, PA.
Source
J Geophys Res Atmos. 2018 Jul 27; 123(14):7444-7461
Date
Jul-27-2018
Language
English
Publication Type
Journal Article
Abstract
Large-eddy simulations of an observed single-layer Arctic mixed-phase cloud are analyzed to study the value of forward modeling of profiling millimeter-wave cloud radar Doppler spectral width for model evaluation. Individual broadening terms and their uncertainties are quantified for the observed spectral width and compared to modeled broadening terms. Modeled turbulent broadening is narrower than the observed values when the turbulent kinetic energy dissipation rate from the subgrid-scale model is used in the forward model. The total dissipation rates, estimated with the subgrid-scale dissipation rates and the numerical dissipation rates, agree much better with both the retrieved dissipation rates and those inferred from the power spectra of the simulated vertical air velocity. The comparison of the microphysical broadening provides another evaluative measure of the ice properties in the simulation. To accurately retrieve dissipation rates as well as each broadening term from the observations, we suggest a few modifications to previously presented techniques. First, we show that the inertial subrange spectra filtered with the radar sampling volume is a better underlying model than the unfiltered -5/3 law for the retrieval of the dissipation rate from the power spectra of the mean Doppler velocity. Second, we demonstrate that it is important to filter out turbulence and remove the layer-mean reflectivity-weighted mean fall speed from the observed mean Doppler velocity to avoid overestimation of shear broadening. Finally, we provide a method to quantify the uncertainty in the retrieved dissipation rates, which eventually propagates to the uncertainty in the microphysical broadening.
Notes
Cites: Nature. 2004 Dec 23;432(7020):1014-7 PMID 15616559
PubMed ID
30467530 View in PubMed
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