TY - JOUR
T1 - On the Forward Modeling of Radar Doppler Spectrum Width From LES
T2 - Implications for Model Evaluation
AU - Chen, Y. S.
AU - Verlinde, J.
AU - Clothiaux, E. E.
AU - Ackerman, A. S.
AU - Fridlind, A. M.
AU - Chamecki, M.
AU - Kollias, P.
AU - Kirkpatrick, M. P.
AU - Chen, B. C.
AU - Yu, G.
AU - Avramov, A.
N1 - Funding Information:
This research was supported by the U.S. Department of Energy Atmospheric Science Program Atmospheric System Research, an Office of Science, Office of Biological and Environmental Research program, under grants DE-FG02-05ER64058 and DE-SC0013953. Fuqing Zhang and his students, in particular, Yongqiang Sun, provided the initial code for the calculation of power spectra of simulated vertical air velocity. Their help is sincerely appreciated. This research used resources of the National Energy Research Scientific Computing Center, a Department of Energy Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under contract DE-AC02-05CH11231. The ARM data sets used in the study (datastreams nsaceilC1.b1, nsammcrspecmomC1.a0, nsamwrret1liljclouC1.s2, and nsasondewnpnC1.b1) can be downloaded from http://www.archive.arm.gov/discovery/#v/datastreams/s/.
Funding Information:
This research was supported by the U.S. Department of Energy Atmospheric Science Program Atmospheric System Research, an Office of Science, Office of Biological and Environmental Research program, under grants DE-FG02-05ER64058 and DE-SC0013953. Fuqing Zhang and his students, in particular, Yongqiang Sun, provided the initial code for the calculation of power spectra of simulated vertical air velocity. Their help is sincerely appreciated. This research used resources of the National Energy Research Scientific Computing Center, a Department of Energy Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under contract DE-AC02-05CH11231. The ARM data sets used in the study (datastreams nsaceilC1.b1, nsammcrspecmomC1.a0, nsamwrret1liljclouC1.s2, and nsasondewnpnC1.b1) can be downloaded from http://www.archive. arm.gov/discovery/#v/datastreams/s/.
Publisher Copyright:
©2018. American Geophysical Union. All Rights Reserved.
PY - 2018/7/27
Y1 - 2018/7/27
N2 - 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 spectrum 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.
AB - 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 spectrum 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.
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U2 - 10.1029/2017JD028104
DO - 10.1029/2017JD028104
M3 - Article
AN - SCOPUS:85050373843
VL - 123
SP - 7444
EP - 7461
JO - Journal of Geophysical Research: Atmospheres
JF - Journal of Geophysical Research: Atmospheres
SN - 2169-897X
IS - 14
ER -