Evaluation of cloud-resolving model simulations of midlatitude cirrus with ARM and A-train observations

Journal Article · Tue Jul 14 00:00:00 EDT 2015 · Journal of Geophysical Research: Atmospheres

DOI:https://doi.org/10.1002/2014JD022570· OSTI ID:1417280

Muhlbauer, A. ^[1]; Ackerman, T. P. ^[2]; Lawson, R. P. ^[3]; Xie, S. ^[4]; Zhang, Y. ^[4]

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1. Univ. of Washington, Seattle, WA (United States). Joint Inst. for Study of the Atmosphere and Ocean
2. Univ. of Washington, Seattle, WA (United States). Joint Inst. for Study of the Atmosphere and Ocean, Dept. of Atmospheric Sciences
3. SPEC Inc., Boulder, CO (United States)
4. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

Cirrus clouds are ubiquitous in the upper troposphere and still constitute one of the largest uncertainties in climate predictions. Our paper evaluates cloud-resolving model (CRM) and cloud system-resolving model (CSRM) simulations of a midlatitude cirrus case with comprehensive observations collected under the auspices of the Atmospheric Radiation Measurements (ARM) program and with spaceborne observations from the National Aeronautics and Space Administration A-train satellites. The CRM simulations are driven with periodic boundary conditions and ARM forcing data, whereas the CSRM simulations are driven by the ERA-Interim product. Vertical profiles of temperature, relative humidity, and wind speeds are reasonably well simulated by the CSRM and CRM, but there are remaining biases in the temperature, wind speeds, and relative humidity, which can be mitigated through nudging the model simulations toward the observed radiosonde profiles. Simulated vertical velocities are underestimated in all simulations except in the CRM simulations with grid spacings of 500 m or finer, which suggests that turbulent vertical air motions in cirrus clouds need to be parameterized in general circulation models and in CSRM simulations with horizontal grid spacings on the order of 1 km. The simulated ice water content and ice number concentrations agree with the observations in the CSRM but are underestimated in the CRM simulations. The underestimation of ice number concentrations is consistent with the overestimation of radar reflectivity in the CRM simulations and suggests that the model produces too many large ice particles especially toward the cloud base. Simulated cloud profiles are rather insensitive to perturbations in the initial conditions or the dimensionality of the model domain, but the treatment of the forcing data has a considerable effect on the outcome of the model simulations. Despite considerable progress in observations and microphysical parameterizations, simulating the microphysical, macrophysical, and radiative properties of cirrus remains challenging. Comparing model simulations with observations from multiple instruments and observational platforms is important for revealing model deficiencies and for providing rigorous benchmarks. But, there still is considerable need for reducing observational uncertainties and providing better observations especially for relative humidity and for the size distribution and chemical composition of aerosols in the upper troposphere.

• Research Organization: Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
• Sponsoring Organization: National Oceanic and Atmospheric Administration (NOAA); National Science Foundation (NSF); USDOE
• Grant/Contract Number: AC52-07NA27344
• OSTI ID: 1417280
• Report Number(s): LLNL-JRNL--735022
• Journal Information: Journal of Geophysical Research: Atmospheres, Journal Name: Journal of Geophysical Research: Atmospheres Journal Issue: 13 Vol. 120; ISSN 2169-897X
• Publisher: American Geophysical Union
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
58 GEOSCIENCES
cirrus
cloud resolving model simulations