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The ARM Cloud Radar Simulator for Global Climate Models

The ARM cloud radar simulator is a ground-based cloud radar simulator developed to facilitate the comparison of climate model-simulated clouds with ARM observations from its vertically pointing 35-GHz radars. It is based on the QuickBeam radar simulator, implemented in the Cloud Feedback Model Intercomparison Project (CFMIP) Observation Simulator Package (COSP) to converts model-calculated cloud properties to what can be directly observed by a cloud radar (i.e., radar reflectivity). The ARM cloud radar simulator is unique in that it uses a finer vertical resolution (100 m compared to 500 m for CloudSat), which can resolve more detailed vertical structures within clouds on the diurnal cycle. With the ARM cloud radar simulator incorporated within COSP, the climate modeling community can easily and routinely compare the model-simulated clouds with ARM cloud observations and evaluate their model performance.

The inputs required to run the ARM cloud radar simulator include the Global Climate Model (GCM) gridbox means of the temperature and relative humidity and the hydrometeor profiles of stratiform/convective cloud fraction, cloud liquid/ice mixing ratio, precipitation fluxes with associated effective radii, and number concentrations (optional). The ARM simulator output summaries are joint histograms of radar reflectivity and altitude [i.e., the Contoured Frequency by Altitude Diagrams (CFADs)]. An example of a CFAD built from observed clouds is given in the figure below. To date, ARM CFADs, constructed from the operational ARM Active Remote Sensing of Clouds (ARSCL), are available for multiple years at the ARM’s Southern Great Plain (SGP), Tropical Western Pacific (TWP) and North Slope Alaska (NSA) Research Facility.

For more detailed information about this data product, please refer to the One-page description and Technical Report. If you have any questions regarding this data product, please contact Yuying Zhang (zhang24@llnl.gov) or Shaocheng Xie (xie2@llnl.gov).

Zhang, Y., S. Xie, S. A. Klein, et al., 2018: The ARM cloud radar simulator for global climate models: Bridging field data and climate models, Bull. Amer. Meteor. Soc., 99, 21-26, doi:10.1175/BAMS-D-16-0258.1.