radarcfad > Radar Contoured Frequency by Altitude DiagramVAP Type(s) > Baseline • Evaluation

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 radars. The simulator converts model-calculated cloud properties to what can be directly observed by a cloud radar (i.e., radar reflectivity). The ARM simulator output are joint histograms of radar reflectivity and altitude [i.e., the Contoured Frequency by Altitude Diagrams (CFADs)].

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To compare with ARM cloud radar simulator outputs, observational reflectivity-height joint histograms, i.e., CFADs, are constructed from the operational ARM Active Remote Sensing of Clouds (ARSCL) Value-Added Product. The reflectivity-height data were produced for every hour with the vertical resolution of 100 m to capture both the diurnal variability and detailed vertical structures of clouds. The reflectivities (in dBZ) are binned in 5 dBZ increments from -50 dBZ to 25 dBZ. The daily- and monthly-mean data can be easily calculated from the hourly data. To date, ARM CFADs have been generated for multiple years at the ARM permanent sites.

The climate modeling community can easily and routinely compare the model-simulated clouds with ARM cloud observations and evaluate their model performance.

The ARM cloud radar simulator cannot be applied to identify model issues in simulating high thin cirrus clouds. Small cirrus cloud particles are not detectable due to the limitations of cloud radars. As a result, the cloud-top height of high thin cirrus clouds is usually underestimated by the ARM cloud radar simulator. Another big data issue is that the historical ARM cloud radar were not well calibrated when the data was created. The data will be reprocessed once the calibrated radar reflectivity is available. We recommend that users refer to the technical report or contact the relevant ARM Translators for more information on the data limitation and uncertainties for this data product.


The data products were produced to compare with the outputs from the ARM radar simulator. This data product and the ARM radar simulator will help the direct comparison of global climate models with the ARM radar measurements.



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  • AMF1
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  • AMF3

Data Details

Developed By Yuying Zhang
Contact Yuying Zhang
Resource(s) Data Directory
Data format netcdf
Site NSA
Content time range 15 February 2011 - 15 April 2014
Attribute accuracy No formal attribute accuracy tests were conducted.
Positional accuracy No formal positional accuracy tests were conducted.
Data Consistency and Completeness Data set is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for addtional details.
Access Restriction No access constraints are associated with this data.
Use Restriction No use constraints are associated with this data.
Citations Y Zhang, S Xie, et al. 2017. "The ARM cloud radar simulator for global climate models: A new tool for bridging field data and climate models." submitted to BAMS