New Southern Great Plains Continuous Large-Scale Forcing Data Released

Published: 13 July 2026

A map of variational analysis domains is situated above a data plot showing surface precipitation in units of mm/hr for the two domains featured on the map. One of the domains has a radius of 75 kilometers, and the other has a radius of 150 kilometers. The map covers a grid of about 95 to 100 degrees west and 34 to 38 degrees north. — (a) The map shows the variational analysis domains for the new VARANAL release (enclosed by the red dots) and previously released VARANAL version 2 data (enclosed by the black dots). Both domains are centered near Lamont, Oklahoma, at ARM’s Southern Great Plains (SGP) Central Facility (blue star). (b) Time series of May 2016 SGP surface precipitation are averaged within the variational analysis domains for the new VARANAL release (75-kilometer radius) and previously released VARANAL version 2 data (150-kilometer radius). Figure was created by Cheng Tao and Shaocheng Xie, Lawrence Livermore National Laboratory.

A new release of continuous large-scale forcing data for the Atmospheric Radiation Measurement (ARM) User Facility’s Southern Great Plains (SGP) atmospheric observatory is now available. The continuous large-scale forcing value-added product (VAP), known as VARANAL, was developed from a constrained variational analysis approach documented in Zhang and Lin (1997) and Zhang et al. (2001).

The VARANAL VAP includes both the large-scale forcing terms and the evaluation fields. These can be used for driving single-column models, cloud-resolving models, or large-eddy simulations (LES), including those from the LES ARM Symbiotic Simulation and Observation (LASSO) activity, and for validating model simulations.

This evaluation release covers 15 years of data (2004–2018). In this new release, a smaller variational analysis domain (75-kilometer radius) has been applied with settings identical to those in previously released SGP VARANAL version 2 data to meet various process modeling needs as earth system model resolutions continue to increase. The previously released version 2 domain had a radius of 150 kilometers.

The new forcing data follow the resolution of the previously released version 2 data, with one-hour time resolution and 25-hPa vertical resolution. The data are in netCDF format.

Scientists can begin using the new SGP VARANAL data for model simulation and evaluation.

Data from January 1, 2004, to April 30, 2012, use combined Rapid Update Cycle (RUC) and constrained variational analyses at 60-minute time resolution and are labeled by ARM as 60varanaruc75km. Data from May 1, 2012, to December 31, 2018, use combined Rapid Refresh (RAP) and constrained variational analyses, also at 60-minute time resolution, and are labeled by ARM as 60varanarap75km.

Access the data in the ARM Data Center. (To download the data, first create an ARM account.)

For questions, feedback, or to report data issues, please contact VAP developer Cheng Tao or ARM translator Shaocheng Xie. More details about the ARM continuous forcing data are in Xie et al. (2004) and Tang et al. (2019).

Data can be referenced as doi:10.5439/2377035 for the 60-minute RAP VARANAL product (60varanarap75km.c1) and doi:10.5439/2377036 for the 60-minute RUC VARANAL product (60varanaruc75km.c1).

References:

Zhang M and J Lin. 1997. “Constrained Variational Analysis of Sounding Data Based on Column-Integrated Budgets of Mass, Heat, Moisture, and Momentum: Approach and Application to ARM Measurements.” Journal of the Atmospheric Sciences, 54(11):1503-1524, https://doi.org/10.1175/1520-0469(1997)054<1503:CVAOSD>2.0.CO;2

Zhang M, J Lin, RT Cederwall, JJ Yio, and SC Xie. 2001. “Objective Analysis of ARM IOP Data: Method and Sensitivity.” Monthly Weather Review, 129(2):295-311, https://doi.org/10.1175/1520-0493(2001)129<0295:OAOAID>2.0.CO;2

Xie S, RT Cederwall, and MH Zhang. 2004. “Developing long-term single-column model/cloud system–resolving model forcing data using numerical weather prediction products constrained by surface and top of the atmosphere observations.” Journal of Geophysical Research: Atmospheres, 109(D1):D01104, https://doi.org/10.1029/2003JD004045

Tang S, C Tao, S Xie, and M Zhang. 2019. Description of the ARM Large-Scale Forcing Data from the Constrained Variational Analysis (VARANAL) Version 2. Ed. by Robert Stafford, ARM. DOE/SC-ARM-TR-222, https://doi.org/10.2172/1808705

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ARM is a DOE Office of Science user facility operated by nine DOE national laboratories.