Updated Southern Great Plains Continuous Large-Scale Forcing Data Released

Published: 16 February 2021
Time series of the derived large-scale vertical velocity (Omega) in a previous VARANAL version 2 release for July 2018 (top) and in a new release with a bug fixed (middle), and the difference between the two releases
The plots show the time series of the derived large-scale vertical velocity (Omega) in a previous VARANAL version 2 release for July 2018 (top) and in a new release with a bug fixed (middle), and the difference between the two releases (bottom). The bug only affects the time periods after 18 UTC July 21, when the first missing period occurs in the Rapid Refresh analysis.

A recent release of updated data from version 2 of the Atmospheric Radiation Measurement (ARM) user facility’s continuous large-scale forcing value-added product (VAP), known as VARANAL, is now available in the ARM Data Center.

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 the LES ARM Symbiotic Simulation and Observation (LASSO) activity—and for validating model simulations. Read about version 2 in this data announcement.

This evaluation release covers almost 16 years of data from ARM’s Southern Great Plains atmospheric observatory. The release includes new data from November 2018 to January 2019 and from March 2019 to August 2019. In addition, data from January 2004 to October 2018 were reprocessed to fix a bug.

The bug was associated with the handling of missing data from the Rapid Update Cycle (RUC, before May 2012) or Rapid Refresh (RAP, from May 2012 onward) analysis and resulted in an erroneous time shift of some data fields. This only has an impact on the days after the first missing period occurs in the RUC/RAP analysis for a given month and only affects the large-scale state variables (horizontal winds, temperature, and moisture) and the derived forcing fields. The impact is minimal for long-term statistical studies, but there may be a significant impact on case studies depending on how big the missing gap is and how large the temporal variability is. See a list of months and beginning dates of affected data and the number of days affected in each month.

Analyzed forcing data follow the resolution of the previous version, with 60-minute time resolution and 25-hPa vertical resolution. The data sets are in netCDF format. See the data plots now.

Scientists can begin using the new and reprocessed version 2 forcing data from VARANAL for model simulation and evaluation.

Data from January 1, 2004, to April 30, 2012, use combined RUC and constrained variational analyses at 60-minute time resolution (60varanaruc). Data from May 1, 2012, to August 31, 2019, use combined RAP and constrained variational analyses, also at 60-minute time resolution (60varanarap).

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

Data can be referenced as doi:10.5439/1647174 for the 60-minute RAP VARANAL product (60varanarap.c1) and doi:10.5439/1647300 for the 60-minute RUC VARANAL product (60varanaruc.c1).

To access the data set, please browse the ARM Data Center. (Go here to create an account to download the data.)

References: Tang S, S Xie, M Zhang, Q Tang, Y Zhang, S Klein, D Cook, and R Sullivan. 2019. “Differences in Eddy‐Correlation and Energy‐Balance Surface Turbulent Heat Flux Measurements and Their Impacts on the Large‐Scale Forcing Fields at the ARM SGP Site.” Journal of Geophysical Research: Atmospheres, 124(6), doi:10.1029/2018JD029689.

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, doi:10.1029/2003JD004045.

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