Large-Scale Forcing Data Released for COMBLE Campaign

Published: 13 June 2022

A map of Scandinavia focuses on the analysis domain around the main site of the COMBLE campaign near Andenes, Norway. Iceland, Norway, Sweden, Finland, and the Norwegian Sea are labeled along with the analysis domain and AMF1 (main ARM COMBLE site).
The map shows the variational analysis domain (enclosed by the red circle) for the Cold-Air Outbreaks in the Marine Boundary Layer Experiment (COMBLE). The domain is centered at 14.9oE, 70.6oN. The first ARM Mobile Facility (AMF1), sited near Andenes, Norway, is located at the edge of the domain.

Continuous large-scale forcing data are now available for the Cold-Air Outbreaks in the Marine Boundary Layer Experiment (COMBLE). The Atmospheric Radiation Measurement (ARM) user facility conducted the COMBLE field campaign from December 2019 through May 2020 in northern Norway.

Forcing data for COMBLE were developed from a constrained variational analysis approach (Zhang and Lin 1997; Zhang et al. 2001). Scientists can use this value-added product (VAP), known as VARANAL, to drive single-column models, cloud-resolving models, and large-eddy simulation models for different cloud and convective systems. To help validate model simulations, the VAP includes diagnostic fields such as diabatic heating profiles, cloud fields, surface measurements, and large-scale conditions.

The COMBLE large-scale forcing data are based on ERA5 reanalysis data from the European Centre for Medium-Range Weather Forecasts and constrained with surface rainfall retrieved from MET Norway radar data.

The forcing data represent an average over the analysis domain, centered at 14.9oE, 70.6oN with a radius of 150 kilometers. The analysis domain represents ocean only to exclude the impact of different surface types on the observed surface radiative and turbulent heat fluxes.

This evaluation data set is in netCDF format, with a time resolution of 60 minutes and a vertical resolution of 25 hPa.

Scientists can begin using the COMBLE large-scale variational analysis forcing data for model simulation and evaluation. Please note that this data set represents averages over the analysis domain. Users need to be cautious when comparing this data set with the ARM single-point measurements.

More information about VARANAL can be found on the VAP web page.

To ask questions, report data problems, or provide feedback on this evaluation product, please contact Cheng Tao or Shaocheng Xie. More details about the ARM continuous forcing data set are in Xie et al. (2004).

Access the data set in the ARM Data Center. (Go here to create an account to download the data.)

Data can be referenced as doi:10.5439/1860369.

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,<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,<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,

# # #

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