New Data Set Available From COMBLE Campaign

Published: 13 June 2022
In the top image, four colored lines, representing back trajectories, extend from the Arctic ice edge to the starred location indicating the ARM Mobile Facility site for the COMBLE campaign. The lat (y-axis) goes from 66 up to 78, while the lon (x-axis) goes left to right from -10 to 30. The bottom image shows the four back trajectories and their elevations from 0 to 36 hours.
Top image: Reflectance from the Aqua MODIS satellite visible channel shows cloud streets extending from the ice edge southward to Norway on March 13, 2020. The black star marks the location of the ARM Mobile Facility site near Andenes, Norway, with red, blue, green, and yellow lines indicating back trajectories at 500 meters, 1,000 meters, 2,000 meters, and 5,000 meters. Bottom image: Air mass elevations are shown for trajectories initiated at different levels.

Now available in the Atmospheric Radiation Measurement (ARM) Data Center are calculated back trajectories for identified cold-air outbreak cases from the Cold-Air Outbreaks in the Marine Boundary Layer Experiment (COMBLE). Back trajectories are commonly used to determine the origin of air masses observed at a given location.

The ARM user facility conducted the COMBLE field campaign from December 2019 through May 2020 at two sites in northern Norway. An ARM Mobile Facility collected data near Andenes, while a smaller instrument site operated on Bear Island. Researchers reported 34 days of cold-air outbreak conditions near Andenes and 38 days on Bear Island during COMBLE.

For every hour of cold-air outbreak cases identified from interpolated sounding by Geerts et al. (2022) at either site, a 36-hour back trajectory was calculated using the NOAA Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model. For air masses at specific elevations at the endpoint where the back trajectories were initiated, their historical locations (latitude, longitude, and altitude) in the past 36 hours were computed.

Three meteorological data sets were used as inputs to HYSPLIT:

  • Global Forecast System (GFS) 0.25 degree
  • Global Data Assimilation System (GDAS) 1 degree
  • National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) Reanalysis.

The back trajectories were calculated for four endpoint elevations: 500 meters, 1,000 meters, 2,000 meters, and 5,000 meters.

Coordinates (latitudes, longitudes, and altitudes) for each hour of the trajectory are reported in the ASCII files.

COMBLE back trajectory data from December 1, 2019, to March 27, 2020, are ready to use now. The U.S. Department of Energy’s Atmospheric System Research (ASR) supported work on these data through the Integrated Cloud, Land-surface, and Aerosol System Study (ICLASS) Science Focus Area.

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

To ask questions or provide feedback about the data, please contact Peng Wu or Mikhail Ovchinnikov.

When citing the data set, please use doi:10.5439/1843763.

Reference: Geerts B, S Giangrande, G McFarquhar, L Xue, S Abel, J Comstock, S Crewell, P DeMott, K Ebell, P Field, T Hill, A Hunzinger, M Jensen, K Johnson, T Juliano, P Kollias, B Kosovic, C Lackner, E Luke, C Lüpkes, A Matthews, R Neggers, M Ovchinnikov, H Powers, M Shupe, T Spengler, B Swanson, M Tjernström, A Theisen, N Wales, Y Wang, M Wendisch, and P Wu. 2022. “The COMBLE campaign: a study of marine boundary-layer clouds in Arctic cold-air outbreaks.” Bulletin of the American Meteorological Society, 103(5):E1371-E1389,

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