Ensembles of HYSPLIT back trajectories for the ARTofMELT 2023 expedition

Jessica Matthew, Julia Kojoj, Sara Blichner, Paul Zieger

This dataset contains HYSPLIT-generated ensembles of back-trajectories for the ARTofMELT 2023 expedition. For every hour along the Icebreaker Oden's path, ensembles of 27 back trajectories were launched at 270m altitude at the location of the ship, and were run 10 days backwards in time with an hourly time-step.

Along each trajectory, the time and location of the simulated air parcel is provided, along with meteorological information, and a mask indicating if the parcel is above open ocean, land, sea-ice, or above the boundary layer.

This dataset contextualises atmospheric observations performed on the Icebreaker Oden. It indicates the journey that the air had taken to arrive at the location of measurement, and is particularly useful for identifying periods of increased influence from different surface types (the ocean, sea-ice, or land).

AtmosphereMeteorologyARTofMELT 2023Back TrajectoriesHYSPLITAerosolAtmospheric Science

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Version

Citation

References

Draxler RR, Rolph GD (2017). HYSPLIT (HYbrid Single-Particle Lagrangian Integrated Trajectory) Model access via NOAA ARL READY Website (http://www.ready.noaa.gov/HYSPLIT.php). NOAA Air Resources Laboratory, Silver Spring, MD.

Rolph G, Stein A, Stunder B (2017) Real-time Environmental Applications and Display sYstem: READY. Environmental Modelling & Software 95:210–228. https://doi.org/10.1016/j.envsoft.2017.06.025

Stein AF, Draxler RR, Rolph GD, Stunder BJB, Cohen MD, Ngan F (2015) NOAA’s HYSPLIT Atmospheric Transport and Dispersion Modeling System. Bulletin of the American Meteorological Society 96:2059–2077. https://doi.org/10.1175/bams-d-14-00110.1

Draxler RR, Hess GD (1998) An overview of the HYSPLIT_4 modelling system for trajectories, dispersion and deposition, Aust. Met. Mag., 47, 295-308.

Draxler RR, Hess GD (1997) Description of the HYSPLIT_4 modelling system, NOAA Technical Memorandum ERL ARL-224, December, 24 p.

Spreen G, Kaleschke L, Heygster G (2008) Sea ice remote sensing using AMSR‐E 89‐GHz channels. Journal of Geophysical Research: Oceans 113. https://doi.org/10.1029/2005jc003384

University of Bremen AMSR2 ASI sea ice concentration v5.4, 6.25 km Arctic (Spreen et al., 2008), https://seaice.uni-bremen.de/sea-ice-concentration/ ; data from https://data.seaice.uni-bremen.de/amsr2/asi_daygrid_swath/n6250/ (accessed December 2023).

Data description

This data is stored in NetCDF file format. It has dimensions:

• launch_time: Date and time of the position of Oden that the back trajectory was launched from (UTC)
• traj_step: Number of steps backwards in time since launch of the ensembles (hours)
• ens_member: 1-27, The individual trajectory held within the ensemble (dimensionless)

Variables provided at hourly intervals along the back trajectories are the latitude, longitude, altitude and time of the air parcel, meteorology, and surface masks:

• traj_time: Time at the location of the air parcel (UTC)
• lat: Air parcel latitude (degrees north)
• lon: Air parcel longitude (degrees east)
• alt: Air parcel height above ground level (m)
• pressure: Pressure of air parcel (hPa)
• bl_height: Planetary boundary layer height at the air parcel location (m)
• pot_temp: Potential temperature of the air parcel (K)
• temp: Temperature of the air parcel (K)
• precip: Surface precipitation rate at the air parcel location (mm h⁻¹)
• relhumid: Relative humidity of the air parcel (%)
• spchumid: Specific humidity of the air parcel (g kg⁻¹)
• terr_msl: Terrain height above mean sea level below the air parcel (m)
• sun_flux: Downward solar radiation flux at the surface below the air parcel (W m⁻²)
• seaice_conc: AMSR2 ASI sea ice concentration at the nearest grid cell, using University of Bremen sea ice data on a Polar Stereographic grid (%) (Spreen et al. 2008)
• icemask: Sea ice surface mask (0 = not ice, 1 = ice), assigned where sea ice concentration is ≥75% or where sea ice data are missing within 325 km of the pole, excluding points above the boundary layer
• landmask: Land surface mask (0 = not land, 1 = land)
• blmask: Above boundary layer mask (0 = within the boundary layer, 1 = above the boundary layer)
• seamask: Open sea surface mask (0 = not sea, 1 = sea)

HYSPLIT v5.2.1 (Draxler and Hess 1987, Draxler and Hess 1988, Stein et. al 2015, Draxler and Rolph 2017, Rolph et. al 2017) was used to simulate the flow of the air, and GDAS data at 1-degree resolution was used for the meteorological inputs. Ensembles were released at 270m altitude above the ship, and the meteorology was offset vertically and horizontally by ~250m to create ensembles of 27 different trajectories.

The sea-ice mask was constructed using satellite data from the University of Bremen, requiring a 75% threshold for it to be determined sea-ice (Spreen et. al 2008). Data was obtained via FTP and can be found by following the link: https://data.seaice.uni-bremen.de/amsr2/asi_daygrid_swath/n6250/.

Project

ARTofMELT 2023

Publisher

Bolin Centre Database

License

Open Data Commons Attribution License (ODC-By) v1.0

First name

Paul

Last name or organisation

Zieger

Email address

paul.zieger@aces.su.se

Address

Department of Environmental Science; Stockholm University

Postal code

114 18

City

Stockholm

Country

Sweden

Begin date

2023-05-08

End date

2023-06-13

DOI

Time