[{"name":"oden-artofmelt-2023-trajectories-forward-circle-1","title":"Forward trajectories within a circle around the ship using the LAGRANTO model, for the expedition ARTofMELT, Arctic Ocean, 2023","summary":"7-day forward trajectories from within a circle around the ship track of the Swedish icebreaker Oden during the ARTofMELT (Atmospheric Rivers and the Onset of Arctic Melt) expedition in the Fram Strait pack ice during the spring transition, 8 May to 13 June of 2023.\r\n\r\nThe trajectories were calculated with the Lagrangian Analysis Tool LAGRANTO on ERA5 data \u2014 fifth generation of ECMWF atmospheric reanalysis data \u2014 initialised at locations 30 km equidistant from each-other within a circle (with origo at the ship and a radius of 100 km) every 6-hour at 14 different vertical starting levels.\r\n\r\nThe data tracked and stored in 1-hour intervals along the trajectories include 4D location (longitude, latitude and pressure), air temperature, humidity variables and distance from start, whereas additional surface variables, such as sea ice fraction, surface pressure and surface temperature, are interpolated along the tracks.\r\n\r\nThe data enable analysis of air mass pathways and air mass transformation of an ensamble of air parcels starting forward from Oden during the ARTofMELT expedition that occurred in the Arctic spring of 2023. A measure of the spread and uncertainty of the trajectories can also be obtained by the data.","citations":"Hersbach H, Bell B, Berrisford P, Biavati G, Hor\u00e1nyi A, Mu\u00f1oz Sabater J, Nicolas J, Peubey C, Radu R, Rozum I, Schepers D, Simmons A, Soci C, Dee D, Th\u00e9paut J-N (2023) ERA5 hourly data on single levels from 1940 to present. Copernicus Climate Change Service (C3S) Climate Data Store (CDS). https:\/\/doi.org\/10.24381\/cds.adbb2d47 (Accessed on 18-Jan-2024 and on 05-Feb-2024)\r\n\r\nMurto S, Tjernstr\u00f6m M (2024a) Air parcel trajectories for the expedition ARTofMELT, Arctic Ocean, 2023 \u2014 raw data. Dataset version 1. Bolin Centre Database. https:\/\/doi.org\/10.17043\/oden-artofmelt-2023-trajectories-raw-1\r\n\r\nMurto S, Tjernstr\u00f6m M (2024b) Backward trajectories along the ship track using the LAGRANTO model, for the expedition ARTofMELT, Arctic Ocean, 2023. Dataset version 1. Bolin Centre Database. https:\/\/doi.org\/10.17043\/oden-artofmelt-2023-trajectories-backward-ship-1\r\n\r\nMurto S, Tjernstr\u00f6m M (2024c) Forward trajectories along the ship track using the LAGRANTO model, for the expedition ARTofMELT, Arctic Ocean, 2023. Dataset version 1. Bolin Centre Database. https:\/\/doi.org\/10.17043\/oden-artofmelt-2023-trajectories-forward-ship-1\r\n\r\nMurto S, Tjernstr\u00f6m M (2024d) Backward trajectories within a circle around the ship using the LAGRANTO model, for the expedition ARTofMELT, Arctic Ocean, 2023. Dataset version 1. Bolin Centre Database. https:\/\/doi.org\/10.17043\/oden-artofmelt-2023-trajectories-backward-circle-1\r\n\r\nMurto S (2024) Scripts for creating and plotting netCDF files from air parcel trajectories for the expedition ARTofMELT, Arctic Ocean, 2023. Software version 1.0.0. Bolin Centre Code Repository. https:\/\/doi.org\/10.57669\/oden-artofmelt-2023-trajectories-1.0.0\r\n\r\nSprenger M, Wernli H (2015) The LAGRANTO Lagrangian analysis tool \u2013 version 2.0. Geoscientific Model Development 8:2569\u20132586. https:\/\/doi.org\/10.5194\/gmd-8-2569-2015","comments":"##### Trajectory model\r\nTrajectories are calculated by the LAGRANTO model ([Sprenger & Wernli, 2015](https:\/\/doi.org\/10.5194\/gmd-8-2569-2015)) on ERA5 data on model levels. Trajectory computations are performed on [ECMWF\u2019s high-performance computing facility (HPCF)](https:\/\/www.ecmwf.int\/en\/computing\/our-facilities\/supercomputer-facility). This final dataset is created from the native output text files provided by LAGRANTO and from ERA5 data on surface levels ([Hersbach et al. 2023](https:\/\/doi.org\/10.24381\/cds.adbb2d47)) that are interpolated along the computed trajectory tracks. (See \"Interpolated surface variables\" as listed above). The trajectory native text files are available as a separate dataset.\r\n\r\n##### Quality control\r\nNo quality control is applied except for within the trajectory model, a jumping flag is utilised to allow for trajectories to continue if they hit the ground (it is raised from the ground a little in order to continue).\r\n\r\n##### Associated raw data, processed data and code\r\nThe raw data (trajectory text files), from which this dataset is derived, was created by [Murto & Tjernstr\u00f6m (2024a)](https:\/\/bolin.su.se\/data\/oden-artofmelt-2023-trajectories-raw-1) and is available separately. The raw-data dataset is provided in a `.zip` file containing text files of four different sets of trajectory runs. User-friendly datasets, in NetCDF format, derived from the raw text files, have been created for all four trajectory runs:\r\n1. Backward trajectories started every hour along the ship track, by [Murto & Tjernstr\u00f6m (2024b)](https:\/\/bolin.su.se\/data\/oden-artofmelt-2023-trajectories-backward-ship-1)\r\n2. Forward trajectories started every hour along the ship track, by [Murto & Tjernstr\u00f6m (2024c)](https:\/\/bolin.su.se\/data\/oden-artofmelt-2023-trajectories-forward-ship-1)\r\n3. Backward trajectories started every 6-hours within a circle around the ship, by [Murto & Tjernstr\u00f6m (2024d)](https:\/\/bolin.su.se\/data\/oden-artofmelt-2023-trajectories-backward-circle-1)\r\n4. Forward trajectories started every 6-hours within a circle around the ship (this dataset)\r\n\r\nThe current dataset is a combination of the original raw data files, with additional surface variables interpolated along the provided trajectory tracks. The computer codes in Python, written by [Murto (2024)](https:\/\/git.bolin.su.se\/bolin\/oden-artofmelt-2023-trajectories), used to derive this dataset in NetCDF format from the raw data files are also available. In the same code repository, we also provide python codes for reading in the netCDF files and plotting the trajectories, as well as example figures to illustrate the trajectories.\r\n\r\n##### Data creator's role\r\nTrajectories were computed post expedition based on the ship's GPS location along the track of the ARTofMELT 2023 expedition. The set-up for the trajectory runs as well as the creation of this dataset in NetCDF format were performed by one of the members of the Stockholm University Meteorology team onboard Oden:\r\n- Sonja Murto (dataset creator)\r\n\r\nAdditionally:\r\n- Michael Tjernstr\u00f6m (chief scientist; project PI)\r\n\r\n##### Acknowledgements\r\nAnna Lewinschal (scientific programmer at Stockholm University) provided with example raw-code for runs on the ECMWF's supercomputing facility. The original setup of the LAGRANTO model to the supercomputer facility was done by Moritz Deinhard (researcher at Karlsruher Institut f\u00fcr Technologie, Germany).\r\n\r\n##### The expedition\r\nData were produced for the ARTofMELT 2023 expedition on board the Swedish icebreaker Oden, which was organized by the [Swedish Polar Research Secretariat](https:\/\/www.polar.se\/en\/expeditions\/previous-expeditions\/arctic\/artofmelt-2023\/) from 8 May through 14 June, 2023.","category":"Atmosphere","subcategory":"Circulation","keywords":"Air parcel trajectories; Arctic; Arctic Ocean; Meteorology; LAGRANTO; ARTofMELT; ARTofMELT 2023 expedition; Icebreaker Oden","scientist":"Sonja Murto, Michael Tjernstr\u00f6m","firstname":"Sonja","lastname":"Murto","address":"Department of Meteorology; Stockholm University","postalcode":"SE-106 91","city":"Stockholm","province":"","country":"Sweden","parameters":"Earth science > Atmosphere","location":"Ocean > Arctic Ocean","progress":"","language":"English","project":"ARTofMELT expedition in spring 2023. The project ARTofMELT was funded by the Swedish Research Council (VR: 2022-03052). The raw-data to this dataset was created on ECMWF\u2019s high-performance computing facility (HPCF).","publisher":"Bolin Centre Database","version":"1","constrains":"","access":""}]