1. ABOUT THE DATASET --------------------- Title: North Atlantic polar low tracks from September 2008 to May 2009 from WRF simulations at 50, 25 and 12.5 km grid spacings Creator(s): Marta Moreno-Ibáñez[1,2] Contributor(s): John J. Cassano[2], Suzanne L. Gray[1], Mark Seefeldt [2] Organisation(s): [1] University of Reading, [2] University of Colorado Boulder Rights-holder(s): Marta Moreno-Ibáñez Publication Year: 2025 Description: This dataset contains: 1) The model configuration files of three simulations conducted with the Advanced Research Weather Research and Forecasting (WRF) Model with 50, 25 and 12.5 km grid spacings. The domain is the North Atlantic and the period covered is 2008-09 to 2009-05. 2) The tracks of polar lows in each simulation. 3) Statistics of the characteristics of the polar low tracks and associated fields. Cite as: Moreno-Ibáñez, M. (2025): North Atlantic polar low tracks from September 2008 to May 2009 from WRF simulations at 50, 25 and 12.5 km grid spacings. University of Reading. Dataset. https://doi.org/10.17864/1947.001433 Related publication: Moreno-Ibáñez, M., Cassano, J. J., Gray, S. L. and Seefeldt, M. (2025). The dependence of the representation of simulated polar lows to typical climate model resolutions. Atmospheric Science Letters (submitted). 2. TERMS OF USE ---------------- Copyright 2025 Marta Moreno-Ibáñez. This dataset is licensed under a Creative Commons Attribution 4.0 International Licence: https://creativecommons.org/licenses/by/4.0/. 3. FUNDING INFORMATION ----------------------- Funding organisation: NOAA Cooperative Agreement Grant: NA22OAR4320151 Funding organisation: U.S. Department of Energy's Office of Science Grant: HiLAT-RASM Funding organisation: National Science Foundation Grant: 2201538 4. CONTENTS ------------ The naming convention is WRF50km, WRF25km, and WRF12km for the simulations with grid spacings of 50 km, 25 km and 12.5 km, respectively. 4.1 Configuration files of the WRF simulations ----------------------------------------------- - WPS namelists: files containing namelist records that define parameters used by WRF Preprocessing System (WPS) programs. namelist_wps_WRF50km.txt namelist_wps_WRF25km.txt namelist_wps_WRF12km.txt - WRF namelists: files containing namelist records that define parameters used by the WRF model. namelist_input_WRF50km.txt namelist_input_WRF25km.txt namelist_input_WRF12km.txt 4.2 Polar low tracks --------------------- WRF50km_PL_tracks.zip WRF25km_PL_tracks.zip WRF12km_PL_tracks.zip Each zip file is organized as follows: Folders: [yyyy][mm] Files within each folder: [sim]_[yyyy][mm]_PL[#].csv where [yyyy] is the year, [mm] is the month, [sim] is the name of the simulation, and [#] is the unique ID for the polar low for the given year and month (i.e., the first polar low that forms in a month is PL1, and so on). Each polar low is assigned to the month when it forms. List of variables in each file: year: year of the track point [UTC] month: month of the track point [UTC] day: day of the track point [UTC] hour: hour of the track point [UTC] lat: latitude of the polar low centre [°] lon: longitude of the polar low centre [°] SLPc: sea level pressure at the polar low centre [hPa] speed: propagation speed since last observation [km/h] 4.3 Statistics of the polar low tracks -------------------------------------- These files contain the statistics of the characteristics of the polar low tracks and associated fields: WRF50km_PL_tracks_200809_200905.csv WRF25km_PL_tracks_200809_200905.csv WRF12km_PL_tracks_200809_200905.csv List of variables in each file: start_year: year of the first track point [UTC] start_month: month of the first track point [UTC] ID: unique ID for the polar low for the given year and month lifetime: lifetime of the polar low [h] radius_Lavg: lifetime average of the equivalent radius [km] speed_Lavg: lifetime average of the propagation speed [m/s] distance: distance travelled [km] SLPc_Lmin: lifetime minimum of the sea level pressure at the polar low centre [hPa] WS10_LmaxAmax: lifetime maximum of the maximum 10-m wind speed within 200 km of the polar low centre [m/s] APCP_LmaxAmax: lifetime maximum of the maximum 1-h accumulated precipitation within 200 km of the polar low centre [mm] SHF_LmaxAavg: lifetime maximum of the average surface sensible heat fluxes within 200 km of the polar low centre [W/m^2] LHF_LmaxAavg: lifetime maximum of the average surface latent heat fluxes within 200 km of the polar low centre [W/m^2] 5. METHODS ----------- Full details of the methods are provided in Moreno-Ibanez et al. (2025, submitted). The methods are summarized below: 1. Three simulations have been performed with the Advanced Research Weather Research and Forecasting (WRF) Model Version 4.5.1 (Skamarock et al., 2019) with grid spacings of 50, 25, and 12.5 km. Each simulation was initialized on 2008-09-01 at 0000 UTC and ended on 2009-06-01 at 0000 UTC. The domain covers the North Atlantic. WRF is available at http://dx.doi.org/10.5065/D6MK6B4K 2. Polar lows have been detected and tracked in each simulation as follows: Step 1: Application of version 13.2 of the cyclone tracking algorithm presented in Crawford et al. (2021), which is available at https://doi.org/10.5281/zenodo.7562953 Step 2: Application of polar low criteria. Step 3: Manual analysis of the shortlisted potential polar low tracks. 3. Statistics of the characteristics of the polar low tracks (e.g., lifetime) and of certain fields within 200 km from the polar low centre (e.g., area-maximum 10-m wind speed) have been computed. References: - Crawford, A. D., Schreiber, E. A. P., Sommer, N., Serreze, M. C., Stroeve, J. C. and co-authors. 2021. Sensitivity of Northern Hemisphere Cyclone Detection and Tracking Results to Fine Spatial and Temporal Resolution Using ERA5. Mon. Weather Rev. 149, 2581-2598. doi: 10.1175/mwr-d-20-0417.1 - Skamarock, W. C., Klemp, J. B., Dudhia, J., Gill, D. O., Liu, Z. and co-authors. 2019. A Description of the Advanced Research WRF Version 4. Tech. Note NCAR/TN-556+STR, NCAR