Dataset: Research data for "Understanding the sea surface temperature impact on an atmospheric blocking event using sensitivity experiments with the ICOsahedral Nonhydrostatic (ICON) model"

This archive contains data presented in the manuscript “From Sea to Sky: Understanding the sea surface temperature impact on an atmospheric blocking event using sensitivity experiments with the ICOsahedral Nonhydrostatic (ICON) model” published in Weather and Climate Dynamics (Svenja Christ, Marta Wenta, Christian M Grams, and Annika Oertel, 2024, DOI: ). For this sensitivity study five simulations with the ICON model were conducted and analysed, whereby each experiment uses different prescribed sea surface temperature (SST) conditions. This data set contains (i) the initial SST fields of each experiment, and (ii) the warm conveyor belt (WCB) trajectory data from the ICON simulations of each experiment. For details on the SST initial fields, ICON simulations, and trajectory data, please refer to the original publication.

The data are in netCDF format and contain the following: (i) Global sea surface temperatures (SST, in K) for each experiment. The unperturbed SST originates from the OSTIA analysis and is used in the ECMWF IFS analysis on the 18. February 2019 at 00 UTC. The SST fields are remapped to the global unstructured ICON grid R03B07 (EXP000 – CNTRL). The five experiments include the following modifications to the original SST field: EXP000 – CNTRL: Original SST fields, remapped to ICON grid. EXP001 – IDEA: In this experiment, the SST field is smoothed with a Gaussian filter in the Gulf Stream region (80 to 25°W and 30 to 55°N). Thereby the SST front’s small-scale eddies are removed. EXP002 – WEAK: The SST gradient in the Gulf Stream region (80 to 25°W and 30 to 55°N) is reduced. EXP003 – P1.5K: The SST in the Gulf Stream region (80 to 25°W and 30 to 55°N) is increased by 1.5 K, while the SST gradient from IDEA in the Gulf Stream region is maintained. EXP004 – extWEAK: The SST gradient in the Gulf Stream region (80 to 25°W and 30 to 55°N) is strongly weakened, and the SST transitions gradually and cools progressively from the equator towards the higher latitudes. More detailed modifications of SST are described in detail in the publication and figures of the resulting SST and SST gradient fields are provided in the publication as well (Fig. 1). EXP000 – CNTRL (ifs_remap_R03B07_G_2019021800_EXP000.nc) EXP001 – IDEA (ifs_remap_R03B07_G_2019021800_EXP001.nc) EXP002 – WEAK (ifs_remap_R03B07_G_2019021800_EXP002.nc) EXP003 – P1.5K (ifs_remap_R03B07_G_2019021800_EXP003.nc) EXP004 – extWEAK (ifs_remap_R03B07_G_2019021800_EXP004.nc). (ii) warm conveyor belt (WCB) trajectory data of the five CON simulations are contained in the following data sets: EXPID_YYYYMMDD_HH.nc. WCB trajectories are started from a 50 km equidistant horizontal grid spanning the North Atlantic region between 80 to 25°W and 30 to 55°N. They are initiated from 10 chosen vertical levels within the lower-most 2 km, specifically at altitudes of 50, 200, 400, 600, 800, 1000, 1250, 1500, 1750, and 2000 m. The date in the file names (YYYYMMDD_HH) refers to the trajectory start time. WCBs are defined as trajectories with at least 500 hPa ascent in 48 h. WCB air parcel positions and characteristics are provided every 3-h. Variables traced along WCB trajectories are: time (in hours, relative to trajectory start), lon and lat (in °): air parcel longitude and latitude positions, z: air parcel altitude (in meter above sea level), P: pressure (in hPa), t_seasfc: SST (in K; this presents a 2D field traced along the lon/lat positions of WCB air parcels), lhfl_s: latent head flux (in W m-2; 2D field; negative fluxes are defined as upward fluxes), shfl_s: sensible heat flux (in W m-2; 2D field; negative fluxes are defined as upward fluxes), pres_msl: mean sea level pressure (in Pa; 2D field), pv: Potential vorticity (in pvu), temp: temperature (in K), qc: specific cloud water content (in g kg-1), qi: specific cloud ice content (in g kg-1), qr: rain mixing ratio (in g kg-1), qs: snow mixing ratio (in g kg-1), qv_1: specific humidity (in g kg-1).