Model Data Set for the study on finding the gravity wave source - POLSTRACC Flight 18
Introduction
This provides access to the ECMWF model experiment dataset of the study Geldenhuys et al. (2021) submitted to ACP. This study uses observations and model runs to identify a new gravity wave source mechanism via the interaction between large scale topography and the jet.
Control-run (a--h) and T21-topography-run (i--p) cross-stream ageostrophic wind and temperature residuals at different times. The cross-stream ageostrophic wind (a--d and i--l) was calculated on pressure levels, hence here it is depicted at 350hPa (~8.1km). The temperature residuals (e--h and m--p) were determined on geopotential heights, hence this is valid for 10km. The temperature residuals are depicted ~2km higher than the cross-stream ageostrophic wind, as the GW structure forms a complex interference pattern with upward and downward propagating GWs within the jet. The temperature residual plots are offset by 6h from the cross-stream ageostrophic wind to allow time for the GWs to propagate to 10km. Times (in h) are since model initialisation (on 9 March at 12:00 UTC) + xxhrs ("xx" as specified in top left corner of each panel). Image: Figure 10 of Geldenhuys et al. (2021)
Data access
The dataset is from the ECMWF model and in grib format. Each grib file contain; latitude, longitude, geopotential height, temperature, pressure, time as well as u-, v- and w-wind on 137 hybrid model levels. The files can be read with standard grib reading tools (e.g. GrADS or pygrib). For the Geldenhuys et al. (2021) study the files were converted to ncdf format using the Juelich tool Juregrid. The model experiment was devised to investigate the influence of orography on the GW. Three global model forecasts with ECMWF Integrated Forecast System (IFS) were conducted: i) CTL-run ii) NoOroDrag and iii) T21-run. The forecasts are performed at TCo1279 horizontal resolution (corresponding to 9km grid-spacing on a cubic octahedral grid) with 137 vertical levels and use the operational ECMWF IFS configuration of cycle 45r1 (https://www.ecmwf.int/en/forecasts/documentation-and-support/evolution-ifs/cycles/summary-cycle-45r1). The second model run was not discussed in the publication but is included for completeness. This model run used the exact same physics as CTL-run, but with the orographic drag parameterisation scheme switched off. This was done to confirm the Rossby wave will still break if there is no surface drag. T21-run differs from CTL-run in the resolution of topography that the runs used. CTL-run used a topography of TCo1279 resolution and T21-run used a T21 resolution. Meaning that T21-run orography is much smoother and does not resolve Fjords and mountains at the Greenland coast. T21-run topography is only 60% of the TCo1279 orography height. The forecasts were initialised on 9 March 2016 at 12:00 UTC and run freely for 72h. The GW observation takes place 30h after initialisation. See the description in Geldenhuys et al. (2021) for more details of the dataset and how it was prepared. Note that these are non-operational research data products, which have been made available to other scientists and the general public.
- download ECMWF control-run (CTL-run): reference simulation
- download ECMWF (NoOroDrag): CTL-run minus the orographic drag parameterization
- download ECMWF T21-topography-run (T21-run): CTL-run input conditions but using a T21-topographic field.
Legal notes
The data sets provided on this site are licensed under a Creative Commons Attribution 4.0 International License. You are free to share the material in any medium or format and adapt it for any purpose, even commercially. You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use. You may not apply legal terms or technological measures that legally restrict others from doing anything the license permits. The licensor cannot revoke these freedoms as long as you follow the license terms. The data are distributed in the hope that it will be useful, but without any warranty. Please follow the link to see the terms and conditions of the license:
We kindly ask to contact the authors, if you use these data.
Reference
The data were used in the following publication:
Geldenhuys, M., Preusse, P., Krisch, I., Zülicke, C., Ungermann, J., Ern, M., Friedl-Vallon, F., and Riese, M.: Orographically induced spontaneous imbalance within the jet causing a large-scale gravity wave event, Atmos. Chem. Phys., 21, 10393–10412, https://doi.org/10.5194/acp-21-10393-2021, 2021.
Citation, if the data are used in publications:
Polichtchouk, I., 2021, "Replication Data for Greenland ECMWF runs 2016-03-10: Orographically-induced Spontaneous Imbalance within the Jet Causing a Large Scale Gravity Wave Event", https://doi.org/10.26165/JUELICH-DATA/OMK2I9, Jülich DATA, DRAFT VERSION
Contact
Please do not hesitate to contact us if you have any further questions:
Markus Geldenhuys;
Forschungszentrum Jülich
Institut für Energie- und Klimaforschung, IEK-7
52425 Jülich
Germany
e-mail: m.geldenhuys@fz-juelich.de
e-mail: markusgeld@gmail.com
