Lamb weather types (reduced set) and gale days over the Baltic Sea since 1948 based on NCEP/NCAR Reanalysis 1 daily mean sea level pressure fields
doi:10.26050/WDCC/LambWTyRSetAndGaleDaysOverTheBa
Loewe, Peter; Schade, Nils
ExperimentDOI
ATMODATatmosatmosphereAtmospheric dynamicsBaltic SeaclimateEASYDABFOS: Earth and related environmental scienceNCEP/NCAR Reanalysis
- Summary
- Much of what was summarized about the North Sea dataset (Loewe, 2022) carries over to the Baltic Sea setting. To make the current text a stand-alone resource that summary is reproduced here mutatis mutandis. Despite all equivalence, there is an important difference as to gale classification arising from relocating the analysis grid that is addressed in the following as well.
Sea level pressure is a fundamental weather and climate element and the very basis of everyday weather maps. Daily sea level pressure distributions provide information on the influence of high and low pressure systems, air flow, weather activity, and, hence, synoptic conditions.
Using sea level pressure distributions from the NCEP/NCAR Reanalysis 1 (Kalnay et al., 1996) and a simplified variant of the weather-typing scheme by Jenkinson and Collison (1977) atmospheric circulation over the Baltic Sea has been classified as to pattern and intensity on a daily basis starting in 1948. A full account of the original weather-typing scheme for the North Sea can be found in Loewe et al. (2005), while the variant scheme has been detailed in Loewe et al. (2006). The original 16-point analysis grid devised for the North Sea was shifted 5 degrees to the North and 15 degrees to the East to accommodate the Baltic Sea. Though formally valid at its central point (60°N, 20°E), results are representative of the Baltic Sea region between 55°N-65°N and 15°E-25°E.
The modified scheme allows for six weather types, namely four directional (NE=Northeast, SE, SW, NW) and two rotational types (C=cyclonic and A=anticyclonic). The strength of the atmospheric circulation is classified by way of a peak-over-threshold technique, employing Coriolis-adjusted thresholds for the gale index G* of 29.9, 38.7, and 47.2 hPa for gale (G), severe gale (SG), and very severe gale (VSG), respectively. These thresholds are elevated by the Coriolis frequency ratio f(60N)/f(55N) (i.e. sin60°/sin55°) over those used with the North Sea dataset (Loewe, 2022) to ensure that gales are identified at an identical geostrophic wind and vorticity scale in either region. G* is a composite measure of gradient and Laplacian of the pressure field at each grid’s central point. Coriolis-adjustment accounts for the fact that the strength of geostrophic flow and vorticity of which G* is indicative also depends on latitude according to Coriolis frequency. Note also that previously given exceedance probabilities of 10, 2, and 1/3.65 % apply to the North Sea thresholds for the period 1971-2000, only. For the same period of reference empirical exceedance probabilities for the Baltic Sea are at 6.4, 1.0, and 0.5/3.65 %.
Technically, the set of weather-typing and gale-classification rules is implemented as a lean FORTRAN code (lwtbssim.f), internally known as "Simple Lamb weather-typing scheme for the Baltic Sea v1". The processing run was done on a Linux server under Debian 10 (Buster).
Both, weather types and gale days, form a catalogue of more than 70 annual calendars since 1948 that is presented and continuously updated to the present day at https://www.bsh.de/DE/DATEN/Klima-und-Meer/Wetterlagen-Stuerme/wetterlagen-und-stuerme_node.html. (A corresponding English page is currently being devised at https://www.bsh.de/EN/DATA/Climate-and-Sea/Weather-and-Gales/weather-and-gales_node.html .) This catalogue concisely documents synoptic conditions in the Baltic Sea region. Possible benefits are manifold. Special events and episodes in regional-scale atmospheric circulation are easily looked up and traced. Beyond that, the dataset is well suited for frequency, trend, persistence, transition, and extreme-value statistics. - Project
- BSHwt (BSH weather type and gale catalogues)
- Contact
- Nils Schade (Nils.Schade@nullbsh.de0000-0002-3558-0581)
Tim Kruschke (Tim.Kruschke@nullbsh.de0000-0002-1205-3754) - Spatial Coverage
- Longitude 15 to 25 Latitude 55 to 65
- Temporal Coverage
- 1948-01-01 to 2023-12-31 (standard)
- Use constraints
- Creative Commons Attribution 4.0 International (CC BY 4.0) (https://creativecommons.org/licenses/by/4.0/)
- Data Catalog
- World Data Center for Climate
- Size
- 4.71 MiB (4943116 Byte)
- Format
- NetCDF
- Status
- will be continued
- Creation Date
- Future Review Date
- 2034-04-22
- Cite as
- Loewe, Peter; Schade, Nils (2024). Lamb weather types (reduced set) and gale days over the Baltic Sea since 1948 based on NCEP/NCAR Reanalysis 1 daily mean sea level pressure fields. World Data Center for Climate (WDCC) at DKRZ. https://doi.org/10.26050/WDCC/LambWTyRSetAndGaleDaysOverTheBa
BibTeX RIS
- Description
- Number of checked netCDF files: 76
Mandatory ATMODAT Standard checks passed: 304/304 (0 missing, 0 error(s))
Recommended ATMODAT Standard checks passed: 1292/1520 (228 missing, 0 error(s))
Optional ATMODAT Standard checks passed: 380/684 (304 missing, 0 error(s))
CF checker errors: 0
CF checker warnings: 0 - Method
- ATMODAT Standard Compliance Checker Version: 1.3.2
- Method Description
- Checking against: ATMODAT Standard 3.0. Metrics documentation: https://doi.org/10.35095/WDCC/atmodat_standard_en_v3_0 and CF Version 1.8
- Method Url
- Result Date
- 2024-05-02
- Description
- The quality of the NCEP/NCAR reanalyses input data is described in detail in Kalnay et al. (1996); see references.
An evaluation of the weather type classification based on NCEP/NCAR reanalyses is given by Loewe et al. (2013); see references.
For a comparative evaluation of different weather type classification methods, please refer to Tveito et al. (2016), COST Action 733: harmonization and application of weather type classifications for European Regions; final scientific report. University of Augsburg, Germany. https://opus.bibliothek.uni-augsburg.de/opus4/3768.
- Description
- Summary:
Findable: 6 of 7 level;
Accessible: 2 of 3 level;
Interoperable: 3 of 4 level;
Reusable: 5 of 10 level - Method
- F-UJI online v3.1.0 automated
- Method Description
- Checks performed by WDCC. Metrics documentation: https://doi.org/10.5281/zenodo.6461229 Metric Version: metrics_v0.5
- Result Date
- 2024-07-12
- Description
- Annotation Nils Schade
- atmodat checker evaluating all netCDF files prior publication
- the NetCDF files do not fulfill the following global attributes which are either recommended or optional in the ATMODAT standard 3.0 because they are not applicable:
- crs
- source_type
- nominal_resolution
- further_info_url
- processing_level
- program
- project - Result Date
- 2024-07-12
- Result Date
- 2024-07-12
- Description
- 1. Number of data sets is correct and > 0: passed;
2. Size of every data set is > 0: passed;
3. The data sets and corresponding metadata are accessible: passed;
4. The data sizes are controlled and correct: passed;
5. The spatial-temporal coverage description (metadata) is consistent to the data: passed;
6. The format is correct: passed;
7. Variable description and data are consistent: passed - Method
- WDCC-TQA checklist
- Method Description
- Checks performed by WDCC. The list of TQA metrics are documented in the 'WDCC User Guide for Data Publication' Chapter 8.1.1
- Method Url
- Result Date
- 2024-07-12
| Contact type | Person | ORCID | Organization |
|---|---|---|---|
Is documented by
[1] Jenkinson, Arthur F.; Collison, Peter. (1977). An Initial Climatology of Gales over the North Sea. Synoptic Climatology Branch Memorandum no. 62. Bracknell, UK Meteorological Office, London.
[2] Loewe, Peter; Klein, Holger; Becker, Gerd; Nies, Hartmut; Brockmann, Uwe; Schmolke, Stefan; Dick, Stephan; Schrader, Dieter; Frohse, Alexander; Schulz, Achim; Herrmann, Jürgen; Theobald, Norbert; Klein, Birgit; Sieglinde, Weigelt. (2006). Nordseezustand 2004. Berichte des Bundesamtes fuer Seeschifffahrt und Hydrographie Nr. 40. ISBN 0946-6010. https://www.bsh.de/download/Berichte-des-BSH-40.pdf
[3] Loewe, Peter; Klein, Holger; Weigelt-Krenz, Sieglinde. (2013). System Nordsee 2006 und 2007 – Zustand und Entwicklungen. Berichte des Bundesamtes fuer Seeschifffahrt und Hydrographie Nr. 49. ISBN 0946-6010. https://www.bsh.de/download/Berichte-des-BSH-49.pdf
[4] DOI Loewe, Peter. (2022). Lamb weather types (reduced set) and gale days over the North Sea since 1948 based on NCEP/NCAR Reanalysis 1 daily mean sea level pressure fields. doi:10.26050/WDCC/LambWTyRSetAndGaleDaysOverTheNo
[5] Loewe, Peter; Klein, Holger; Schmolke, Stefan; Müller-Navarra, Sylvin; Becker, Gerd; Nies, Hartmut; Brockmann, Uwe; Schmelzer, Natalija; Dick, Stephan; Schrader, Dieter; Engelke, Clemens; Schulz, Achim; Frohse, Alexander; Theobald, Norbert; Horn, Wilfried; Weigelt, Sieglinde. (2005). Nordseezustand 2003. Berichte des Bundesamtes fuer Seeschifffahrt und Hydrographie Nr. 38. ISBN 0946-6010 . https://www.bsh.de/download/Berichte-des-BSH-38.pdf
Is derived from
[1] DOI Kalnay, E.; Kanamitsu, M.; Kistler, R.; Collins, W.; Deaven, D.; Gandin, L.; Iredell, M.; Saha, S.; White, G.; Woollen, J.; Zhu, Y.; Leetmaa, A.; Reynolds, R.; Chelliah, M.; Ebisuzaki, W.; Higgins, W.; Janowiak, J.; Mo, K. C.; Ropelewski, C.; Wang, J.; Jenne, Roy; Joseph, Dennis. (1996). The NCEP/NCAR 40-Year Reanalysis Project. doi:10.1175/1520-0477(1996)077<0437:TNYRP>2.0.CO;2
[2] NOAA/OAR/ESRL Physical Sciences Laboratory, Boulder, Colorado, USA. (2014). NCEP/NCAR Reanalysis 1: Surface - Sea Level Pressure (Daily), 1948-continuing. https://www.psl.noaa.gov/data/gridded/data.ncep.reanalysis.surface.html
Attached Datasets ( 1 )
Parent project(s)
[Entry acronym: LambWTyRSetAndGaleDaysOverTheBa] [Entry id: 5275170]