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 North 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 can be found in Loewe et al. (2005), while the variant scheme has been detailed in Loewe et al. (2006). The analysis has been carried out on the original 16-point grid. Though formally valid at its central point (55°N, 5°E), results are representative of the North Sea region between 50°N-60°N and 0°E-10°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 re-calibrated thresholds for the gale index G* of 28.3, 36.6, and 44.6 hPa for gale (G), severe gale (SG), and very severe gale (VSG), respectively (Loewe et al., 2013). Technically, the set of weather-typing and gale-classification rules is implemented as a lean FORTRAN code (lwtnssim.f), internally known as "Simple Lamb weather-typing scheme for the North 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/EN/DATA/Climate-and-Sea/Weather-and-Gales/weather-and-gales_node.html. This catalogue concisely documents synoptic conditions in the North 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.
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. World Data Center for Climate (WDCC) at DKRZ. https://doi.org/10.26050/WDCC/LambWTyRSetAndGaleDaysOverTheNo
The quality of the NCEP/NCAR reanalyses input data is described in detail in Kalnay et al. (1996); see reference.
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Description
The quality of the NCEP/NCAR reanalyses input data is described in detail in Kalnay et al. (1996); see reference.
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.
FAIR
F-UJI result: total 66 %
Description
Summary: Findable: 6 of 7 level; Accessible: 2 of 3 level; Interoperable: 3 of 4 level; Reusable: 5 of 10 level
Annotation Angelika Heil
- 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
Scientific Quality Assurance (SQA)
SQA - Scientific Quality Assurance 'approved by author'
Result Date
2022-02-17
Technical Quality Assurance (TQA)
TQA - Technical Quality Assurance 'approved by WDCC'
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 temporal coverage description (metadata) is consistent to the data: passed;
6. The format is correct: passed;
7. Variable description and data are consistent: passed 2023-05-09 data added with TQA checks
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
[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.
[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