Details

Autor(en) / Beteiligte

• Rohrer, M.
• Martius, O.
• Raible, C. C.
• Brönnimann, S.

Titel

Sensitivity of Blocks and Cyclones in ERA5 to Spatial Resolution and Definition Sensitivity of blocks and cyclones in ERA5 to spatial resolution and definition

Ist Teil von

• Geophysical research letters, 2020-04, Vol.47 (7), p.n/a

Ort / Verlag

Washington: Blackwell Publishing Ltd

Erscheinungsjahr

2020

Link zum Volltext

Quelle

Wiley Online Library - AutoHoldings Journals

Beschreibungen/Notizen

• ERA5, the fifth‐generation reanalysis of the European Center for Medium‐Range Weather Forecasts, provides long time series of atmospheric fields at high spatial and temporal resolution. It allows detailed studies of atmospheric flow features such as blocks or cyclones. We investigate characteristics of blocks and cyclones in ERA5 using different algorithms, compare the results to ERA5's predecessor, ERA‐interim, and investigate how these characteristics depend on spatial resolution. Generally, ERA5 and ERA‐interim characterize blocks and cyclones similarly. For Lagrangian detection and tracking methods, blocks are more robust than cyclones to changes in resolution and reanalysis choice. Eulerian methods are robust to changes in resolution. Thus, ERA5 provides a state‐of‐the‐art reanalysis for the synoptic‐scale extratropical circulation. We find that Lagrangian cyclone characteristics are strongly dependent on spatial resolution and therefore recommend that model and reanalysis data should be mapped to a common resolution for verification. Plain Language Summary Reanalyses are among the most widely used data sets in the geosciences as they provide a state of the atmosphere that is complete in both space and time by combining a state‐of‐the‐art weather prediction model with historical observations. Their applications range from climatological studies to the closer examination of extreme events. Reanalyses are often the primary tool to assess the performance of climate models. Recently, the ERA5 reanalysis was published, and thus, many users may consider using this new product. However, due to its novelty, ERA5 is not yet investigated extensively. We examine midlatitudinal atmospheric flow features such as blocks and cyclones and their dependence on input resolution and choice of reanalysis. We find that blocks and cyclones characteristics are very similar in ERA5 and its predecessor ERA‐interim. Input resolution often plays a more important role on block and cyclone characteristics than the choice between ERA5 and ERA‐interim, particularly in case of cyclone characteristics. For many applications, the full resolution of ERA5 may not be necessary, easing the computational requirement to use this high‐resolution data set. In case of modeling studies where reanalysis data is compared to modeled data, we recommend using the same resolution. Key Points Characteristics of blocks and cyclones are generally similar in ERA5 and ERA‐interim Characteristics are more sensitive to the spatial resolution than the choice of the reanalysis, especially for cyclones We recommend comparing climate model and reanalysis data using a common resolution