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Introduction

ERA5 (ECMWF Reanalysis 5th Generation) reanalysis data is the most recent, global weather dataset covering the time-period from 1950 until today. The data is obtained by combining a numerical weather prediction model with empirical observations (4DVar data assimilation in CY41R2 of ECMWFs IFS). It contains estimates of atmospheric variables, such as air temperature, pressure, and wind, as well as surface variables such as rainfall and soil moisture. The meteorological variables are available with hourly temporal resolution on a global data grid with approximate horizontal resolution of 31km and 137 vertical model levels.For more information, please see the ECMWFs documentation of ERA5: https://confluence.ecmwf.int/display/CKB/ERA5%3A+data+documentation

Met.3D can be used for interactive visual exploration of meteorological phenomena in ERA5. Available methods used for this visual data exploration study include:

  • sliding of horizontal and vertical cross-sections through data-cubes
  • computation of 3-D isosurfaces with interactive variation of isovalues
  • direct volume rendering of clouds using raycasting
  • flow visualization via wind barbs and trajectories. 

In contrast to the widely-used visualization software packages, Met.3D allows visual data exploration at interactive frame-rates, enabling you to quickly discover interesting features and explore system dependencies.

Step by step procedure

The following steps are performed as part of this study.

  1. Obtain ERA5 data on regular lat-lon grid
  2. Visual exploration of ERA5 using the features of Met.3D

1.Obtain ERA5 data on regular lat-lon grid

1.1 Data acquisition

 ERA5 data is freely available for download. For a detailed description on how to download ERA5, please see: https://confluence.ecmwf.int/display/CKB/How+to+download+ERA5
Alternatively, the ERA5 data is also available at the German Climate Computing Center (DKRZ). For details, please see: https://www.dkrz.de/up/services/data-management/projects-and-cooperations/era

1.2 Pre-processing of ERA5 for visual analysis in Met.3D

Met.3D requires meteorological data on a regular lat-lon grid. If you download ERA5 on a regular grid, you should be able to directly load the data into Met.3D and start your visual data exploration. If the data is on a Gaussian or Spectral grid, you need to interpolate the data to a regular grid before you can analyse it in Met.3D.The Climate Data Operators (CDO) provide a convenient way to interpolate ERA5 data onto a regular grid.For a detailed documentation of CDO, please see: https://code.mpimet.mpg.de/projects/cdo/. The code-snippets provided in           minimal examples for conversion to a grid that can be processed in Met.3D.

---> Minimal example CDO gridfile regular lat-lon grid (cylindrical proj): /MM/project.notes/mcao.configfiles/ERA5_postprocessing/CDOGridFiles_RegLL/gridLatLon_forCaseStudies.txt

---> Minimal example CDO gridfile for data in a polar stereographic projection: MM/project.notes/mcao.configfiles/ERA5_postprocessing/CDOGridFiles_StereographicProj/gridPolarStereo_forCaseStudies.txt

---> Minimal example CDO command for interpolation from Gaussian / Spherical grid to regular lat-lon: MM/project.notes/mcao.configfiles/SI_HelperTools


For a documenation of the supported data and file types in Met.3D, please see: https://met3d.readthedocs.io/en/latest/dataformats.html


2 Visual exploration of ERA5 using the features of Met.3D

Please


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