ERA40 Atmospheric Analysis on Pressure Surfaces at T106 Resolution

2004-2005 archive of ERA-40 6-hourly upper air variables transformed to a 320 by 160 regular Gaussian grid. The dataset includes geopotential, temperature, wind components, vorticity, divergence, humidity, and ozone on 23 pressure levels. It was created by NCAR's Data Support Section using ECMWF EMOS and NCAR SPHEREPACK libraries.

Use Cases

• Analyze temporal trends in geopotential height and temperature on pressure surfaces for climate studies.
• Validate modern weather models by comparing derived horizontal wind components from spectral vorticity and divergence.
• Study atmospheric composition and processes using specific humidity, relative humidity, and ozone mass mixing ratio fields.
• Examine synoptic-scale weather patterns using 6-hourly data for variables like potential vorticity and vertical pressure velocity.

Strengths

• Includes 23 pressure levels providing vertical atmospheric profiles.
• Data transformed to a consistent 320x160 T106 Gaussian grid for spatial analysis.
• Derived horizontal wind components from spectral data using the SPHEREPACK library.

Limitations

• Spatial resolution (T106) is lower than the subsequent ERA-Interim reanalysis (T255).
• Model is based on older 3DVAR data assimilation, not the more advanced 4DVAR used later.
• Temporal coverage is limited to segments archived in late 2004 and early 2005.

Provenance

Source

European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-40 reanalysis.

Collection Method

Variables transformed from spherical harmonics or a reduced N80 Gaussian grid using ECMWF EMOS and NCAR SPHEREPACK libraries.

Time Range

Segments from the ERA-40 period, processed in late 2004 and early 2005.

Freshness

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Geography

Global coverage on a regular Gaussian grid.