ERA40 Monthly Atmospheric Analysis on 23 Pressure Surfaces

ERA40 T106 data provides monthly mean upper air variables transformed to a 320 by 160 regular Gaussian grid. The dataset was created by NCAR's Data Support Section from the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-40 reanalysis project. This archive was produced in late 2004 and early 2005.

Use Cases

• Analyze long-term trends in geopotential height and temperature across 23 pressure levels.
• Study atmospheric dynamics using derived horizontal wind components from spectral vorticity and divergence.
• Validate modern reanalysis products like ERA-Interim by comparing humidity and ozone mass mixing ratio fields.
• Model historical climate variability using the transformed potential vorticity and specific humidity data on the T106 Gaussian grid.

Strengths

• Data transformed to a standardized 320 by 160 regular Gaussian grid for consistency.
• Contains multiple upper air variables across 23 pressure levels for atmospheric profile analysis.

Limitations

• Dataset is superseded by higher-resolution ERA-Interim reanalysis starting in 1989.
• Original ERA-40 model uses older 3DVAR assimilation, not the more current 4DVAR method.
• Temporal coverage ends before 2005, limiting analysis of recent climate trends.

Provenance

Source

European Centre for Medium-Range Weather Forecasts (ECMWF) ERA 40 reanalysis, processed by NCAR Data Support Section.

Collection Method

Variables transformed from spherical harmonics or a reduced N80 Gaussian grid to a T106 spectral truncation grid using ECMWF EMOS and NCAR SPHEREPACK libraries.

Time Range

Covers the ERA-40 period, which ends before 2005.

Freshness

null

Geography

Global coverage on a Gaussian grid.