Atmospheric Angular Momentum (AAM) data

Introduction

Atmospheric Angular Momentum (AAM) plays a significant role in causing variations in the length of day. Study of AAM can also yield information about the Earth's orientation in space and the large scale behaviour of the atmosphere.

The BADC stores AAM data from the Met Office and the European Centre for Medium Range Weather Forecasting (ECMWF). The data are available as ASCII files containing values of the 3 angular momentum components at 12 or 24-hourly intervals, from 1979 to 1997 and can be obtained via this World Wide Web interface or by anonymous FTP.

Access to Data - File Format

The AAM data are held online at the BADC. They are stored in ASCII (plain text and "human" readable) tables which can be displayed on your web browser and then "saved" on to your computer.

Specific information relative to temporal coverage, parameters and the AAM data file format is available.
A guide explains how to acquire the AAM data from the BADC and also how to read the data files.

Documentation

General information about the Atmospheric Angular Momentum has been compiled to provide scientific background on the subject.

Links to Further Information and Data Updates

There are four historical AAM datasets:

AAM (NMC) - National Meteorological Center
AAM (JMA) - Japanese Meteorological Agency
AAM (UKMO) - Met Office
AAM (ECMWF) - European Centre for Medium-Range Weather Forecasting

The most complete archive of AAM data are held by the International Earth Rotation Service's (IERS) Special Bureau for the Atmosphere (SBA).

Effective Atmospheric Angular Momentum Functions data from the Met Office (1986 to present day) and from ECMWF (1988 to present day) may also be directly downloaded from the anonymous FTP service at ftp.aer.com, together with relative documentation. AAM data from NMC and JMA can also be found at this FTP site.

Should you wish to know more about the AAM data, there is a set of useful references which provide more comprehensive information.

Citation

Date of citation

Who to Contact

You can contact David Salstein at the SBA for more information. David Salstein is located at Atmospheric and Environmental Research (AER).

If you have queries about these pages or about obtaining the AAM data from the BADC then you should contact BADC Support. Your query should be answered within one working day. When follow-up work is required, the BADC support will carry out the work as quickly and efficiently as possible, and in any case, the user will be kept informed of progress.

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