Product: EAMF from NCEP/NCAR Reanalyses
AAMF from NCEP reanalysis - 2021 - Version metadata

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Title

AAMF from NCEP reanalysis - 2021
Date

2023-02-04
Volume

2021
Content

Data are NCEP values of effective atmospheric angular momentum functions as calculated from NCEP/NCAR reanalyses archived on pressure surfaces. The Transfer functions and Principal moments in Eubanks (1993)are employed to derive the atmospheric angular momentum functions.
Data are given four-times daily, and each epoch consists of a header record giving the date and time (year,month, day, hour), and data records.
The line after the header contains 9 values of inverted barometer (IB) pressure (or, mass) terms, Non-IB pressure terms, wind (or, motion) terms of X1, X2 and X3, respectively. The wind terms are computed by integrating winds from the Earth surface to 10 hPa, the top of atmospheric model. Note that the inverted barometer correction involves applying the mean atmospheric surface pressure over the whole world ocean to every point over the world ocean.
Documentation

To convert AAMF_X and Y to milliarcsecond (mas) and AAMF_Z to millisecond (ms), one needs to apply the following scale factors:
AAMF_X and Y (in mas) = AAMF_X and Y *360*60*60*1000/(2*pi);
AAMF_Z (in ms) = AAMF_Z * 24*60*60*1000;

http://files.aer.com/aerweb/AAM/readme.aamf.ncep.reanalysis
Time Interval

6 hours
Time Start

2021-01-01 00:00:00
Time End

2021-12-31 18:00:00
Data Points

1460
Data

year, month, day, hour, mass_IB_X, mass_IB_Y, mass_IB_Z, mass_NonIB_X, mass_NonIB_Y, mass_NonIB_Z, motion_X, motion_Y, motion_Z
Format

ASCII
Format Description

13(e16.7)
Frequency

Irregular
Keywords

Geophysical fluids, excitation functions, NCEP/NCAR reanalyses
Reference

- Salstein, D.A., and R.D. Rosen, 1997: Global momentum and energy signals from reanalysis systems. Preprints, 7th Conf. on Climate Variations, American Meteorological Society, Boston, MA, 344-348.
- Kalnay, E., et al., 1996: The NCEP/NCAR 40-year reanalysis project. Bull. Amer. Meteor. Soc., 77, 437-471.
- Barnes, R.T.H., R. Hide, A.A. White, and C.A. Wilson, 1983: Atmospheric angular momentum fluctuations, length-of-day changes and polar motion. Proc. R. Soc. London, Ser. A, 387, 31-73.
Created by

U. S. National Centers for Environmental Prediction (NCEP)
Published by

GGFC Special Bureau for the Atmosphere
Contact

pnelson@aer.com

Distribution

onLine
Source

http://files.aer.com/aerweb/AAM/aamf.ncep.reanalysis.2021