On latitudinal profiles of zonal means
Article first published online: 12 OCT 2005
Copyright 2005 by the American Geophysical Union.
Geophysical Research Letters
Volume 32, Issue 19, October 2005
How to Cite
2005), On latitudinal profiles of zonal means, Geophys. Res. Lett., 32, L19713, doi:10.1029/2005GL023652.(
- Issue published online: 12 OCT 2005
- Article first published online: 12 OCT 2005
- Manuscript Accepted: 1 AUG 2005
- Manuscript Revised: 19 JUL 2005
- Manuscript Received: 27 MAY 2005
 A well-known effect of the near-spherical shape of Earth is that longitude-latitude map projections result in a spatial stretching of the information in the zonal direction in high latitudes. It is also well known that the variance of mean value estimates of climatic data varies inversely with the size of the area or length of interval over which the means are taken. A perhaps lesser-known implication is that the real degrees of freedom in the zonal mean value vary with latitude. Therefore taking zonal means for different latitudes involves averaging over different number of truly independent observations. It is shown here that a comparison between zonal mean values from different latitudes can give misleading results if the effect of latitudinal varying real degrees of freedom is not properly accounted for.