**University of Copenhagen**

**Department of Geophysics.**

C.C.Tscherning.

30 June 1999

**
2. Progress Peport.
**

### I.2.2., WP 1. Overall scientific data strategy.

Further work has not been done on this WP.

### I.2.2., WP 2. Detailled Scientific data processing.

The direct estimation of potential coefficients has been described in a
technical note

C.C.Tscherning: Prediction of spherical harmonic coefficients using
Least-Squares Collocation - basic theory. Department of Geophysics
May 1999,

available.

The solution of very large systems using predonditioning based on locally
supported kernels has been theoretically and numerically investigated.
A draft paper ( to be included in a PhD-thesis) has been written:

G.Moreaux: Harmonic spherical splines with locally supported kenels,
Department of Geophysics, June 23, 1999.

###
I2.2., WP 3. Scientific data processing algorithms.

The algorithms for coefficient estimation using least squares collocation
have been implemented in new versions of GRAVSOFT
programs GEOCOL (now geocol15) and COVFIT (now covfit12).

Numerical testing of recursive algorithms for the calculation of up to
second order derivatives of solid spherical harmonics has been done.

An extensive testing program for the prediction of spherical
harmonic coefficients has been agreed upon at a meeting in
Thessaloniki between D.Arabelos and CC.Tscherning, see the
plan for testing.

Last update 1999-06-30 by cct.