Abstract
A new finite difference scheme is constructed for the divergence term with a view to decreasing the errors in its computation.
A divergence scheme is designed such that it will give zero divergence for any non-divergent wind field.In other words, the computational error in applying this scheme to any non-divergent wind field is zero. Since any wind field can be separated into a non-divergent part and a divergent part, the computational error in applying this scheme to any wind field is equal to the error involved with the divergent part only. At the same time, the divergent part wind is an order of magnitude smaller than the non-divergent part. Hence the error is reduced.
The new scheme is simple, especially in latitude-longitude or Mercator map projections.
The scheme has been applied to a 3-Ievel limited area primitive equation model for Hong Kong and is found to give much improvement over the usual divergence schemes.
