DOMAIN-INDEPENDENT ATTRIBUTION .1. RECONSTRUCTING THE WIND FROM ESTIMATES OF VORTICITY AND DIVERGENCE USING FREE-SPACE GREENS-FUNCTIONS

Free space Green's functions may be used to reconstruct the wind over a limited domain from vorticity, divergence, and the wind at the bound ary of the domain. When standard finite-difference estimates of the vo rticity/divergence field are used, the technique fails to accurately r econstruct the wind in regions where the vorticity or divergence chang e markedly between grid boxes. The standard finite-difference estimate of vorticity/divergence is accurate provided that the wind varies lin early with distance along the edges of grid boxes. An estimate of vort icity/divergence is derived that accounts for the fact that these requ irements are not met when the vorticity/divergence field is locally he terogeneous. This improved estimate is named the G4 estimate. It is no t derived from Taylor series. When the G4 estimate of vorticity/diverg ence is used to reconstruct the wind field, the magnitude of the recon struction error is an order of magnitude smaller than the reconstructi on error associated with the standard estimate of vorticity/divergence .