Zusammenfassung: Sea surface height may be measured by a satellite-borne altimeter and its along-track slope used to infer geostrophic currents. A major difficulty is that, in general, the local geoid and satellite orbit are not known to the accuracy desired. Thus, comparison is often made between repeat flights of an altimeter along fixed ground tracks in order to infer the changes in the currents. In practice, it is convenient to calculate a mean height profile from many repeat passes and use this as a reference, so that individual altimetric profiles yield variations about this mean. It is thus important to derive a high-quality reliable estimate of the altimetric mean in order to minimize the errors in the inferred flows for the individual repeats. This work examines various methods for deriving the mean profile.

Zusammenfassung: A mathematical model which simulates sport-fish production yield and economic value in the Rio Grande basin of New Mexico is described. The model links hydrologic, biologic, and economic components into a mathematical representation of fisheries habitat, fishery dynamics, economic benefits, and income generated by sport-fishing in New Mexico. The model has a research version programmed in FORTRAN. The model users can modify water volume flowing through the basin by month, water stored in each reservoir, water discharged through connecting water material concentrations (suspended solids, total phosphorus, total nitrogen) in the water, site access, and site quality. (Prepared in cooperation with New Mexico State Univ., Las Cruces. Dept. of Fishery and Wildlife Sciences. Sponsored by Geological Survey, Reston, VA (USA). Water Resources Div.)