On the calculation of wind stress curl over open ocean areas from synoptic meteorological data with application to time dependent ocean circulation

Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution January, 1972
The method used by N. P. Fofonoff for estimating wind stress curl from surface atmospheric pressure maps is developed for use with the National Meterological Center analysis grid. A formula is developed relating the wind stress curl directly to geometrically apparent features of the surface pressure analyses. The sensitivity of the formula to small deviations in the basic pressure field is estimated. Some statistical properties of the resulting formula as applied to actual pressure analyses are investigated. In particular, the geostrophic wind estimated for two finite difference grids is compared to observed winds from an independent anemometer located at W.H.O.L site "D". The statistical distribution of wind stress curl estimates is found to be non-Gaussian. The difficulty in estimating a mean value from such distributions is discussed. The root mean square values of wind stress curl are found to be approximately 10 times the mean values. Means are estimated and found to be inadequate to drive the mean transports in the Gulf Stream and Kuroshio. The formula is applied at Bermuda and the results compared to the record from the tide gauge located there. A significant relation between wind stress curl and sea level is found after tidal and inverted barometer effects are suppressed. The formula is applied to time dependent motions of the Labrador Current as evidenced by iceberg drifts for the 1959 ice season. Agreement is found between calculated and observed iceberg motions on the eastern slope of the Grand Banks using static Sverdrup dynamics.
Supported by the Office of Naval Research under Contract N00014-66-C0241; NR 083-004, and the U. S. Coast Guard contract DOT-CG- 10618-A.