Observed Ocean Conditions and Hurricane Hilda, 1964

Hurricane Hilda crossed the Gulf of Mexico in the period 30 September to 4 October 1964, developing into a very severe hurricane in the central Gulf. Sea temperature data available prior to the storm indicated what was probably a typical late summer situation with some surface temperatures running above 30C. Beginning 5 October 1964, a 7-day cruise was conducted over the area where hurricane winds had been observed. Using the GUS III of the Galveston Biological Laboratory of the Bureau of Commercial Fisheries, four crossings of the hurricane path were made. Bathythermograph observations were taken regularly to 270 m and hydrographic casts to 125 m. The data on all four crossings indicated similar patterns. The observed temperature-depth structures after the storm indicated that the warm ocean surface layers were transported outward from the hurricane center, cooling and mixing as they moved; that these waters converged outside of the central storm area with the result that downwelling to some 80 to 100 m in depth took place there; and that cold waters upwelled along the hurricane path from depths of approximately 60 m. Sea surface temperatures decreased by more than 5C over an area of some 70 to 200 ml. A cyclonic current system was observed around the area of greatest hurricane intensity. It is estimated that the total heat loss from the ocean to the atmosphere in the area of hurricane force winds was 10.8 × 1018 cal with the transfer per unit area being 4500 cal cm−2. The data collected on the GUS III cruise are the first systematic observations available immediately after a severe hurricane in deep water.