Deep-Sea Research, Vol. 26/6A, pp. 661 to 672 0011-7471/79/0601-0661 $02.00/0 (~) Pergamon Press Ltd 1979. Printed in Great Britain Seasonal variations of temperature and salinity in the Gulf of Elat (Aqaba) N. PALDOR* and D. A. ANATI* (Received 13 January 1978 ; in revised Jorm 19 September 1978 ; accepted 13 January 1979) Abstract--The distributions of temperatures, salinites, and their month-to-month variations in the upper 300m in the Gulf of Elat (Aqaba) from 1974 to 1977 are described. Both temperature and salinity are high in summer (~ 26C, ~ 41!I,,,,, at the surface), and low in winter (~ 21C, ~ 40.57~;,,, at the surface). The summer transition of salinity occurs 2 to 3 months later (August, September) than that of temperature (May, June, July). The water column is stratified throughout the year but much less so in winter and less so in the north (far away from the straits) than in the south (near the straits). The winter stratification is mainly due to salt, while the summer stratification is mainly due to temperature. An attempt to estimate the temperature and salinity distributions at the Straits of Tiran from neighbouring stations was only partially satisfactory. INTRODUCTION THE GULF OF ELAT (Aqaba) is a fingerlike extension projecting north-northeastward from the Red Sea. It is 180km long and 14km wide on the average and small enough that atmospheric conditions may be assumed, for most purposes, to be uniform over the whole surface (ASSAF and KESSLER, 1974), yet it is large enough to be influenced by the rotation of the earth. The climate is arid, with a yearly average net evaporation of 1 cm day-1 (ASSAF and KESSLER, 1974). Winds blow along the main axis, predominantly from the north, switching abruptly to southerlies in short gales of a few days' duration and at predictable seasons, much as in a wind-tunnel experiment. The gulf is confined at its southern end by the short Straits of Tiran, 'short' in the dynamic sense (ANATI, ASSAF and THOMPSON, 1977), so that friction can be neglected in strait-dynamics considerations. The similarity of the gulf to the Red Sea proper (e.g. AssAr and ANATI, 1974; ANATI, 1977) makes its study useful in understanding the latter, which is considerably more difficult to explore. Unfortunately, there has been no major expedition in the gulf since the Pola cruise almost a century ago (1895-1896). Some minor field work carried out in the present century was briefly reviewed by ANATI (1974). Existing studies deal mainly with the steady state, not because time variations are negligible, but chiefly for want of data. Since 1974 intense field work, the DCPEt, has been undertaken (KLINKER, REISS, KROPACH, LEVANON, HARPAZ, HALICZ and ASSAE, 1977) and for the first time month-to- month variations can be reported. The present study uses the DCPE data and concentrates on the seasonal cycle of temperature and salinity. *The Weizmann Institute of Science, Rehovot, Israel. t The Data Collection Program in the Gulf of Elat is operated by the H. Steinitz Marine Biological Laboratory in Elat and sponsored by the Hebrew University of Jerusalem, the Israel Ocenographic and Limnological Research in Haifa, the Weizman Institute of Science in Rehovot, the Israel National Academy of Sciences and Humanities in Jerusalem, and the Israel-U.S.A. Binational Science Foundation. 661