* Corresponding author: Fax: 0039-06-2066-0291. E-mail address: emanuele@ekman.ifa.rm.cnr.it (E. Bo K hm) Deep-Sea Research II 46 (1999) 1531}1549 The Ras al Hadd Jet: Remotely sensed and acoustic Doppler current pro"ler observations in 1994}1995 Emanuele Bo K hm*, John M. Morrison, Vijayakumar Manghnani, Hyun-Sook Kim, Charles N. Flagg Department of Marine, Earth and Atmospheric Science, North Carolina State University, Raleigh, NC 27695-8208, USA Istituto di Fisica dell+Atmosfera } CNR, Via del Fosso del Cavaliere, 100, 00133, Roma, Italy  Center for Marine Science and Technology, University of Massachusetts, Dartmouth, 706 Rodney French Blvd., New Bedford, MA 02744, USA Department of Applied Science, Brookhaven National Laboratory, Upton, NY 11973, USA Received 10 September 1997; received in revised form 10 December 1998; accepted 18 December 1998 Abstract The existence of a surface barotropic front-jet system at the con#uence region o! the eastern tip of Oman (Ras Al Hadd or RAH) is documented for 1994}1995 through advanced very high resolution radiometer (AVHRR) and acoustic Doppler current pro"ler (ADCP) observations. The thermal signature of this con#uence is visible in 1995 between early May and the end of October, i.e., throughout the SW Monsoon and into the transition period between SW and NE Monsoons. The thermal characteristics are those of a NE-oriented front between cooler water of southern (upwelled) origin and warmer waters of northern Gulf of Oman origin. During the period when the thermal front is absent, ADCP data suggest that the con#uence takes a more southward direction with Gulf of Oman waters passing RAH into the southeastern Oman coastal region. The thermal gradient is initially small (June}July) but later increases (August}October) into a front that exhibits small-scale instabilities. Surface current velocities within the jet, estimated by tracking these features in consecutive satellite images, are 0.5}0.7 m s and in remarkable agreement with concurrent ADCP retrievals in which the seasonal maximum in velocity is 1 m s. ADCP observations collected during several US JGOFS cruises reveal a weakly baroclinic current in the con#uence region that drives the waters into the o!shore system. The fully developed jet describes a large meander that demarcates two counter-rotating eddies (cyclonic to the north and anticyclonic to the south of 0967-0645/99/$ - see front matter  1999 Elsevier Science Ltd. All rights reserved. PII: S 0 9 6 7 - 0 6 4 5 ( 9 9 ) 0 0 0 3 4 - X