Structure and variability of the Oman coastal low-level jet

In this study, reanalysis and regional atmospheric modelling was used to resolve the climatology and mesoscale structure, spatial variability and temporal characteristics of the Oman coastal low-level jet (CLLJ). The limited area model COAMPS® was used at a 6-km horizontal resolution for a 5-month period (May–September) during 2009. Analysis of high-resolution model fields reveals the mesoscale structure of the Oman CLLJ, clearly distinguishing it from the large-scale South Asia monsoon circulation farther offshore, and from the previously identified Findlater (or Somali) jet, which occurs at a higher altitude. The Oman CLLJ is closer to the coast and spreads northeastward along the coast of Oman, clearly interacting with the coastal topography and headlands. It has a very strong annual cycle, related to the South Asia monsoon, with July exhibiting the highest CLLJ frequency of occurrence (around 80%) and highest wind speeds (around 27 ms⁻¹), and May and September being the transition months. The southerly location of the Oman CLLJ, along with the very strong inland summer heating in the Arabian Peninsula, affects its diurnal cycle, with highest number of occurrences early in the morning, whereas the highest wind speeds occur during late afternoon, setting this CLLJ apart from other coastal jets in mid-latitude areas along eastern boundary currents.