Shallow mesoscale flows at the north‐eastern Adriatic coast

Abstract

AbstractA summertime anticyclonic situation over the northern part of the eastern Adriatic coast is studied using a three‐dimensional nonhydrostatic mesoscale model. The aim is to evaluate small‐scale variability, such as mesoscale eddies, sea‐breeze convergence zones (CZs) and the coastal jet‐like flow in the thermally driven mesoscale circulations over very complex terrain. The results show that the model reproduces main known features of the diurnal flow with certain local specific characteristics, in addition to some new ones, previously only somewhat qualitatively known. After comparisons with measurements, further analyses are performed by sensitivity tests in which topography and synoptic input are varied.The simulations show a development of two diurnal intensive mesoscale eddies inside Kvarner Bay (∼20 km×20 km). The night‐time deeper eddies exhibit anticlockwise rotation, while the late afternoon shallow one shows the opposite rotation. Their appearance and dynamics are connected primarily to the coastline shape and topography; meanwhile, the large‐scale flow in the anticyclonic weather type, as addressed here, has small influence. Moreover, a CZ develops over Istria and the island of Krk as a result of merged sea breezes. The intensity, speed, position and configuration of the sea‐breeze cells are examined. The results also show that the topography is more important for the formation of the CZ over the island of Krk and for the coastal jet‐like flow between the island and mainland than for the Istrian CZ. Copyright © 2006 Royal Meteorological Society