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In process‐oriented studies, accurate representation of severe bora rotor dynamics in the northern Adriatic is known to require the use of model resolutions of the order of 100 m. In regional climate studies, computation time and numerical cost are, however, minimized with resolutions of the order of 10 km. The latter is not accurate enough to drive the coastal dense water formation and the long‐term Adriatic‐Ionian thermohaline circulation resulting from these events. This work leverages the capacity of kilometer‐scale atmospheric models to balance accuracy and efficiency in coupled atmosphere‐ocean climate studies in the Adriatic Sea. The sensitivity of severe bora dynamics and air‐sea interactions to atmospheric model resolution is thus tested within the Adriatic Sea and Coast (AdriSC) modeling suite as well as with the best available reanalysis. The Weather Research and Forecasting (WRF) model at 15‐km, 3‐km, and 1.5‐km resolution, and ERA5 at 30‐km resolution, are compared for an ensemble of 22 severe bora storms spanning between 1991 and 2019. It is found that (1) ERA5 reanalysis and WRF 15‐km model highly diverge (up to 43% for the wind speed) from WRF 3‐km results while (2) WRF 3‐km conditions converge toward the WRF 1.5‐km solution for both basic bora dynamics (differences below 6% for the wind speed) and air‐sea interactions (differences 5 times smaller than with WRF 15‐km results). Consequently, kilometer‐scale atmospheric models should be used to reproduce properly the dense water formation during severe bora events and the long‐term thermohaline circulation of the Adriatic‐Ionian basin. Key Points: Atmospheric reanalysis at 30 km of resolution is inadequate for the evaluation of atmospheric models during extreme bora eventsBora dynamics can be partially described with kilometer‐scale model via a statistical approach using an ensemble of severe stormsKilometer‐scale atmospheric climate models up to 3‐km resolution can be used to drive dense water formation in the northern Adriatic Sea [ABSTRACT FROM AUTHOR]

The paper is about characteristics analysis of major winds across the Croatian part of the Adriatic Sea and their impact on organization of sailing ship navigation from prehistory until mid nineteenth century. Research area was divided into northern, middle and southern part of eastern Adriatic, and parameters for three prevailing winds – bora, jugo and mistral, were observed over four climatological seasons and also over annual average values on 18 main meteorological and climatological weather monitoring stations. Information generated from such data was intertwined with archaeological findings from the eastern Adriatic coast and historical writings that witness sailing across the area. Historical writings that were used consist of itineraries and some of the earliest nautical pilots written as a navigational aid for the area of the eastern Adriatic. The prime goal was to determine if there is a correlation between reconstructed sailing routes that existed in times when information about landscape and surrounding occurrences and processes (wind in this case) was collected by observation and contemporary measured data. It was also important to determine if navigation was affected by advances in nautical technology, particularly ship hull and sail construction, and navigation equipment.

The paper is about characteristics analysis of major winds across the Croatian part of the Adriatic Sea and their impact on organization of sailing ship navigation from prehistory until mid nineteenth century. Research area was divided into northern, middle and southern part of eastern Adriatic, and parameters for three prevailing winds – bora, jugo and mistral, were observed over four climatological seasons and also over annual average values on 18 main meteorological and climatological weather monitoring stations. Information generated from such data was intertwined with archaeological findings from the eastern Adriatic coast and historical writings that witness sailing across the area. Historical writings that were used consist of itineraries and some of the earliest nautical pilots written as a navigational aid for the area of the eastern Adriatic. The prime goal was to determine if there is a correlation between reconstructed sailing routes that existed in times when information about landscape and surrounding occurrences and processes (wind in this case) was collected by observation and contemporary measured data. It was also important to determine if navigation was affected by advances in nautical technology, particularly ship hull and sail construction, and navigation equipment. [ABSTRACT FROM AUTHOR]

This note examines two Adriatic bora events recorded in TerraSAR-X (TS-X) images taken in the winters of 2011 (Case 1) and 2012 (Case 2). In Case 1, the TS-X captured an image of a deep anticyclonic bora, whereas in Case 2 a shallow cyclonic bora was sampled. High-resolution TS-X images resolved the finer bora spatial structure to a scale of ≈1 km, which has not previously been reported in bora research. In particular, the structures in Case 2 appear to be driven by surface convective heat fluxes caused by substantial temperature differences between the relatively high sea surface temperature (SST) and the overflowing very cold air. The Weather Research and Forecasting (WRF) model simulations used to aid the analyses suggest that the very low upwind 2m temperature in Case 2 reinforced the orographic wave breaking by enhancing the cross-mountain pressure gradient. The ensuing strong cross-mountain flow was responsible for the appearance of secondary jets in the lee of Mount Velebit, for which the TS-X Case 2 scene provides the first satellite-borne evidence. [ABSTRACT FROM AUTHOR]

The along-coast, offshore turbulence structure of the Bora flow that occurred on 7 November 1999 during the Mesoscale Alpine Programme (MAP) Intensive Observation Period 15 is examined. In this analysis we employ the aircraft and dropsonde data obtained over the Adriatic Sea, where the turbulence structure is determined by estimating turbulent kinetic energy (TKE) and its dissipation rate along the flight legs. The turbulence characteristics of Bora in the lee of the Dinaric Alps is greatly influenced by the mesoscale Bora flow structure over the Adriatic Sea, which in the cross-wind direction features an interchange of jets and wakes related to mountain gaps and peaks. In order to establish the origin of turbulence, the Weather Research and Forecasting-Advanced Research WRF (WRF-ARW) numerical model is used and its results are compared to the measurements. All five TKE-prediction parametrization schemes available in the model show reasonable agreement with the measured values. Since these parametrization schemes do not have horizontal advection included, they suggest that the along-flight structure of the Bora turbulence is principally generated by the local vertical wind shear. Further evidence is needed to support this hypothesis. [ABSTRACT FROM AUTHOR]

Two simulations of the response of Adriatic Sea to severe wind performed by an atmosphere-ocean coupled model and the comparisons with observed data and modelled fields published in literature are presented. The model RAMS-DieCAST was applied to simulate the variations of sea currents and temperature profiles, from surface to bottom, induced by two episodes of intense wind over the Adriatic sea: a Bora wind event that occurred in January 1995 and a Sirocco wind event in November 2002. The results of the simulations are compared with observed data at the sea surface. In the Bora episode, the computed surface temperatures are compared with satellite SSTs and in situ observed temperatures; in the Sirocco event the simulated surface currents and temperatures are compared with experimental data collected by surface drifters released in different regions of the Adriatic Sea during the same Sirocco event. In both episodes the simulated temperature trends agree with the observed values and during the Sirocco episode the current fields are in quite good agreement with the drifter data. The modelled sea temperature and velocity fields show also a good concordance with other simulation results in literature. [ABSTRACT FROM AUTHOR]

Abstract: Surface patterns of the low-frequency current in a 20×30km region in front of the Venice Lagoon were analysed from a 13-month-long HF radar data set. Surface circulation was related to prevalent wind regimes in the area and to the tidal flow through the lagoon inlet. Three different categories of wind-forcing were defined: bora (NE wind), sirocco (SE wind), and finally the category containing all other wind directions and calms (winds lower than 3m/sec). Mean flow and vorticity spatial distributions were discussed for different wind conditions. The coastal area about 5km wide is characterized by a flow field with maximum vorticity. Outside the coastal boundary layer the interior flow is part of the Adriatic basin-wide cyclonic circulation. Two counter-rotating vortices of the dimension of about 4–5km were evidenced in the average flow field in front of the lagoon inlet (Malamocco inlet) in all situations except for the bora. The vortex-pair is probably associated with the tidal flow through the inlet. The bora wind induces a strong southward coastal jet detached from the coast by about 5km homogenizing the flow and eliminating the dipole. The average coastal flow pattern in calm wind conditions was also analysed as a function of the strong inflow/outflow (currents in the inlet>0.7ms−1) from the lagoon inlet. In both cases the vorticity pattern is similar, with the negative vorticity to the left of the inlet and positive to the right looking seaward. [Copyright &y& Elsevier]

Abstract: Data from an Acoustic Doppler Current Profiler (ADCP) mooring maintained during the winter of 2001 in 57m of water near Senigallia, Italy are used to describe the winter conditions of the Western Adriatic Current in the northern Adriatic Sea. Wind and water temperature measurements from the Acqua Alta tower in 19m water depth off Venice and winds from a 4-km resolution reanalysis model, COAMPS™, are used to interpret the ADCP data, especially with respect to currents generated by bora winds. At the ADCP site, mean depth-average current for the winter deployment period was 10.4cm/s toward 140°, roughly aligned with local bathymetric contours. Both mean currents and fluctuations about the means were highly barotropic during the winter. Southeastward (along-shore), mean currents increased slightly (1.8cm/s) with depth between 7 and 47m following a nearly linear trend. Offshore (cross-slope), mean currents only increased (2.0cm/s) deep in the water column, between 35 and 51m. Current variability was dominated by four bursts of currents in which flow toward the southeast greatly increased. These bursts followed bora winds, the timing of which was identified by measured winds at the Acqua Alta tower. Depth-averaged, de-tided currents exceeded 30cm/s during all four events, and reached 45cm/s during one event. Correlations between these along-shore currents and simulated wind stress from the COAMPS model were calculated over the whole north Adriatic. The cross-covariance between currents and wind stress had a spatial pattern similar to the bora wind itself, reaching maxima along the northern Adriatic coast, off the southern tip of Istria, and near Ilovik Island (14.5°N, 44.4°E). Wind stress in these regions had stronger correlation with currents at the mooring than did wind stress anywhere near the mooring. Bottom water at the mooring was too warm for it to have been North Adriatic Dense Water, except perhaps for a brief pulse of cold water associated with the third current burst on April 1st. [Copyright &y& Elsevier]

Abstract: Obtaining realistic meteorological fields that are necessary for numerical modelling and prediction of sea state within operational oceanography as well as for Rapid Environmental Assessment (REA) tasks is not easy in the regions like the Adriatic Sea, which is surrounded by complex local orography. By analysing the output fields from the mesoscale meteorological model LAMI and the global ECMWF model between October 2005 and September 2006, this paper investigates effects that orography may exert on meteorological fields over the Adriatic region. The analysis is performed over four weather regimes typical for the Adriatic Sea, namely those characterized by bora, sirocco, bora–sirocco and etesian winds. Analysed are mean fields and mean differences between the two models. Results indicate that all investigated flow regimes are significantly affected by the Apennines and the Dinaric Alps, but also by smaller scale orography that is, at least along the Italian coast, adequately represented by LAMI and not by the ECMWF model. A kind of symmetry is found between sirocco and etesian regimes on the Adriatic scale, as well as on smaller scales, e.g. around the Gargano peninsula which acts as a typical 3D obstacle. Well known jets-and-wakes bora pattern along the eastern coast is clearly seen in the mean fields. The enhanced cloudiness and precipitation regions are shown to appear in convergence zones of bora, bora–sirocco and sirocco regimes, related to the mountain ridges perpendicular to the respective flow. Additionally, within the bora–sirocco regime a relatively narrow convergence zone at the boundary between the bora and sirocco flow is noticed. The authors believe that methods used in this paper can be useful when applied to other coastal regions and models. By considering the differences between output fields from two models of different resolution, the areas affected by smaller scale phenomena could be clearly seen. On the other side, the mean modelled fields show persistent meso to synoptic scale structures thus enabling better understanding of dynamical and climatological characteristics, both of the considered region and the models used. [Copyright &y& Elsevier]