Northern Adriatic response to a wintertime bora wind event

The unprecedented suite of research activities that focused on the Adriatic in winter 2003 provided a multi-faceted view of bora events and the resulting oceanic response

TerraSAR-X observations of the northeastern Adriatic bora: Early results

Some early results of the TerraSAR - X observations of the northeastern Adriatic bora wind are presented in this paper. TerraSAR - X is a German X - band radar satellite launched in 2007 that carries phased array X - band synthetic aperture radar (SAR) operating in different polarizations and providing multiple imaging modes. SAR backscatter can be used to derive wind fields at spatial re solution that no other instrument can provide. Terrain - induced jet and wake patterns are particularly conductive to the SAR - instrument examination. Bora, a cold and dry downslope wind blowing from north - easterly directions on the e astern side of the Adriatic Sea, exhibits such a response. Since bora is primarily winter wind and the town of Senj is known for frequent and severe bora episodes we focus on TerraSAR - X scenes collected in the winter s of 2011 and 2012 over an area with Senj roughly in its center. Recently developed XMOD2 geophysical model function is used for wind magnitude derivation, whereas the WRF model was employed to estimate the wind direction. The selected TerraSAR - X scenes have captured representative bora events exhibiting rich details in bora - induced jet and wake patterns on the lee of the Dinaric Alps. T h e details registered in the normalized radar cross section response strongly suggest the need for still higher resolution numerical simulations in order to properly model the orographic impact on and the fine details in the surface wind field. Comparisons with both research and operational modeling results indicate that the currently used geophysical model function may benefit from enlarging the matchup data base with samples of severe winds

Examining deep and shallow Adriatic bora events

This Note examines the differences observed between two Adriatic bora events, that took place in the winter of 2011 (Case 1) and 2012 (Case 2), using the Weather Research and Forecasting (WRF) model aided by two TerraSAR-X (TSX) images. The former was a deep bora event, predominantly of an anti-cyclonic type, whereas the latter was a shallow bora case, simultaneously pertaining to cyclonic and frontal types. The high resolution of the TS-X ScanSAR scenes offered for the first time the opportunity to examine the finer details of the bora jet and wake patterns. In the Case 1 bora, the bright patterns of the two major jets dominated the TS-X image, with a well-defined broad wake zone in between. In the Case 2 bora, a much richer pattern was registered in the TS-X Normalised Radar Cross Section (NRCS) field, with a notable difference in the intensity of the response. The major jets were broader, each exhibiting features apparently reflecting the impact of smaller ridges in the Dinaric mountain chain; The impact was also observed in the narrower wake zone, which was populated with three additional but shorter jets. In both cases, the TS-X derived surface wind field convincingly conveyed the rich morphology of the jet-and-wake response. The WRF model near-surface wind simulations, in a one way nested four domain setup, closely resembled the ones obtained with the satellite sensor. Additionally, the vertical along coast cross section of the lower troposphere indicated jets within the lowest 1 km corresponding to the ones registered in the TS-X derived surface wind, with the jets in Case 2 exhibiting much higher velocities. Both the satellite observations and the model simulations indicated that these low level jets (LLJs) can maintain their coherence and speed at considerable offshore distances, which is in agreement with certain theoretical studies. The longer offshore extent and higher velocities suggested by the WRF simulations have yet to be verified with field data

Abstracts of The Second Eurasian RISK-2020 Conference and Symposium

This abstract book contains abstracts of the various research ideas presented at The Second Eurasian RISK-2020 Conference and Symposium.The RISK-2020 Conference and Symposium served as a perfect venue for practitioners, engineers, researchers, scientists, managers and decision-makers from all over the world to exchange ideas and technology about the latest innovation developments dealing with risk minimization