1,720,988 research outputs found
Accuracy of global and high resolution models in stormy conditions
No full textWe analyse the performance of two top level meteorological models and their associated analyses versus the corresponding results obtained with high resolution nesting both for wind and for the derived wave field using the same advanced wave model. The comparison is also done versus both locally (buoys) and large scale (altimeter and scatterometer) measured data. It turns out that nested high resolution modelling does in general lead to a lower bias, but at the expense of larger root mean square errors and scatter indexes when compared with measured data. The reasons for this are discussed and a possible solution is indicated. Copyright © 2013 by the International Society of Offshore and Polar Engineers (ISOPE)
Climatology and trends of the Adriatic Sea wind waves: analysis of a 37-year long instrumental data set
No full textThis study concerns the analysis of a 37-year long directional wave time series recorded since 1979 at the CNR-ISMAR oceanographic research tower, located in the Northern Adriatic Sea. The length of the time series allows to describe the wave climate in the North Adriatic and to identify trends and links with large-scale climate patterns. The northern part of the Adriatic Sea is characterized by two main wind and correspondingly wave regimes, strongly forced by the regional orography: the long-fetch south-easterly ‘sirocco’ and the short-fetch strong north-easterly ‘bora’ wind generated waves, blowing along the major and minor axis of the basin, respectively. Bora is the most frequent regime, but high waves are mostly associated to sirocco. A clear decrease of the significant wave height 99th percentile is evident, paralleled by a smaller, but distributed along the annual cycle, increase of the 50th and 75th ones. The estimated trend of the frequency of events above a certain threshold confirms an increase of the average storm frequency, with a shift from both the lower and the higher to the central part of the distribution, paralleled by a decrease of the maximum Hs values. In particular, a distributed decrease of the bora significant wave height is recognized. For sirocco the tendency is less pronounced, but with an evident increase of the frequency of the mean values. The high sensitivity of this particular area to even small variations of large-scale climate allows to explore possible links of the local wave, hence wind, activity with large-scale Northern Hemisphere circulation patterns or weather regimes. Our main interest is on the storm tracks and jet stream location/intensity over vast areas, which led us to choose four reference patterns: the North Atlantic Oscillation and the East Atlantic (EA), EA/Western Russia and Scandinavian patterns
Data Descriptor: 39 years of directional wave recorded data and relative problems, climatological implications and use
No full text39 years of directional wave recorded data at the Acqua Alta oceanographic tower
No full textThe dataset consists of 39 years of directional wave time series recorded since 1979 at the CNR-ISMAR “Acqua Alta” oceanographic research tower, located in the Northern Adriatic Sea. The extent of the time series allows us to describe the wave climate in the North Adriatic region and to identify trends and links with large scale climate patterns obtained from a single and permanent observational source. The northern part of the Adriatic Sea is characterized by two main wind and correspondingly wave regimes, strongly forced by the regional orography. The high sensitivity of this particular area to even small variations of large scale meteorological patterns allows to explore possible links of the local wave, hence wind, activity with large-scale north hemisphere circulation or weather regimes. Different wave gauges have been used since the start of the measurements, progressively upgraded and repositioned during maintenance operations. The recorded wave data have been thoroughly verified and corrected where necessary
Climatology and trends of the Adriatic Sea wind waves: analysis of a 37-year long instrumental data set
No full textThis study concerns the analysis of a 37-year long directional wave time series recorded since 1979 at the CNR-ISMAR oceanographic research tower, located in the Northern Adriatic Sea. The length of the time series allows to describe the wave climate in the North Adriatic and to identify trends and links with large-scale climate patterns. The northern part of the Adriatic Sea is characterized by two main wind and correspondingly wave regimes, strongly forced by the regional orography: the long-fetch south-easterly ‘sirocco’ and the short-fetch strong north-easterly ‘bora’ wind generated waves, blowing along the major and minor axis of the basin, respectively. Bora is the most frequent regime, but high waves are mostly associated to sirocco. A clear decrease of the significant wave height 99th percentile is evident, paralleled by a smaller, but distributed along the annual cycle, increase of the 50th and 75th ones. The estimated trend of the frequency of events above a certain threshold confirms an increase of the average storm frequency, with a shift from both the lower and the higher to the central part of the distribution, paralleled by a decrease of the maximum Hs values. In particular, a distributed decrease of the bora significant wave height is recognized. For sirocco the tendency is less pronounced, but with an evident increase of the frequency of the mean values. The high sensitivity of this particular area to even small variations of large-scale climate allows to explore possible links of the local wave, hence wind, activity with large-scale Northern Hemisphere circulation patterns or weather regimes. Our main interest is on the storm tracks and jet stream location/intensity over vast areas, which led us to choose four reference patterns: the North Atlantic Oscillation and the East Atlantic (EA), EA/Western Russia and Scandinavian patterns
Waverider buoy processed wave parameters and raw data of an exceptionally high wave at the Acqua Alta Oceanographic Tower on December 15, 2009
No full textWaverider buoy processed wave parameters and raw data of an exceptionally high wave at the Acqua Alta Oceanographic Tower on December 15, 2009. In: Pomaro, A et al. (2020): An exceptionally high wave at the Acqua Alta Oceanographic Tower on December 15, 2009. Istituto di Scienze Marine - CNR, PANGAEA, https://doi.org/10.1594/PANGAEA.91546
The 2015 exceptional swell in the Southern Pacific: Generation, advection, forecast and implied extremes
Get PDFA very severe storm in the Antarctic belt is analysed that sent a very large swell throughout the South-Pacific Ocean. The reasons for the storm were a deep depression passing over an anomalous warm sea area, with consequent increased intensity, more active wind input, gustiness, with also dynamical generation. Wind and wave model results are verified with scatterometer and altimeter data. We follow the swell evolution during the five days required to reach the Galapagos Islands and a buoy off the Peruvian coast. The first forerunners peaked at 0.032 Hz at these locations, well represented in the model thanks to a purposely extended frequency range used in the WAM model. A nonlinear combined analysis is carried out to estimate the overall maximum single wave heights that may have impinged on the Galapagos coasts. Single wave heights up to 6 m have been estimated. Once generated, the swell conditions at Galapagos and the buoy are perfectly anticipated. Including generation, useful forecasts extend till at least eight days before the event. The lack of any local communication is discussed. An analysis using ERA5 winds, but a respectively higher resolution long-term wave hindcast, shows that a similar, actually stronger, event happened in 2006. A simple, but sound method, based on physical principles and elementary geometry, is proposed to estimate, firsthand and after any time, the maximum height of a once generated swell. The results for the 2015 storm are correct within 5% of the model values
Winds and waves in the Arabian Gulf: Physics, characteristics and long-term hindcast
No full textA 40-year hindcast of the wave conditions in the Arabian Gulf, the elongated basin between the Arabian Peninsula and Iran, is described. The input wind fields were derived from the ERA5 reanalysis by the European Centre for Medium-Range Weather Forecasts for the period 1979-2019. Extensive comparisons with scatterometer data suggested a direction-dependent wind calibration with a strong influence on the underestimation of offshore blowing winds. The dominant wave patterns in the basin are described together with the characteristics of the related winds. After characterizing the possible meteorological conditions, the corresponding wave fields were hindcast using the WAVEWATCH III model. Extensive validation against altimeter data shows an almost unitary fit and a 0.02-m bias; a comparison with measured data strongly demonstrates that the general patterns and conditions were well reproduced. The wave physics was also analysed, revealing the crucial role of their dynamic generation in the investigated area domain. The very shallow nature of some limited coastal zones suggests that locally focused studies, with more detailed and specific physics, are required for the best description of the waves in these areas
Unraveling climatic wind and wave trends in the Red Sea using wave spectra partitioning
No full textThe wind and wave climatology of the Red Sea is derived from a validated 30-yr high-resolution model simulation. After describing the relevant features of the basin, the main wind and wave systems are identified by using an innovative spectral partition technique to explain their genesis and characteristics. In the northern part of the sea, wind and waves of the same intensity are present throughout the year, while the central and southern zones are characterized by a marked seasonality. The partition technique allows the association of a general decrease in the energy of the different wave systems with a specific weather pattern. The most intense decrease is found in the northern storms, which are associated with meteorological pulses from the Mediterranean Sea
AWAC processed wave parameters of an exceptionally high wave at the Acqua Alta Oceanographic Tower on December 15, 2009
No full textAWAC processed wave parameters of an exceptionally high wave at the Acqua Alta Oceanographic Tower on December 15, 2009. In: Pomaro, A et al. (2020): An exceptionally high wave at the Acqua Alta Oceanographic Tower on December 15, 2009. Istituto di Scienze Marine - CNR, PANGAEA, https://doi.org/10.1594/PANGAEA.91546
- …
