scholarly journals Lee wave detection over the Mediterranean Sea using the Advanced Infra-Red WAter Vapour Estimator (AIRWAVE) total column water vapour (TCWV) dataset

2019 ◽  
Vol 12 (12) ◽  
pp. 6683-6693
Author(s):  
Enzo Papandrea ◽  
Stefano Casadio ◽  
Elisa Castelli ◽  
Bianca Maria Dinelli ◽  
Mario Marcello Miglietta
Keyword(s):  
Mediterranean Sea ◽  
Water Vapour ◽  
Small Scale ◽  
Tyrrhenian Sea ◽  
Infrared Measurements ◽  
Infra Red ◽  
Lee Waves ◽  
Lee Wave ◽  
The Mediterranean ◽  
Total Column

Abstract. Atmospheric gravity waves generated downstream by orography in a stratified airflow are known as lee waves. In the present study, such mesoscale patterns have been detected, over water and in clear-sky conditions, using the Advanced Infra-Red WAter Vapour Estimator (AIRWAVE) total column water vapour (TCWV) dataset, which contains about 20 years of day and night products, obtained from the thermal infrared measurements of the Along Track Scanning Radiometer (ATSR) instrument series. The high accuracy of such data, along with the native 1 km×1 km spatial resolution, allows the investigation of small-scale features such as lee waves. In this work, we focused on the Mediterranean Sea, the largest semi-enclosed basin on the Earth. The peculiarities of this area, which is characterised by complex orography and rough coastlines, lead to the development of these structures over both land and sea. We developed an automatic tool for the rapid detection of areas with high probability of lee wave occurrence, exploiting the TCWV variability in spatial regions with a 0.15∘×0.15∘ area. Through this analysis, several occurrences of structures connected with lee waves have been observed. The waves are detected in spring, autumn and summer seasons, with TCWV values usually falling in the range of 15 to 35 kg m−2. In this article, we describe some cases over the central (Italy) and the Eastern Mediterranean Basin (Greece, Turkey and Cyprus). We compared a case of perturbed AIRWAVE TCWV fields due to lee waves occurring over the Tyrrhenian Sea on 18 July 1997 with the sea surface winds from the synthetic aperture radar (SAR), which sounded the same geographical area, finding a good agreement. Another case has been investigated in detail: on 2 August 2002 the Aegean Sea region was almost simultaneously sounded by both the second sensor of the ATSR series (ATSR-2) and the Advanced ATSR (AATSR) instruments. The AIRWAVE TCWV fields derived from the two sensors were successfully compared with the vertically integrated water vapour content simulated with the Weather Research and Forecasting (WRF) numerical model for the same time period, confirming our findings. Wave parameters such as amplitude, wavelength and phase are described through the use of the Morlet continuous wavelet transformation (CWT). The performed analysis derived typical wavelengths from 6 to 8 km and amplitudes of up to 20 kg m−2.

scholarly journals Lee waves detection over the Mediterranean Sea using the Advanced Infra-Red WAter Vapour Estimator (AIRWAVE) Total Column Water Vapor (TCWV) dataset

2019 ◽  
Author(s):  
Enzo Papandrea ◽  
Stefano Casadio ◽  
Elisa Castelli ◽  
Bianca Maria Dinelli ◽  
Mario Marcello Miglietta
Keyword(s):  
Water Vapour ◽  
Eastern Mediterranean ◽  
Geographical Area ◽  
Central Italy ◽  
Small Scale ◽  
Tyrrhenian Sea ◽  
Infra Red ◽  
Lee Waves ◽  
The Mediterranean ◽  
Total Column

Abstract. Atmospheric gravity waves generated downstream by the orography in a stratified airflow are known as lee waves. In the present study, such mesoscale patterns have been detected, over water and in clear sky conditions, using the Advanced Infra-Red WAter Vapour Estimator (AIRWAVE) Total Column Water Vapour (TCWV) dataset, which contains about 20-year day-night products, obtained from the thermal infra-red measurements of the Along Track Scanning Radiometer (ATSR) instrument series. The good accuracy of such data, along 5 with the native 1 × 1 km2 spatial resolution, allows the investigation of small scale features as the lee waves. In this work, we focused on the Mediterranean region, the largest semi-enclosed basin on the Earth. The peculiarities of this area, which is characterized by complex orography and rough coastlines, lead indeed to a possible development of these structures both over land and over sea. We developed an automatic tool for the rapid detection of areas with high probability of lee waves occurrence, exploiting the TCWV variability in spatial regions 0.15° × 0.15° wide. Through this analysis, several occurrences of structures connected with lee waves have been observed. The waves are detected in spring, fall and summer seasons, with TCWV values usually falling in the range from 15 to 35 kg m−2. In this article we describe some cases over the Central (Italy) and the Eastern Mediterranean basin (Greece, Turkey, Cyprus). We compared a case of perturbed AIRWAVE TCWV fields due to lee waves occurred over the Tyrrhenian Sea on 18 July 1997 with the sea surface winds from the Synthetic Aperture Radar (SAR), which sounded the same geographical area, finding a good agreement. Another case has been investigated in detail: on 2 August 2002 the Aegean sea region was almost simultaneously sounded by both ATSR-2 and AATSR instruments. The AIRWAVE TCWV fields derived from the two sensors were successfully compared with the vertically integrated water vapour content simulated with the Weather Research and Forecasting (WRF) numerical model for the same time period, confirming our findings. Wave parameters such as amplitude, wavelength and phase, are described through the use of the Morlet ContinuousWavelet Transformation (CWT). The performed analysis derived typical wavelengths from 6 to 8 km and amplitude that may extend up to 20 kg m−2.

scholarly journals Ophelia roscoffensis Augener, 1910: a new polychaete record in Italian waters

Check List ◽  
2019 ◽  
Vol 15 (3) ◽  
pp. 489-495
Author(s):  
Emanuele Mancini ◽  
Francesco Tiralongo ◽  
Daniele Ventura ◽  
Andrea Bonifazi
Keyword(s):  
Mediterranean Sea ◽  
First Record ◽  
Posidonia Oceanica ◽  
Tyrrhenian Sea ◽  
The Mediterranean

Ophelia roscoffensis Augener, 1910 is an opheliid worm identifiable by the number of anterior abranchiate chaetigers and the number of the gill pairs. Although it was already reported in the Mediterranean Sea, it has never been found in the Italian waters. This study represents the first record of Ophelia roscoffensis in the Italian waters. A total of 18 specimens were collected along the coast of Civitavecchia (Tyrrhenian Sea) in a Posidonia oceanica (L.) Delile bed at a depth of 7 m.

scholarly journals Social equity and marine protected areas: Perceptions of small-scale fishermen in the Mediterranean Sea

2020 ◽  
Vol 244 ◽  
pp. 108531 ◽  
Author(s):  
Nathan J. Bennett ◽  
Antonio Calò ◽  
Antonio Di Franco ◽  
Federico Niccolini ◽  
Daniela Marzo ◽  
...  
Keyword(s):  
Protected Areas ◽  
Mediterranean Sea ◽  
Marine Protected Areas ◽  
Social Equity ◽  
Small Scale ◽  
The Mediterranean

Two live sightings of Sowerby's beaked whale (Mesoplodon bidens) from the western Mediterranean (Tyrrhenian Sea)

2017 ◽  
Vol 98 (5) ◽  
pp. 1003-1009 ◽  
Author(s):  
Luca Bittau ◽  
Mattia Leone ◽  
Adrien Gannier ◽  
Alexandre Gannier ◽  
Renata Manconi
Keyword(s):  
Mediterranean Sea ◽  
Western Mediterranean ◽  
Tyrrhenian Sea ◽  
Beaked Whale ◽  
Long Distance ◽  
The North ◽  
Western Mediterranean Sea ◽  
Beaked Whales ◽  
Species Groups ◽  
The Mediterranean

Sowerby's beaked whale (Mesoplodon bidens) was previously known in the Mediterranean Sea from a single live stranding of two individuals in the French Riviera. We report here on two live sightings in the western Mediterranean, central-western Tyrrhenian Sea off eastern Corsica (Montecristo Trough) and off eastern Sardinia (Caprera Canyon) in 2010 and 2012, respectively. In both cases single individuals, possibly the same individual, occurred within groups of Cuvier's beaked whales (Ziphius cavirostris) suggesting inter-specific interactions. Based on our close observations of mixed-species groups of Sowerby's and Cuvier's beaked whales, we hypothesize that some previous long-distance sightings of beaked whales in the Mediterranean may not be reliably attributed to Z. cavirostris. The present sightings and previous live stranding indicate that the western Mediterranean Sea is the easternmost marginal area of M. bidens within the North Atlantic geographic range. Notes on behaviour are also provided.

First record of Amphiura securigera (Echinodermata: Ophiuroidea) in the Tyrrhenian (Mediterranean) Sea

2000 ◽  
Vol 80 (1) ◽  
pp. 175-176
Author(s):  
P. Rinelli
Keyword(s):  
Mediterranean Sea ◽  
First Record ◽  
Water Circulation ◽  
Brittle Star ◽  
Tyrrhenian Sea ◽  
Bathymetric Range ◽  
First Finding ◽  
The Mediterranean

The first finding of the brittle star Amphiura securigera (Echinodermata: Ophiuroidea) in the Tyrrhenian Sea is reported. According to literature data, biotopic and edaphic features of the bottom indicate that this species preferentially lives in detritic mud-free biotopes characterized by good water circulation. Present data show that in the Mediterranean Sea A. securigera extends its bathymetric range as far as the circalittoral and upper bathyal floors.

scholarly journals Acoustic correction factor estimate for compensating vertical diel migration of small pelagics

2021 ◽  
Author(s):  
ANGELO BONANNO ◽  
MARCO BARRA ◽  
ANDREA DE FELICE ◽  
MARIANNA GIANNOULAKI ◽  
MAGDALENA IGLESIAS ◽  
...  
Keyword(s):  
Data Acquisition ◽  
Mediterranean Sea ◽  
Correction Factor ◽  
Pelagic Fish ◽  
Tyrrhenian Sea ◽  
Fish Community Structure ◽  
Northern Spain ◽  
Small Pelagic Fish ◽  
Acoustic Data ◽  
The Mediterranean

Differences in acoustic estimates of small pelagic fish biomass, due to data acquisition during daytime and nighttime surveys, have been recognized for many years as a problem in acoustic surveys. In the absence of a single rule for all species and for all locations, some expert groups identified specific time intervals for acoustic data acquisition in relation to the schooling behavior of the target species. In the Mediterranean Sea, the research groups working in the MEDIAS (Mediterranean International Acoustic Survey) agreed on the importance that acoustic sampling are conducted only during day-time. Only when available time does not permit to complete the survey during daytime, data collection might be extended. In this case, working on data collected during both daytime and nighttime, a bias may occur in the biomass estimates. In order to evaluate and correct such bias, specific experiments were performed in some geographical sub-areas of the Mediterranean Sea. The data analysis allowed the estimation of a mean correction factor for the Strait of Sicily, where five surveys were carried out in different years. The correction factor was estimated also for the Adriatic Sea, Tyrrhenian Sea and Northern Spain; the observed variability among areas highlighted the importance of the spatial and temporal coverage of the survey area in order to obtain reliable estimates of the correction factor. Further studies are necessary to improve the interpretation of the obtained estimates in relation to area-related peculiarities such as zooplankton composition and abundance along with small pelagic fish community structure. 

scholarly journals Sinking microplastics in the water column: simulations in the Mediterranean Sea

Ocean Science ◽  
2021 ◽  
Vol 17 (2) ◽  
pp. 431-453
Author(s):  
Rebeca de la Fuente ◽  
Gábor Drótos ◽  
Emilio Hernández-García ◽  
Cristóbal López ◽  
Erik van Sebille
Keyword(s):  
Vertical Distribution ◽  
Mediterranean Sea ◽  
Water Column ◽  
Large Scale ◽  
Circulation Model ◽  
Small Scale ◽  
The Mediterranean ◽  
Scale Turbulence ◽  
Non Gaussian ◽  
The Vertical Distribution

Abstract. We study the vertical dispersion and distribution of negatively buoyant rigid microplastics within a realistic circulation model of the Mediterranean sea. We first propose an equation describing their idealized dynamics. In that framework, we evaluate the importance of some relevant physical effects (inertia, Coriolis force, small-scale turbulence and variable seawater density), and we bound the relative error of simplifying the dynamics to a constant sinking velocity added to a large-scale velocity field. We then calculate the amount and vertical distribution of microplastic particles on the water column of the open ocean if their release from the sea surface is continuous at rates compatible with observations in the Mediterranean. The vertical distribution is found to be almost uniform with depth for the majority of our parameter range. Transient distributions from flash releases reveal a non-Gaussian character of the dispersion and various diffusion laws, both normal and anomalous. The origin of these behaviors is explored in terms of horizontal and vertical flow organization.

scholarly journals Eukaryotic community composition in the sea surface microlayer across an east-west transect in the Mediterranean Sea

2020 ◽  
Author(s):  
Birthe Zäncker ◽  
Michael Cunliffe ◽  
Anja Engel
Keyword(s):  
Mediterranean Sea ◽  
Community Composition ◽  
Significant Proportion ◽  
Sea Surface ◽  
Surface Microlayer ◽  
Tyrrhenian Sea ◽  
Ionian Sea ◽  
Western Basin ◽  
Sea Surface Microlayer ◽  
The Mediterranean

Abstract. The sea surface microlayer (SML) represents the boundary layer at the air-sea interface. Microbial eukaryotes in the SML potentially influence air-sea gas exchange directly by taking up and producing gases, and indirectly by excreting and degrading organic matter, which may modify the viscoelastic properties of the SML. However, little is known about the controlling factors that influence microbial eukaryote community composition in the SML. We studied the composition of the microbial community, transparent exopolymer particles and polysaccharides in the SML during the PEACETIME cruise along a west-east transect in the Mediterranean Sea, covering the western basin, Tyrrhenian Sea and Ionian Sea. At the stations located in the Ionian Sea, fungi were found in high relative abundances determined by 18S sequencing efforts, making up a significant proportion of the sequences recovered. At the same time, bacterial and phytoplankton counts were decreasing from west to east, while transparent exopolymer particle (TEP) abundance and total carbohydrate (TCHO) concentrations remained the same between Mediterranean basins. Thus, the presence of substrates for fungi, such as Cladosporium known to take up phytoplankton-derived polysaccharides, in combination with decreased substrate competition by bacteria suggests that fungi could be thriving in the neuston of the Ionian Sea.

scholarly journals Changes in ventilation of the Mediterranean Sea during the past 25 year

Ocean Science ◽  
2014 ◽  
Vol 10 (1) ◽  
pp. 1-16 ◽  
Author(s):  
A. Schneider ◽  
T. Tanhua ◽  
W. Roether ◽  
R. Steinfeldt
Keyword(s):  
Mediterranean Sea ◽  
Deep Water ◽  
Adriatic Sea ◽  
Western Mediterranean ◽  
Tyrrhenian Sea ◽  
Deep Water Formation ◽  
Technical Problems ◽  
Water Formation ◽  
The Mediterranean ◽  
Transient Tracer

Abstract. Significant changes in the overturning circulation of the Mediterranean Sea has been observed during the last few decades, the most prominent phenomena being the Eastern Mediterranean Transient (EMT) in the early 1990s and the Western Mediterranean Transition (WMT) during the mid-2000s. During both of these events unusually large amounts of deep water were formed, and in the case of the EMT, the deep water formation area shifted from the Adriatic to the Aegean Sea. Here we synthesize a unique collection of transient tracer (CFC-12, SF6 and tritium) data from nine cruises conducted between 1987 and 2011 and use these data to determine temporal variability of Mediterranean ventilation. We also discuss biases and technical problems with transient tracer-based ages arising from their different input histories over time; particularly in the case of time-dependent ventilation. We observe a period of low ventilation in the deep eastern (Levantine) basin after it was ventilated by the EMT so that the age of the deep water is increasing with time. In the Ionian Sea, on the other hand, we see evidence of increased ventilation after year 2001, indicating the restarted deep water formation in the Adriatic Sea. This is also reflected in the increasing age of the Cretan Sea deep water and decreasing age of Adriatic Sea deep water since the end of the 1980s. In the western Mediterranean deep basin we see the massive input of recently ventilated waters during the WMT. This signal is not yet apparent in the Tyrrhenian Sea, where the ventilation seems to be fairly constant since the EMT. Also the western Alboran Sea does not show any temporal trends in ventilation.

scholarly journals Implementation and validation of a coastal forecasting system for wind waves in the Mediterranean Sea

2012 ◽  
Vol 12 (2) ◽  
pp. 485-494 ◽  
Author(s):  
R. Inghilesi ◽  
F. Catini ◽  
G. Bellotti ◽  
L. Franco ◽  
A. Orasi ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Coastal Area ◽  
Large Scale ◽  
Wind Waves ◽  
Coastal Areas ◽  
Small Scale ◽  
Tyrrhenian Sea ◽  
Coastal System ◽  
Forecasting System ◽  
Propagation Of Waves

Abstract. A coastal forecasting system was implemented to provide wind wave forecasts over the whole Mediterranean Sea area, and with the added capability to focus on selected coastal areas. The goal of the system was to achieve a representation of the small-scale coastal processes influencing the propagation of waves towards the coasts. The system was based on a chain of nested wave models and adopted the WAve Model (WAM) to analyse the large-scale, deep-sea propagation of waves; and the Simulating WAves Nearshore (SWAN) to simulate waves in key coastal areas. Regional intermediate-scale WAM grids were introduced to bridge the gap between the large-scale and each coastal area. Even applying two consecutive nestings (Mediterranean grid → regional grid → coastal grid), a very high resolution was still required for the large scale WAM implementation in order to get a final resolution of about 400 m on the shores. In this study three regional areas in the Tyrrhenian Sea were selected, with a single coastal area embedded in each of them. The number of regional and coastal grids in the system could easily be modified without significantly affecting the efficiency of the system. The coastal system was tested in three Italian coastal regions in order to optimize the numerical parameters and to check the results in orographically complex zones for which wave records were available. Fifteen storm events in the period 2004–2009 were considered.

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