scholarly journals Interpreting elevated space-borne HCHO columns over the Mediterranean Sea using the OMI and SCIAMACHY sensors

2011 ◽  
Vol 11 (6) ◽  
pp. 17913-17940
Author(s):  
A. Sabolis ◽  
N. Meskhidze ◽  
G. Curci ◽  
P. I. Palmer ◽  
B. Gantt
Keyword(s):  
Mediterranean Sea ◽  
Hot Spot ◽  
Water Bodies ◽  
Urban Atmosphere ◽  
Saharan Dust ◽  
Ozone Monitoring Instrument ◽  
Remotely Sensed Data ◽  
Spatial And Seasonal Variation ◽  
Wide Range ◽  
The Mediterranean

Abstract. Formaldehyde (HCHO) is an oxidation product of a wide range of volatile organic compounds (VOCs) and important atmospheric constituent found in both the polluted urban atmosphere and remote background sites. In this study, remotely sensed data of HCHO vertical column densities are analyzed over the Mediterranean Sea using the Ozone Monitoring Instrument (OMI). Data analysis indicates a marked seasonal cycle with a summer maximum and winter minimum confined to the marine environment during a three year period (2005–2007) examined. A possible retrieval artifact associated with Saharan dust transport over the region is explored by changing intensity of Saharan dust sources in GEOS-Chem following the recommendation of Generoso et al. (2008). Recalculated air mass factors (AMF), based on the new values of aerosol loadings, lead to a reduction of the summertime "hot spot" in OMI retrieval of HCHO columns over the Mediterranean Sea; however, even after the correction, enhanced values are still present in this region. To explain these values, marine biogenic sources of VOCs are examined. Calculations indicate that emissions of phytoplankton-produced isoprene and monoterpenes are not likely to explain the enhanced HCHO columns over the Mediterranean Sea. To further understand spatial and seasonal variation of HCHO over the Mediterranean Sea, OMI HCHO columns are compared to those of the SCanning Imaging Absorption spectroMeter for Atmospheric CartograpHY (SCIAMACHY) sensor. Unlike OMI retrievals, over the Mediterranean Sea SCIAMACHY HCHO columns did not reveal clear seasonality during the three years and the two sensors did not agree within their retrieval uncertainty. Overall, comparison of OMI and SCIAMACHY HCHO columns were inconclusive. Moreover, retrievals of HCHO columns over other water bodies showed that the two sensors agree reasonably well over the Equatorial Pacific region, Gulf of Mexico, and the North Sea, but do not show similar magnitudes or seasonal variations over oligotrophic water bodies such as Mediterranean Sea, Northwestern and Southern Pacific Oceans. Model simulations in conjunction with measurements studies may be required to fully explore the complex mechanism of HCHO formation over the Mediterranean and its implications for the air quality in the region.

scholarly journals Interpreting elevated space-borne HCHO columns over the Mediterranean Sea using the OMI sensor

2011 ◽  
Vol 11 (24) ◽  
pp. 12787-12798 ◽  
Author(s):  
A. Sabolis ◽  
N. Meskhidze ◽  
G. Curci ◽  
P. I. Palmer ◽  
B. Gantt
Keyword(s):  
Mediterranean Sea ◽  
Hot Spot ◽  
Urban Atmosphere ◽  
Saharan Dust ◽  
Ozone Monitoring Instrument ◽  
Remotely Sensed Data ◽  
Vertical Column ◽  
Dust Transport ◽  
Wide Range ◽  
The Mediterranean

Abstract. Formaldehyde (HCHO) is an oxidation product of a wide range of volatile organic compounds (VOCs) and important atmospheric constituent found in both the polluted urban atmosphere and remote background sites. In this study, remotely sensed data of HCHO vertical column densities are analyzed over the Mediterranean Sea using the Ozone Monitoring Instrument (OMI). Data analysis indicates a marked seasonal cycle with a summer maximum and winter minimum confined to the marine environment during a three year period (2005–2007) examined. A possible retrieval artifact associated with Saharan dust transport over the region is explored by changing intensity of Saharan dust sources in GEOS-Chem following the recommendation of Generoso et al. (2008). Recalculated air mass factors (AMF), based on the new values of aerosol loadings, lead to a reduction of the summertime "hot spot" in OMI retrieval of HCHO vertical columns over the Mediterranean Sea; however, even after the correction, enhanced values are still present in this region. To explain these values, marine biogenic sources of VOCs are examined. Calculations indicate that emission of phytoplankton-produced isoprene is not likely to explain the enhanced HCHO vertical columns over the Mediterranean Sea. Model simulations in conjunction with measurements studies may be required to fully explore the complex mechanism of HCHO formation over the Mediterranean and its implications for the air quality in the region.

scholarly journals Longitudinal variability of the biogeochemical role of Mediterranean aerosols in the Mediterranean Sea

2011 ◽  
Vol 8 (5) ◽  
pp. 1067-1080 ◽  
Author(s):  
E. Ternon ◽  
C. Guieu ◽  
C. Ridame ◽  
S. L'Helguen ◽  
P. Catala
Keyword(s):  
Mediterranean Sea ◽  
Forest Fires ◽  
Saharan Dust ◽  
Aerosol Sampling ◽  
Modest Contribution ◽  
Anthropogenic Contribution ◽  
The Mediterranean ◽  
June July ◽  
Atmospheric Inputs ◽  
Longitudinal Variability

Abstract. The Mediterranean Sea is a semi-enclosed basin characterized by a strong thermal stratification during summer during which the atmosphere is the main source of new nutrients to the nutrient-depleted surface layer. From aerosol sampling and microcosm experiments performed during the TransMed BOUM cruise (June–July 2008) we showed that: (i) the Mediterranean atmosphere composition (Al, Fe, P) was homogeneous over ~28° of longitude and was a mixture with a constant proportion of anthropogenic contribution and a variable but modest contribution of crustal aerosols. This quite stable composition over a one month period and a long transect (~2500 km) allowed to define the Mediterranean atmospheric "background" that characterizes the summer season in the absence of major Saharan event and forest fires, (ii) primary production significantly increased at all tested stations after aerosols addition collected on-board and after Saharan dust analog addition, indicating that both additions relieved on-going (co)-limitations. Although both additions significantly increased the N2 fixation rates at the western station, diazotrophic activity remained very low (~0.2 nmol N L−1 d−1), (iii) due to the presence of anthropogenic particles, the probable higher solubility of nutrients associated with mixed aerosols (crustal + anthropogenic contribution), conferred a higher fertilizing potential to on-board collected aerosol as compared to Saharan dust analog. Finally, those experiments showed that atmospheric inputs from a mixed atmospheric event ("summer rain" type) or from a high-intensity Saharan event would induce comparable response by the biota in the stratified Mediterranean SML, during summer.

The High Frequency coastal radar network in the Mediterranean: joint efforts towards a fully operational implementation

2021 ◽  
Author(s):  
Pablo Lorente ◽  
Keyword(s):  
Marine Environment ◽  
High Frequency ◽  
Production Management ◽  
Hot Spot ◽  
Coastal Areas ◽  
Coastal Hazards ◽  
Current Status ◽  
Wide Range ◽  
The Mediterranean

<p>The Mediterranean Sea is considered a relevant geostrategic region and a prominent climate change hot spot. This semi-enclosed basin has been the subject of abundant studies due to its vulnerability to sea-level rise and other coastal hazards. With the steady advent of new technologies, a growing wealth of observational data are nowadays available to efficiently monitor the sea state and properly respond to socio-ecological challenges and stakeholder needs, thereby strengthening the community resilience at multiple scales.</p><p>Nowadays, High-Frequency radar (HFR) is a worldwide consolidated land-based remote sensing technology since it provides, concurrently and in near real time, fine-resolution maps of the surface circulation along with (increasingly) wave and wind information over broad coastal areas. HFR systems present a wide range of practical applications: maritime safety, oil spill emergencies, energy production, management of extreme coastal hazards. Consequently, they have become an essential component of coastal ocean observatories since they offer a unique dynamical framework that complement conventional in-situ observing platforms. Likewise, within the frame of the Copernicus Marine Environment Monitoring Service (CMEMS), HFR are valuable assets that play a key pivotal role in both the effective monitoring of coastal areas and the rigorous skill assessment of operational ocean forecasting systems.</p><p>The present work aims to show a panoramic overview not only of the current status of diverse Mediterranean HFR systems, but also of the coordinated joint efforts between many multi-disciplinary institutions to establish a permanent HFR monitoring network in the Mediterranean, aligned with European and global initiatives. In this context, it is worth highlighting that many of the Mediterranean HFR systems are already integrated into the European HFR Node, which acts as central focal point for data collection, homogenization, quality assurance and dissemination and promotes networking between EU infrastructures and the Global HFR network.</p><p>Furthermore, priority challenges tied to the implementation of a long-term, fully integrated, sustainable operational Mediterranean HFR network are described. This includes aspects related to the setting up of such a system within the broader framework of the European Ocean Observing System (EOOS), and a long-term financial support required to preserve the infrastructure core service already implemented. Apart from the technological challenges, the enhancing of the HFR data discovery and access, the boosting of the data usage as well as the research integration must be achieved by building synergies among academia, management agencies, state government offices, intermediate and end users. This would guarantee a coordinated development of tailored products that meet the societal needs and foster user uptake, serving the marine industry with dedicated smart innovative services, along with the promotion of strategic planning and informed decision-making in the marine environment.</p>

Predominant transport paths of Saharan dust over the Mediterranean Sea to Europe

2012 ◽  
Vol 117 (D2) ◽  
pp. n/a-n/a ◽  
Author(s):  
P. Israelevich ◽  
E. Ganor ◽  
P. Alpert ◽  
P. Kishcha ◽  
A. Stupp
Keyword(s):  
Mediterranean Sea ◽  
Saharan Dust ◽  
The Mediterranean

scholarly journals Saharan Dust Deposition May Affect Phytoplankton Growth in the Mediterranean Sea at Ecological Time Scales

PLoS ONE ◽  
2014 ◽  
Vol 9 (10) ◽  
pp. e110762 ◽  
Author(s):  
Rachele Gallisai ◽  
Francesc Peters ◽  
Gianluca Volpe ◽  
Sara Basart ◽  
José Maria Baldasano
Keyword(s):  
Mediterranean Sea ◽  
Time Scales ◽  
Phytoplankton Growth ◽  
Saharan Dust ◽  
Dust Deposition ◽  
The Mediterranean

scholarly journals Large Saharan dust storms: Implications for chlorophyll dynamics in the Mediterranean Sea

2016 ◽  
Vol 30 (11) ◽  
pp. 1725-1737 ◽  
Author(s):  
Rachele Gallisai ◽  
Gianluca Volpe ◽  
Francesc Peters
Keyword(s):  
Mediterranean Sea ◽  
Dust Storms ◽  
Saharan Dust ◽  
The Mediterranean

scholarly journals Multivariate Sub-Regional Ocean Indicators in the Mediterranean Sea: From Event Detection to Climate Change Estimations

2021 ◽  
Vol 8 ◽  
Author(s):  
Mélanie Juza ◽  
Joaquín Tintoré
Keyword(s):  
Climate Change ◽  
Mediterranean Sea ◽  
Ocean Circulation ◽  
Heat Waves ◽  
Mesoscale Eddy ◽  
Value Added ◽  
Policy Decision ◽  
Balearic Islands ◽  
Wide Range ◽  
The Mediterranean

The increasing science and society requests for ocean monitoring from global to regional and local scales, the need for integration and convergence into a globally consistent ocean observing system as well as the need for improvement of access to information are now internationally recognized goals to progress toward the sustainable management of a healthy ocean. To respond to these challenges at regional level, the Balearic Islands Coastal Observing and Forecasting System (SOCIB) is developing a comprehensive set of ocean indicators in the Mediterranean Sea and around the Balearic Islands, key environments that are strongly affected by climate change and human pressure. This new SOCIB value-added product addresses the sub-regional ocean variability from daily (events) to interannual/decadal (climate) scales. A user-friendly interface has been implemented to monitor, visualize and communicate ocean information that is relevant for a wide range of sectors, applications and regional end-users. These sub-regional indicators allowed us to detect specific events in real time. Remarkable events and features identified include marine heat waves, atmospheric storm, extreme river discharge, mesoscale eddy, deep convection among others, all of them being oceanic phenomena that directly impact the ocean circulation and marine ecosystems. The long-term variations, in response to climate change, are also addressed highlighting and quantifying trends in physical and biogeochemical components of the ocean as well as sub-regional differences. At both (sub-) regional, national and international levels, a society-aligned science will have stronger impact on policy decision-makings and will support society to implement specific actions to address worldwide environmental challenges.

scholarly journals Assessing the role of dust deposition on phytoplankton ecophysiology and succession in a low-nutrient low-chlorophyll ecosystem: a mesocosm experiment in the Mediterranean Sea

2012 ◽  
Vol 9 (12) ◽  
pp. 19199-19243 ◽  
Author(s):  
V. Giovagnetti ◽  
C. Brunet ◽  
F. Conversano ◽  
F. Tramontano ◽  
I. Obernosterer ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Phytoplankton Community ◽  
Phytoplankton Bloom ◽  
Community Response ◽  
Mesocosm Experiment ◽  
Saharan Dust ◽  
Dust Deposition ◽  
Layer System ◽  
Pigment Analysis ◽  
The Mediterranean

Abstract. In this study, we investigate the phytoplankton community response, with emphasis on ecophysiology and succession, after two experimental additions of Saharan dust in the surface layer of a low-nutrient low-chlorophyll ecosystem in the Mediterranean Sea. Three mesocosms were amended with evapocondensed dust to simulate realistic Saharan dust events while three additional mesocosms were kept unamended and served as controls. Experiments consisted in two consecutive dust additions and samples were daily collected at different depths (−0.1, −5 and −10 m) during one week, starting before each addition occurred. Data concerning HPLC pigment analysis on two size classes (< 3 and > 3 µm), electron transport rate (ETR) versus irradiance curves, non-photochemical fluorescence quenching (NPQ) and phytoplankton cell abundance (measured by flow cytometry), are presented and discussed in this paper. Results show that picophytoplankton mainly respond to the first dust addition, while the second addition leads to an increase of both pico- and nano-/microphytoplankton. Ecophysiological changes in the phytoplankton community are revealed, and an increase in NPQ development, as well as in pigment concentration per cell, follows the dust additions. ETR does not show large variations between dust-amended and control conditions, while biomass increases in response to the dust additions. Furthermore, the biomass increase observed during this mesocosm experiment allows us to attempt a quantitative assessment and parameterization of the onset of a phytoplankton bloom in a nutrient-limited ecosystem. These results are discussed focusing on the adaptation of picophytoplankton to such a nutrient-limited mixed layer system, as well as on size-dependent competition ability in phytoplankton.

scholarly journals Distribution and host diversity of Amoebophryidae parasites across oligotrophic waters of the Mediterranean Sea

2011 ◽  
Vol 8 (2) ◽  
pp. 267-278 ◽  
Author(s):  
R. Siano ◽  
C. Alves-de-Souza ◽  
E. Foulon ◽  
El M. Bendif ◽  
N. Simon ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Marine Ecosystems ◽  
Natural Environments ◽  
Coastal Station ◽  
Host Diversity ◽  
Eukaryotic Community ◽  
Wide Range ◽  
The Mediterranean ◽  
Host Infection

Abstract. Sequences affiliated to Syndiniales (Marine alveolate, MALV) regularly dominate 18S rDNA genetic libraries of nearly all marine ecosystems investigated so far. Among them, Amoebophryidae (MALV group II) is composed of numerous and genetically distant environmental sequences, where Amoebophrya is the only known and formally described genus. Amoebophrya species include virulent pathogens for a wide range of dinoflagellate species. Beside their regular occurrence in marine ecosystems, their quantitative distribution and the environmental factors triggering host infection have barely been studied in open oligotrophic waters. In order to understand the functional role of these parasites in natural environments, we studied the distribution and contribution to the eukaryotic community of the small free-living stage of Amoebophryidae (the dinospores) along a transect in the Mediterranean Sea, as well as their host diversity at three oligotrophic stations. Dinospores were more abundant at a coastal station (max. 1.5 × 103 cells ml−1) than in oligotrophic waters (max. 51 ± 16.3 cells ml−1), where they represented 10.3 to 34.9% of the total eukaryotic community at 40 and 30 m depth, respectively and 21.2% on average along the water column. Positive correlation was found between dinospore occurrence and higher concentration of NO3 + NO2 at the coastal station. At selected stations, out of 38 different dinoflagellates taxa identified, 15 were infected, among which a majority were not recognized as Amoebophryidae host so far. Prevalences (percentage of infected cells) generally varied between 1% and 10%, with a notable exception for Blepharocysta paulsenii for which 25% of cells were infected at the most oligotrophic station. The present study shows that dinospores are able to thrive and infect dinoflagellates both in coastal and ultra-oligotrophic open waters. Our results emphasize the role of parasitism in microbial food web dynamics and ultimately on biogeochemical cycles.

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