Mediterranean hurricanes: large-scale environment and convective and precipitating areas from satellite microwave observations

Subsynoptic scale vortices that have been likened to tropical cyclones or polar lows (medicanes) are occasionally observed over the Mediterranean Sea. Generated over the sea, they are usually associated with strong winds and heavy precipitation and thus can be highly destructive in islands and costal areas. Only an accurate forecasting of such systems could mitigate these effects. However, at the moment, the predictability of these systems remains limited. <br><br> Due to the scarcity of conventional observations, use is made of NOAA/MetOp satellite observations, for which advantage can be taken of the time coverage differences between the platforms that carry it, to give a very complete temporal description of the disturbances. A combination of AMSU-B (Advanced Microwave Sounding Unit-B)/MHS (Microwave Humidity Sounder) observations permit to investigate precipitation associated with these systems while coincident AMSU-A (Advanced Microwave Sounding Unit-A) observations give insights into the larger synoptic-scale environment in which they occur. <br><br> Three different cases (in terms of intensity, location, trajectory, duration, and periods of the year – May, September and December, respectively) were investigated. Throughout these time periods, AMSU-A observations show that the persisting deep outflow of cold air over the sea together with an upper-level trough upstream constituted a favourable environment for the development of medicanes. AMSU-B/MHS based diagnostics show that convection and precipitation areas are large in the early stage of the low, but significantly reduced afterwards. Convection is maximum just after the upper-level trough, located upstream of cold mid-tropospheric air, reached its maximum intensity and acquired a cyclonic orientation

Hypoxia and fatigue impair rapid torque development of knee extensors in elite alpine skiers

This study examined the effects of acute hypoxia on maximal and explosive torque and fatigability in knee extensors of skiers. Twenty-two elite male alpine skiers performed 35 maximal, repeated isokinetic knee extensions at 180∘s-1 (total exercise duration 61.25 s) in normoxia (NOR, FiO2 0.21) and normobaric hypoxia (HYP, FiO2 0.13) in a randomized, single-blind design. Peak torque and rate of torque development (RTD) from 0 to 100 ms and associated Vastus Lateralis peak EMG activity and rate of EMG rise (RER) were determined for each contraction. Relative changes in deoxyhemoglobin concentration of the VL muscle were monitored by near-infrared spectroscopy. Peak torque and peak EMG activity did not differ between conditions and decreased similarly with fatigue (p < 0.001), with peak torque decreasing continuously but EMG activity decreasing significantly after 30 contractions only. Compared to NOR, RTD, and RER values were lower in HYP during the first 12 and 9 contractions, respectively (both p < 0.05). Deoxyhemoglobin concentration during the last five contractions was higher in HYP than NOR (p = 0.050) but the delta between maximal and minimal deoxyhemoglobin for each contraction was similar in HYP and NOR suggesting a similar muscle O2 utilization. Post-exercise heart rate (138 ± 24 bpm) and blood lactate concentration (5.8 ± 3.1 mmol.l-1) did not differ between conditions. Arterial oxygen saturation was significantly lower (84 ± 4 vs. 98 ± 1%, p < 0.001) and ratings of perceived exertion higher (6 ± 1 vs. 5 ± 1, p < 0.001) in HYP than NOR. In summary, hypoxia limits RTD via a decrease in neural drive in elite alpine skiers undertaking maximal repeated isokinetic knee extensions, but the effect of hypoxic exposure is negated as fatigue develops. Isokinetic testing protocols for elite alpine skiers should incorporate RTD and RER measurements as they display a higher sensitivity than peak torque and EMG activity

LONG LIFE FOR THE EASTERN MEDITERRANEAN MESOSCALE EDDIES

Abstract The three-dimensional structure of the eastern Mediterranean mesoscale eddies was studied using a combination of a high horizontal resolution numerical model (∼5 km) outputs, in-situ and satellite data. Most of these eddies show good similarity between model results and observations. The structure, formation, development and propagation of each feature were studied separately and the results were then compared. Westward propagation in the southern Ionian Sea and eastward propagation in the southern Levantine Basin were observed with lifetime of more than two years

Regional and experiential differences in surgeon preference for the treatment of cervical facet injuries: a case study survey with the AO Spine Cervical Classification Validation Group

Purpose: The management of cervical facet dislocation injuries remains controversial. The main purpose of this investigation was to identify whether a surgeon’s geographic location or years in practice influences their preferred management of traumatic cervical facet dislocation injuries. Methods: A survey was sent to 272 AO Spine members across all geographic regions and with a variety of practice experience. The survey included clinical case scenarios of cervical facet dislocation injuries and asked responders to select preferences among various diagnostic and management options. Results: A total of 189 complete responses were received. Over 50% of responding surgeons in each region elected to initiate management of cervical facet dislocation injuries with an MRI, with 6 case exceptions. Overall, there was considerable agreement between American and European responders regarding management of these injuries, with only 3 cases exhibiting a significant difference. Additionally, results also exhibited considerable management agreement between those with ≤ 10 and &gt; 10&nbsp;years of practice experience, with only 2 case exceptions noted. Conclusion: More than half of responders, regardless of geographical location or practice experience, identified MRI as a screening imaging modality when managing cervical facet dislocation injuries, regardless of the status of the spinal cord and prior to any additional intervention. Additionally, a majority of surgeons would elect an anterior approach for the surgical management of these injuries. The study found overall agreement in management preferences of cervical facet dislocation injuries around the globe

The sensitivity of Mediterranean thermohaline circulation to gateway depth: a model investigation

The Neogene sedimentary record of the Mediterranean Sea holds evidence for changes in water properties and circulation. These paleoceanographic changes have been attributed to changes in the flow through the ocean gateway between the Mediterranean Sea and the Atlantic Ocean. We use an oceanic general circulation model to achieve quantitative, physics-based understanding of the effect of changes in the depth of the gateway such as may result from tectonic activity or variation in sea level. To isolate these effects we use idealized basin geometry and impose simplified atmospheric forcing. A reference experiment with present-day sill depth demonstrates that the model simulates reasonably well the main features of the present-day Mediterranean thermohaline circulation as inferred from observations and previous numerical studies. Subsequently, a series of sensitivity simulations is performed with different sill depths. The model results show that Mediterranean temperature, salinity, and thermohaline circulation depend strongly on sill depth. As the sill depth decreases, the upper overturning cell is quasi-linearly reduced in strength, while, contrary to what one would expect, the deep cell intensifies and does so in a nonlinear way. We find that a shoaling of the sill depth induces a “blocking effect” on the outflow waters, which creates a strong recirculation in the deep layers, strengthening the deep cell. Nevertheless, deep-water formation is reduced, and, as a consequence, the ventilation of the deep layers diminishes. We identify three different circulation modes of the Mediterranean thermohaline circulation depending on the sill depth: “shallow sill,” “moderate sill,” and “deep sill” modes coupled with strong, weak, and negligible blocking effects, respectively. Our results are consistent with the pre-Messinian paleoceanographic record of the Mediterranean Sea and may be useful to understanding the behavior of other land-locked basins, both extant and from the geological past

Copernicus Sentinel-2 and Sentinel-3 Radiometric Performance: Inter-Comparison with LANDSAT8/ 9 and Aqua-MODIS Using Vicarious Methods Over Desert-PICS and DCC Targets

As part of the Copernicus program of the European Commission, the European Space Agency (ESA) developed and operates the Sentinel-2 constellation (S2A, S2B); and in cooperation with the EUMETSAT, they are operating the Sentinel-3 constellation (S3A, S3B). Both are Earth Observation optical missions, where the MultiSpectral Instrument (MSI) is carried on board Sentinel-2 mission and the Ocean and Land Colour Instrument (OLCI) and Sea Land Surface Temperature Radiometer (SLSTR) are on board the Sentinel-3 mission. In the framework of the Copernicus Optical Mission Performance Cluster (OPT-MPC), we use the Database for Imaging Multispectral Instruments and Tools for Radiometric Inter-comparison (DIMITRI) to perform the radiometry intercomparison of the Level-1 products. The aims of this presentation are: 1) to assess the quality of the user products; 2) to monitor the temporal evolution of the radiometry of the instruments MSI, OLCI and SLSTR for both units A and B and; 3) to perform radiometric intercomparison with similar optical missions such as Landsat-8, Landsat-9 and Aqua-MODIS. The results of the intercomparison show a good stability of the sensors, although SLSTR-A & B show slight positive trends. MSI, OLI and SLSTR pairs show good agreement better than 1% while OLCI-A is brighter than OLCI-B up to 2-3% over the VNIR spectral range. The results show a good agreement between MSI/OLI to better than 1% except band B01 (443 nm) over VNIR bands. Furthermore, a radiometric validation has been performed using Deep Convective Clouds (DCC) method. All level 1 products from satellites Sentinel-2A, Sentinel-2B, Landsat-8 and Landsat-9 within ±20° of latitude are monitored and monthly radiometric statistics are computed over the detected DCCs. The DCC results are consistent with the PICS method ones over the VNIR spectral range

Sentinel-2/MSI and LANDSAT8/OLI Radiometry Intercomparison Using RadCalNet Dataset and DIMITRI-toolbox

The Radiometric Calibration Network (RadCalNet) has been established by the Committee on Earth Observation Satellites (CEOS) Working Group on Calibration and Validation (WGCV) Infrared and Visible Optical Sensors Subgroup (IVOS) in 2013 and is open to public since July 2018. The RadCalNet consists of four international test sites providing automated in situ measurements and estimates of propagated top-of-atmosphere (TOA) reflectance (Bouvet et al. 2019). This work based on the work of Alhammoud et al. (2019) for the Sentinel-2/MSI validation; and on the work of Jing et al. (2019) to correct the directional effect. In this study we extend Alhammoud et al. (2019) analysis over RadCalNet up to 2021, instead of 2018. In addition, we will present the results of a cross-mission intercomparison over RadCalNet sites for MSI-A, MSI-B and OLI-8 using DIMITRI-Toolbox. The results confirm the viewing angle effect in the Sentinel-2 data at the RVUS and LCFR sites. The correction of the directional effect improves the results over the ratios of the individual orbits by up to 5% -10%, while the average ratios has been improved by barely about 1%. However the intercomparison results illustrate the relevance of RadCalNet dataset for the vicarious validation activity. Alhammoud et al. Sentinel-2 Level-1 Radiometry Assessment Using Vicarious Methods from DIMITRI Toolbox and Field Measurements From RadCalNet Database. IEEE JSTAR, 2019, Vol: 12(9) Bouvet et al. RadCalNet: A Radiometric Calibration Network for Earth Observing Imagers Operating in the Visible to Shortwave Infrared Spectral Range. Remote Sens. 2019, 11, 2401. https://doi.org/10.3390/rs11202401 Jing et al. Evaluation of RadCalNet Output Data Using Landsat 7, Landsat 8, Sentinel 2A, and Sentinel 2B Sensors. Remote Sens. 2019, 11, 541

Analysis of two mesoscale eddies in the Southern Ionian and Cretan Basins in 2006

38th CIESM Congress, Istanbul, Turkey.-- 1 pageDuring the EGYPT-1 campaign in April 2006, two mesoscale eddies, a Libyan eddy and the Ierapetra 2005, have been sampled in detailmainly with CTD casts. The goal of this study is to compare these hydrographic measurements with results of two simulations donewith high resolution models developed in the framework of the Mercator project. Focus is on the generation, the vertical water massdistribution, and the drift of these eddie

In-Orbit Radiometric Performance of Sentinel-2/MSI: Inter-comparison with LANDSAT8/OLI-1 and LANDSAT9/OLI-2 Over Desert PICS using DIMITRI-toolbox

The Sentinel-2 constellation consists of two units MSI-A & MSI-B, which are Earth Observation (EO) optical missions developed and operated by the European Space Agency (ESA) in the framework of the Copernicus programme of the European Commission. The Copernicus Sentinel Optical Mission Performance Cluster (OPT-MPC) is responsible of the calibration, validation, and image quality of the user product. The inter-unit consistency of the radiometry measurements is critical for the mission as more Sentinel-2 platforms are planned in the future. In order to assess the validity and temporal stability of the radiometry measurements we use independent vicarious calibration methods for EO optical sensors, that are implemented in DIMITRI (Database for Imaging Multispectral Instruments and Tools for Radiometric Intercomparison) toolbox. The results of the validation show an excellent image quality and stable radiometric performance, which meets the mission requirements target. However, a small bias of 1.1% between the two sensors was observed in the VIS/NIR domain (see e.g. Alhammoud et al. 2021). Consequently, MSI-B measurements have been aligned with MSI-A by introducing a radiometric harmonisation factor on January 25th 2022 (PB04.00). Moreover, the OPT-MPC proposed to harmonize the sensors using MSI-A as reference for the new Collection 1 reprocessing campaign which is currently under preparation. This presentation provides a status of the Sentinel-2/MSI radiometric validation activities performed by the OPT-MPC. The results illustrate the expected improvement of the radiometric harmonisation between both units MSI-A & B. Furthermore, we present the results of cross-mission intercomparisons over desert PICS for MSI-A, MSI-B, OLI-1 and OLI- 2. The preliminary results show a good agreement between MSI/OLI to better than 2% while the OLI-1/OLI-2 agreement to better than 1% over VNIR bands. B. Alhammoud, C. Quang, V. Boccia and R. Q. Iannone, “Assessment of Copernicus Sentinel-2 Constellation After Five Years In-Orbit: Level-1C User-Products,” 2021 IEEE International Geoscience and Remote Sensing Symposium IGARSS, 2021, pp. 7759-7762, doi: 10.1109/IGARSS47720.2021.955485