Succession Of Storms Research Articles

The Portuguese man-of-war: Adrift in the North Atlantic Ocean

On 11 February 2014, dozens of Portuguese man-of-war specimens were washed ashore along the entire stretch of Patos Beach (northwestern Spain). Here we performed both field experiments and numerical simulations to estimate the possible trajectories and region of origin of this swarm. On the one hand, our field experiments confirm the need to consider the main characteristics of an organism when predicting its drift. On the other hand, the numerical simulations show that this swarm originated in the open North Atlantic Ocean. The drift of the swarm was controlled by the succession of storms that hit the coasts of Western Europe in the winter of 2013–14. Our findings also suggest that most of the individuals of the swarm were right-handed.

Linking sea level dynamic and exceptional events to large-scale atmospheric circulation variability: A case of the Seine Bay, France

Summary In this study, the multi-time-scale variability of the South English Channel (case of the Seine Bay, North France) sea level and its exceptional events have been investigated in relation with the global climate patterns by the use of wavelet multi-resolution decomposition techniques. The analysis has been focused on surges demodulating by an envelope approach. The low-frequency components of the interannual (2.1-yr, 4-yr, 7.8-yr) and the interdecadal (15.6-yr and 21.2-yr) time-scales, extracted from 46-years demodulated surges, have been correlated to 36 exceptional stormy events according to their intensity. Results have revealed five categories of storms function on their correlation with the interannual and the interdecadal demodulated surges: events with high energy are manifested at the full scales while moderate events are only observed at the interannual scales. The succession of storms is mainly carried by the last positive oscillations of the interannual and the interdecadal scales. A statistical downscaling approach integrating the discrete wavelet multi-resolution analysis for each time-scale has been used to investigate the connection between the local dynamic of surges and the global atmospheric circulation from SLP composites. This relation illustrates dipolar patterns of high-low pressures suggesting positive anomalies at the interdecadal scales of 15.6-yr and 21.3-yr and the interannual scales of 4-yr while negative anomalies at 7.8-yr should be related to a series of physical mechanisms linked to the North-Atlantic and ocean/atmospheric circulation oscillating at the same time-scales. The increasing storm frequency is probably related to the Gulf Stream variation and its weakening trend in the last years.

Assessment of the Barren Ground Caribou Die‐off During Winter 2015–2016 Using Passive Microwave Observations

AbstractIn summer 2016, more than 50 Arctic Barren Ground caribous were found dead on Prince Charles Island (Nunavut, Canada), a species recently classified as threatened. Neither predator nor sign of diseases was observed and reported. The main hypothesis is that caribous were not able to access food due to a very dense snow surface, created by a strong storm system in spring. Using satellite microwave data, a significant increase in brightness temperature polarization ratio at 19 and 37 GHz was observed in spring 2016 (60% higher than previous two winter seasons). Based on microwave radiative transfer simulations, such anomaly can be explained with a very dense snow surface. This is consistent with the succession of storms and strong winds highlighted in ERA‐Interim over Prince Charles Island in spring 2016. Using several sources of data, this study shows that changes in snow conditions explain the caribou die‐off due to restricted foraging.

Meteorological conditions in a thinner Arctic sea ice regime from winter to summer during the Norwegian Young Sea Ice expedition (N‐ICE2015)

AbstractAtmospheric measurements were made over Arctic sea ice north of Svalbard from winter to early summer (January–June) 2015 during the Norwegian Young Sea Ice (N‐ICE2015) expedition. These measurements, which are available publicly, represent a comprehensive meteorological data set covering the seasonal transition in the Arctic Basin over the new, thinner sea ice regime. Winter was characterized by a succession of storms that produced short‐lived (less than 48 h) temperature increases of 20 to 30 K at the surface. These storms were driven by the hemispheric scale circulation pattern with a large meridional component of the polar jet stream steering North Atlantic storms into the high Arctic. Nonstorm periods during winter were characterized by strong surface temperature inversions due to strong radiative cooling (“radiatively clear state”). The strength and depth of these inversions were similar to those during the Surface Heat Budget of the Arctic Ocean (SHEBA) campaign. In contrast, atmospheric profiles during the “opaquely cloudy state” were different to those from SHEBA due to differences in the synoptic conditions and location within the ice pack. Storm events observed during spring/summer were the result of synoptic systems located in the Barents Sea and the Arctic Basin rather than passing directly over N‐ICE2015. These synoptic systems were driven by a large‐scale circulation pattern typical of recent years, with an Arctic Dipole pattern developing during June. Surface temperatures became near‐constant 0°C on 1 June marking the beginning of summer. Atmospheric profiles during the spring and early summer show persistent lifted temperature and moisture inversions that are indicative of clouds and cloud processes.

The exceptional surface turbidity of the North-West European shelf seas during the stormy 2013–2014 winter: Consequences for the initiation of the phytoplankton blooms?

A succession of storms during the winter 2013–2014 enhanced the resuspension of sediments in the surface waters of the North-West European shelf seas. The effects of waves on satellite-derived non-algal SPM (Suspended Particulate Matters) are discussed for the January 2008–March 2014 period. A simple statistical model relating locally SPM to tidal intensity and waves helps us analyse the main characteristics of the winter 2013–2014. The exceptional run of storms observed in this stormy and rainy winter has resulted in the highest SPM concentration in the Celtic Sea and the Bay of Biscay ever observed by remote-sensing during the 1998–2014 period. Despite the lower clarity of the surface waters over a large part of the continental shelf during the first days of March 2014, blooms occurred early off the coast of Southern Brittany (Bay of Biscay) and later in April, as usual, in the Celtic Sea. Off the coast of southern Brittany, a region of freshwater influence, the lower clarity of the waters was counterbalanced by stronger haline stratification, due to high river discharges, enabling the initiation of blooms in late winter when the solar irradiance is sufficient; which was the case in March 2014 with 7 sunny days in a row just after the last storm. As a consequence, we can postulate that a possible increase in the intensity of waves occurring from December to early March, along with a possible scenario of global change, would not restrict the productive period in the Bay of Biscay. However an extension of the period of storms later in March would delay the timing of the blooms as observed in March 2008 in most of the investigated area.

Sedimentary effects of flood‐producing windstorms in playa lakes and their role in the movement of large rocks

AbstractThis paper sheds light on the hydrodynamic conditions of transport and sedimentary effects of wind‐induced water currents produced during strong windstorms in low gradient systems. Repeated field surveys were conducted in a playa lake in central Spain to determine the impacts of major winter storms on the bed form morphology in real time. The succession of storms that passed through the area from mid‐December 2013 to early February 2014 left behind a variety of sedimentary structures: mainly ripple marks showing complex patterns and erosional structures. The latter include obstacle scours, grooves and other tool marks. In situ observations revealed that strong storm events in almost flat, extremely shallow lakes (less than 5 cm) have enough hydraulic energy to erode and remove high volumes of sediments and may also lead to large stones sliding across the bed, thus creating long grooves.Sole marks found in ancient continental successions have been typically attributed to fluvial conditions. We suggest that shallow lake basins should not be discounted when storm‐generated structures are preserved in ancient rocks. The identification of such sedimentary structures provides valuable information for reconstructing hydrodynamic conditions and paleoclimatic conditions in semi‐arid environments. Copyright © 2014 John Wiley & Sons, Ltd.

Les forêts plantées de Pin maritime. Réalités actuelles et évolution de la sylviculture landaise

The forested area of the Landes area, which is extensive and plays an important economic and environmental role, is confronted with reconstruction in the wake of the two storms of 1999 and 2009. As a result of these, resources have considerably decreased which in turn will lead to difficulties in maintaining the industrial facilities starting in 2016. The article offers a number of areas worth investigating, on the basis of an inventory of the silvicultural practices, so as to take on board lessons learned from the succession of storms, prepare for climate change, and cater for the needs of the industry and for growing pressures in the environmental area. It analyses the fundamentals of maritime pine cultivation that might be maintained and opportunities for change, in particular stand management approaches that may be worth pursuing.

The effects of human activities and extreme meteorological events on sediment nitrogen dynamics in an urban estuary, Escambia Bay, Florida, USA

This study examined how sediment-sorbed PCBs and several large storms affected sediment nutrient dynamics based on potential nitrification rates and benthic flux measurements. PCBs were hypothesized to negatively affect potential nitrification rates due to the sensitivity of nitrifying bacteria. Sediment disturbance caused by the succession of storms, which can enhance nutrient inputs and phytoplankton production, was hypothesized to enhance both potential nitrification rates and benthic flux measurements as a result of higher nutrient and organic matter concentrations. Potential nitrification rates, benthic fluxes (NO3 − + NO2 −, NH4 +, and DIP), sediment PCB content, water content, organic content, salinity, bottom water dissolved oxygen, and sediment chlorophyll were measured at 13 different sites in Escambia Bay during the summer of 2005. Potential nitrification rates were highest at deep, organic-rich sites. Total PCB content did not have a direct effect on potential nitrification rates. An analysis of recent changes in benthic processes in relation to extreme meteorological events was performed by comparing the 2005 results with data from 2000, 2003, and 2004. Storm effects on sediment biogeochemistry were mixed with sediment nitrogen dynamics enhanced at some sites but not others. In addition, SOC and NH4 + fluxes increased in deeper channel sites after Hurricanes Ivan and Dennis, which could be attributed to the deposition of phytoplankton blooms. Sediment nutrient dynamics in Escambia Bay appear to be resilient to these extreme meteorological events since there were no significant effects on sediment processes in the Bay as a whole.

Phosphorus–discharge hysteresis during storm events along a river catchment: the River Swale, UK

Variations in the concentration of determinands in rivers during storms often result in a hysteresis effect with different concentration during the rising and falling limb of the hydrograph. This is investigated here by measuring total phosphorus, particulate phosphorus and soluble reactive phosphorus at 3-h intervals at three points along the River Swale. Phosphorus concentration-discharge hysteresis from 10 storm events were quantified using an empirical model. The size and direction of the hysteresis loops were described by a response factor, and the slope of the loop quantified by a gradient constant. The modelled loops produced acceptable agreement with the field measurements. Hysteresis patterns for all phosphorus fractions changed markedly downstream, with predominantly anticlockwise trajectories in the upland moors (indicating a slow diffuse phosphorus delivery to the river) and clockwise in the intensively farmed lowland (indicating mobilisation of within-channel and riverbank phosphorus, and rapid inputs from field drains). The size of the hysteresis loops increased downstream, indicating an increased capacity for phosphorus storage and mobilisation within the lower catchment. During a succession of storms, lowland hysteresis loops decreased in magnitude, tending towards anticlockwise behaviour, indicating a depletion of mobile phosphorus from the river channel and margins. The modelling of hysteresis trajectories offers a convenient method of determining the relative contributions of diffuse and within-channel phosphorus sources.

Observations of turbulence in ocean wave boundary layers

A bistatic geometry, coherently sampled, acoustic Doppler profiler has been developed to measure turbulent stresses in wave-forced ocean boundary layers. The profiler is typically configured to measure over-resolved profiles of three-component velocity vectors sampled in O(2 cm3) sample volumes at 20 Hz over a 60 cm range above the ocean bed. Examples of bottom boundary layer observations made at Duck, NC and Monterey, CA during two field experiments illustrate approaches to measuring Reynolds stresses and shear in thin oscillatory boundary layers over a rippled bed. During the ONR-funded Shoaling Waves Experiment (SHOWEX) the profiler was mounted on an instrumented frame at 12 m depth and continuously measured velocity profiles and changes in wave-induced bed morphology through a succession of storms over a two month period. In the second example, observations of mean currents, wave-induced velocities, and turbulence were made in the surf zone just offshore from a steep-sloping beach.

Coastal Morphodynamics at Skallingen, SW Denmark: High Energy Conditions

Geografisk Tidsskrift, Danish Journal of Geography 1998: 20–30. The present paper discusses some preliminary results from a field experiment on sediment transport and morphological change on a beach subjected to storm surge activity. The data were collected at the barrier spit of Skallingen during October/November 1996. This period was characterized by a succession of storms which resulted in high water and wave energy levels, culminating in a storm surge per se. The beach and the dune ramp eroded; however, contrary to expectations, a subtidal bar migrated onshore and the intertidal swash bar appeared to display a cyclic behaviour dependent upon strong linkages between morphology and hydrodynamics. Morphological changes in the intertidal zone were primarily accomplished by mean currents with oscillatory motions playing a subordinate role. Longshore sediment transport measured during conditions with moderately strong winds blowing alongshore, was dominated by wave-induced currents with aeolian transport being a secondary contribution. Preliminary estimates suggest that some 30–35% of the sediment eroded from the beach and dunes is retained on the barrier through onshore aeolian transport and over-wash activity.