Features of Formation of the Cyclone Wakes (Fluctuations in Seawater Temperature) in the Area of Cape Svobodny, the Southeastern Part of the Sakhalin Island

Purpose. The purpose of this work is to study the particulars of the formation of cyclone wakes after the regular passage of cyclones over the area of the wave measurements, and to estimate the internal wave parameters along the track according to the field observations. Methods and Results. The analysis of data from the field observations of sea waves and water temperature is presented. The measurements were carried out by a ARW-K14 device (autonomous recorder of the waves and water temperature) in the area of the Cape Svobodny on the southeastern coast of the Sakhalin Island at a depth about 8 m. The recorded time series of the sea level and temperature fluctuations, lasting about one and a half months, were subjected to spectral analysis using specialized Kyma spectral analysis software. Dominant temperature fluctuations reaching 8.5 °C with a 13.1 h period were detected in the upper mixed layer of the ocean. These fluctuations were identified as the cyclone wakes in the stage of their relaxation. Taking into account the synoptic circumstances that existed during the passage of several cyclones and the associated storms in the observation area, the authors investigated the presence or absence of a trace. Conclusions. It is shown that if the next storm arrives earlier than 10 days after the previous one, the trace may be shorter or even absent due to active water mixing in the upper mixed layer of the ocean. For the data obtained, the value of the coefficient ∈ in the expression ω = (1 + ∈ ) f, which connects the dominant frequency ω of internal waves, i.e. almost inertial oscillations in the trace of each typhoon, with the inertial frequency f (the Coriolis parameter determined by the geographical latitude of the water area where the waves propagate), is close to the value proposed in the paper by E. Kunze. Using a formula due to J. F. Price, the characteristic horizontal lengths of internal waves in the direction of movement inside the wakes of cyclones moving at a speed 15–35 knots are determined. These lengths range from 304.6 to 1066.1 km

Continuum limit of amorphous elastic bodies: A finite-size study of low frequency harmonic vibrations

The approach of the elastic continuum limit in small amorphous bodies formed by weakly polydisperse Lennard-Jones beads is investigated in a systematic finite-size study. We show that classical continuum elasticity breaks down when the wavelength of the sollicitation is smaller than a characteristic length of approximately 30 molecular sizes. Due to this surprisingly large effect ensembles containing up to N=40,000 particles have been required in two dimensions to yield a convincing match with the classical continuum predictions for the eigenfrequency spectrum of disk-shaped aggregates and periodic bulk systems. The existence of an effective length scale \xi is confirmed by the analysis of the (non-gaussian) noisy part of the low frequency vibrational eigenmodes. Moreover, we relate it to the {\em non-affine} part of the displacement fields under imposed elongation and shear. Similar correlations (vortices) are indeed observed on distances up to \xi~30 particle sizes.Comment: 28 pages, 13 figures, 3 table

Better operational forecasting for the contemporary arctic via ocean wave integration

Document ID ISOPE-I-12-065Whether configured for operational purposes or for research, current coupled ice-ocean models and OGCMs lack sophistication in regard to core aspects of sea ice behavior, notably the determinative contribution that ocean waves make in evolving the sea ice canopy and hastening its annihilation. Considerably enhanced climate resolving accuracy and reliability can potentially be achieved by incorporating naturally pervasive ocean wave / sea ice interactivity into a state-of-the-art polar ocean modeling framework originally developed and hosted by NERSC in Norway. This paper focuses on how to do this, recognizing the benefits that will flow from the research through better model parameterization and forecasting precision – especially with reference to contemporary adverse global warming effects.Vernon A. Squire, Timothy D. Williams, Luke G. Bennettshttp://www.isope.org/publications/publications.ht

Preliminary results from a two-dimensional model of wave-ice interactions in the Fram Strait

We present numerical results arising from a parameterization of wave-ice interactions in a two-dimensional ice-ocean model of the Fram Strait (HYCOM: HYbrid Coordinate Ocean Model). The model takes wave predictions/hindcasts from the WAM wave model and these waves are advected into the ice, breaking it as they go. They in turn are attenuated by the ice using the model of Bennetts and Squire (2012). We use a truncated power law for the floe size distribution, following the observations of Toyota et al. (2011). The maximum floe size is determined by the dominant wavelength in the ice field. The maximum value increases with distance from the ice edge as shorter waves are attenuated more strongly than long ones. At some distance from the ice edge, breaking is no longer able to occur, and this marks the end of the Marginal Ice Zone (MIZ). Consequently, we now have a model that predicts the expected floe size and wave intensity at any point in the ice, something that current wave models are unable to do at present, and which is a notable weakness. Recognizing that a combination of large waves and ice can be extremely hazardous, Arctic operators who need to know both wave and ice conditions in ice-infested areas will use the model as a forecasting tool when it is fully operational.T. D. Williams, L. G. Bennetts, V. A. Squire, D. Dumon

Granular flow in the marginal ice zone

The region of sea ice near the edge of the sea ice pack is known as the marginal ice zone (MIZ), and its dynamics are complicated by ocean wave interaction with the ice cover, strong gradients in the atmosphere and ocean and variations in sea ice rheology. This paper focuses on the role of sea ice rheology in determining the dynamics of the MIZ. Here, sea ice is treated as a granular material with a composite rheology describing collisional ice floe interaction and plastic interaction. The collisional component of sea ice rheology depends upon the granular temperature, a measure of the kinetic energy of flow fluctuations. A simplified model of the MIZ is introduced consisting of the along and across momentum balance of the sea ice and the balance equation of fluctuation kinetic energy. The steady solution of these equations is found to leading order using elementary methods. This reveals a concentrated region of rapid ice flow parallel to the ice edge, which is in accordance with field observations, and previously called the ice jet. Previous explanations of the ice jet relied upon the existence of ocean currents beneath the ice cover. We show that an ice jet results as a natural consequence of the granular nature of sea ice