The tsunami on Sakhalin on August 2, 2007: Mareograph evidence and numerical simulation

Instrumental data on the tsunami registration on Sakhalin and Hokkaido islands are presented. The numerical simulation of the tsunami propagation in the Tatar Strait was performed. The results of the calculations are in satisfactory agreement with the observed data.     

The influence of the Kuril Islands on the penetration of tsunamis into the Sea of Okhotsk (on the example of the Japan tsunami on March 11, 2011)

The features of the propagation of the tsunami of March 11, 2011 in the northeastern Pacific have been studied with the aim of revealing the degree of influence of the Kuril Islands on the penetration of the tsunami in the Sea of Okhotsk. For this, a series of computational experiments have been performed within the shallow water theory using bathymetry (1) with and (2) without the Kuril Islands. The wave heights calculated have been analyzed, and the tsunami’s magnitude and intensity in the Sea of Okhotsk have been estimated. The computational experiments performed allow assessment of a decrease in the tsunami intensity while passing the Kuril Islands.     

Response of the midlatitude ionosphere to extreme geomagnetic storms of the 23rd solar cycle

The ionospheric response in the Irkutsk region (52.3° N, 104.3° E) to the extreme geomagnetic storms of solar cycle 23 was studied based on the data of the Irkutsk incoherent scatter radar (ISR) and DPS-4 vertical sounding digital ionosonde. The deviations of parameters from the undisturbed level, i.e., from the monthly medians or the values obtained on a quiet day, were considered as an ionospheric response. Values of the electron concentration maximum (N _mF2) and electron temperature (T _e) at a height of 350 km were chosen as parameters. The ionospheric response is interpreted in the scope of the concept of a thermospheric storm and penetration of the magnetospheric electric field.     

Anomalous Ionospheric Reflections from the Irkutsk Chirp Ionosonde Data for 2012–2016

Geomagnetism and Aeronomy - Vertical ionograms often contain traces of reflections that cannot be attributed to any type of the sporadic Es layer and are classified as anomalous reflections....     

Influence of Nonlinear Interaction on the Evolution of Waves in a Shallow Basin

Izvestiya, Atmospheric and Oceanic Physics - The influence of nonlinear interaction of oppositely directed nonlinear waves in a shallow basin is studied theoretically and numerically within the...     

On the nonlinear interactions in triads of edge waves on the sea shelf

We study nonlinear three-wave interactions between edge waves propagating in the same direction over the shelf step. The conditions of synchronism are determined and the coefficient of interaction is computed for the cases where the waves of the five lowest modes participate in the interaction. The space-time dynamics is studied by analyzing, as an example, a single triad of edge waves. The possibility of interaction of edge waves in the regions with actual topography is demonstrated. __________ Translated from Morskoi Gidrofizicheskii Zhurnal, No. 3, pp. 3–19, May–June, 2008.     

Structure of currents in the soliton of an internal wave

The characteristics of strongly nonlinear solitary internal waves (solitons), which are calculated by the nonlinear numerical model of the Massachusetts Institute of Technology (MITgcm), are studied. The model is verified and adopted on the basis of a laboratory experiment [6]. The field of the vertical and horizontal current in a wave is calculated. The formation of a reversible stream in the near-bottom layer is detected directly behind a soliton.     

Interpretation of edge waves observations on Shikotan Island

The observations of short-period edge waves and accompanying morphological features of the coast line in the Dimitrov Bay on Shikotan Island on August 11, 2005, are presented. The wave field characteristics and form of the coastline are interpreted within the frameworks of the exact solutions of three-dimensional nonlinear equations for the waves propagating over a flat sloping bottom.     

Ionospheric response to geomagnetic disturbances in the north-eastern region of Asia during the minimum of 23rd cycle of solar activity

We present the results of studies of the subauroral and mid-latitude ionosphere variations in the north-eastern region of Asia. We used the data from network of vertical and oblique-incidence sounding ionosondes and optical measurements. Long-term experiments on the radio paths Magadan–Irkutsk and Norilsk–Irkutsk were carried out within the period 2005–2007. Vertical sounding stations operated in standard regime. Observation of airglow near Irkutsk was provided by the zenith photometer that measured intensities of 557.7 and 630.0 nm atomic oxygen emissions. The results may be summarized as follows. (1) Large daytime negative disturbances are observed during the main and recovery phases mainly at high latitudes, whereas the positive disturbances observed during the main phase at mid latitudes. The disturbances changed their sign between Yakutsk and Irkutsk. (2) During the main and recovery storm phases the fall of foF2 associated with the equatorward wall of the main ionospheric trough is observed in the afternoon and evening. (3) Fluctuations of the electron density more intensive at mid latitudes during the storm main phase are observed during all considered periods. They are classed as traveling ionospheric disturbances (TID). Such sharp gradients of electron density are responsible for the strong changes in the characteristics of the radio wave propagation, particularity MOF. (4) A large-scale ionospheric disturbance is noted at the meridional chain of ionosonds in December 2006 as the sharp increase of foF2. It appears in the evening in the minimum of D_st at high latitude and propagate to equator. (5) A maximum of 630 nm emission above Irkutsk corresponds to the foF2 increase. (6) The obtained experimental data on the net of vertical and oblique-incidence sounding with high time resolution show that such net is the effective facility to study the conditions of the radio wave propagation and can be used for the diagnostic of the ionosphere.