On model validation for meso/submesoscale currents: Metrics and application to ROMS off Central California

ROMS with horizontal grid spacing of 3.5 km for the region off Central California was compared to RAFOS float observations and satellite altimetry on meso/submesoscales. The approach introduced and used two new metrics for model-data comparison, as well as suggested how to calculate these metrics for different spatio-temporal scales. The first metric consisted of the first two moments of exit time and was used to compare ROMS against RAFOS float observations at mid-depths (between 300 m and 350 m). Exit time is the time a float launched at a point takes to leave a domain for the first time. The second metric was spectral entropy and was used to estimate how well ROMS reproduced variability of the sea surface height (SSH) anomaly field extracted from an AVISO data set (1992–2007) for specified temporal and spatial scales. Calculations showed that ROMS reproduced the mid-depth mesoscale/submesoscale currents next to the coast in a very accurate manner (low-order exit time statistics of floats were reproduced by ROMS with an accuracy better than 95%); but ROMS overestimated the speed of westward drift of floats by as much as 20–30% at distances greater than 350 km from the coastline. ROMS predicted the variability of the mesoscale (100–400 km) SSH anomaly field for temporal scales of 1–12 months with a reasonable accuracy. A wavelet transform modulus maxima technique applied to the spectral entropy of SSH anomaly also demonstrated good agreement between ROMS and satellite altimetry for mesoscales characterized by singular exponents and multi-fractal spectra for 1–12 month time scales.     

Simulation of wind-induced oscillations of the Azov-Sea level

The prognostic fields of the surface winds and atmospheric pressure obtained according to the data of the Skiron prognostic system are used to study the surge phenomena in the Azov Sea by using a three-dimensional nonlinear model. The accumulated numerical results are compared with the data of direct measurements of the sea level at the coastal stations. The degree of sensitivity of the computed levels of surges to the value of the coefficient of surface friction is evaluated. Translated from Morskoi Gidrofizicheskii Zhurnal, No. 6, pp. 53–65, November–December, 2008.     

Structural Connections between the Urals and Western Siberia: A Common Stage of Formation at the Permian–Triassic Boundary

Doklady Earth Sciences - The 40Ar–39Ar dating of mica from schists and blastomylonites, sampled within the limits of a fault that separates the Eastern zone of the Middle Urals, sinking...     

Landscape diversity of the Kuril Islands

We consider the use of two approaches in assessing landscape diversity of a territory: qualitative and quantitative analyses of the landscape structure on the basis of landscape maps, and a space imagery-based calculation of landscape diversity. This study revealed that the two approaches under consideration reflect different properties of landscape. It is established that the various indicators used in analyzing landscape maps unveil the aspects of a complicated and multifaceted notion of “landscape diversity”. A number of indicators overlap to a significant extent. Landscape diversity has a high degree of dependence on an island’s area.     

The Amur River runoff formation in the Amur liman

Periodical surface currents with the periods of 46.5, 61, and 91 days detected from the satellite data in the Tatar Strait and Sakhalin Bay are presented as an effect of the Amur River runoff transformation in the estuary. The estuary transforms the flow as a flip-flop directing the Amur runoff by turns to the Sea of Japan or to the Sea of Okhotsk. The flip-flop period is six months. From May 23 to November 10, the Amur River flows into the Sea of Okhotsk and from November 10 to May 25, into the Sea of Japan.     

Correlation between tropical cyclones and magnetic storms during cycle 23 of solar activity

The correlation between cyclic (11-year) variations in geomagnetic activity and tropical cyclogenesis during the completed solar activity cycle (cycle 23, 1996–2006) is studied. The total number of the semidiurnal intervals, with the mean values of the planetary a _p index not less than 40, for each year and the annual number of cyclones, regardless of their intensity, are used as the characteristics. The correlation coefficients r are calculated for each of the following four cyclogenesis regions: the Atlantic, northeastern and central Pacific, northwestern Pacific, and water areas of oceans and seas in the Southern Hemisphere. The conclusion that the correlation exists between magnetic storms and tropical cyclones in the Atlantic, obtained earlier by Ivanov [2006] on the basis of the data for 1996–2005, is confirmed. It has been found that the linear correlation coefficient r changed in different regions from positive to negative values: 0.55, 0, ?0.50, and ?0.50, respectively.     

Field experiment on studying solar radiation passing through aerosol layers

Results of a field experiment on studying solar radiation passing in the visible wavelength range are described with the model aerosol media created in the surface atmosphere. High-efficiency thermocondensation generators were used for creating model aerosol media. The index of refraction and an average size of the aerosol particles formed are close to those characteristic of the natural stratospheric aerosol. The composition and technical characteristics of the equipment complex used in the experiments to control aerosol optical and microphysical parameters and meteorological conditions of the experiment are considered. The Gaussian model of impurity dispersion in the boundary layer is used for the analysis and interpretation of measurement results. It is found that with a number concentration of aerosol particles of ～10²–10³ cm^?3 (which corresponds to the aerosol density in the deposited layer of about 1–10 mg/m² with the layer thickness along the ray path of about 100 m) the solar radiation attenuation with artificial aerosol layers accounts for 1 to 10%. Model estimates are in satisfactory agreement with the measurement results.     

Discriminant and factor analyses as tools for comparison of terrestrial and Venusian volcanic rocks

Statistical methods of multi-dimensional analysis (discriminant functions and factor analysis) were applied to compare the chemical analyses obtained by Venera-13, -14, and Vega-2 landers (contents of major oxides except for sodium) with petrochemical data compiled into the data base on terrestrial ocean. It is shown that the distribution of major petrogenic elements in the terrestrial rocks ascribed to different geodynamic settings (spreading zones, hot spots, and subduction zones) is determined by crystallization differentiation. This process is best manifested in hot spot volcanics (volcanic islands). In spite of the difficulties related to the poor precision of chemical determinations of Venusian rocks, obtained data indicate that the rocks from the Venera-13 and Vega-2 landing sites have no petrochemical analogues among terrestrial oceanic volcanic rocks. Rocks analyzed in the Venera-14 landing site may resemble the mid-ocean ridge volcanic rocks, although geological setting in the Venera-14 landing site ellipse strongly differs from terrestrial spreading zones.     

On the problem of determination of hummocky formation albedo

It is demonstrated within the frameworks of the analysis of determination methods of snowice cover reflectance that the problem of the measurement technique of hummocky formation albedo has not been studied enough. The results of in situ experiments carried out on the Arctic sea ice are presented. The results of ice hummock albedo measurements using different techniques are discussed. The need to organize the special experimental research for the development of practical recommendations for estimating the hummocky formation albedo is declared.