Determination of characteristics of atmospheric motions from satellite multiwave remote sensing data

A method of determination of atmospheric dynamic characteristics from the data of remote sensing from a geostationary satellite is described. The method is based on the use of inhomogeneities in the concentration field of a conservative additive as tracers and on the application of correlation-extreme algorithms. Unlike the common methods used abroad, this method is able to determine not only the vector field of wind velocity but also the coefficient of turbulent diffusion and vorticity. Results of computations of the fields of the horizontal component of wind velocity and the effective coefficient of horizontal mesoscale turbulent diffusion from the Meteosat-8 SEVIRI water-vapor channel data are presented. It is shown that the average values of the effective coefficient of mesoscale horizontal turbulent diffusion in the areas with a predominantly turbulized air-mass motion are 1.5 times greater than in the areas where a laminar motion dominates. Specific features of the calculated values of the upper-troposphere dynamic characteristics in different stages of the North Atlantic TC Helene (September 2006) are analyzed.     

Manifestation of the Arctic Oscillation and El Niño-Southern Oscillation in the tropical stratosphere

Characteristics of the Arctic Oscillation and El Niño-Southern Oscillation effects manifested on interannual scales in the equatorial stratosphere are determined. Wavelet analysis of local phase shifts, coherence, and correlation is used to obtain correlation portraits of the largest factors of climate variability against the background of coherent variations in the equatorial stratospheric wind speed at the 50- and 15-hPa pressure levels. It is shown that the Arctic Oscillation and El Niño-Southern Oscillation signals may reach the tropical stratosphere. The signals are easily identified in a wide range of scales, including quasi-biennial, 3-to 5-year, and 10-to 11-year periods. The results obtained reflect a coherent pattern of the manifestation of these signals at the selected stratospheric levels. It is found that the El Niño-Southern Oscillation effect at periods close to 10–11 years reaches the stratospheric level rather rapidly, in the same or next month, while the effects of the Arctic Oscillation index are delayed by nine months. The estimates obtained show that a phase shift of almost 180° in the Arctic Oscillation index relative to the equatorial stratospheric wind occurred in almost all of the range of interannual periods in 1978 and 1992. For the El Niño-Southern Oscillation, an increase in local correlations on a scale of 3-to 5-year variations was observed in 1980–1990, a 180° phase shift occurred in 1992, and the correlation with stratospheric wind increased in 1992–2004. The estimates obtained are indicative of a change in the atmospheric circulation pattern that took place in the Northern Hemisphere in 1978–1991.     

Pacific decadal oscillation and European climatic anomalies

By using the NCEP/NCAR reanalysis data sets for 1951–2001, we study the characteristics of Pacific cyclones. It is shown that the northeast-southwest direction is predominant in the displacements of cyclones in the North Pacific. We study the variability of the field of surface atmospheric pressure in different phases of the Pacific decadal oscillation characterizing the temperature anomalies on the surface of the ocean in the region bounded by 20 and 60°N. It is shown that the decadal variations of the North Atlantic Oscillation supported by the large-scale anomalies of the Pacific decadal oscillation is the most important cause of natural decadal oscillations in the European region. We study and evaluate the regional response to the Pacific decadal oscillation by using, as an example, the analysis of variations of the discharge of European rivers. __________ Translated from Morskoi Gidrofizicheskii Zhurnal, No. 4, pp. 13–23, July–August, 2007.     

Statistical analysis of a global photochemical model of the atmosphere

This is a study of the sensitivity of model results (atmospheric content of main gas constituents and radiative characteristics of the atmosphere) to errors in emissions of a number of atmospheric gaseous pollutants. Groups of the model variables most dependent on these errors are selected. Two variants of emissions are considered: one without their evolution and the other with their variation according to the IPCC scenario. The estimates are made on the basis of standard statistical methods for the results obtained with the detailed onedimensional radiative—photochemical model of the Main Geophysical Observatory (MGO). Some approaches to such estimations with models of higher complexity and to the solution of the inverse problem (i.e., the estimation of the necessary accuracy of external model parameters for obtaining the given accuracy of model results) are outlined.     

Nonlinear effects manifested in infrasonic signals in the region of a geometric shadow

Nonlinear effects manifested in infrasonic signals passing through different atmospheric heights and recorded in the region of a geometric shadow have been studied. The source of infrasound was a surface explosion equivalent to 20–70 t of TNT. The frequencies of the spectral maxima of infrasonic signals, which correspond to the reflections of acoustic pulses from atmospheric inhomogeneities at different heights within the stratosphere-mesosphere-lower thermosphere layer, were calculated using the nonlinear-theory method. A satisfactory agreement between experimental and calculated data was obtained.     

The origin and age of the Alpha-Mendeleev and Lomonosov ridges in the Amerasia Basin

The results of the bathymetry simulation indicate the emplacement of the Mesozoic Arctic plume into the lithosphere of the Alpha-Mendeleev and Lomonosov ridges. The study also presents a model of the thermal subsidence to the asthenosphere. The calculated coefficients are compared with those obtained for the Greenland-Iceland and Iceland-Faeroe ridges, which were formed in response to hotspot activity. It was shown that the coefficients of the thermal subsidence in the central part of the Alpha-Mendeleev and Lomonosov Ridges are similar to those calculated for the Greenland-Iceland and Iceland-Faeroe ridges. This indicates the thermal regime of the subsidence of the Alpha-Mendeleev and Lomonosov ridges since the Early Miocene and the increased influence of the Arctic plume on the ridge genesis. The ridges are interpreted to have formed over a broad geological timeframe, from the late Cretaceous to the Cenozoic. A geothermal method, which is highly informative in terms of the age of the lithosphere, provides better constraints on the timing of ridge formation. The age estimates for the Alpha-Mendeleev (97–79 Ma) and Lomonosov ridges (69–57 Ma) derived from the geothermal data allowed us to draw a convincing conclusion about the genesis of these ridges.     

Determination of stratospheric aerosol parameters from two-wavelength lidar sensing data

We calculate the microphysical characteristics of stratospheric aerosol from lidar-sensing data at wavelengths of 355 and 532 nm using a priori information about the aerosol spectra obtained from balloon and aircraft measurement data. We analyze the mode structure of the spectra and its coupling with the integral microphysical characteristics of aerosol. For most implementations, it was shown that two aerosol modes (of background and volcanic natures) make commensurate contributions to integral aerosol characteristics, which makes it difficult to use the traditional method of model estimates. It is more efficient to use an optical model of a statistical character that is based on approximation dependences between the required integral aerosol characteristics and lidar-measured optical characteristics. We found that the area, volume, and effective size of particles and the lidar ratio at a wavelength of 355 nm correlated with the absolute values of backscattering coefficients at wavelengths of 355 or 532 nm and the lidar ratio at the wavelength of 532 nm correlated with the ratio of backscattering coefficients at these wavelengths. We estimate the error in the determination of integral characteristics of aerosol using the model developed. The model efficiency is demonstrated on real data of stratospheric aerosol lidar sensing.     

Scenarios of nonlinear wave transformation in the coastal zone

On the basis of field experiments and numerical modeling, we show that coastal zones are classifiable according to manifestations of wind wave nonlinearity, which herein is recognized as periodic energy exchange between the first and second nonlinear wave harmonics depending on the average bottom slope and the Iribarren and Ursell numbers. The results offer a basis for developing vulnerability criteria for the coastal zone taking into account its nonlinear dynamics.     

Space-time variability of the field of mechanical energy transfer from the atmosphere to the Indian Ocean

An analysis of the spatial and temporal variability of the field of mechanical energy transfer (MET) from the atmosphere into the ocean is based on a separate numerical simulation of evolution for the terms of source function for a wind-wave model conducted in the Indian Ocean area for the period 1998 to 2009. The MET field is described by two integral values calculated per unit area: the total rate of energy flux from the wind to waves, I _E (x, t), and the rate of energy-loss flux for the wind waves, D _E (x, t). To solve this problem, the wind field W(x, t) is used, downloaded from the NCEP/NOAA archive [1], and the fields I _E (x, t) and D _E (x, t) were calculated using the numerical model WAM [2] with the modified source function proposed in [3]. Maps for the fields I _E (x, t) and D _E (x, t) were obtained by calculations with different scales of the space-time averaging, extreme and average values of the MET were found, seasonal and interannual variability was estimated, and the 12-year trend for several mean quantities was obtained.     

Coral communities and reefs from Guerrero,Southern Mexican Pacific

Corals in the Eastern Pacific extend south from the Gulf of California to Ecuador and oceanic Chile, and west from Colombia to Clipperton Atoll. Nevertheless, large stretches of the Mexican Pacific remain fundamentally unstudied. Therefore, to assess the current conditions of coral communities, a coastal fringe ～300 km long (17°40′ N, 101°39′ W to 16°46′ N, 99°49′ W) was surveyed within the Southern Mexican Pacific, between 2005 and 2009. Fifteen stony coral species were identified at 13 coral communities and six Pocillopora‐dominated fringing reefs, with Pocillopora verrucosa and Pocillopora damicornis the primary contributing taxa. Reef development was identified in embayments or behind rocks or islands that offered shelter from northern and northwestern winds. Observations of Pocillopora effusus, Pocillopora inflata, Porites lobata, Pavona clavus, and Pavona varians expanded the species known geographic ranges by several degrees of latitude, suggesting reef building fauna comprised a mixture of widespread and relatively rare Eastern Pacific corals. Results indicated greater live coral cover in the Ixtapa‐Zihuatanejo area (15–73%) than in the Acapulco localities, which had high algal dominance; the reefs in the latter region exhibited high erosion. Regional differences are likely the result of long‐standing anthropogenic pressures around Acapulco since 1950, when it became an important tourist destination. This paper is the first detailed report of ecologically stressed corals and coral reefs from the state of Guerrero on the Mexican Southern Pacific coast.