Kudryavtsev V.N.,Russian State Hydrometeorological University |
Makin V.K.,Royal Netherlands Meteorological Institute
Boundary-Layer Meteorology | Year: 2011
The impact of ocean spray on the dynamics of the marine near-surface air boundary layer (MABL) in conditions of very high (hurricane) wind speeds is investigated. Toward this end, a model of the MABL in the presence of sea-spume droplets is developed. The model is based on the classical theory of the motion of suspended particles in a turbulent flow, where the mass concentration of droplets is not mandatory small. Description of the spume-droplet generation assumes that they, being torn off from breaking waves, are injected in the form of a jet of spray into the airflow at the altitude of breaking wave crests. The droplets affect the boundary-layer dynamics in two ways: via the direct impact of droplets on the airflow momentum forming the so-called spray force, and via the impact of droplets on the turbulent mixing through stratification. The latter is parametrized applying the Monin-Obukhov similarity theory. It is found that the dominant impact of droplets on the MABL dynamics appears through the action of the 'spray force' originated from the interaction of the 'rain of spray' with the wind velocity shear, while the efficiency of the stratification mechanism is weaker. The effect of spray leads to an increase in the wind velocity and suppression of the turbulent wind stress in the MABL. The key issue of the model is a proper description of the spume-droplet generation. It is shown that, after the spume-droplet generation is fitted to the observations, the MABL model is capable of reproducing the fundamental experimental finding-the suppression of the surface drag at very high wind speeds. We found that, at very high wind speeds, a thin part of the surface layer adjacent to the surface turns into regime of limited saturation with the spume droplets, resulting in the levelling off of the friction velocity and decrease of the drag coefficient as U -2 10, U 10 being the wind speed at 10-m height. © 2011 The Author(s).
Kourzeneva E.,Russian State Hydrometeorological University
Boreal Environment Research | Year: 2010
Lake parameterizations in atmospheric modeling include a set of external data to indicate and to map physical properties of lakes. The main challenge is the need to consider all the lakes in the atmospheric model domain and to specify the corresponding parameters. For Numerical Weather Prediction (NWP), we also need the data to initialize the lake time-dependent variables (so-called cold start data). The first steps to make the set of lake parameters for the needs of atmospheric modeling are described in this paper. The mean lake depth was chosen to be the key lake parameter for which direct measurements were collected and processed. The Global Land Cover Characteristics (GLCC) dataset was used for mapping, and the mapping method was based on a probabilistic approach. Empirical Probability Density Functions were used to project the lake information onto the target grid of an atmospheric model. The pseudo-periodical regime of the lake model was used to obtain the initial fields of lake variables. © 2010.
Badulin S.I.,Russian State Hydrometeorological University
Journal of Geophysical Research: Oceans | Year: 2014
A physical model for sea wave period from altimeter data is presented. Physical roots of the model are in recent advances of the theory of weak turbulence of wind-driven waves that predicts the link of instant wave energy to instant energy flux to/from waves. The model operates with wave height and its spatial derivative and does not refer to normalized radar cross-section σ0 measured by the altimeter. Thus, the resulting formula for wave period does not contain any empirical parameters and does not require features of particular satellite altimeter or any calibration for specific region of measurements. A single case study illustrates consistency of the new approach with previously proposed empirical models in terms of estimates of wave periods and their statistical distributions. The paper brings attention to the possible corruption of dynamical parameters such as wave steepness or energy fluxes to/from waves when using the empirical approaches. Applications of the new model to the studies of sea wave dynamics are discussed. Key Points A physical model for sea wave period from altimeter data is presented The resulting formula for wave period does not contain any empirical parameters Relevance of the new model is shown in a case study © 2014. American Geophysical Union. All Rights Reserved.
Zimin A.V.,Russian State Hydrometeorological University
Oceanology | Year: 2012
Experimental data obtained in the summer of 2010 are used for the analysis of the intense internal waves and their relation with the barotropic tides. It is shown that these waves are characterized by significant nonlinearity with their amplitudes amounting to half values of the water depth and periods of tens of minutes. The contribution of intense internal waves to the vertical exchange is assessed. © 2012 Pleiades Publishing, Ltd.
Gogoberidze G.,Russian State Hydrometeorological University
Journal of Coastal Conservation | Year: 2012
For elaboration of strategy and spatial planning of sustainable coastal regions development it's very important to know a real potential of development of the region. As parameter, which is comprehensively characterized marine economic, political and military power of the coastal region, it is possible to use the marine economy potential with comprehensive estimations of socio-economic, political, environment and military profits (damages) from coastal planning decisions. Some results, including the European and Russian coastal regions are presented. © 2011 Springer Science+Business Media B.V.