Dynamic processes and their influence on the transformation of the passive admixture in the sea of Azov     

V. A. Ivanov  L. V. Cherkesov  T. Ya. Shul’ga 《Oceanology》2014,54(4):426-434

In this model, we apply a nonlinear three-dimensional sigma-coordinate model to study the waves and currents in the Sea of Azov generated by different fields of wind forcing: a constant wind, a quickly varying real wind obtained using the data of reanalysis applying the SKIRON model, and the wind resulting from their combined forcing. This mathematical model was also applied to study the transformation of the passive admixture appearing under the influence of wind fields in the Sea of Azov considered here. We compared the results of numerical calculations with the field data obtained under the wind forcing at a number of hydrological stations. We found the regularities of the water transport driven by onshore and offshore winds, the velocities of the currents, and the characteristics of the evolution of polluted regions at different depths as functions of the nonstationary wind intensity and the velocities of the stationary currents.  相似文献   

Retrieval of optical characteristics of the aerosol atmosphere and Earth’s surface by the joint processing of different satellite information     

A. P. Ivanov  I. L. Katsev  A. S. Prikhach  E. P. Zege 《Izvestiya Atmospheric and Oceanic Physics》2014,50(2):188-195

Methods and algorithms for the retrieval of optical characteristics of the aerosol atmosphere and underlying surface by data from a multispectral satellite sensor (MSSS) are described. A procedure for the joint processing of MSSS and multizonal imaging system (MZIS) data is proposed and described with the aim of retrieving the albedo of the Earth’s surface with a high spatial resolution. In this case the spectral optical characteristics of the aerosol atmosphere are retrieved by MSSS data in the visible range of 400–700 nm. According to these results, transmission functions of the atmosphere in MZIS spectral channels are calculated and an atmospheric correction of MZIS data is performed. The accuracy of determining the albedo of the underlying surface in spectral channels of MZIS with high-spatial-resolution is estimated.  相似文献   

Time-dependent uptake of NO3 by sea salt     

Vladislav V. Zelenov  Elena V. Aparina  Andrey V. Ivanov 《Journal of Atmospheric Chemistry》2014,71(1):33-53

Using a coated-insert flow tube reactor coupled to a low-energy electron-impact mass spectrometer with molecular beam sampling, we studied uptake of NO₃ by sea salt at room temperature and [NO₃]?=?8?10¹¹???4?10¹³ molecule cm^?3. The radical uptake coefficient γ(t) is time dependent: its initial value (γ _ini) decreases exponentially with the characteristic time (τ) to its steady-state value (γ _ss) at given [NO₃]. The parameters γ _ini, γ _ss and τ depend on [NO₃], whereas γ _ss is water vapor independent at [H₂O]?=?8?10¹²???1.6?10¹⁵ molecule cm^?3 and RH ≤ 0.5 %. HCl and NO₂ are uptake products detected in the gas phase. We used these findings to estimate γ values under tropospheric conditions for urban coastal and remote marine environments: at high NO₃ (~90 ppt), the time dependence becomes important, and the γ value averaged over the aerosol lifetime is 4?10^?3; at low NO₃ (~1 ppt), the radical uptake is time independent and proceeds faster with γ _ini?=?8?10^?3  相似文献   

Climatic factors controlling plant sensitivity to warming     

Andrei Lapenis  Hugh Henry  Mathias Vuille  James Mower 《Climatic change》2014,122(4):723-734

Plant sensitivity to warming can be expressed as β or the number of days of advance in leafing or flowering events per 1 °C of Mean Annual Temperature (MAT) change. Many local studies demonstrate that β estimates for spring flowering species are usually larger than estimates for plants flowering in summer or fall. Until now, however, neither observational nor experimental estimates of this parameter were considered to be climate or geographically dependent. Here we question this paradigm through reanalysis of observational β estimates and mathematical modeling of the seasonal warming signal. Statistical analysis of a large number of bulk (averaged over species) estimates of β derived from the Pan European Phenology Data network (PEP725) revealed a positive spatial correlation with MAT, as well as a negative correlation with the Seasonal Temperature Range (STR). These spatial correlations of bulk β values as well as interseasonal variability in β were explained using a simple deterministic model of the Thermal Growing Season (TGS). More specifically, we found that the geographic distribution of bulk plant sensitivity to warming as well as the seasonal decline of β were controlled by the seasonal patterns in the warming signal and by average soil thermal properties. Thus, until recently, plants managed to keep pace with climate warming by shifting their leafing and flowering events by the same number of days as the length of the period of weather suitable for their growth. Our model predicts, however, an even greater increase in the TGS for subsequent increases in MAT. Depending on how they interact with other factors such as changes in precipitation and increased temperature variability, these longer thermal growing seasons may not be beneficial for plant growth.  相似文献   

Mercury in bottom sediments of marginal seas of northeast Asia     

M. V. Ivanov 《Russian Journal of Pacific Geology》2014,8(4):288-299

The analysis of the concentrations and distribution of mercury in bottom sediments of marginal seas in northeastern Asia revealed that its maximum contents are characteristic of areas with an active geodynamic regime and some areas of the Amur Bay in the Sea of Japan subjected to anthropogenic impact. The geochemical associations of mercury with other chemical elements and its background concentrations in bottom sediments of these sea basins are defined.  相似文献   

Optimization of calcium-based bioclogging and biocementation of sand   总被引：1，自引：0，他引：1  

Jian Chu  Volodymyr Ivanov  Maryam Naeimi  Viktor Stabnikov  Han-Long Liu 《Acta Geotechnica》2014,9(2):277-285

Bioclogging and biocementation can be used to improve the geotechnical properties of sand. These processes can be performed by adsorption of urease-producing bacterial cells on the sand grain surfaces, which is followed by crystallization of calcite produced from the calcium salt and urea solution due to bacterial hydrolysis of urea. In this paper, the effect of intact cell suspension of Bacillus sp. strain VS1, suspension of the washed bacterial cells, and culture liquid without bacterial cells on microbially induced calcite precipitation in sand was studied. The test results showed that adsorption/retention of urease activity on sand treated with washed cells of Bacillus sp. strain VS1 was 5–8 times higher than that treated with culture liquid. The unconfined compressive strength of sand treated with the suspension of washed cells was 1.7 times higher than that treated with culture liquid. This difference could be due to fast inactivation of urease by protease which was present in the culture liquid. The adsorption of bacterial cells on sand pretreated with calcium, aluminum, or ferric salts was 29–37 % higher as compared with that without pretreatment. The permeability of sand varied with the content of precipitated calcium. For bioclogging of sand, the content of precipitated calcium had to be 1.3 % (w/w) or higher. The shear strength of biotreated sand was also dependent on the content of precipitated calcium. To achieve an unconfined compressive strength of 1.5 MPa or higher, the content of precipitated calcium in the treated sand had to be 4.2 % (w/w) or higher. These data can be used as the reference values for geotechnical applications such as bioclogging for reducing the permeability of sand and biocementation for increasing the shear strength of soil.  相似文献   

Assessment of recharge capacity potential of groundwater using comparative multi-criteria decision analysis approaches     

Minea  Ionut  Boicu  Daniel  Chelariu  Oana-Elena  Iosub  Marina  Enea  Andrei 《地理学报(英文版)》2022,32(4):735-756

Journal of Geographical Sciences - Groundwater resources have always been some of the most valuable resources of human settlements. Climate changes and ever-increasing water demands registered in...  相似文献   

Wide-field optical monitoring with Mini-MegaTORTORA (MMT-9) multichannel high temporal resolution telescope     

G. M. Beskin  S. V. Karpov  A. V. Biryukov  S. F. Bondar  E. A. Ivanov  E. V. Katkova  N. V. Orekhova  A. V. Perkov  V. V. Sasyuk 《Astrophysical Bulletin》2017,72(1):81-92

We describe the properties of Mini-MegaTORTORA (MMT-9) nine-channel wide-field optical sky monitoring system with subsecond temporal resolution. This instrument can observe sky areas as large as 900 deg², perform photometry in three filters close to Johnson BV R system and polarimetry of selected objects or areas with 100–300 deg2 sizes. The limiting magnitude of the system is up to V = 11m for 0.1 s temporal resolution, and reaches V = 15^m in minute-long exposures. The system is equipped with a powerful computing facility and dedicated software pipeline allowing it to perform automatic detection, real-time classification, and investigation of transient events of different nature located both in the near- Earth space and at extragalactic distances. The objects routinely detected by MMT-9 include faint meteors and artificial Earth satellites.We discuss astronomical tasks that can be solved using MMT-9, and present the results of the first two years of its operation. In particular, we report the parameters of the optical flare detected on June 25, 2016, which accompanied the gamma-ray burst GRB160625B.  相似文献   

Latitude-time evolution of the large-scale magnetic field in the 21st and 22nd cycles of solar activity     

R. N. Ikhsanov  V. G. Ivanov 《Geomagnetism and Aeronomy》2012,52(8):987-991

Using the observational data of the Stanford observatory on photospheric magnetic fields for 1976?C2001, we separate open and closed configurations of the magnetic field with a filter of a specified spatial scale and demonstrate that the 11-year solar cycle passes two significantly different phases.  相似文献   

Nuclear Aspects of the Solar Neutrino Problem     

H. Oberhummer  A.N. Ivanov  N.I. Troitskaya  M. Faber 《Astrophysics and Space Science》1997,258(1-2):133-144

The present status of the nuclear reaction rates determining the solar neutrino flux is discussed. This includes the reaction rates for the two branching ratios of the three pp-chains involving the reactions 3He(3He,2p)4He and 3He(4He,γ)7Be for the first branching, and 7Be(e−, νe)7Li and 7Be(p, γ)8B for the second branching. Mainly we will concentrate on the basic nuclear reaction p + p → D + e+ + νe of the pp-chains. This reaction rate can only be determined using the theoretical methods. The present status of the application of the relativistic field theory model of the deuteron for this reaction will be discussed. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献