Kara-Bogaz-Gol Bay: Physical and Chemical Evolution     

Aleksey N. Kosarev  Andrey G. Kostianoy  Igor S. Zonn 《Aquatic Geochemistry》2009,15(1-2):223-236

Kara-Bogaz-Gol Bay is a large (around 18,000 km²) and shallow (few meters deep) lagoon located east of the Caspian Sea. Its water surface was several meters to several dozens cm lower than in the Caspian Sea, so water flows from the Caspian Sea through a narrow strait into the bay, where it evaporates. Kara-Bogaz-Gol Bay is one of the saltiest bodies of water in the world; its water salinity amounts to 270–300 g/l. Different kinds of salts available in this natural evaporative basin has been used commercially since at least the 1920s. In March 1980, in order to decelerate a continuous fall of the Caspian Sea level, which in 1977 was the lowest over the last 400 years (?29 m), the Kara-Bogaz-Gol Strait was dammed. In response to this human intervention, the bay had already dried up completely by November 1983. In 1992, the dam was destroyed, and Kara-Bogaz-Gol Bay had been filling up with the Caspian Sea water at a rate of about 1.7 m/year up to 1996 as observed by the TOPEX/Poseidon satellite altimetry mission. Since then, Kara-Bogaz-Gol Bay level evolution with characteristic seasonal and interannual oscillations has been similar to that of the Caspian Sea. Physical and chemical evolution of the bay in the twentieth and twenty-first centuries is traced in detail in the paper.  相似文献   

Turbulent measurements in the stable atmospheric boundary layer during SHEBA: ten years after   总被引：4，自引：0，他引：4  

Andrey A. Grachev  Edgar L. Andreas  Christopher W. Fairall  Peter S. Guest  P. Ola G. Persson 《Acta Geophysica》2008,56(1):142-166

This paper surveys results of the comprehensive turbulent measurements in the stable boundary layer (SBL) made over the Arctic pack ice during the Surface Heat Budget of the Arctic Ocean experiment (SHEBA) in the Beaufort Gyre from October 1997 through September 1998. Turbulent fluxes and mean meteorological data were continuously measured and reported hourly at five levels on a 20-m main SHEBA tower. Eleven months of measurements during SHEBA cover a wide range of stability conditions, from the weakly unstable regime to very stable stratification, and allow studying the SBL in detail. A brief overview of the SBL regimes, the flux-profile relationships, the turbulent Prandtl number, and other parameters obtained during SHEBA is given. The traditional Monin—Obukhov approach, z-less scaling, and gradient-based scaling are evaluated and discussed based on the data from SHEBA.  相似文献   

Mesoscale dynamics and walleye pollock catches in the Navarin Canyon area of the Bering Sea     

Andrey G. Andreev  Maxim V. Budyansky  Michael Yu. Uleysky  Sergey V. Prants 《Ocean Dynamics》2018,68(11):1503-1514

Large canyons incise the shelf break of the eastern Bering Sea to be preferred sites of the cross-shelf exchange. The mesoscale eddy activity is particularly strong near the shelf-break canyons. To study the mesoscale dynamics in the Navarin Canyon area of the Bering Sea, the time series of velocities derived from AVISO satellite altimetry between 1993 and 2015, drifters, Argo buoys, and ship-borne data are analyzed. We demonstrate that the strength of anticyclonic eddies along the shelf edge in spring and summer is determined by the wind stress in March–April. The increased southward wind stress in the central Bering Sea forced a supply of low-temperature and low-salinity outer shelf water to the deep basin and formation of the anticyclonic mesoscale circulation seaward of the Navarin Canyon. Enhanced northwestward advection of the Bering Slope Current water leads to increase in an ice-free area in March and April and increased bottom-layer temperature at the outer shelf. The strong (weak) northwestward advection of the eastern Bering Sea waters, determined by eastern winds in spring, creates favorable (unfavorable) conditions for the pollock abundance in the western Navarin Canyon area in summer.  相似文献   

Water dynamics in the western Bering Sea and its impact on chlorophyll a concentration     

Andreev  Andrey G.  Budyansky  Maxim V.  Khen  Gennady V.  Uleysky  Michael Yu. 《Ocean Dynamics》2020,70(5):593-602

Ocean Dynamics - To study the water dynamics in the western Bering Sea, the time series of geostrophic velocities derived from satellite altimetry, Global total current (Copernicus Globcurrent)...  相似文献   

On the role of diffractions in velocity model building: a full-waveform inversion example     

Dell  Sergius  Abakumov  Ivan  Znak  Pavel  Gajewski  Dirk  Kashtan  Boris  Ponomarenko  Andrey 《Studia Geophysica et Geodaetica》2019,63(4):538-553

Studia Geophysica et Geodaetica - Imaging of small-scale heterogeneities is important for the geological exploration in complex environments. It requires a processing sequence tuned to...  相似文献   

Mesoscale circulation along the Sakhalin Island eastern coast   总被引：1，自引：1，他引：0  

Sergey V. Prants  Andrey G. Andreev  Michael Yu. Uleysky  Maxim V. Budyansky 《Ocean Dynamics》2017,67(3-4):345-356

The seasonal and interannual variability of mesoscale circulation along the eastern coast of the Sakhalin Island in the Okhotsk Sea is investigated using the AVISO velocity field and oceanographic data for the period from 1993 to 2016. It is found that mesoscale cyclones with the horizontal dimension of about 100 km occur there predominantly during summer, whereas anticyclones occur predominantly during fall and winter. The cyclones are generated due to a coastal upwelling forced by northward winds and the positive wind stress curl along the Sakhalin coast. The anticyclones are formed due to an inflow of low-salinity Amur River waters from the Sakhalin Gulf intensified by southward winds and the negative wind stress curl in the cold season. The mesoscale cyclones support the high biological productivity at the eastern Sakhalin shelf in July– August.  相似文献   

Study of variable stars associated with maser sources: G025.65+1.05     

Andrey M.Sobolev  Anastasia P.Bisyarina  Stanislav Yu.Gorda  Andrey M.Tatarnikov 《天文和天体物理学研究(英文版)》2019,(3):47-52

We report variation of K-band infrared(IR) emission in the vicinity of the G025.65+1.05 water and methanol maser source. New observational data were obtained with the 2.5 m telescope at the Caucasian Mountain Observatory(CMO) of Moscow State University on 2017–09–21 during a strong water maser flare. We found that the IR source situated close to the maser position had decreased brightness in comparison to archive data. This source is associated with a massive young stellar object(MYSO) corresponding to the compact IR source IRAS 18316–0602(RAFGL 7009 S). A similar decrease in K-brightness of the IR source close to the maser position was observed in March 2011 when the water maser experienced a period of increased activity. The dips in MYSO brightness can be related to the maser flare phases. Maser flares that are concurrent with dips in the IR emission can be explained if the lower IR radiation field enables a more efficient sink for the pumping cycle by allowing IR photons to escape the maser region.  相似文献   

Spectroscopic and photometric observations of symbiotic nova PU Vul during 2009–2016     

Anna Tatarnikova  Marina Burlak  Eugene Kolotilov  Natalia Metlova  Victor Shenavrin  Sergei Shugarov  Taisija Tarasova  Andrey Tatarnikov 《天文和天体物理学研究(英文版)》2018,(8)

A new set of low-resolution spectral and UBVJHKL-photometric observations of the symbiotic nova PU Vul is presented. The binary has been evolving after its symbiotic nova outburst in 1977 and now it is in the nebular stage. It is found that the third orbital cycle(after 1977) was characterized by great changes in associated light curves. Now, PU Vul exhibits a sine-wave shape in all the light curves(with an amplitude in the U band of about 0.7 mag), which is typical for symbiotic stars in the quiescent state. Brightness variability due to pulsations of the cool component is now clearly visible in the VRI light curves. The amplitude of the pulsations increases from 0.5 mag in the V band to 0.8 mag in the I band. These two types of variability, as well as a very slow change in the physical parameters of the hot component due to evolution after the outburst of 1977, influence the spectral energy distribution(SED)of the system. The variability of emission lines is highly complex. Only hydrogen line fluxes vary with orbital phase. An important feature of the third orbital cycle is the first emergence of the OVI, 6828  Raman scattering line. We determine the temperature of the hot component by means of the Zanstra method applied to the He II, 4686  line. Our estimate is about 150 000 K for the spectrum obtained near orbital maximum in 2014. The VO spectral index derived near pulsation minimum corresponds to M6 spectral class for the cool component of PU Vul.  相似文献   

Testing the genetic relationship between fluid alteration and brecciation in CM chondrites     

Maximilien J. Verdier‐Paoletti  Yves Marrocchi  Lionel G. Vacher  Jrme Gattacceca  Andrey Gurenko  Corinne Sonzogni  Matthieu Gounelle 《Meteoritics & planetary science》2019,54(8):1692-1709

Boriskino is a poorly studied CM chondrite with numerous millimeter‐ to centimeter‐scale clasts exhibiting sharp boundaries. Clast textures and mineralogies attest to diverse geological histories with various degrees of aqueous alteration. We conducted a petrographic, chemical, and isotopic study on each clast type of the breccia to investigate if there exists a genetic link between brecciation and aqueous alteration, and to determine the controlling parameter of the extent of alteration. Boriskino is dominated by CM2 clasts for which no specific petrographic type could be assigned based on the chemical compositions and modal abundances of constituents. One clast stands out and is identified as a CM1 lithology, owing to its lack of anhydrous silicates and its overall abundance of dolomite‐like carbonates and acicular iron sulfides. We observe that alteration phases near clast boundaries exhibit foliation features, suggesting that brecciation postdated aqueous alteration. We measured the O‐isotopic composition of Ca‐carbonates and dolomite‐like carbonates to determine their precipitation temperatures following the methodology of Verdier‐Paoletti et al. (2017). Both types of carbonates yield similar ranges of precipitation temperatures independent of clast lithology, ranging from ?13.9 ± 22.4 (2σ) to 166.5 ± 47.3 °C, precluding that temperature alone accounts for the differences between the CM1 and CM2 lithologies. Instead, we suggest that initial water/rock ratios of 0.75 and 0.61 for the CM1 and CM2 clasts, respectively, might control the extent of aqueous alteration. Based on these estimates, we suggest that Boriskino clasts originated from a single parent body with heterogeneous distribution of water either due to local differences in the material permeability or in the initial content of ice available. These conditions would have produced microenvironments with differing geochemical conditions thus leading to a range of degrees of aqueous alteration.  相似文献   

Composition and origin of holotype Al‐Cu‐Zn minerals in relation to quasicrystals in the Khatyrka meteorite          下载免费PDF全文

Marina A. Ivanova  Cyril A. Lorenz  Sergey E. Borisovskiy  Andrey A. Burmistrov  Dmitriy V. Korost  Alexander V. Korochantsev  Maria N. Logunova  Sergei I. Shornikov  Michail I. Petaev 《Meteoritics & planetary science》2017,52(5):869-883

We investigated the khatyrkite–cupalite holotype sample, 1.2 × 0.5 mm across. It consists of khatyrkite (Cu,Zn)Al₂, cupalite (Cu,Zn)Al, and interstitial material with approximate composition (Zn,Cu)Al₃. All mineral phases of the holotype sample contain Zn and lack Fe that distinguishes them from khatyrkite and cupalite in the Khatyrka meteorite particles (Bindi et al. 2009 , 2011 , 2012 , 2015 ; MacPherson et al. 2013 ; Hollister et al. 2014 ). Neither highly fractionated natural systems nor geo‐ or cosmochemical processes capable of forming the holotype sample are known so far. The bulk chemistry and thermal history of khatyrkite–cupalite assemblage in the holotype sample hint for its possible industrial origin. Likewise, the aluminides in the Khatyrka meteorite particles may also be derived from industrial materials and mixed with extraterrestrial matter during gold prospecting in the Listvenitovy Stream valley.  相似文献