Estimation of Annual Kara Sea Primary Production     

A. B. Demidov  S. V. Sheberstov  V. I. Gagarin 《Oceanology》2018,58(3):369-380

Primary production of phytoplankton and ice and under-ice flora of the Kara Sea and regions thereof has been assessed using region-specific models and MODIS-Aqua satellite data for 2002–2015. Average annual primary production of phytoplankton calculated for the growing season (April–October) amounted to 165 mg С m^–2 day^–1. Annual primary production of phytoplankton was 35 g C/m². Annual primary production of phytoplankton in the entire Kara Sea was 13 × 10¹² g C. Annual primary production of ice and underice flora calculated using an integrated biophysical model was 1.7 × 10¹² g C, or 12% of total primary production of the Kara Sea; the ice cover dynamics and published data were taken into account for the calculations. The results have been compared to earlier primary production estimates for the Kara Sea. The extent of the increase in sea productivity during warming of the Arctic and the decrease in ice cover area are discussed.  相似文献   

Phytoplankton production characteristics in the southern Atlantic and the Atlantic sector of the Southern Ocean in the austral summer of 2009–2010     

A. B. Demidov  S. A. Mosharov  V. I. Gagarin 《Oceanology》2012,52(2):206-218

In December–January of 2010 the spatial distribution of the phytoplankton production characteristics was studied along transects in the vicinity of the Greenwich meridian (I) and in the Drake Passage (II). On transect I, the surface chlorophyll a concentration and primary production varied from 0.11 up to 3.57 mg/m³ and from 4.38 up to 37.47 mgC/m³ per day, respectively. The chlorophyll a in the photosynthetic layer and the integrated primary production varied from 10.7 up to 66.1 mg/m² and from 83 to 646 mgC/m² per day, respectively. On transect II in the surface layer, the chlorophyll a concentration changed within the range of 0.09–1.02 mg/m³ and the primary production ranged from 2.08 to 9.49 mgC/m³. The integrated values ranged from 6.32 to 38.29 mg/m² and from 41 to 221 mgC/m² per day, respectively. The moderate means of themaximum quantum yield (F _v/F _m) on transects I and II (0.41 and 0.35, respectively) testify to the low activity of the phytoplankton’s photosynthetic apparatus. The studied water areas in the Southern Ocean differed both in the phytoplankton biomass expressed in the chlorophyll a concentration values and in the conditions of the primary production formation.  相似文献   

Water distribution in Martian permafrost regions from joint analysis of HEND (Mars Odyssey) and MOLA (Mars Global Surveyor) data     

N. E. Demidov  W. V. Boynton  D. A. Gilichinsky  M. T. Zuber  A. S. Kozyrev  M. L. Litvak  I. G. Mitrofanov  A. B. Sanin  R. S. Saunders  D. E. Smith  V. I. Tretyakov  D. Hamara 《Astronomy Letters》2008,34(10):713-723

We jointly analyze data from the High-Energy Neutron Detector (HEND) onboard the NASA Mars Odyssey spacecraft and data from the Mars Orbiter Laser Altimeter (MOLA) onboard the Mars Global Surveyor spacecraft. The former instrument measures the content of hydrogen (in the form of H₂O or OH) in the subsurface layer of soil and the latter instrument measures the surface albedo with respect to the flux of solar energy. We have checked the presence of a correlation between these two data sets in various Martian latitude bands. A significant correlation has been found between these data at latitudes poleward of 40° in the northern hemisphere and at latitudes 40°–60° in the southern hemisphere. This correlation is interpreted as evidence for the presence of stable water ice in these regions under a dry layer of soil whose thickness is determined by the condition for equilibrium between the condensation of water from the atmosphere and its sublimation when heated by solar radiation. For these regions, we have derived an empirical relation between the flux of absorbed solar radiation and the thickness of the top dry layer. It allows the burial depth of the water ice table to be predicted with a sub-kilometer resolution based on near-infrared albedo measurements. We have found no correlation in the southern hemisphere at latitudes >60°, although neutron data also suggest that water ice is present in this region under a layer of dry soil. We conclude that the thickness of the dry layer in this region does not correspond to the equilibrium condition between the water ice table and the atmosphere.  相似文献   

The structure of phytoplankton communities in the eastern part of the Laptev Sea     

I. N. Sukhanova  M. V. Flint  E. Ju. Georgieva  E. K. Lange  M. D. Kravchishina  A. B. Demidov  A. A. Nedospasov  A. A. Polukhin 《Oceanology》2017,57(1):75-90

Studies have been performed on a transect along 130°30′ E from the Lena River delta (71°60′ N) to the continental slope and adjacent deepwater area (78°22′ N) of the Laptev Sea in September 2015. The structure of phytoplankton communities has distinct latitudinal zoning. The southern part of the shelf (southward of 73°10′ N), the most desalinated by riverine discharge, houses a phytoplankton community with a biomass of 175–840 mg/m², domination of freshwater Aulacoseira diatoms, and significant contribution of green algae (both in abundance and biomass). The northern border for the distribution range of the southern complex of phytoplankton species lies between the 8 and 18 psu isohalines (~73°10′ N). The continental slope and deepwater areas of the Laptev Sea (north of 77°30′ N), with a salinity of >27 psu in the upper mixed layer, are populated by the community prevalently composed of Chaetoceros and Rhizosolenia diatoms, very abundant in the Arctic, and dinoflagellates. The phytoplankton number in this area fall in the range of 430–1100 × 10⁶ cell/m², and the biomass, in the range of 3600 mg/m². A moderate desalinating impact of the Lena River discharge is observed in the outer shelf area between 73°20′ and 77°30′ N; the salinity in the upper mixed layer is 18–24 psu. The phytocenosis in this area has a mosaic spatial structure with between-station variation in the shares of different alga groups in the community, cell number of 117–1200 × 10⁶ cells/m², and a biomass of 1600–3600 mg/m². As is shown, local inflow of “fresh” nutrients to the euphotic layer in the fall season leads to mass growth of diatoms.  相似文献   

Depth-integrated and depth-resolved models of Kara Sea primary production     

A. B. Demidov  S. A. Mosharov  V. A. Artemyev  A. N. Stupnikova  U. V. Simakova  S. V. Vazyulya 《Oceanology》2016,56(4):515-526

Primary production (PP) models of the Kara Sea are developed based on data collected on fall expeditions (September–October 1993, 2007, and 2011) and their precision assessment utilizes the dataset collected in September 2013. The algorithms for different model types (depth-integrated and depth-resolved) are compared. The depth-resolved model performs slightly better than the depth-integrated one (the rootmean- square-difference (RMSD) are 0.29 and 0.31, respectively). These algorithms utilize the daily assimilation number (DAN) and photosynthetic efficiency (ψ) as the model coefficients, and surface chlorophyll a (chl a) and photosynthetically active radiation (PAR) as input variables. These algorithms perform better than the models that use chl a alone. Our results suggest that an increase in the performance of the Kara Sea PP models depends on the input of the photophysiological characteristics of phytoplankton (DAN and ψ) and PAR. To a lesser extent, this concerns the advantages of the depth-resolved model over the depth-integrated one. The constructed region-specific Kara Sea PP models combined with satellite-derived chl a and PAR can be used to estimate annual values and long-term variation of PP in hydrologically and hydrochemically similar waters of the Arctic Ocean.  相似文献   

Transport of Deep and Bottom Waters through the Mid-Atlantic Ridge in the Vema Fracture Zone     

Demidov  A. N.  Ivanov  A. A.  Gippius  F. N.  Dobroliubov  S. A. 《Doklady Earth Sciences》2020,494(1):735-740

Doklady Earth Sciences - This paper addresses changes of Antarctic Bottom Water (AABW) transport through the Vema Fracture Zone based on direct measurements and Glorys12v1 reanalysis. Instrumental...  相似文献   

Zooplankton in Bays of the Novaya Zemlya Archipelago: Composition,Distribution, and Role in Phytoplankton Grazing and Biosedimentation     

Amelina  A. B.  Drits  A. V.  Sergeeva  V. M.  Soloviyev  K. A.  Belyaev  N. A.  Dara  O. M.  Demidov  A. B.  Flint  M. V. 《Oceanology》2018,58(6):825-837

Oceanology - The zooplankton community in two bays of the eastern coast of the Novaya Zemlya archipelago (Blagopoluchiya Bay and Tsivolki Bay) has been studied for the first time. Copepods of the...  相似文献   

Spatial Variability of Phytoplankton Primary Production Characteristics in the North Atlantic in Summer 2013     

Demidov  A. B.  Mosharov  S. A.  Gagarin  V. I.  Gladyshev  S. V.  Dukhova  L. A.  Romanova  N. D.  Mosharova  I. V. 《Oceanology》2019,59(2):223-234

Oceanology - The spatial variability of phytoplankton primary production characteristics has been studied along transects between the Shetland Islands and Iceland (transect I) and along 59.5°...  相似文献   

Geocryological and Hydrogeological Conditions of the Western Part of Nordenskiold Land (Spitsbergen Archipelago)     

Demidov  N. E.  Borisik  A. L.  Verkulich  S. R.  Wetterich  S.  Gunar  A. Yu.  Demidov  V. E.  Zheltenkova  N. V.  Koshurnikov  A. V.  Mikhailova  V. M.  Nikulina  A. L.  Novikov  A. L.  Savatyugin  L. M.  Sirotkin  A. N.  Terekhov  A. V.  Ugrumov  Yu. V.  Schirrmeister  L. 《Izvestiya Atmospheric and Oceanic Physics》2020,56(11):1376-1400

Izvestiya, Atmospheric and Oceanic Physics - This work summarizes the archived data of geocryological and hydrogeological conditions in the west of Nordenskiold Land on the Spitsbergen Archipelago....  相似文献   

Seasonal Variability and Estimation of Annual East Siberian Sea Phytoplankton Primary Production and Comparison with the Other Siberian Seas     

Demidov  A. B.  Gagarin  V. I.  Sheberstov  S. V. 《Oceanology》2020,60(5):603-616

Oceanology - Studies of seasonal variability of the East Siberian Sea (ESS) water column primary production (IPP) and evaluation of its total annual value (PPtot) were performed using MODIS-Aqua...  相似文献