The study of Arctic sea ice has traditionally been focused on large-scale such as reductions of ice coverage,thickness,volumes and sea ice regime shift.Research has primarily concentrated on the impact of large-scale ...The study of Arctic sea ice has traditionally been focused on large-scale such as reductions of ice coverage,thickness,volumes and sea ice regime shift.Research has primarily concentrated on the impact of large-scale external factors such as atmospheric and oceanic circulations,and solar radiation.Additionally,Arctic sea ice also undergoes rapid micro-scale evolution such as gas bubbles formation,brine pockets migration and massive formation of surface scattering layer.Field studies like CHINARE(2008-2018)and MOSAiC(2019-2020)have confirmed these observations,yet the full understanding of those changes remain insufficient and superficial.In order to cope better with the rapidly changing Arctic Ocean,this study reviews the recent advances in the microstructure of Arctic sea ice in both field observations and laboratory experiments,and looks forward to the future objectives on the microscale processes of sea ice.The significant porosity and the cyclical annual and seasonal shifts likely modify the ice's thermal,optical,and mechanical characteristics,impacting its energy dynamics and mass balance.Current thermodynamic models,both single-phase and dual-phase,fail to accurately capture these microstructural changes in sea ice,leading to uncertainties in the results.The discrepancy between model predictions and actual observations strongly motivates the parameterization on the evolution in ice microstructure and development of next-generation sea ice models,accounting for changes in ice crystals,brine pockets,and gas bubbles under the background of global warming.It helps to finally achieve a thorough comprehension of Arctic sea ice changes,encompassing both macro and micro perspectives,as well as externaland internal factors.展开更多
A retrieval algorithm of arctic sea ice concentration （SIC） based on the brightness temperature data of “HY-2” scanning microwave radiometer has been constructed. The tie points of the brightness temperature were ...A retrieval algorithm of arctic sea ice concentration （SIC） based on the brightness temperature data of “HY-2” scanning microwave radiometer has been constructed. The tie points of the brightness temperature were selected based on the statistical analysis of a polarization gradient ratio and a spectral gradient ratio over open water （OW）, first-year ice （FYI）, and multiyear ice （MYI） in arctic. The thresholds from two weather filters were used to reduce atmospheric effects over the open ocean. SIC retrievals from the “HY-2” radiom-eter data for idealized OW, FYI, and MYI agreed well with theoretical values. The 2012 annual SIC was calcu-lated and compared with two reference operational products from the National Snow and Ice Data Center （NSIDC） and the University of Bremen. The total ice-covered area yielded by the “HY-2” SIC was consistent with the results from the reference products. The assessment of SIC with the aerial photography from the fifth Chinese national arctic research expedition （CHINARE） and six synthetic aperture radar （SAR） images from the National Ice Service was carried out. The “HY-2” SIC product was 16% higher than the values de-rived from the aerial photography in the central arctic. The root-mean-square （RMS） values of SIC between “HY-2” and SAR were comparable with those between the reference products and SAR, varying from 8.57% to 12.34%. The “HY-2” SIC is a promising product that can be used for operational services.展开更多
Due to low damping ratio, fiat permanent magnet linear synchronous motor＇s vibration is difficult to be damped and the accuracy is limited. The vibration suppressing results are not good enough in the existing resear...Due to low damping ratio, fiat permanent magnet linear synchronous motor＇s vibration is difficult to be damped and the accuracy is limited. The vibration suppressing results are not good enough in the existing research because only the longitudinal direction vibration is considered while the normal direction vibration is neglected. The parameters of the direct-axis current controller are set to be the same as those of the quadrature-axis current controller commonly. This causes contradiction between signal noise and response. To suppress the vibration, the electromagnetic force model of the flat permanent magnet synchronous linear motor is formulated first. Through the analysis of the effect that direct-axis current noise and quadrature-axis current noise have on both direction vibration, it can be declared that the conclusion that longitudinal direction vibration is only related to the quadrature-axis current noise while the normal direction vibration is related to both the quadrature-axis current noise and direct-axis current noise. Then, the simulation test on current loop with a low-pass filter is conducted and the results show that the low-pass filter can not suppress the vibration but makes the vibration more severe. So a vibration suppressing strategy that the proportional gain of direct-axis current controller adapted according to quadrature-axis reference current is proposed. This control strategy can suppress motor vibration by suppressing direct-axis current noise. The experiments results about the effect of Kp and Ti on normal direction vibration, longitudinal vibration and the position step response show that this strategy suppresses vibration effectively while the motor＇s motion performance is not affected. The maximum reduction of vibration can be up to 40%. In addition, current test under rated load condition is also conducted and the results show that the control strategy can avoid the conflict between the direct-axis current and the quadrature-axis current under typical load. Adaptive PI control strategy can effectively suppress the flat permanent magnet linear synchronous motor＇s vibration without affecting the motor＇s performance.展开更多
The aims of this study were to explore the interspecific differences of Populus euphratica Oliv.and Populus pruinosa Schrenk populations and the intraspecific differences of males and females within the same species i...The aims of this study were to explore the interspecific differences of Populus euphratica Oliv.and Populus pruinosa Schrenk populations and the intraspecific differences of males and females within the same species in flowering phenological traits,and the effects of temperatures on flowering phenological traits in different growth years(2001–2003 and 2013–2015).The results showed that P.euphratica population flowered earlier than P.pruinosa population.Moreover,flowering phenological period of population,number of days of flowering phenological period per population,number of days of flowering phenological period per plant and average number of days of flowering period per plant of P.euphratica population were less than those of P.pruinosa population.The differences between male and female within the same species indicated that the flowering periods of males P.euphratica and P.pruinosa populations were earlier than those of female plants.For both species,flowering phenological traits were significantly and negatively correlated with the average temperatures in previous ten days,previous one month and previous three months of flowering.Both species are sensitive to temperature changes and adjust to the changes by advancing the start of flowering and prolonging the duration of flowering.展开更多
Evolution of the Arctic sea ice and its snow cover during the SHEBA year were simulated by applying a high-resolution thermodynamic snow/ice model （HIGHTSI）. Attention was paid to the impact of albedo on snow and se...Evolution of the Arctic sea ice and its snow cover during the SHEBA year were simulated by applying a high-resolution thermodynamic snow/ice model （HIGHTSI）. Attention was paid to the impact of albedo on snow and sea ice mass balance, effect of snow on total ice mass balance, and the model vertical resolution. The SHEBA annual simulation was made applying the best possible external forcing data set created by the Sea Ice Model Intercomparison Project. The HIGHTSI control run reasonably reproduced the observed snow and ice thickness. A number of albedo schemes were incorporated into HIGHTSI to study the feedback processes between the albedo and snow and ice thickness. The snow thickness turned out to be an essential variable in the albedo parameterization. Albedo schemes dependent on the surface temperature were liable to excessive positive feedback effects generated by errors in the modelled surface temperature. The superimposed ice formation should be taken into account for the annual Arctic sea ice mass balance.展开更多
Many interesting characteristics of sea ice drift depend on the atmospheric drag coefficient （Ca） and oceanic drag coefficient （Cw）. Parameterizations of drag coefficients rather than constant values provide us a ...Many interesting characteristics of sea ice drift depend on the atmospheric drag coefficient （Ca） and oceanic drag coefficient （Cw）. Parameterizations of drag coefficients rather than constant values provide us a way to look insight into the dependence of these characteristics on sea ice conditions. In the present study, the parameterized ice drag coefficients are included into a free-drift sea ice dynamic model, and the wind factor a and the deflection angle θ between sea ice drift and wind velocity as well as the ratio of Ca to Cw are studied to investigate their dependence on the impact factors such as local drag coefficients, floe and ridge geometry. The results reveal that in an idealized steady ocean, Ca/Cw increases obviously with the increasing ice concentration for small ice floes in the marginal ice zone, while it remains at a steady level （0.2-0.25） for large floes in the central ice zone. The wind factor a increases rapidly at first and approaches a steady level of 0.018 when A is greater than 20%. And the deflection angle ~ drops rapidly from an initial value of approximate 80° and decreases slowly as A is greater than 20% without a steady level like a. The values of these parameters agree well with the previously reported observations in Arctic. The ridging intensity is an important parameter to determine the dominant contribution of the ratio of skin friction drag coefficient （Cs＇/Cs） and the ratio of ridge form drag coefficient （Cr＇/Cr） to the value of Ca/Cw, a, and 8, because of the dominance of ridge form drag for large ridging intensity and skin friction for small ridging intensity among the total drag forces. Parameterization of sea ice drag coefficients has the potential to be embedded into ice dynamic models to better account for the variability of sea ice in the transient Arctic Ocean.展开更多
The seasonal cycle of ice thickness and temperature in Lake Wuliangsuhai,a typical shallow lake in the central Asian arid climate zone,was simulated using the HIGHTSI model and the MERRA-2 data as the meteorological f...The seasonal cycle of ice thickness and temperature in Lake Wuliangsuhai,a typical shallow lake in the central Asian arid climate zone,was simulated using the HIGHTSI model and the MERRA-2 data as the meteorological forcing.The average ice growth rate was 0.64 cm·d^(−1) and −1.65 cm·d^(−1) for the growth and melting stage of the ice cover,respectively.The ice thickness agreed well with the field observations conducted in winter 2017,with a correlation coefficient of 0.97.The ice temperature field also agreed with observations in both daily variations and the vertical profile,and a better agreement in the daily amplitude and profile shape of ice temperature could be achieved if field data on physical properties of snow cover andmelting ice were available.This study proved the feasibility of both the HIGHTSI model and the MERRA-2 data for modeling the ice cover evolution in Lake Wuliangsuhai,providing a basis for a deep insight into the difference of lake ice evolution between central Asian arid climate zone and polar/sub-polar regions.展开更多
Leaf traits can directly reflect the adaptation strategies of plants to the environment.However,there is limited knowledge on the adaptation strategies of heteromorphic leaves of male and female Populus euphratica Oli...Leaf traits can directly reflect the adaptation strategies of plants to the environment.However,there is limited knowledge on the adaptation strategies of heteromorphic leaves of male and female Populus euphratica Oliv.in response to individual developmental stages(i.e.,diameter class)and canopy height changes.In this study,morphological and physiological properties of heteromorphic leaves of male and female P.euphratica were investigated.Results showed that both male and female P.euphratica exhibited increased leaf area(LA),leaf dry weight(LDW),leaf thickness(LT),net photosynthetic rate(P_(n)),transpiration rate(T_(r)),stomatal conductance(g_(s)),proline(Pro),and malondialdehyde(MDA)concentration,decreased leaf shape index(LI)and specific leaf area(SLA)with increasing diameter and canopy height.Leaf water potential(LWP)increased with increasing diameter,LWP decreased significantly with increasing canopy height in both sexes,and carbon isotope fraction(δ^(13)C)increased significantly with canopy height in both sexes,all of which showed obvious resistance characteristics.However,males showed greater LA,LT,P_(n),T_(r),and Pro than females at the same canopy height,and males showed significantly higher LA,SLA,LT,P_(n),T_(r),g_(s),and MDA,but lower LWP and δ_(1)3C than females at the same canopy height,suggesting that male P.euphratica have stronger photosynthetic and osmoregulatory abilities,and are sensitive to water deficiency.Moreover,difference between male and female P.euphratica is closely related to the increase in individual diameter class and canopy height.In summary,male plants showed higher stress tolerance than female plants,and differences in P_(n),g_(s),T_(r),Pro,MDA,δ_(13)C,and LWP between females and males were related to changes in leaf morphology,diameter class,and canopy height.The results of this study provide a theory for the differences in growth adaptation strategies during individual development of P.euphratica.展开更多
During the winter and spring of 2006, we investigated the sea ice physics and marine biology in the northwest Weddell Sea, Antarctica aboard R/V Polarstern. We determined the texture of each ice core and 71 ice crysta...During the winter and spring of 2006, we investigated the sea ice physics and marine biology in the northwest Weddell Sea, Antarctica aboard R/V Polarstern. We determined the texture of each ice core and 71 ice crystal thin sections from 27 ice cores. We analyzed 393 ice cores, their temperatures, 348 block density and salinity samples,and 311 chlorophyll a（Chl a） and phaeophytin samples along the cruise route during the investigation. Based on the vertical distributions of 302 groups of data for the ice porosity and Chl a content in the ice at the same position, we obtained new evidence that ice physical parameters influence the Chl a content in ice. We collected snow and ice thickness data, and established the effects of the snow and ice thickness on the Chl a blooms under the ice, as well as the relationships between the activity of ice algae cells and the brine volume in ice according to the principle of environmental control of the ecological balance. We determined the upper limits for Chl a in the brine volume of granular and columnar ice in the Antarctica, thereby demonstrating the effects of ice crystals on brine drainage, and the contributions of the physical properties of sea ice to Chl a blooms near the ice bottom and on the ice-water interface in the austral spring. Moreover, we found that the physical properties of sea ice affect ice algae and they are key control elements that modulate marine phytoplankton blooms in the ice-covered waters around Antarctica.展开更多
基金supported by the National Natural Science Foundation of China(Grant nos.42320104004 and 42276242)the National Key Research and Development Program of China(Grant no.2023YFC2809102).
文摘The study of Arctic sea ice has traditionally been focused on large-scale such as reductions of ice coverage,thickness,volumes and sea ice regime shift.Research has primarily concentrated on the impact of large-scale external factors such as atmospheric and oceanic circulations,and solar radiation.Additionally,Arctic sea ice also undergoes rapid micro-scale evolution such as gas bubbles formation,brine pockets migration and massive formation of surface scattering layer.Field studies like CHINARE(2008-2018)and MOSAiC(2019-2020)have confirmed these observations,yet the full understanding of those changes remain insufficient and superficial.In order to cope better with the rapidly changing Arctic Ocean,this study reviews the recent advances in the microstructure of Arctic sea ice in both field observations and laboratory experiments,and looks forward to the future objectives on the microscale processes of sea ice.The significant porosity and the cyclical annual and seasonal shifts likely modify the ice's thermal,optical,and mechanical characteristics,impacting its energy dynamics and mass balance.Current thermodynamic models,both single-phase and dual-phase,fail to accurately capture these microstructural changes in sea ice,leading to uncertainties in the results.The discrepancy between model predictions and actual observations strongly motivates the parameterization on the evolution in ice microstructure and development of next-generation sea ice models,accounting for changes in ice crystals,brine pockets,and gas bubbles under the background of global warming.It helps to finally achieve a thorough comprehension of Arctic sea ice changes,encompassing both macro and micro perspectives,as well as externaland internal factors.
基金The International Science and Technology Cooperation Project of China under contract No.2011DFA22260the National Natural Science Foundation of China under contract No.41276191+1 种基金the Public Science and Technology Research Funds Projects of Ocean by the State Oceanic Administration under contract No.201205007-05the Chinese Polar Environment Comprehensive Investigation & Assessment Program by the State Oceanic Administration under contract Nos 2013-02-04 and 2012-04-03-02
文摘A retrieval algorithm of arctic sea ice concentration （SIC） based on the brightness temperature data of “HY-2” scanning microwave radiometer has been constructed. The tie points of the brightness temperature were selected based on the statistical analysis of a polarization gradient ratio and a spectral gradient ratio over open water （OW）, first-year ice （FYI）, and multiyear ice （MYI） in arctic. The thresholds from two weather filters were used to reduce atmospheric effects over the open ocean. SIC retrievals from the “HY-2” radiom-eter data for idealized OW, FYI, and MYI agreed well with theoretical values. The 2012 annual SIC was calcu-lated and compared with two reference operational products from the National Snow and Ice Data Center （NSIDC） and the University of Bremen. The total ice-covered area yielded by the “HY-2” SIC was consistent with the results from the reference products. The assessment of SIC with the aerial photography from the fifth Chinese national arctic research expedition （CHINARE） and six synthetic aperture radar （SAR） images from the National Ice Service was carried out. The “HY-2” SIC product was 16% higher than the values de-rived from the aerial photography in the central arctic. The root-mean-square （RMS） values of SIC between “HY-2” and SAR were comparable with those between the reference products and SAR, varying from 8.57% to 12.34%. The “HY-2” SIC is a promising product that can be used for operational services.
基金supported by National Science and Technology Major Projects of China (Grant Nos. 2011ZX04016-011,2009ZX04010-022)
文摘Due to low damping ratio, fiat permanent magnet linear synchronous motor＇s vibration is difficult to be damped and the accuracy is limited. The vibration suppressing results are not good enough in the existing research because only the longitudinal direction vibration is considered while the normal direction vibration is neglected. The parameters of the direct-axis current controller are set to be the same as those of the quadrature-axis current controller commonly. This causes contradiction between signal noise and response. To suppress the vibration, the electromagnetic force model of the flat permanent magnet synchronous linear motor is formulated first. Through the analysis of the effect that direct-axis current noise and quadrature-axis current noise have on both direction vibration, it can be declared that the conclusion that longitudinal direction vibration is only related to the quadrature-axis current noise while the normal direction vibration is related to both the quadrature-axis current noise and direct-axis current noise. Then, the simulation test on current loop with a low-pass filter is conducted and the results show that the low-pass filter can not suppress the vibration but makes the vibration more severe. So a vibration suppressing strategy that the proportional gain of direct-axis current controller adapted according to quadrature-axis reference current is proposed. This control strategy can suppress motor vibration by suppressing direct-axis current noise. The experiments results about the effect of Kp and Ti on normal direction vibration, longitudinal vibration and the position step response show that this strategy suppresses vibration effectively while the motor＇s motion performance is not affected. The maximum reduction of vibration can be up to 40%. In addition, current test under rated load condition is also conducted and the results show that the control strategy can avoid the conflict between the direct-axis current and the quadrature-axis current under typical load. Adaptive PI control strategy can effectively suppress the flat permanent magnet linear synchronous motor＇s vibration without affecting the motor＇s performance.
基金financially supported by the National Natural Sciences Foundation of China(30060007)the National Basic Research Program of China(2012CB723204)the National Programs for Science and Technology Development of China(2013BAC10B01)
文摘The aims of this study were to explore the interspecific differences of Populus euphratica Oliv.and Populus pruinosa Schrenk populations and the intraspecific differences of males and females within the same species in flowering phenological traits,and the effects of temperatures on flowering phenological traits in different growth years(2001–2003 and 2013–2015).The results showed that P.euphratica population flowered earlier than P.pruinosa population.Moreover,flowering phenological period of population,number of days of flowering phenological period per population,number of days of flowering phenological period per plant and average number of days of flowering period per plant of P.euphratica population were less than those of P.pruinosa population.The differences between male and female within the same species indicated that the flowering periods of males P.euphratica and P.pruinosa populations were earlier than those of female plants.For both species,flowering phenological traits were significantly and negatively correlated with the average temperatures in previous ten days,previous one month and previous three months of flowering.Both species are sensitive to temperature changes and adjust to the changes by advancing the start of flowering and prolonging the duration of flowering.
基金supported by the EC-funded project DAMOCLES (grant 18509)which is part of the Sixth Framework Program of DFG(grant LU 818/1-1)Natural Science Foundation of China(grants No.40233032,40376006).
文摘Evolution of the Arctic sea ice and its snow cover during the SHEBA year were simulated by applying a high-resolution thermodynamic snow/ice model （HIGHTSI）. Attention was paid to the impact of albedo on snow and sea ice mass balance, effect of snow on total ice mass balance, and the model vertical resolution. The SHEBA annual simulation was made applying the best possible external forcing data set created by the Sea Ice Model Intercomparison Project. The HIGHTSI control run reasonably reproduced the observed snow and ice thickness. A number of albedo schemes were incorporated into HIGHTSI to study the feedback processes between the albedo and snow and ice thickness. The snow thickness turned out to be an essential variable in the albedo parameterization. Albedo schemes dependent on the surface temperature were liable to excessive positive feedback effects generated by errors in the modelled surface temperature. The superimposed ice formation should be taken into account for the annual Arctic sea ice mass balance.
基金The National Natural Science Foundation of China under contracts Nos 41276191 and 41306207the Public Science and Technology Research Funds Projects of Ocean under contract No.201205007-05the Global Change Research Program of China under contract No.2015CB953901
文摘Many interesting characteristics of sea ice drift depend on the atmospheric drag coefficient （Ca） and oceanic drag coefficient （Cw）. Parameterizations of drag coefficients rather than constant values provide us a way to look insight into the dependence of these characteristics on sea ice conditions. In the present study, the parameterized ice drag coefficients are included into a free-drift sea ice dynamic model, and the wind factor a and the deflection angle θ between sea ice drift and wind velocity as well as the ratio of Ca to Cw are studied to investigate their dependence on the impact factors such as local drag coefficients, floe and ridge geometry. The results reveal that in an idealized steady ocean, Ca/Cw increases obviously with the increasing ice concentration for small ice floes in the marginal ice zone, while it remains at a steady level （0.2-0.25） for large floes in the central ice zone. The wind factor a increases rapidly at first and approaches a steady level of 0.018 when A is greater than 20%. And the deflection angle ~ drops rapidly from an initial value of approximate 80° and decreases slowly as A is greater than 20% without a steady level like a. The values of these parameters agree well with the previously reported observations in Arctic. The ridging intensity is an important parameter to determine the dominant contribution of the ratio of skin friction drag coefficient （Cs＇/Cs） and the ratio of ridge form drag coefficient （Cr＇/Cr） to the value of Ca/Cw, a, and 8, because of the dominance of ridge form drag for large ridging intensity and skin friction for small ridging intensity among the total drag forces. Parameterization of sea ice drag coefficients has the potential to be embedded into ice dynamic models to better account for the variability of sea ice in the transient Arctic Ocean.
基金This research was supported by the National Natural Science Foundation of China(Grant nos.51979024,41876213,41676187)the Open Fund of State Key Laboratory of Frozen Soil Engineering(Grant no.SKLFSE201604)+1 种基金the Fundamental Research Funds for the Central Universities(Grant no.DUT20GJ206)Matti Leppäranta was supported by the Bilateral Exchange Programme of the Chinese Academy of Sciences and Academy of Finland(Grant no.325363).
文摘The seasonal cycle of ice thickness and temperature in Lake Wuliangsuhai,a typical shallow lake in the central Asian arid climate zone,was simulated using the HIGHTSI model and the MERRA-2 data as the meteorological forcing.The average ice growth rate was 0.64 cm·d^(−1) and −1.65 cm·d^(−1) for the growth and melting stage of the ice cover,respectively.The ice thickness agreed well with the field observations conducted in winter 2017,with a correlation coefficient of 0.97.The ice temperature field also agreed with observations in both daily variations and the vertical profile,and a better agreement in the daily amplitude and profile shape of ice temperature could be achieved if field data on physical properties of snow cover andmelting ice were available.This study proved the feasibility of both the HIGHTSI model and the MERRA-2 data for modeling the ice cover evolution in Lake Wuliangsuhai,providing a basis for a deep insight into the difference of lake ice evolution between central Asian arid climate zone and polar/sub-polar regions.
基金funded by the National Natural Science Foundation of China(U1803231,31860198,31060026)the Innovative Team Building Plan for Key Areas of Xinjiang Production and Construction Corps(2018CB003).
文摘Leaf traits can directly reflect the adaptation strategies of plants to the environment.However,there is limited knowledge on the adaptation strategies of heteromorphic leaves of male and female Populus euphratica Oliv.in response to individual developmental stages(i.e.,diameter class)and canopy height changes.In this study,morphological and physiological properties of heteromorphic leaves of male and female P.euphratica were investigated.Results showed that both male and female P.euphratica exhibited increased leaf area(LA),leaf dry weight(LDW),leaf thickness(LT),net photosynthetic rate(P_(n)),transpiration rate(T_(r)),stomatal conductance(g_(s)),proline(Pro),and malondialdehyde(MDA)concentration,decreased leaf shape index(LI)and specific leaf area(SLA)with increasing diameter and canopy height.Leaf water potential(LWP)increased with increasing diameter,LWP decreased significantly with increasing canopy height in both sexes,and carbon isotope fraction(δ^(13)C)increased significantly with canopy height in both sexes,all of which showed obvious resistance characteristics.However,males showed greater LA,LT,P_(n),T_(r),and Pro than females at the same canopy height,and males showed significantly higher LA,SLA,LT,P_(n),T_(r),g_(s),and MDA,but lower LWP and δ_(1)3C than females at the same canopy height,suggesting that male P.euphratica have stronger photosynthetic and osmoregulatory abilities,and are sensitive to water deficiency.Moreover,difference between male and female P.euphratica is closely related to the increase in individual diameter class and canopy height.In summary,male plants showed higher stress tolerance than female plants,and differences in P_(n),g_(s),T_(r),Pro,MDA,δ_(13)C,and LWP between females and males were related to changes in leaf morphology,diameter class,and canopy height.The results of this study provide a theory for the differences in growth adaptation strategies during individual development of P.euphratica.
基金The National Natural Science Foundation of China under contract Nos 51221961 and 41376186Chinese Arctic and Antarctic Administration for expedition and external cooperation foundations under contract No.IC201209the foundation of State Key Laboratory of Coastal and Offshore Engineering,Dalian University of Technology,China under contract No.SL14-5-3
文摘During the winter and spring of 2006, we investigated the sea ice physics and marine biology in the northwest Weddell Sea, Antarctica aboard R/V Polarstern. We determined the texture of each ice core and 71 ice crystal thin sections from 27 ice cores. We analyzed 393 ice cores, their temperatures, 348 block density and salinity samples,and 311 chlorophyll a（Chl a） and phaeophytin samples along the cruise route during the investigation. Based on the vertical distributions of 302 groups of data for the ice porosity and Chl a content in the ice at the same position, we obtained new evidence that ice physical parameters influence the Chl a content in ice. We collected snow and ice thickness data, and established the effects of the snow and ice thickness on the Chl a blooms under the ice, as well as the relationships between the activity of ice algae cells and the brine volume in ice according to the principle of environmental control of the ecological balance. We determined the upper limits for Chl a in the brine volume of granular and columnar ice in the Antarctica, thereby demonstrating the effects of ice crystals on brine drainage, and the contributions of the physical properties of sea ice to Chl a blooms near the ice bottom and on the ice-water interface in the austral spring. Moreover, we found that the physical properties of sea ice affect ice algae and they are key control elements that modulate marine phytoplankton blooms in the ice-covered waters around Antarctica.
