海冰中侧向传播光衰减系数的解析验证

The attenuation of lateral propagating light(LPL) in sea ice was measured using an artificial light source in the Canadian Arctic during the 2007/2008 winter. The apparent attenuation coefficient μ(λ) for lateral propagating light was obtained from the measured logarithmic relative variation rate. In this study an analytical solution based on the strict optical theories is developed to validate the measured result. There is a good consistency between theoretical solution and measured data, by which a quite simple but very rigorous relationship among the light source, measurement geometry, and measured irradiance is established. The attenuation coefficients acquired by measurement and theory are the diffusion attenuation as an apparent optical property of ice, independent of the light source and shining condition. The attenuation ability of sea ice should be caused by the microstructure of sea ice, such as crystal size, ice density, brine volume, air inclusion, etc. It also includes the leak from both interfaces by directional scattering. It is verified that the measuring approach is operational and accurate to measure the attenuation of the LPL. The solution from this study did not tell the connection among the extinction and the inclusions of sea ice theoretically because of insufficient understanding.     

Variation of diffuse attenuation coefficient of downwelling irradiance in the Arctic Ocean

The diffuse attenuation coefficient(Kd) for downwelling irradiance is calculated from solar irradiance data measured in the Arctic Ocean during 3rd and 4th Chinese National Arctic Research Expedition(CHINARE), including 18 stations and nine stations selected for irradiance profiles in sea water respectively. In this study, the variation of attenuation coefficient in the Arctic Ocean was studied, and the following results were obtained. First, the relationship between attenuation coefficient and chlorophyll concentration in the Arctic Ocean has the form of a power function. The best fit is at 443 nm, and its determination coefficient is more than 0.7. With increasing wavelength, the determination coefficient decreases abruptly. At 550 nm, it even reaches a value lower than 0.2. However, the exponent fitted is only half of that adapted in low-latitude ocean because of the lower chlorophyll-specific absorption in the Arctic Ocean. The upshot was that, in the case of the same chlorophyll concentration, the attenuation caused by phytoplankton chlorophyll in the Arctic Ocean is lower than in low-latitude ocean. Second, the spectral model, which exhibits the relationship of attenuation coefficients between 490 nm and other wavelength, was built and provided a new method to estimate the attenuation coefficient at other wavelength, if the attenuation coefficient at 490 nm was known. Third, the impact factors on attenuation coefficient, including sea ice and sea water mass, were discussed. The influence of sea ice on attenuation coefficient is indirect and is determined through the control of entering solar radiation. The linear relationship between averaging sea ice concentration(ASIC, from 158 Julian day to observation day) and the depth of maximum chlorophyll is fitted by a simple linear equation. In addition, the sea water mass, such as the ACW(Alaskan Coastal Water), directly affects the amount of chlorophyll through taking more nutrient, and results in the higher attenuation coefficient in the layer of 30–60 m. Consequently, the spectral model of diffuse attenuation coefficient, the relationship between attenuation coefficient and chlorophyll and the linear relationship between the ASIC and the depth of maximum chlorophyll, together provide probability for simulating the process of diffuse attenuation coefficient during summer in the Arctic Ocean.     

Characteristics of Underwater Irradiation in the Black Sea in Spring (1993 and 1995)

We present the data on the values of the coefficients of vertical attenuation and diffusive reflection of light in the Black Sea in spring 1993 and 1995, compute the depths of one-percent quantum irradiation and the parameter Μ specifying the fraction of attenuation of directed light as a result of scattering: Μ = σ/ɛ, and compare the characteristics of underwater irradiation in the sea in different seasons for 1989–1995. __________ Translated from Morskoi Gidrofizicheskii Zhurnal, No. 3, pp. 44–48, May–June, 2005.     

Monitoring regional sea ice of the Bohai Sea by SSM/I scattering index

SSM/I data on the Bohai Sea of China from 1994 to 1996 have been studied.The sea ice algorithms of calibration/validation such as the brightness temperature index [AES/YORK TBI (Hollinger et al.,1992)] and ocean scattering index [OSI (Ferraro et al.,1996, The Bulletin of the American Meteorological Society, 77(5), 891-905)] are not applicable to the detection of regional sea ice of mid-latitude Bohai area.This paper presents a method of the scatfeting index SI and polarization index PI to identify regional Bohai Sea ice.Numerical results of vector radiative transfer for a model of a layer of sea ice over ocean simulate the relationship between SI/PI and sea ice depth, and others.It is employed to categorize the SI/PI indexes for the detection of sea ice.     

Monitoring regional sea ice of the Bohai Sea by SSM/I scattering index

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Application of approximate formulae to analyse the spectral distribution of the light attenuation coefficient

An analysis is made of the spectral distribution curves of the light attenuation coefficient in natural water areas and artificial roily oils in sea water samples under various conditions of salinity and storage time, using the approximate formulae based on the Mie theory.     

北极阿蒙森湾一年冰物理和光学性质的观测研究

利用加拿大环极冰间水道系统研究项目,作者对2007年11月24日至2008年1月26日北极群岛阿蒙森湾海域秋冬季节一年冰的物理和光学性质进行了观测研究。结果显示,观测期间的海冰厚度整体在27～108 cm范围内变化,积雪厚度仅为0～6 cm。海冰温度、盐度和密度在冰内的分布特征为:海冰表层最低温度为–22.4℃,底层最高温度为–2.2℃,冰内温度随深度单调增大;盐度变化范围为3.30～11.70,冰内盐度剖面呈现“C”形,即表层和底层盐度较大,而中间层盐度较小;海冰的平均密度略大,为（0.91±0.03）g/cm3。通过观测人造光源在海冰中的透射辐射谱分布,发现一年冰的光谱透射辐射在490 nm和589 nm处呈明显的双峰结构,但随着海冰厚度的增加,双峰结构逐渐减弱,体现了海冰对于不同谱段辐射能衰减作用的差异。在可见光范围内,裸冰和雪覆冰的吸收率最小值出现在490 nm,在443～490 nm范围内二者的吸收率随波长增大而降低,在490～683 nm范围内二者的吸收率随波长增大而升高,但雪覆冰的吸收率在可见光范围内基本保持不变,体现了雪覆冰吸收率的光谱独立性。一年冰的谱衰减系数随波长呈“U”字形分布,紫光和红光谱段的衰减系数较大,中间谱段的衰减系数较小,589 nm波长的衰减系数最小,为1.7 m–1。将谱衰减系数在可见光范围内积分,得到一年冰的积分漫射衰减系数约为2.3 m–1,略高于多年浮冰的漫射衰减系数1.5 m–1。阿蒙森湾一年冰与加拿大海盆北部多年浮冰辐射光学性质的差异,主要源于陆源物质输入引起的海冰内含物组分的改变,而不同组分对光谱的吸收和散射性质不同,进一步导致了光学性质的整体变化。     

Effects of light intensity on Opsin4, Opsin5, and Pax6 expressions of the sea urchin Strongylocentrotus intermedius

The detection of light intensity and subsequent phototaxis are essential for the fitness of sea urchins in intertidal and shallow subtidal waters, where light intensity varies in accordance with the depth and other hydrographic conditions. The molecular basis of photoresponse, however, remains largely unknown. We compared the expression of SiOpsin4, SiPax6, and SiOpsin5 among tube feet, coelomocytes, gonads, and gut of the sea urchin Strongylocentrotus intermedius. All three genes showed the significantly highest expression in tube feet. To test whether r-opsin genes (for example, Opsin4) and Pax6 in tube feet, rather than chaopsin genes (for example, Opsin5), are involved in the molecular responses to light intensity, we investigated the expression of Opsin4, Pax6, and Opsin5 among four light intensities. Both Opsin4 and Pax6 expressions were significantly higher in the sea urchins at 1,500 lx than at 100, 300, and 700 lx, indicating a co-upregulation of Opsin4 and Pax6 expressions in sea urchins exposed to the high light intensity (for example, 1,500 lx). However, there was no significant difference of SiOpsin5 expression among the four light intensity groups. Consistent with our hypothesis, there was no significant difference in either Opsin4 or Pax6 expression between the two light intensity environments (low light intensity environment: 50–100 lx; high light intensity environment: 330–1400 lx). This indicates that positive phototaxis and negative phototaxis probably regulate the expression of Opsin4 and Pax6 to a similar level when sea urchins are exposed to the high and low light intensities, respectively. The present study provides new insights into the molecular basis of light intensity detection and subsequent phototaxis of eyeless species.     

The beam attenuation to chlorophyll ratio: an optical index of phytoplankton physiology in the surface ocean?

The particulate beam attenuation coefficient (c_p) is proportional to the concentration of suspended particles in a size domain overlapping that of the phytoplankton assemblage. c_p is largely insensitive to changes in intracellular chlorophyll concentration, which varies with growth irradiance (a process termed ‘photoacclimation’). Earlier studies have shown that the ratio of c_p:chlorophyll (i.e., c_p^*) exhibits depth-dependent changes that are consistent with photoacclimation. Similar relationships may likewise be expected in the horizontal and temporal dimensions, reflecting changes in mixing depth, incident irradiance, and light attenuation. A link between c_p^* and more robust photoadaptive variables has never been explicitly tested in the field. Here we use five historical field data sets to directly compare spatial and temporal variability in c_p^* with two independent indices of photoacclimation: the light-saturated, chlorophyll-normalized photosynthetic rate, P^b_opt, and the light-saturation index, E_k. For the variety of oceanographic conditions considered, a first-order correlation emerged between c_p^* and P^b_opt or E_k. These simple empirical results suggest that a relationship exists between a bio-optical variable that can potentially be retrieved remotely (c_p^*) and physiological variables crucial for estimating primary productivity in the sea.     

机载海洋激光雷达测量叶绿素a浓度、悬移质浓度和浅海深度的性能估计

以14:00时离水辐亮度作为背景光强度,模拟355nm激光雷达测量不同深度水层叶绿素a荧光的信噪比.分析体积衰减系数c、辐照度衰减系数k、散射系数b和透明度盘深度(SDD)的关系.最后模拟532nm激光雷达测量悬移质浓度的最大测量深度和误判率小于10%时的最大海底探测深度随SDD的变化.     

小尺度海底沉积物的声衰减特性研究

为研究小尺度海底沉积物样品的声衰减特性,作者提出了用声学探针测量海底沉积物声波幅值的新方法,对沉积物样品扰动小,两个测量点的距离可小于波长,为海底沉积物微观声衰减测量提供了新手段。作者用小于波长的间隔逐点测量了沉积物的压缩波幅值,数据分析表明沿沉积物柱状样全长的声衰减满足指数衰减模型。目前主要用同轴差距衰减测量法获得海底沉积物声衰减数据,但该方法不能辨识声衰减模型,因此不同海区的测量结果难以建立联系。对此作者又提出用声吸收系数反演的幅值比与声衰减系数反演的R值(两种幅值比的比值)作评价依据,分析了垂直轴差距衰减测量法获得的南海海底沉积物声衰减测量数据,发现部分沉积物样品声衰减的R值远大于1,其声衰减不满足指数衰减模型。在声衰减满足指数衰减模型的条件下,用Hamilton的声衰减和频率经验公式预报的南海沉积物声衰减比与作者用声学探针测量海底沉积物所得的声衰减比对比,通过对R值分析得出Hamilton的声衰减和频率经验公式可以预报南海沉积物声衰减比的范围。作者提出的声学探针测量海底沉积物声衰减的方法的优点是既能获得声衰减数据又能辨识声衰减模型,不同海区测量的沉积物声衰减比可用R值建立联系。     

The structure of the nearshore branch of the Tsushima current on the shelf off the San'in coast in summer

Current measurements were made at five moored stations over the continental shelf off the San'in coast of the Japan Sea for a month in the summer of 1980 to study the vertical structure of the nearshore branch of the Tsushima Current. The time-mean current for the observational period is 20 to 25 cm sec^–1 eastward near the surface and about 10 cm sec^–1 westward near the sea bottom except at the shallowest station. The time-mean current,i.e. the nearshore branch of the Tsushima Current is mainly due to the baroclinic modes. The currents are less variable in the first half of the observational period, but fluctuate with a several-day period in the latter half. The obtained current data were decomposed into barotropic and baroclinic modes to investigate the detailed characteristics of the fluctuations. In the latter half, the current fluctuations of the two modes with about a 5-day period are well correlated with each other, as the baroclinic mode lagging behind the barotropic mode by 12 hr. The barotropic current fluctuation is correlated to the sea level, with the former leading the latter by about 12 hr. The baroclinic current is correlated to the temperature at the subsurface layer with a shorter time lag.     

Western Arctic primary productivity regulated by shelf-break warm eddies

The response of phytoplankton to the Beaufort shelf-break eddies in the western Arctic Ocean is examined using the eddy-resolving coupled sea ice–ocean model including a lower-trophic marine ecosystem formulation. The regional model driven by the reanalysis 2003 atmospheric forcing from March to November captures the major spatial and temporal features of phytoplankton bloom following summertime sea ice retreat in the shallow Chukchi shelf and Barrow Canyon. The shelf-break warm eddies spawned north of the Barrow Canyon initially transport the Chukchi shelf water with high primary productivity toward the Canada Basin interior. In the eddy-developing period, the anti-cyclonic rotational flow along the outer edge of each eddy moving offshore occasionally traps the shelf water. The primary production inside the warm eddies is maintained by internal dynamics in the eddy-maturity period. In particular, the surface central area of an anti-cyclonic eddy acquires adequate light, nutrient, and warm environment for photosynthetic activity partly attributed to turbulent mixing with underlying nutrient-rich water. The simulated biogeochemical properties with the dominance of small-size phytoplankton inside the warm eddies are consistent with the observational findings in the western Arctic Ocean. It is also suggested that the light limitation before autumn sea ice freezing shuts down the primary production in the shelf-break eddies in spite of nutrient recovery. These results indicate that the time lag between the phytoplankton bloom in the shelf region following the summertime sea ice retreat and the eddy generation along the Beaufort shelf break is an important index to determine biological regimes in the Canada Basin.     

基于GAM的西北太平洋日本鲭资源丰度预测模型建立

日本鲭(Scomber japonicus)是西北太平洋重要的鱼类资源之一，科学预测日本鲭的资源丰度有利于其资源的合理开发和利用。本研究依据日本渔业机构提供的1987–2012年日本鲭太平洋群体的资源量数据，结合产卵场和渔场的海洋环境数据以及气候因子，使用广义加性模型对影响日本鲭太平洋群体的海洋环境和气候因子进行分析，筛选出有显著影响的因子并建立该群体的资源量预测模型。结果表明，与该群体资源量有显著关系的影响因子有:北极涛动指数、太平洋年代际振荡指数、渔场海表面高度、渔场海表面盐度和渔场海表面温度。基于赤池信息准则筛选出的4个资源量预测模型分析表明，包含北极涛动指数、渔场海表面高度和渔场海表面温度的模型有较好的预测效果，该模型的验证结果也通过了t检验(P<0.05)，可用于日本鲭太平洋群体资源量的预测。     

Fitness‐related consequences shed light on the mechanisms of covering and sheltering behaviors in the sea urchin Glyptocidaris crenularis

We know of no comparative assessment on the benefits and costs of long‐term covering and sheltering behaviors in sea urchins. The present study investigated the long‐term effects of conditions suitable for sheltering and covering behaviors on fitness‐related traits of sea urchins Glyptocidaris crenularis. In general, conditions suitable for covering and sheltering behaviors significantly affected the fitness‐related traits of G. crenularis in a long‐term laboratory study of 31 months. Glyptocidaris crenularis kept in conditions suitable for sheltering behavior (bricks with openings) showed significantly lower test size, body weight, organ (test, lantern, gonad and gut) weights, gonad index and slower gonad development than those kept in conditions suitable for covering behavior (presence of shells) and the control conditions (without conditions for covering and sheltering). However, the index of maximum pressure resistance of the test was significantly higher in G. crenularis kept in the sheltering conditions than those in the covering and control conditions. The present study provides new insight into the mechanisms of covering and sheltering behaviors and has implications for the conservation and aquaculture of sea urchins.     

一个可用于实时计算的太阳辐射模型

拓展了Smith等(1984)关于海面辐照度的数值算法,给出了一个可实时计算海面和海水中太阳辐射强度的模型,通过计算1998年9月24日—10月7日以及1999年4月28日—5月11日渤海表面太阳辐射量(两个时间段内的辐照总量误差分别为0.27%和6.67%),显示出该模型与实测结果良好的适应性。另外,模型还揭示在不考虑其它限制因素的前提下,当浮游植物生物量处于较小的状态时,海水中的太阳辐射能促进浮游植物的快速生长,但是当浮游植物的生物量增大到一定程度时,由于对太阳辐射的遮蔽作用增强,浮游植物的生长明显受到抑制。     

东北大西洋海洋捕捞渔获物营养级变化研究

东北大西洋是重要的海洋捕捞海域,该海域渔业栖息环境易受北极气候变化的影响。为此,本文基于1950-2012年东北大西洋FAO的渔获统计数据,对已开发的293种渔获物平均营养级(mTL)、营养级平衡指标(FIB)和渔获营养级分类(TrC)进行时间序列的统计,为进一步研究该海域渔业资源受北极气候变化的影响提供基础。研究认为,平均营养级(mTL)从1950年(mTL=3.71)下降至2012年(mTL=3.57),每年下降约0.02TL(r=-0.614;P<0.01),而近8年来营养级平衡指数持续下降。同时,研究表明,东北大西洋渔获物平均营养级和气候变化(海表温上升、北大西洋涛动和海冰缩减等)息息相关,其中渔获量出现高产值均在海表温异常年份:1956年、1976年和1997年。本文分析了东北大西洋渔获物营养级变动情况,为研究东北大西洋渔获组成变化与气候变化的关系提供研究基础,也为渔业资源的可持续开发提供了理论依据。     

Estimation of chlorophyll concentration from the specific fluorescence at 685nm in the upward irradiance just below the sea surface

An algorithm for estimating the chlorophyll concentration from the fluorescence intensity at 685nm in upward irradiance observed just below the sea surface is presented and discussed. The observed chlorophyll concentration is closely related to the ratio of the fluoresced quanta to the total incident quanta (downward plus upward quanta) in the spectral range between 350nm and 600nm. The correlation between them, however, is not good and the rate of increase of the ratio decreases as the chlorophyll concentration increases. This is due to the fact that the number of fluoresced quanta varies with attenuation of the incident light by various materials in the sea.A better correlation is obtained between the ratio of the fluoresced quanta to the upward quanta at wavelengths around 480nm. This is explained by the fact that dividing by the upward quanta at the appropriate wavelength compensates for apparent variation of fluorescence intensity with attenuation by the sea water. In this method, upward quanta at the four wavelengths of 480nm, 640nm, 685nm and 740nm are necessary for estimation of chlorophyll concentration. The quanta at 640nm and 740nm are used for interpolating the quanta at 685nm in the absence of fluorescence.It is also shown that the correlation of the observed chlorophyll concentration with the ratio of upward quanta at the wavelengths of 685nm and 480nm is also good. Use of this ratio is recommended for remote sensing of chlorophyll concentration since the number of spectral channels required by the remote multispectral imager can be minimized.     

海水叶绿素a现场测量仪研究

采用荧光测量方法研究成功的海水叶绿素a现场测量仪，是用于海上现场实时测量海洋中浮游植物体内叶绿素a含量的新型海洋仪器。本仪器采用低功耗、高强度、低重复频率、窄脉冲宽度的脉冲氙灯，为激发光源及相应的脉冲检测技术测量荧光信号。该仪器可在海表层至50m水深内任一日光强度下工作；测量海洋中浮游植物体内叶绿素a的浓度范围为1×10-6—1×10-9g／cm3；当仪器走航拖曳速度为2m／s时，其空间分辨度为1m，仪器具有海上现场测量实用价值。     

Summer dynamics of phytoplankton pigments and its correlation with the optical parameters of shelf waters in the Black Sea (2001–2002)

We study the space and time variations of the concentration of chlorophyll in the Black-Sea coastal zone (near Katsiveli) in summer 2001–2002. Typical vertical profiles of the pigments are presented. The relations between the concentration of chlorophyll and the optical parameters of seawater (including the Secchi depth, sea reflectance, effective wavelength of the upwelling radiation, and the vertical attenuation coefficient of light) are analyzed. The equations for the biological parameters of seawater and its optical characteristics are presented. __________ Translated from Morskoi Gidrofizicheskii Zhurnal, No. 3, pp. 36–51, May–June, 2006.