Updating the Continuous Plankton Recorder: an improved tool for integrated plankton monitoring   总被引：1，自引：0，他引：1  

Mills  D. K.; Walne  A.; Reid  P. C.; Heaney  S. I. 《ICES Journal of Marine Science》1998,55(4):814-817

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Temporal variability of chlorophyll in Narragansett Bay, 1973-1990     

Li  Yaqin; Smayda  Theodore J. 《ICES Journal of Marine Science》1998,55(4):661-667

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Effect of sampling frequency on detection of natural variability in phytoplankton: unattended high-frequency measurements on board ferries in the Baltic Sea     

Rantajarvi  Eija; Olsonen  Riitta; Hallfors  Seija; Leppanen  Juha-Markku; Raateoja  Mika 《ICES Journal of Marine Science》1998,55(4):697-704

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大亚湾冬季水位的亚潮变化及其与南海的耦合   总被引：1，自引：0，他引：1  

李立 《台湾海峡》1998,17(4):383-390

本文应用常规时间序列谱分析方法和频域的多输入线性模型研究了冬季广东省大亚湾内水位的亚潮变化及其与大亚湾本地和外海远处各种强迫作用因素间的关系。结果表明：冬季在亚湾亚潮水位的能量主要集中在６．４ｄ和３．６ｄ频带,而在１０．７ｄ频带还有一较弱谱峰,同期广东沿海风的低频能量也主要集中于２－７ｄ频段。造成冬季亚潮水位变化的原因包含了大亚湾本地气象条件的影响,但主要是远地因素作用于大亚湾的结果。外海影响一方  相似文献   

The Effect of Chessboard Variability of the Surface Fluxes on the Aggregated Turbulence Fields in a Convective Atmospheric Surface Layer   总被引：1，自引：1，他引：0  

Jun Asanuma  Wilfried Brutsaert 《Boundary-Layer Meteorology》1999,91(1):37-50

To what degree the variability of surface features can be identified in the turbulent signals observed in the atmospheric boundary layer is still an unresolved problem. This was investigated by conducting an analytical experiment for a one-dimensional 'chessboard'-type surface-flux distribution on the basis of local free convection scaling. The results showed that, due to their nonlinear dependency on the surface fluxes, the dimensionless gradients of the mean quantities and the dimensionless standard deviations are altered by the surface-flux variability. Furthermore, passive scalars, such as humidity, are considerably more sensitive to surface variability than the main active scalar, temperature. However, the response of the gradients of the mean quantities is fairly negligible in the range of variability studied herein as compared to that of the standard deviations, which were found to be more sensitive to the surface-flux variability. In addition, the phase difference between the active and the passive scalar flux distribution strongly affects the passive scalar turbulence. This dissimilarity between passive and active scalars, or between passive scalars when their source distributions are different, brings into question the use of variance methods for the measurement of a scalar flux, such as evaporation, over variable surfaces. The classical Bowen ratio method, which depends on the validity of the Reynolds analogy for the vertical gradients of the mean quantities, was shown to be relatively more robust. However, under conditions of strong surface variability, it can also be expected to fail.  相似文献   

The Surface Albedo Of The Vatnajökull Ice Cap, Iceland: A Comparison Between Satellite-Derived And Ground-Based Measurements   总被引：1，自引：0，他引：1  

Carleen H. Reijmer  Wouter H. Knap  Johannes Oerlemans 《Boundary-Layer Meteorology》1999,92(1):123-143

The temporal and spatial variations in the surface albedo of the Vatnajökull ice cap, Iceland, are investigated. A time series of the surface albedo is composed for the summer of 1996 using satellite radiance measurements from the Advanced Very High Resolution Radiometer (AVHRR). This time series is compared with ground measurements carried out during a glacio-meteorological experiment during the same summer on the ice cap. The AVHRR is able to reproduce the development in time of the surface albedo fairly well. The large systematic differences found for some of the stations on the ice are attributed to sub-pixel-scale variations in the albedo. An attempt is made to confirm this hypothesis using satellite radiance measurements carried out by the Thematic Mapper (TM) and measurements made with a portable albedometer. The TM has a pixel size of 30 × 30 m whereas the pixel size of the AVHRR is 1 × 1 km. Although the TM measurements show greater variability in the albedo than do the AVHRR measurements, the large systematic difference remains. Measurements with the portable albedometer show a large spread in the albedo at sites with large systematic differences. This implies that the scale of the albedo variations is smaller than the scale of the AVHRR and TM pixels.  相似文献   

A Preliminary Study on the Polar Climate Predictability     

Wang Huijun 《大气科学进展》1999,16(3):361-366

Studies have revealed that predictability of the atmospheric general circulation is generally high in the tropics throughout the year and that there is some predictability in the Northern extra-tropical winter at-mospheric circulation through some patterns of tele connection. Predictability of the general circulation at the polar regions has still remained as a ‘cold’ topic and little has been known about this question. Based on a preliminary study on the predictability by using the Institute of Atmospheric Physics (IAP) general circulation model, it is found that the SST-related predictability of the Southern winter lower atmospheric circulation in Antarctica is reasonably high and that there is some predictability in the 500 hPa and 200 hPa geopotential height fields over Europe and the Okhotsk Sea region during the Northern winter. It is sug-gested that more researches on this issue based on data analysis and model simulations are needed to obtain better understanding.  相似文献   

初论变异性不整合--以滇西北中甸地区为例   总被引：5，自引：0，他引：5  

葛孟春  冯庆来  江元生 《地球科学》1999,24(6):563-567

通过对滇西北中甸地区１：５万地质填图,并结合地质构造综合研究,首次提出了下三叠统布伦组与下伏上古生界为变异性不整合的新看法,它是在大陆引张环境下形成的一种层接触关系,主要识别标志是：区域性强烈起伏的不整合面;下伏基盘伸 引张环境玄武岩的发育;上覆沉积厚度显著变化、相变急剧;不整合表现形式多样,以及“基质”＋“岩块”的图面效应,它的识别对地质填图、地质构造演化以及构造运动的时空论形式等方面的研究具有  相似文献   

Transverse Dispersion of a Kinetically Sorbing Solute     

A. K. Mishra  A. Gutjahr 《Mathematical Geology》1999,31(7):771-791

A recursion formulation for the transverse spreading of a solute is developed, and under conditions of steady flow in a stratified aquifer, the transport of a linearly sorbing solute undergoing nonequilibrium sorption is studied. The effect of spatial variability in the velocity field and the sorption kinetics are modeled to see the combined effect of the two processes on the spreading of the solute injected at a point in the aquifer. The main result of this work is a transport model based on a discrete formulation that includes local dispersion and leads to nonasymptotic behavior in the spreading of the plume in a direction normal to the mean flow velocity.  相似文献   

Seasonal Variation in the Phytoplanktonic Community,Seston and Environmental Variables During a 2-Year Period and Oyster Growth at Two Mariculture Sites,Southern Chile     

Jorge E. Toro  Pamela I. Paredes  Darío J. Villagra  Carolina M. Senn 《Marine Ecology》1999,20(1):63-89

Phytoplankton and its relationships with physical and chemical variables were analysed over a 2-year period in Hueihue and Linao Bays (southern Chile). Samples were collected on a monthly basis from May 1991 to May 1993. The growth rate of a single stock of hatchery-produced oysters (Ostrea chilensis) distributed between these two bays was also monitored monthly. The growth rate of oysters maintained at Linao Bay (site associated with a fish farm) was significantly higher, at every depth, compared with the oysters maintained at Hueihue Bay. Temperature and salinity values and their annual fluctuations were similar at both locations, presenting higher variations at the surface (1 m) due to the influence of air temperature and local precipitation than at depth. However, significant differences in phytoplankton abundance and composition were found between the two locations. The phytoplankton community was characterized by high biomass values during spring and summer, the dominance of diatoms and an inverse relationship between temperature and species diversity. However, phytoplankton cell abundance, biovolume and chlorophyll a concentration were significantly higher at Linao at every depth sampled. Cell abundance ranged between 4.49 × 10⁴ and 7.45 × 10⁶ cells · l^?1 in Hueihue and between 6.48 × 10⁴ and 8.71 × 10⁶ cells ·1^?1 in Linao. The influence of temperature on chlorophyll a concentration was significant except at 8 m at both locations. The instantaneous oyster growth rate was found to be positively correlated with temperature, chlorophyll a concentration and particulate organic matter at both locations. A significant negative relationship between oyster growth and amount of particulate inorganic matter was found; this confirms the important role played by seston composition in oyster growth. The demonstration of variation in oyster growth rate associated with differences in food availability between the two locations provides insight into the ecological role played by fish farms in southern Chile. The results suggest a strong link between food availability and oyster growth.  相似文献