Spatial variability in the partial pressures of CO2 in the northern Bering and Chukchi seas

In the summers of 1999 and 2003, the 1st and 2nd Chinese National Arctic Research Expeditions measured the partial pressure of CO₂ in the air and surface waters (pCO₂) of the Bering Sea and the western Arctic Ocean. The lowest pCO₂ values were found in continental shelf waters, increased values over the Bering Sea shelf slope, and the highest values in the waters of the Bering Abyssal Plain (BAP) and the Canadian Basin. These differences arise from a combination of various source waters, biological uptake, and seasonal warming. The Chukchi Sea was found to be a carbon dioxide sink, a result of the increased open water due to rapid sea-ice melting, high primary production over the shelf and in marginal ice zones (MIZ), and transport of low pCO₂ waters from the Bering Sea. As a consequence of differences in inflow water masses, relatively low pCO₂ concentrations occurred in the Anadyr waters that dominate the western Bering Strait, and relatively high values in the waters of the Alaskan Coastal Current (ACC) in the eastern strait. The generally lower pCO₂ values found in mid-August compared to at the end of July in the Bering Strait region (66–69°N) are attributed to the presence of phytoplankton blooms. In August, higher pCO₂ than in July between 68.5 and 69°N along 169°W was associated with higher sea-surface temperatures (SST), possibly as an influence of the ACC. In August in the MIZ, pCO₂ was observed to increase along with the temperature, indicating that SST plays an important role when the pack ice melts and recedes.     

Primary production in the eastern tropical Pacific: A review

The eastern tropical Pacific includes 28 million km² of ocean between 23.5°N and S and Central/South America and 140°W, and contains the eastern and equatorial branches of the north and South Pacific subtropical gyres plus two equatorial and two coastal countercurrents. Spatial patterns of primary production are in general determined by supply of macronutrients (nitrate, phosphate) from below the thermocline. Where the thermocline is shallow and intersects the lighted euphotic zone, biological production is enhanced. In the eastern tropical Pacific thermocline depth is controlled by three interrelated processes: a basin-scale east/west thermocline tilt, a basin-scale thermocline shoaling at the gyre margins, and local wind-driven upwelling. These processes regulate supply of nutrient-rich subsurface waters to the euphotic zone, and on their basis we have divided the eastern tropical Pacific into seven main regions. Primary production and its physical and chemical controls are described for each.Enhanced rates of macronutrient supply maintains levels of primary production in the eastern tropical Pacific above those of the oligotrophic subtropical gyres to the north and south. On the other hand lack of the micronutrient iron limits phytoplankton growth (and nitrogen fixation) over large portions of the open-ocean eastern tropical Pacific, depressing rates of primary production and resulting in the so-called high nitrate-low chlorophyll condition. Very high rates of primary production can occur in those coastal areas where both macronutrients and iron are supplied in abundance to surface waters. In these eutrophic coastal areas large phytoplankton cells dominate; conversely, in the open-ocean small cells are dominant. In a ‘shadow zone’ between the subtropical gyres with limited subsurface ventilation, enough production sinks and decays to produce anoxic and denitrified waters which spread beneath very large parts of the eastern tropical Pacific.Seasonal cycles are weak over much of the open-ocean eastern tropical Pacific, although several eutrophic coastal areas do exhibit substantial seasonality. The ENSO fluctuation, however, is an exceedingly important source of interannual variability in this region. El Niño in general results in a depressed thermocline and thus reduced rates of macronutrient supply and primary production. The multi-decadal PDO is likely also an important source of variability, with the ‘El Viejo’ phase of the PDO resulting in warmer and lower nutrient and productivity conditions similar to El Niño.On average the eastern tropical Pacific is moderately productive and, relative to Pacific and global means, its productivity and area are roughly equivalent. For example, it occupies about 18% of the Pacific Ocean by area and accounts for 22–23% of its productivity. Similarly, it occupies about 9% of the global ocean and accounts for 10% of its productivity. While representative, these average values obscure very substantial spatial and temporal variability that characterizes the dynamics of this tropical ocean.     

莱州湾海湾扇贝养殖区海水中悬浮颗粒的动态变化

1997年10月和1998年6月，在莱州湾两个主要海湾扇贝养殖区－芙蓉岛海区和金城海区，各定点进行了24h连续观测和取样，并在实验室内分析了总颗粒物（TPM）、颗粒有机物（POM）和叶绿素α的含量。结果表明，6月份金城海区的颗粒有机物和叶绿素α的含量均高于荚蓉岛海区；在10月份，芙蓉岛海区颗粒有机物的含量高于金城海区，但其叶绿素α的含量却低于金城海区，表明金城海区颗粒有机物的质量高于芙蓉岛海区。     

Enhanced red fluorescence emission in the oxygen minimum zone of the Arabian Sea

 Depth profiles of fluorescence at several excitation and emission wavelengths were measured along with CTD data during the cruise So119 of RV Sonne in the Arabian Sea from 12 May to 10 June 1997. In addition to chlorophyll fluorescence from phytoplankton in the near-surface layer, the profiles in the oxygen minimum region well below the euphotic zone show enhanced red fluorescence. Red fluorescence intensity is inversely related to the oxygen concentration in intermediate and deep waters. A relationship to characteristic water masses of the region cannot be found in the data, and this holds also with chemical data such as DOC. Absorbance spectra of water samples taken in the oxygen minimum zone show an absorption band at 420 nm wavelength with about 50 nm bandwidth, much weaker than gelbstoff absorbance in the same wavelength range. The absorption band remains stable after sample filtration with 0.45 μm glass fibre filters. Hence, the size of the absorbing matter is in the range of dissolved molecules or particles much smaller than 1 μm. Fluorescence spectra of unfiltered samples with 420 nm excitation show a weak emission band at 600 nm and a more pronounced one at 660 nm wavelength. The trailing edge of the 660 nm band falls into the range of chlorophyll emission, thus giving rise to the observed depth profiles of red fluorescence in the oxygen minimum zone. Red fluorescence measured on samples remain stable during a few hours after sampling even in the presence of oxygen. It is not detectable after several weeks of sample storage in the dark and cannot be reproduced even after depletion of dissolved oxygen. Received: 22 May 2002 / Accepted: 18 February 2003 Responsible Editor: Andreas Oschlies Acknowledgements. This work was supported by a grant from the Federal Minister of Education and Technology, Bonn, within the frame work of the JGOFS Arabian Sea program. We are grateful to the captain and the crew of RV Sonne for their support. We are indebted to Mrs. Kirsten Neumann from the Institute of Marine Chemistry and Biogeochemistry of the University of Hamburg for providing the oxygen data, and to Mr. Nikolai Delling from the same institute for making the DOC and chlorophyll data available to us.     

浮游植物叶绿素a含量测定方法的比较测定

本文比较研究了浮游植物叶绿素ａ含量测定的２种常用方法－国内常用的丙酮萃取分光光度法和国际上较通用的热乙萃取分光光度法。实验结果显示：热乙醇法具有操作简便、快捷、萃取完全,低毒等优点。两种方法有显著统计差异及很好的相关性,其回归方程为：Ｃｈｌａ乙醇＝１．２６１Ｃｈｌａ丙醇－３．５（Ｒ＝０．９９８）。     

基于双隐层ANN模型的叶绿素a浓度智能预报方法

利用2019年5月WZ02生态浮标监测数据,建立了两种不同隐层人工神经网络(ANN)模型的叶绿素a(Chl-a)智能预报方法,并对单隐层和双隐层模型的预测结果做了对比.结果表明:双隐层结构预测结果精度更高,泛化能力更强,一定程度上说明了深层学习比浅层学习对信息的主要特征提取能力更有优势.同时,对数据样本集合进行了系统预...     

Estimation of Seasonal Sun-Induced Fluorescence Dynamics of Indian Tropical Deciduous Forests using SCOPE and Sentinel-2 MSI

This paper presents a new approach to estimate spatial Sun-Induced Fluorescence (SIF) using the empirical relationship between simulated Canopy Chlorophyll Concentration (CCC) and simulated SIF. PROSAIL model [PROpriétésSPECTrales (PROSPECT) and Scattering by Arbitrarily Inclined Leaves (SAIL) models] was used to simulate CCC. CCC maps were generated through an Automated Radiative Transfer Model Operator (ARTMO) using the PROSAIL model and Sentinel-2 Multi-Spectral Imager (MSI) imagery. The Soil Canopy Observation, Photochemistry, and Energy fluxes (SCOPE) model was used to simulate SIF emitted at 740 nm (SIF₇₄₀), at 760 nm (SIF₇₆₀), and top of canopy (SIF_TOC) (640-850 nm). The SCOPE model, configured with the specification of the Sentinel-2 sensor, simulates SIF within the spectrum range of 640-850 nm. A non-linear logarithmic relationship (R²>0.9, p < 0.05) was observed between simulated SIF and simulated CCC. Simulated CCC was linearly related to observed CCC with R² 0.88, 0.92 and 0.89 and RMSE = 0.04, 0.17 and 0.09 gm/m² at p < 0.05 for summer, post-monsoon and early winter respectively. Whereas, the simulated CCC did not capture the full range of CCC variability for the post-monsoon season. Simulated SIF (SIF₇₆₀) was well correlated with SIF from Orbiting Carbon Observatory-2 (OCO-2) satellite with R² 0.68, 0.73 and 0.73 (RMSE = <1 W/m²/sr/μm, p < 0.05) for the month of summer (April), pre-monsoon (May) and early winter season (November) respectively. Temporal SIF_TOC effectively captured the seasonal variability associated with the phenology of deciduous tree species. Among various Sentinel-2 MSI derived VIs, Red Edge NDVI (RENDVI) exhibited maximum sensitivity with SIF (highest monthly average R²> 0.6, p < 0.05). The spatial SIF would serve as an useful link between airborne /satellite derived SIF and in-situ fluorescence measurements to understand multiscale SIF variability of terrestrial vegetation.     

太湖水体光学衰减系数的特征及参数化

利用2001-2002年周年太湖全湖不同湖区湖泊光学及表层水样的实测资料,分析了太湖水体表层光学衰减系数与透明度、无机和有机颗粒物质及叶绿素a的相关关系,建立了表层水光学衰减系数与无机、有机颗粒物质及叶绿素a多元线性回归方程。结果表明,光学衰减系数与透明度的关系为：Kdg0.096 1.852/ST;表层水光学衰减系数与无机、有机颗粒物质及叶绿素a多元线性回归方程为：Kd=0.219 0.0768Ciss 0.214Cdet 0.006Cchl;光学衰减系数变化的主要影响因子是无机及有机颗粒物。     

东北季风期海南岛三亚湾初级生产力分布特征及其影响因素

根据2006年10月和2007年1月的监测资料,对三亚湾在东北季风初始期和盛行期初级生产力的分布特征及其受水体环境的影响因素进行了分析。三亚湾秋、冬季表层潜在初级生产力平均值分别为6.81mgC·m-3·h-1和7.47mgC·m-3·h-1;水柱初级生产力平均值分别为504.96mgC·m-2·d-1和495.33mgC·m-2·d-1。东北季风期间,三亚湾水体垂直混合作用加强,层化现象减弱,水动力过程和营养盐等环境因子是该海湾初级生产力分布特征和季节变化的重要调控因素;其中冬季较高的DIN分布对表层初级生产力有潜在促进作用,而水体扰动增强、真光层深度下降则导致水柱初级生产力低于秋季。三亚河口近岸水域秋、冬季均为营养盐、叶绿素a及初级生产力的高值区,其中表层潜在初级生产力在秋季和冬季分别达到了45.80mgC·m-3·h-1和39.27mgC·m-3·h-1,表明调查期间三亚河营养盐输入对近岸水体浮游植物初级生产过程的显著影响。