Quantitative estimation of submarine groundwater discharge using airborne thermal infrared data acquired at two different tidal heights     

Ki‐mook Kang  Duk‐jin Kim  Yunjee Kim  Eunhee Lee  Bong‐Gwan Kim  Seung Hee Kim  Kyoochul Ha  Dong‐Chan Koh  Yang‐Ki Cho  Guebuem Kim 《水文研究》2019,33(7):1089-1100

Submarine groundwater discharge (SGD) plays an important role in coastal biogeochemical processes and hydrological cycles, particularly off volcanic islands in oligotrophic oceans. However, the spatial and temporal variations of SGD are still poorly understood owing to difficulty in taking rapid SGD measurements over a large scale. In this study, we used four airborne thermal infrared surveys (twice each during high and low tides) to quantify the spatiotemporal variations of SGD over the entire coast of Jeju Island, Korea. On the basis of an analytical model, we found a linear positive correlation between the thermal anomaly and squares of the groundwater discharge velocity and a negative exponential correlation between the anomaly and water depth (including tide height and bathymetry). We then derived a new equation for quantitatively estimating the SGD flow rates from thermal anomalies acquired at two different tide heights. The proposed method was validated with the measured SGD flow rates using a current meter at Gongcheonpo Beach. We believe that the method can be effectively applied for rapid estimation of SGD over coastal areas, where fresh groundwater discharge is significant, using airborne thermal infrared surveys.  相似文献   

上层海洋对台风"凯萨娜"(2009)的响应特征   总被引：1，自引：1，他引：0  

王冠琳  李大伟  徐腾飞  滕飞  魏泽勋 《海洋科学》2019,43(9):1-11

本文利用多源卫星遥感数据和Argo浮标数据对2009年台风"凯萨娜"过后,南海上层海洋的物理和生态响应特征进行了分析。结果表明,"凯萨娜"引起的上升流流速最大可以达到1.6×10~(–3)m/s,台风过后,海表面温度(SST)下降显著,最大降温幅度可以达到6℃,海表面高度降低,先前存在的中尺度冷涡进一步加强。台风过后,沿着台风路径,叶绿素浓度升高,最大值可以达到2 mg/m~3以上,初级生产力升高到台风过境前的5倍。SST的最大降温中心与海面高度下降区域以及叶绿素浓度升高的区域一致。Argo数据表明台风诱发了强烈的垂向混合和艾克曼泵吸,不同位置处,垂向混合和艾克曼泵吸的强度不一样。通过混合和泵吸过程,台风可以把海洋内部的营养盐输送到海洋表层,对整个南海的物理和生态过程有重要影响。  相似文献   

近20年渤海叶绿素a浓度时空变化   总被引：3，自引：0，他引：3  

田洪阵  刘沁萍  Joaquim I. Goes  Helga do Rosario Gomes  杨萌萌 《海洋学报》2019,41(8):131-140

浮游植物作为食物链的基础，对海洋生态系统具有重要作用。渤海作为我国最大的内海和重要渔业生物的产卵场、育幼场和索饵场，该区浮游植物研究具有重要意义。叶绿素a浓度是反映浮游植物生物量的重要指标。利用Google Earth Engine平台，对1997–2010年的宽视场海洋观测传感器(SeaWiFS)叶绿素a浓度数据和2002–2018年的水色卫星中分辨率成像光谱仪传感器(MODIS Aqua)叶绿素a浓度数据进行合并，并研究其时空变化特征。研究表明，近20年来，渤海全年叶绿素a浓度增加了14.1%，且增加显著。叶绿素a浓度在所有季节都呈现增加趋势；除11月外，其他各月都呈现稳定或增加趋势。从滦河入河口沿岸至渤海海峡的渤海中部，叶绿素a浓度增加较明显。同时也分析了海洋表面温度、风速和降水量数据。夏季渤海周边区域降水量和风速增加以及秋季海表温度的降低都有助于同季叶绿素a浓度的升高。渤海浮游植物可能受陆源营养物质输入影响较大。  相似文献   

LED光色对欧洲舌齿鲈幼鱼抗氧化能力和消化能力的影响   总被引：1，自引：0，他引：1  

代明允  任纪龙  费凡  魏平平  马贺  高东奎  宋昌斌  喻胜  刘鹰 《海洋科学》2019,43(4):16-21

作者利用循环水养殖实验系统,研究了红、绿、白、黄、蓝5种光色对欧洲舌齿鲈(Dicentrarchus labrax)幼鱼抗氧化能力和消化能力的影响。结果表明,红光组的欧洲舌齿鲈幼鱼超氧化物歧化酶(SOD)活力显著高于其他光色组(P0.05),而绿、白、黄和蓝光色组的SOD活力没有显著性差异;红光组的还原型谷胱甘肽(GSH)含量显著高于其他光色组(P0.05),绿、白光组与黄、蓝光组的GSH含量之间有显著性差异(P0.05);红光组过氧化氢酶(CAT)活力显著高于其他光色组(P0.05),白光组的CAT活力显著低于其他光色组(P0.05)。黄光组的胃蛋白酶活力显著高于红、绿、白光组(P0.05),绿光组的胃蛋白酶活力显著低于其他光色组(P0.05);红、绿、蓝光组的淀粉酶活力要显著高于白、黄光组(P0.05),红、绿、蓝光组的淀粉酶活力没有显著性差异,黄、白光组的淀粉酶活力没有显著性差异;白光组纤维素酶活力显著高于其他光色组(P0.05),绿光组的纤维素酶活力显著高于红、蓝光组(P0.05),黄光组的纤维素酶活力和绿、红、蓝光组没有显著性差异。因此,欧洲舌齿鲈在红光下养殖,其体内的抗氧化能力强,能有效应对氧化应激,而在黄光或红光下养殖其消化能力更强。  相似文献   

紫刺参早期生长发育与体色形成的研究     

陈相堂  赵斌  李成林  韩莎  胡炜 《海洋科学》2019,43(6):95-101

本研究对紫刺参胚胎和幼体发育过程进行了显微观测,比较分析了其幼体早期生长情况与体色形成过程。结果表明:(1)在水温21.0±0.2℃条件下,紫刺参受精卵在受精10～15min后释放第一极体,5h 30min～6h 30min进入囊胚期, 18～20h发育成原肠胚; 30～34h进入耳状幼体阶段, 8～10d变态发育为樽形幼体, 12～14d发育成稚参;紫刺参胚胎和幼体发育时序与普通刺参无显著差异。(2)紫刺参早期发育中的樽形幼体发生率和附着变态率分别为58.4±4.7%和45.1±2.7%,高于普通刺参。(3)紫刺参浮游阶段后期随日龄增长表现出较普通刺参发育更快的优势,在日龄6～7d表现出显著差异(P0.05)。(4)紫刺参稚参在日龄35d前后自背部开始着色,50d～60d腹部开始着色,110d体表紫色转变近乎成参体色,完成变色过程。  相似文献   

Sea Level Prediction in the Yellow Sea From Satellite Altimetry With a Combined Least Squares-Neural Network Approach     

Jian Zhao  Yanguo Fan  Yuxiang Mu 《Marine Geodesy》2019,42(4):344-366

Accessible high-quality observation datasets and proper modeling process are critically required to accurately predict sea level rise in coastal areas. This study focuses on developing and validating a combined least squares-neural network approach applicable to the short-term prediction of sea level variations in the Yellow Sea, where the periodic terms and linear trend of sea level change are fitted and extrapolated using the least squares model, while the prediction of the residual terms is performed by several different types of artificial neural networks. The input and output data used are the sea level anomalies (SLA) time series in the Yellow Sea from 1993 to 2016 derived from ERS-1/2, Topex/Poseidon, Jason-1/2, and Envisat satellite altimetry missions. Tests of different neural network architectures and learning algorithms are performed to assess their applicability for predicting the residuals of SLA time series. Different neural networks satisfactorily provide reliable results and the root mean square errors of the predictions from the proposed combined approach are less than 2?cm and correlation coefficients between the observed and predicted SLA are up to 0.87. Results prove the reliability of the combined least squares-neural network approach on the short-term prediction of sea level variability close to the coast.  相似文献   

The southern Norwegian Sea during the last 45 ka: hydrographical reorganizations under changing ice‐sheet dynamics     

《第四纪科学杂志》2017,32(7):908-922

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Late Quaternary tephra layers around Raoul and Macauley Islands,Kermadec Arc: implications for volcanic sources,explosive volcanism and tephrochronology     

Phil Shane  Ian C. Wright 《第四纪科学杂志》2011,26(4):422-432

A suite of deep‐sea cores were collected along transects up to 100 km across the fore‐arc and back‐arc regions of the predominantly submarine Kermadec arc near Raoul and Macauley islands, southwest Pacific. The cores reveal a macroscopic tephra record extending back >50 ka. This is a significant addition to the dated record of volcanism, previously restricted to fragmented late Holocene records exposed on the two islands. The 27 macroscopic tephra layers display a wide compositional diversity in glass (～50–78 wt% SiO₂). Many tephra layers comprise silicic shards with a subordinate mafic shard population. This could arise from magma mingling and may reflect mafic triggering of the silicic eruptions. Broadly, the glass compositions can be distinguished on diverging high‐K and low‐K trends, most likely arising from different source volcanoes. This distinction is also reflected in the tephra records exposed on Raoul (low‐K) and Macauley (high‐K) islands, the likely source areas. Heterogeneous tephra comprising shards of both high‐ and low‐K affinity, silicic and mafic compositions, and more homogeneous tephra with subordinate outlier shard compositions, are best explained by post‐depositional mixing of separate eruption deposits or contemporaneous eruptions. Evidently, the slow sedimentation rates of the calcareous oozes (～10¹–10² mm ka^?1) were insufficient to adequately separate and preserve closely spaced eruption deposits. This exemplifies the difficulty in assessing eruption frequencies and magmatic trends, and erecting a tephrostratigraphy, using geochemical fingerprinting in such environments. Despite these difficulties, the ca. 5.7 ka Sandy Bay Tephra erupted from Macauley Island can be correlated over a distance of >100 km, extending east and west of the island, showing that the mostly submerged volcanoes are capable of wide tephra dispersal. Hence there is potential for developing chronostratigraphies for the southwest Pacific beyond the region covered by the extensive rhyolite marker beds from the Taupo Volcanic Zone. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

高分五号热红外传感器多通道SST反演     

崔文杰  李家国  李忠  朱利  王殿忠  张宁 《遥感学报》2020,24(7):852-866

2018-05高分五号（GF-5）卫星发射升空，其上搭载的全谱段成像仪在热红外8—13 μm谱段范围内具有4个温度反演通道（B09,B10,B11,B12），空间分辨率设计优于40 m，在国内民用传感器领域实现了由单通道向多通道、中空间分辨率向高空间分辨率的跨越式突破，使得GF-5卫星热红外数据在地表热环境遥感领域具有极其重要应用价值。本研究基于GF-5的4个热红外通道的通道响应函数，利用全球742条TIGR（Thermodynamic Initial Guess Retrieval）探空廓线数据，进行不同观测角度、水汽含量和海表发射率条件下的MODTRAN4.0（Moderate resolution atmospheric Transmittance and Radiance code4.0)辐射传输过程模拟，基于模拟结果分别对两通道、三通道和四通道劈窗算法海表温度SST（ Sea Surface Temperature）反演系数进行修订，并分析观测角度、水汽含量和海表发射率对不同通道组合的精度影响，并通过GF-5卫星实际反演的SST结果进行验证。GF-5全谱段成像仪SST反演两通道劈窗算法组合共有6种，即B09-B10、B09-B11、B09-B12、B10-B11、B10-B12、B11-B12；三通道劈窗算法组合共有4种，即B09-B10-B11、B09-B10-B12、B09-B11-B12、B10-B11-B12；四通道劈窗算法组合1种，即B09-B10-B11-B12。通过对不同通道组合形式研究发现，水汽含量对SST反演精度有较大的影响，且温度反演的精度随着水汽含量的增加而降低；其次是观测角度，SST反演精度随着观测天顶角的增大而降低；最后是发射率的影响，两通道、三通道和四通道劈窗算法SST反演精度随着发射率的变化总体在0.1 K以内变化。最后以大亚湾核电站周围海域为验证区，用GF-5热红外遥感影像进行SST的反演并做误差分析，结果表明B09-B10通道SST反演实际误差为0.57 K，反演精度较高，实际误差与理论模拟误差相差0.24 K，差异的来源主要包括辐射定标和传感器噪声等要素影响，其他通道形式反演精度有待于传感器响应稳定后进一步验证。  相似文献   

复杂卫星图像中的小目标船舶识别   总被引：1，自引：1，他引：0  

姚红革  王诚  喻钧  白小军  李蔚 《遥感学报》2020,24(2):116-125

船舶作为海上的重要目标,实现对船舶自动识别有重要的意义。针对卫星图像中云雾、海岸背景等复杂海情对船舶识别带来的干扰,以及小目标船舶高漏检率问题,本文提出一种多尺度深度学习模型训练策略,在此基础上构建了一种船舶识别的深度学习网络,该网络可分为多尺度训练、特征提取、生成目标建议区域、船舶分类这4个部分。首先,采用多尺度的训练策略,将多尺度的船舶样本送入网络中进行训练,这样在训练样本中加入了大量小目标船舶的样本,使网络充分提取到小目标船舶的特征;其次,通过卷积神经网络对目标船舶进行特征自适应提取;然后,目标区域建议网络可依据卷积神经网络提取到的特征,在图像中找到感兴趣目标区域,即框定船舶的位置;最后,通过多个全连接层的组合,将高维特征映射到一个4元组中,再运用分类函数输出每一类船舶的概率值,概率值最大的则为该船舶的类别。同时为解决云雾遮挡和海岸背景的干扰,采用了一种负样本增强学习的方法,在样本数据集中加入了大量只含有云雾和海岸背景的图片,进行负样本扩充,增强网络模型对云雾及海岸背景的特征学习能力,以此解决复杂海情的影响。实验结果表明,所提方法有效解决了复杂海情条件下的船舶识别难,以及小目标船舶识别难的问题,实现了复杂海情条件下的船舶识别。同时,与现有成熟的深度学习目标识别算法相比,本文算法的精确度和召回率分别提升了6.98%和18.17%,所训练的模型具有良好的泛化能力和鲁棒性。  相似文献