NPP/VIIRS多时相夜光遥感影像校正方法

针对NPP/VⅡRS影像含有短暂光源和背景噪声的问题,研究了月度影像的辐射特征,提出了多时相夜光遥感影像校正方法。该方法采用峰值特征化放大影像的辐射差异,通过卷积运算区分稳定像元与异常像元,结合最大熵阈值自适应滤波分割了卷积边界的混淆噪声。试验结果表明,该方法修正了原始影像的异常波动,剔除了异常像元,影像拟合经济数据的能力明显提升,弥补了夜光数据微观小尺度研究的缺失,可为社会经济数据动态评估提供新的途径。     

去除DMSP/OLS影像模糊的RTSVD算法

DMSP/OLS作为最早的夜光遥感数据具有很大的应用价值,解决该数据存在的模糊问题,能够大幅提高数据质量。本文分析模糊原因,提出了一种结合Pct影像发光频率滤波的正则化截断奇异值分解（RTSVD）算法,该算法能有效消除影像模糊现象并保留影像真实信息。首先考虑到光源像素发光频率必定高于非光源像素,利用Pct影像中的像素发光频率排除平均灯光影像中的非光源像素,然后利用L曲线求得正则化截断奇异值分解的截断参数,以此对影像进行分解重组。试验表明,结合Pct影像发光频率滤波的正则化截断奇异值分解法可在保留影像信息的基础上去除模糊现象。     

Depth influence on biochemical performance and thallus size of the red alga Gelidium corneum

Recent declines in the foundation species Gelidium corneum (Hudson) J.V. Lamouroux in pristine coastal stretches of the Southeastern Bay of Biscay have been documented in which individuals showed a high bleaching incidence. Among the potential factorsthat may be responsible for these changes in G. corneum abundance, it has been suggested that high levels of irradiance may be imposing stressful environmental conditions for shallow populations. Given that light is reduced exponentially as depth increases, in this investigation we examined the influence of depth on the stress of G. corneum by comparing the performance of several biochemical parameters and thallus size in plants collected at three different depths. The results revealed that plants growing in shallow waters showed lower antioxidant activity, lower concentrations of photosynthetic pigments (Chl‐a, total carotenoids, phycoerythrin), lower internal nitrogen levels (higher C:N ratio) and shorter thallus lengths than those living in deeper waters. Some of these results may be an expression of photoacclimation, but the low antioxidant activity and total carotenoid concentration detected in plants living in shallow waters suggest that the photoprotective mechanisms of G. corneum may have failed to offset photodamage. If so, our findings support previous studies that suggest that recent changes in solar radiation are partially responsible for G. corneum declines. Nevertheless, given that the metabolic performance of macroalgae is determined by the inter‐play of irradiance with other factors, including temperature and nutrient availability, further research is needed to reach a better understanding of the factors causing stress in G. corneum.     

光质对三角褐指藻光保护过程的影响

光能一方面驱动光合作用固定二氧化碳,另一方面当光能过剩就会对光合细胞产生氧化性损伤,甚至导致细胞死亡。硅藻等光合生物通过叶绿素荧光非光化学淬灭(NPQ)把过剩的光能转化为无害的热,达到保护细胞的目的。硅藻NPQ的诱导受硅甲藻黄素循环调节,并且与众多环境因子密切相关。作者通过对海洋环境的模拟,研究了不同光质下三角褐指藻(Phaeodactylum tricornutum)受到的影响测定并比较了红、绿、蓝3种单色光处理的三角褐指藻响应高光胁迫时的NPQ及硅甲藻黄素循环的差异。叶绿素荧光的结果显示,在相同的胁迫性强光和胁迫时间内,蓝光下处理的三角褐指藻形成的NPQ更高,而且胁迫阶段淬灭的荧光在低光阶段恢复的更快。色素测定的结果显示,3种单色光下处理的三角褐指藻的硅甲藻黄素循环的环脱氧比(DEPS)与对照组没有显著差异。实验结果表明,蓝光对三角褐指藻响应高光、形成NPQ至关重要。     

太平洋海底光缆中国段路由条件及评价

根据在太平洋海底光缆中国段路由勘察中所获得的多波束、侧扫声呐、浅地层剖面、海洋磁力、柱状取样等资料,结合勘察区的自然环境特征,对路由区的自然环境条件、海底工程地质条件进行了详细的分析,并对该段路由条件进行了综合评价。研究发现,此段路由在大陆架路由区海底地形平缓,平均坡度小于2°,其中发现沙波、麻坑、冲刷沟等轻微不良地貌因素,跨越了黏土/粉砂、砂砾、砾/固结砂海底,地震活动少,地壳稳定性好,适合海底光缆铺设;在大陆架与大陆坡结合带地形起伏大,最大落差达500 m,发育有海底峡谷、海槽、陡坎等海底地形,路由条件相对较差,综合所获资料,针对路由不良区域进行了适当调整,并提出应对措施。调整后的路由基本适合海底光缆的铺设。     

离体培养的虫黄藻(Symbiodinium voratum)对温度和光照的生理响应

虫黄藻是珊瑚礁生态系统中最主要的初级生产者,并在珊瑚礁的建造过程中起着关键作用。为探究虫黄藻对温度和光照的生理响应,本研究以E型虫黄藻（Symbiodinium voratum）为实验对象,通过室内培养,并结合谢尔福德耐受性定律建立了基于温度的虫黄藻生长速率的耐受性模型。结果显示：E型虫黄藻在光强90μE培养下,最适生长温度为22.56℃,适温范围为16.72—28.40℃;温度培养实验中,23℃时,虫黄藻中有机碳（C）、氮（N）积累最多; 27℃时,虫黄藻PSⅡ的原初光能转化效率（F_v/F_m）显著高于其余两个温度组;光照培养实验中,E型虫黄藻在温度23℃培养下,光强的适宜范围为100—200μE;并通过提高细胞内叶绿素a含量和F_v/F_m两种方式应对外界光照不足。     

High-order ghost imaging with N-colour thermal light

High-order ghost imaging with thermal light consisting of N different frequencies is investigated. The high-order intensity correlation and intrinsic correlation functions are derived for such N-colour light. It is found that they are similar in form to those for the monochromatic case, thus most of the conclusions we obtained previously for monochromatic Nth-order ghost imaging are still applicable. However, we find that the visibility of the N-colour ghost image depends strongly on the wavelength used to illuminate the object, and increases as this wavelength increases when the test arm is fixed. On the contrary, changes of wavelength in the reference arms do not lead to any change of the visibility.     

基于无人机可见光影像的紫菜养殖筏架信息提取方法及应用

海上紫菜养殖筏架分布无规律、大小不规则且数量较多,现场测量难度大、卫星影像空间分辨率低,不能精确测量出紫菜筏架面积。无人机机动性强、影像空间分辨率高,可在紫菜养殖调查中发挥重要作用。本研究以连云港海州湾紫菜养殖筏架为研究对象,开展可见光波段在养殖筏架与水体的光谱可区分度研究,基于6种植被指数,进行自动提取实验,以目视解译结果作为真值,进行精度分析,同时利用不同时相、不同区域的无人机可见光影像,开展方法的普适性研究。结果表明：绿色度坐标（green, G）和植被（vegetativen,VEG）指数方法在浅水区和深水区均表现较好,养殖筏架个数识别精度、面积识别精度均超过91.00%。基于此,利用上述两种方法,开展其他区域自动提取实验,养殖筏架个数识别精度、面积识别精度分别超过93.02%和89.37%。结果验证了无人机可见光影像可以实现紫菜养殖筏架的自动提取,精度基本满足紫菜养殖调查需求。     

额济纳绿洲胡杨的光合特征及其对光强和CO2浓度的响应

以额济纳绿洲胡杨(Populus euphratica Oliv)为研究对象,用美国Li-cor公司生产的Li-6400便携式光合作用测定仪测定其光合速率的日变化及控制光强、CO2浓度和温度等环境因子,阐述了光合速率对光强和CO2浓度的响应特征。结果表明:在生长季胡杨阳叶光合速率的日变化呈现双峰曲线,具有明显的光合“午休”现象,但胡杨阴叶光合速率的日变化呈单峰曲线。光照、温度和CO2浓度皆对胡杨的光合作用有显著的影响。在控制环境条件下,光合速率随光强或CO2浓度的升高而增大,分别遵循Farquhar模型和Michaelis-Menten模型;在不同CO2浓度下,光饱和点随CO2浓度的升高而增大,表观量子效率和光补偿点则随CO2浓度的升高而减小,但在相同的CO2浓度条件下,阳叶的光补偿点高于阴叶;在不同光强下,表观羧化效率也随光的增强而增大。CO2补偿点随光强的增强而有所下降,且在同等光强条件下,阴叶的CO2补偿点大于阳叶。