A New Method for In-Situ Measurement of Internal Solitary Waves Based on the Stimulated Raman Scattering in Optical Fibers

In-situ measurement of internal solitary waves(ISWs)is complicated in the ocean due to their randomness.At present,the ISWs are mainly detected by the chain structure of conductivity-temperature-depth systems(CTDs)or temperature sensors.The high cost limits the spatial resolution,which ultimately affects the measuring accuracy of the ISW amplitude.In this paper,we developed an experimental measurement system for detecting ISWs based on the stimulated Raman scattering in distributed optical fibers.This system has the advantages of high precision,low cost,and easy operation.The experimental results show that the system is consistent with CTDs in the measurement of vertical ocean temperature variation.The spatial resolution of the system can reach 1.0 m and the measuring accuracy of temperature is 0.2℃.We successfully detected 3 ISWs by the system in the South China Sea and two optical remote sensing images collected on May 18,2021,the same day of two detected ISWs,verify the occurrence of the measured ISWs.We used the image pairs method to calculate the phase velocity of ISW and the result is 1.71 ms^(-1).By extracting the distances between wave packets,it can be found that the semi-diurnal tide generates the detected ISWs.The impact of the tidal current velocity on the ISW in amplitude is undeniable.Undoubtedly,the system has a great application prospect for detecting ISWs and other dynamic phenomena in the ocean.

Jason-2高度计电离层GIM误差分析及修正研究

基于Jason-2高度计2015年地球物理数据集(GDR)38个周期太平洋海域的全球电离层图(GIM)电离层校正值和双频校正值的数据,分不同季度和不同纬度区域比较二者的差异,结果表明:GIM值与双频校正值之间存在明显的差异,GIM校正值普遍高于双频校正值,说明GIM高估了电离层路径延迟,GIM校正值与双频校正值的差异与季节和纬度区间有关。用梯度下降法得到GIM值的修正方程,将修正方程应用于2016年Jason-2的全年数据,修正后的GIM值与双频校正值十分接近,在各年份中均具有良好的适用性。在单频高度计不能使用电离层双频校正算法的情况下,可以利用不同季度和不同纬度区域的修正方程对同等高度的高度计GIM值进行修正以达到双频校正值的精度水平。

Fe^(3+) 偶联的Eosin-Y染料敏化Pt/ZnO可见光制氢活性

以浸渍法制备了Eosin-Y染料敏化的EY-Pt/ZnO和Fe^(3+)偶联的EY-Fe-Pt/ZnO光催化剂。利用XRD、UV-Vis漫反射光谱、FTIR光谱、XPS能谱和电化学方法对催化剂进行了表征。以三甲胺(TMA)为电子给体,考察了催化剂在可见光(λ≥420 nm)照射下的光催化分解水制氢活性。结果表明:Eosin-Y染料的敏化使Pt/ZnO对可见光有较强的吸收和放氢活性。Fe^(3+)离子偶联后提高了Eosin-Y染料在Pt/ZnO光催化剂表面的吸附,促进了光生电子-空穴的分离,使催化剂可见光制氢活性和稳定性得以提高。最佳条件下,经过8 h光照,Fe^(3+)离子偶联的催化剂EY(0.05)-Fe(0.003)-Pt/ZnO的制氢活性比单一用Eosin-Y染料敏化的催化剂EY(0.05)-Pt/ZnO的制氢活性提高了47%。

三维成像微波高度计对流层延迟估计模型研究

对流层延迟是引起高度计高程测量误差的重要来源,三维成像微波高度计(InIRA)相对于传统剖面高度计有着更大的天线视角范围,不能直接沿用其对流层延迟估计方法。文中以Sentinel-3A数据为基准,对常用的垂向对流层延迟估计模型进行对比筛选,并将筛选出来的模型进行适用于InIRA的改进,并结合第三方气象数据计算出改进后的模型结果并分析天线视角对干、湿对流层延迟估计值的影响。结果表明:干对流层延迟估计值受天线视角的影响较为明显,湿对流层延迟估计值受天线视角的影响较小。

Estimating the Baseline Error of Wide-Swath Altimeters Using Nadir Altimeters via Numerical Simulation

The baseline roll and length errors for wide-swath altimeters are major error sources in sea surface measurements that exhibit strong spatial characteristics in the cross-track direction.These errors can be identified and estimated in accordance with height differences at crossover points generated with nadir altimeters after excluding the interference from other error sources.Most of the wide-swath altimeter baseline estimation methods considered only the roll error in previous studies.A numerical simulation was conducted in this study using nadir altimeters to estimate the roll and length errors simultaneously to provide a selectable scheme for baseline error estimation and correction for future wide-swath altimeters.Results based on the parameters of the surface water and ocean topography mission and Sentinel-3A show that the correlation coefficient of the roll error between the estimated and simulated values is 0.89,while the correlation coefficient of the length error is 0.85.The sea surface height root mean square error(RMSE)can be reduced from 12.18 cm to 6.45 cm based on the two estimated results.The estimation effect can be increased by using multiple nadir altimeters to form an observation constellation.The numerical simulation of the five nadir altimeter constellation shows that the correlation coefficients of the roll and length errors would increase to 0.97,which reduces the sea surface height RMSE to 2.88 cm.In addition,the stability of this method is indicated in simulation experiments,which introduce different degrees of sea state errors.

利用星下点干涉相位法提高三维成像高度计测高精度

基线倾角是三维成像高度计获取海表面高度的一个重要参数。基线倾角误差造成的高程误差随着交轨距离增加而增大。微小的基线倾角误差在整个观测刈幅内会引起大幅度的高程测量误差,因此精确获得基线倾角值是十分必要的。星下点干涉相位与基线倾角具有较强的相关性,利用二者之间的关系进行基线倾角的计算可以获得比一般硬件测量更高的基线倾角测量精度,进而对基线倾角误差进行校正,以满足厘米级测高精度的需求。通过在仿真海面上进行基于几何关系模拟测量与高程重建,可以进行利用星下点干涉相位法校正基线倾角误差的研究。对已设定三维成像高度计的系统参数进行数值模拟,结果表明:在10-3 rad的干涉相位测量精度条件下,基线倾角精度可以达到0.03角秒,在10～60km刈幅范围内,对高程平均测量精度的影响由模拟硬件测量得到的0.36角秒对应的6.02cm降低至0.48cm,与理论计算结果一致,说明星下点干涉相位法能够有效地对基线倾角误差进行校正。