Inversion method of deflection of the vertical based on SWOT wide-swath altimeter data

The deflection of the vertical(DOV)is the key information in the study of ocean gravity field.However,in most areas,the precision of the prime component of DoV is significantly lower than that of the meridian component.To obtain higher accuracy and resolution of ocean gravity information,researchers have proposed a novel altimeter called the wide-swath altimeter.This altimeter allows for the simultaneous acquisition of high-precision and high-resolution two-dimensional measurements of sea surface height(SSH).In this paper,the Surface Water and Ocean Topography(SWOT)mission with a wide-swath altimeter on board is selected for research.One cycle of swoT sea surface height data is simulated to inverse the DOV in the Arabian Sea(45°E—80°E,0°-30°N),and the inversion results are compared with those of conventional altimeter data.The results demonstrate that the difference between the meridian and prime components derived from the inversion of swoT wide-swath data is minimal,significantly outperforming the inversion results of conventional nadir altimeter data.The advantage of swoT wide-swath altimeter lies in its ability to use the multi-directional geoid slope at any sea surface measurement point to invert the components in the meridian and prime directions.To investigate the impact of this advantage on inversion precision,this paper employs a method to calculate the gradient of the geoid in multiple directions to invert DoV components.The improvement effect of calculating the gradient of the geoid in multiple directions on the precision of DoV component is analyzed.It is found that the accuracy of DoV inversion has significantly improved with the increase of geodetic gradient calculation direction.In addition,the effects of various errors and grid spacing in SwoT wide sea surface height data on the precision of Dov inversion are also analyzed.

Retrieval of Antarctic sea ice freeboard and thickness from HY-2B satellite altimeter data

Antarctic sea ice is an important part of the Earth’s atmospheric system,and satellite remote sensing is an important technology for observing Antarctic sea ice.Whether Chinese Haiyang-2B(HY-2B)satellite altimeter data could be used to estimate sea ice freeboard and provide alternative Antarctic sea ice thickness information with a high precision and long time series,as other radar altimetry satellites can,needs further investigation.This paper proposed an algorithm to discriminate leads and then retrieve sea ice freeboard and thickness from HY-2B radar altimeter data.We first collected the Moderate-resolution Imaging Spectroradiometer ice surface temperature(IST)product from the National Aeronautics and Space Administration to extract leads from the Antarctic waters and verified their accuracy through Sentinel-1 Synthetic Aperture Radar images.Second,a surface classification decision tree was generated for HY-2B satellite altimeter measurements of the Antarctic waters to extract leads and calculate local sea surface heights.We then estimated the Antarctic sea ice freeboard and thickness based on local sea surface heights and the static equilibrium equation.Finally,the retrieved HY-2B Antarctic sea ice thickness was compared with the CryoSat-2 sea ice thickness and the Antarctic Sea Ice Processes and Climate(ASPeCt)ship-based observed sea ice thickness.The results indicate that our classification decision tree constructed for HY-2B satellite altimeter measurements was reasonable,and the root mean square error of the obtained sea ice thickness compared to the ship measurements was 0.62 m.The proposed sea ice thickness algorithm for the HY-2B radar satellite fills a gap in this application domain for the HY-series satellites and can be a complement to existing Antarctic sea ice thickness products;this algorithm could provide long-time-series and large-scale sea ice thickness data that contribute to research on global climate change.

LncRNA NALT通过调控Notch信号通路对H2O2诱导的人晶状体上皮细胞损伤的影响

目的探讨lncRNA NALT(简称NALT)对H_(2)O_(2)诱导的人晶状体上皮细胞损伤的影响及其作用机制。方法使用不同浓度H_(2)O_(2)处理人晶状体上皮SRA01/04细胞24 h,CCK-8和qRT-PCR检测细胞增殖活性及NALT表达水平。将NALT过表达质粒转染至SRA01/04细胞中,再经100μmol/L H_(2)O_(2)或联合10μmol/L Notch信号通路抑制剂DAPT干预24 h,CCK-8检测细胞增殖活性;DCFH-DA荧光探针标记法检测各组细胞ROS水平;化学法检测SOD活性和MDA含量;Annexin V-FITC/PI法检测细胞凋亡情况;Western blot检测细胞中Notch1和Hes1蛋白表达水平。结果随着H_(2)O_(2)干预浓度的增加,SRA01/04细胞增殖活性和NALT表达水平均呈剂量依赖性降低(P<0.05)。H_(2)O_(2)干预后,NALT过表达可显著提高SRA01/04细胞增殖活性和SOD活性,降低ROS、MDA及细胞凋亡水平,上调Notch1和Hes1蛋白表达水平(均P<0.05)。然而,联合DAPT干预可逆转NALT过表达对H_(2)O_(2)诱导的SRA01/04细胞损伤的保护作用。结论过表达NALT可改善H_(2)O_(2)诱导的人晶状体上皮细胞损伤,其机制可能与激活Notch信号通路有关。

Preliminary results of the global ocean tide derived from HY-2A radar altimeter data

The HY-2A satellite,which is equipped with a radar altimeter and was launched on August 16,2011,is the first Chinese marine dynamic environmental monitoring satellite.Extracting ocean tides is one of the important applications of the radar altimeter data.The radar altimeter data of the HY-2A satellite from November 1,2011 to August 16,2014 are used herein to extract global ocean tides.The constants representing the tidal constituents are extracted by HY-2A RA data with harmonic analysis based on the least squares method.Considering tide aliasing issues,the analysis of the alias periods and alias synodic periods of different tidal constituents shows that only the tidal constituents M_(2),N_(2),and K_(2)are retrieved precisely by the HY-2A RA data.The derived tidal constants of the tidal constituents M_(2),N_(2)and K_(2)are compared to those of tidal gauge data and the TPXO tide model results.The comparison between the derived results and the tidal gauge data shows that the RMSEs of the tidal amplitude and phase lag are 9.6 cm and 13.34°,2.4 cm and 10.47°,and 8.1 cm and 14.19°for tidal constituents M_(2),N_(2),and K_(2),respectively.The comparisons of the semidiurnal tides with the TPXO model results show that tidal constituents have good consistency with the TPXO model results.These findings confirm the good performance of HY-2A RA for retrieving semidiurnal tides in the global ocean.

鱼类鼻黏膜相关淋巴组织的研究进展

鱼类黏膜相关淋巴组织是抵御病原入侵的第一道防线。其中,鱼类鼻黏膜相关淋巴组织(nasal-associated lymphoid tissue,NALT)近年来被国内外学者所关注,并被证明是嗅觉器官中抗原识别和启动黏膜免疫应答的重要场所,在细菌、病毒和寄生虫感染后可发挥快速的局部免疫响应。以NALT为靶点,对鱼类开展疫苗鼻内接种可起到良好的免疫保护效果。但目前,对NALT中复杂的免疫细胞与分子网络及其互作机制知之甚少。本文对鱼类嗅觉器官结构与功能、NALT的细胞与分子网络及免疫应答、鼻内接种的应答及免疫保护效果等方面的最新研究进展进行综述,旨在阐明鱼类NALT在黏膜局部发挥的免疫防御机制,以期为新型黏膜疫苗的设计与研发提供参考。

高精度地形星载激光测高仪在轨几何标定方法

激光测高仪数字化标定方法由于标定频次高、人力物力消耗少等突出性优点越来越受到关注。本文提出了一种两步法的激光测高仪数字化标定方法,针对线性体制激光测高仪的几何定位模型,构建了关于翻滚角、俯仰角和测距系统误差的几何标定模型,并使用公开参考地形数据SRTM与高精度机载LiDAR点云进行了标定试验。与GF-14实际外场面探测器试验标定的数据比较分析。结果显示,本文提出的几何标定方法与地面探测器标定参数测角差异在0.5角秒以内,测距差异在0.2 m以内。通过独立数据验证标定结果的高程精度,本文提出的数字化标定方法和探测器标定方法的足印高程偏差表现出良好的一致性,两种方法标定所获取的足印高程与高精度机载点云高程的RMSE均优于0.3 m。本文方法在保证精度的同时,减少了人力物力的消耗,为星载激光测高仪在轨常态化标定提供了新的思路和方法。

梳状高度计编队探测海洋涡旋仿真分析

单颗星下点高度计卫星可进行一维海面高度测量,但时空分辨率较低,对涡旋的探测能力不足。梳状高度计卫星编队可提升海面高度时空分辨率,增强对涡旋的识别探测能力。为定量分析高度计编队下的涡旋探测能力,本文在黑潮延伸体海域开展观测仿真实验,对海平面高度进行沿轨采样,经优化插值算法处理后得到逐天海面高度异常数据场并进行涡旋识别与统计分析。此外,本文还同步开展了单颗星下点高度计和成像高度计卫星涡旋探测仿真实验及对比分析。结果表明,梳状高度计卫星编队在涡旋数量、极性、半径及振幅等方面识别效果较好,与成像高度计探测结果相近。

弓形虫复合黏膜疫苗滴鼻免疫小鼠诱导NALT和GALT黏膜部位的免疫应答

目的观察弓形虫复合黏膜疫苗滴鼻免疫小鼠诱导的鼻相关淋巴组织(NALT)和肠相关淋巴组织(GALT)黏膜部位的免疫应答,探讨弓形虫黏膜疫苗能否在感染起始阶段有效诱导免疫应答。方法将BALB/c小鼠随机分为免疫和对照组,免疫组小鼠以弓形虫复合黏膜疫苗20μl/只(20μgSTAg+1μgCT)滴鼻免疫2次(间隔2周),对照组PBS滴鼻。于末次滴鼻后14d颈椎脱臼处死小鼠,ELISA测定粪便和鼻咽冲洗液IgA抗体水平;计数NALT、NC及PP、IEL淋巴细胞数,免疫细胞化学法检测CD4+、CD8+T细胞亚群水平。结果免疫组小鼠粪便IgA和鼻咽冲洗液IgA抗体显著高于对照组(P<0.05)。NALT内淋巴细胞明显增生(P<0.05),其中CD4+、CD8+T细胞均有增生(P<0.01),CD4+/CD8+比值降低(P<0.05)。NC中淋巴细胞数明显升高(P<0.01),以CD4+T细胞水平为主(P<0.01)。GALT部位PP淋巴细胞增生显著(P<0.01),主要以CD4+T细胞为主;而IEL以CD8+T细胞增生为主(P<0.01),CD4+/CD8+比值降低(P<0.05)。结论弓形虫复合黏膜疫苗滴鼻免疫BALB/c小鼠可有效诱导NALT和GALT黏膜部位免疫应答。

Study of the ability of SWOT to detect sea surface height changes caused by internal solitary waves

Surface Water and Ocean Topography(SWOT)is a next-generation radar altimeter that offers high resolution,wide swath,imaging capabilities.It has provided free public data worldwide since December 2023.This paper aims to preliminarily analyze the detection capabilities of the Ka-band radar interferometer(KaRIn)and Nadir altimeter(NALT),which are carried out by SWOT for internal solitary waves(ISWs),and to gather other remote sensing images to validate SWOT observations.KaRIn effectively detects ISW surface features and generates surface height variation maps reflecting the modulations induced by ISWs.However,its swath width does not completely cover the entire wave packet,and the resolution of L2/L3 level products(about 2 km)cannot be used to identify ISWs with smaller wavelengths.Additionally,significant wave height(SWH)images exhibit blocky structures that are not suitable for ISW studies;sea surface height anomaly(SSHA)images display systematic leftright banding.We optimize this imbalance using detrending methods;however,more precise treatment should commence with L1-level data.Quantitative analysis based on L3-level SSHA data indicates that the average SSHA variation induced by ISWs ranges from 10 cm to 20 cm.NALTs disturbed by ISWs record unusually elevated SWH and SSHA values,rendering the data unsuitable for analysis and necessitating targeted corrections in future retracking algorithms.For the normalized radar cross section,Ku-band and four-parameter maximum likelihood estimation retracking demonstrated greater sensitivity to minor changes in the sea surface,making them more suitable for ISW detection.In conclusion,SWOT demonstrates outstanding capabilities in ISW detection,significantly advancing research on the modulation of the sea surface by ISWs and remote sensing imaging mechanisms.

基于近端算子PHMC的机载雷达高度表参数估计

传统雷达高度表参数估计算法在面对参数的高维特性时会出现过拟合情况,导致参数估计精确度降低。为此,提出一种新颖的基于近端算子修正的哈密顿蒙特卡洛(PHMC)算法,通过统计学的手段估计高程参数。首先假设高程参数具有稀疏特性,并使用拉普拉斯分布对其进行表征,这种稀疏先验可表征高程突变的地形场景。稀疏先验与似然函数之间为非共轭关系,使用分层贝叶斯的方法获得后验分布函数的闭合解,采用哈密顿蒙特卡洛(HMC)方法通过采样的方式解决贝叶斯推论中的参数估计问题,引入近端算子提供次梯度完成参数估计。仿真数据验证了所提PHMC算法优于其他传统算法。

高重频激光地面足印探测器峰检电路的设计

设计了一款两级峰值检测电路,实现对上升沿为3ns、脉宽为5ns、下降沿为3ns、重频为10kHz的脉冲信号的峰值检测与保持,利用STM32单片机的模数转换器完成电压信号采集。给出以APD为光电探测器件的地面探测器系统的基本结构框图,利用探测器系统中的放大电路模块使接收激光脉冲宽度从1ns展宽至5ns,搭配峰值检测电路模块实现窄脉宽、高重频激光信号的检测与数据记录。利用信号源完成峰值检测电路部分的功能测试,使用重频为1kHz、脉宽约为1ns的激光器完成探测器系统整体的功能测试,实验证明此系统可以较好地检测并记录该激光信号的峰值。

基于双频段雷达高度计数据的海面阵风反演研究

海面阵风是海洋资源开发、海洋防灾减灾和海洋科研等领域所需的重要海洋动力环境信息。但迄今为止,海面阵风观测数据严重缺失,阻碍了阵风预报、应用研究等方面的发展。本文利用双频的HY-2B卫星高度计C、Ku波段的后向散射系数,对现有海面风速(U_(10))进行修正,建立了阵风风速(U_(g))反演算法。反演结果与美国国家浮标数据中心(NDBC)2018-2022年的浮标数据进行真实性检验,相关系数(R)为0.91,均方根误差(RMSE)为1.82 m/s;国外同类卫星Jason-3基于本方法的反演结果与2018-2022年NDBC站点数据进行检验,RMSE优于常规2 m/s精度要求;反演结果与处于不同纬度的近海远洋站点进行个例验证,RMSE均优于2 m/s。因此,本文在现有的HY-2B卫星高度计海面风速观测数据的基础上,利用不同波段信息实现了海面阵风的观测,具有较高的观测精度。同时,该方法也适用于相同观测体制的国外卫星高度计。

Unveiling three-dimensional sea surface signatures caused by internal solitary waves:insights from the surface water ocean topography mission

Internal solitary waves(ISW),characterized by large amplitude and long propagation distance,are widespread in global oceans.While remote sensing images have played an essential role in studying ISWs,they mainly exploit two-dimensional image information.However,with the launch of the surface water ocean topography(SWOT)satellite on December 16,2022,a unique opportunity has emerged to capture wide-swath three-dimensional ISW-induced sea surface information.In this study,we examine ISWs in the Andaman Sea using data from the Ka-band Radar Interferometer(KaRIN),a crucial sensor onboard SWOT.KaRIN not only provides backscattering satellite images but also employs synthetic aperture interferometry techniques to retrieve wide-swath two-dimensional sea surface height measurements.Our observations in the Andaman Sea revealed the presence of ISWs characterized by dark-bright strips and surface elevation solitons.The surface soliton has an amplitude of 0.32 m,resulting in an estimation of ISW amplitude of approximately 60 m.In contrast to traditional two-dimensional satellite images or nadir-looking altimetry data,the SWOT mission’s capability to capture threedimensional sea surface information represents a significant advancement.This breakthrough holds substantial promise for ISW studies,particularly in the context of ISW amplitude inversion.

基于高度计辅助的GNSS欺骗干扰检测

气压高度计可以获得精确高程数据,且不受外界电磁干扰,利用气压高度计辅助全球导航卫星系统(global navigation satellite system,GNSS)进行欺骗检测具有显著优势。为了评估气压高度计在GNSS欺骗检测中的能力并提高检测概率,首先对系统误差进行建模分析,并利用差分整合移动平均自回归(autoregressive integrated moving average,ARIMA)模型对气压高度计和GNSS测量结果进行处理。同时,通过计算欧氏距离构建数据空间,提出一种基于移动方差的自适应门限检测方法。试验结果表明,在虚警率为10^(-6)的情况下,检测率达到了92%,所提方法能够在高程信息上有效监测潜在的欺骗威胁,增强了GNSS系统的可靠性。

一种伪码连续波体制的无线电高度表功能指标分解设计方法

文章分析了伪码测距体制无线电测高功能的基本原理和基于伪码测距体制的指标体系,重点研究无线电测高功能的各个组成部分分解各端到端的设计指标是否能满足用户需求,并通过天线仿真各种可能指标,验证指标分解方法的合理性,为后续的无线电测高功能设计提供指标分解思路,也为后续无线电高度表功能方案改进提供数据参考。

基于坡度检测与点密度自约束调整的LOLA地理定位误差校正

月球轨道器激光高度计(Lunar Orbiter Laser Altimeter, LOLA)是目前月球探测中获取数据量最大、精度最高的激光高度计,可为其他月球产品提供地理控制。然而由于定轨不确定性和激光指向偏差,部分激光剖面存在地理定位误差。针对这些异常轨道数据,提出了一种改进的激光自约束调整方法。首先基于坡度将与周围地形差异过大的激光剖面识别为异常轨,并使用其余轨道作为参考对其进行基于点密度的自约束轨道调整(根据参考点密度自动选取合适的调整策略),最后合并两类轨道数据并进行最终调整,再将其作为改正后的结果。交叉点分析结果表明,该方法能有效校正异常轨道,从而提升数据精度。

无基点海洋重力测量数据归算补救方法

针对海洋重力测量中可能出现基点信息缺失(也就是无有效基点信息,统称无基点)的一些特殊情况,在分析评估国际上近期发布的全球重力位模型和卫星测高重力模型的可靠性及有效性基础上,提出了利用前述两类模型作为海域重力场中长波控制基准,进而开展无基点海洋重力测量数据归算的补救方法研究,给出了数据归算的流程和步骤,分析评估了补救处理方法的适用条件和精度水平,使用海上实际观测数据对推荐的补救方法进行了有效性验证,证明将两类模型应用于无基点海洋重力测量数据补救处理是有效可行的。

无线电高度表出现异常数据问题与对策研究

无线电高度表是飞机上的重要航空设备之一,它通过无线电波测量飞机距离地面的高度,为飞行员提供关键的高度信息。然而,在实际飞行操作中,无线电高度表出现异常数据的情况时有发生。这些异常数据可能由多种因素引起,包括设备故障、电磁干扰、误操作等。这些异常数据如果未能及时发现和处理,可能会对飞行安全产生严重的影响,甚至导致事故发生。基于此,本文首先讨论无线电高度表出现异常数据问题,然后深入探讨解决对策,以供参考。

家兔鼻腔的形态学特点及NALT分布规律的研究

为探讨鼻相关淋巴组织(nose-associated lymphoid tissue,NALT)在鼻腔的分布特点,将20只健康成年家兔鼻腔依次分为Ⅰ、Ⅱ、Ⅲ、Ⅳ和Ⅴ5段,通过大体解剖观察和组织切片染色,对每段的形态与NALT的分布特征进行研究。结果显示,家兔鼻腔从前向后依次主要被上颌鼻甲、鼻鼻甲和筛鼻甲所占据;鼻黏膜上皮从前向后依次为复层扁平上皮、变移上皮与呼吸上皮,嗅上皮,分别对应鼻腔前庭区、呼吸区和嗅区。特别是在Ⅲ、Ⅳ段鼻腔的腹鼻道底部侧壁的固有层中,存在长度约1.5 cm^2.0cm的长条状淋巴集结,其上覆有一单层网状上皮,上皮内可见大量淋巴细胞和浆细胞;同时,在Ⅲ、Ⅳ段其他位置及第Ⅴ段鼻咽管侧壁,其黏膜固有层内可见孤立淋巴滤泡分布;此外,各段鼻甲骨和鼻腔侧壁的黏膜固有层中,也有弥散淋巴组织和散在的淋巴细胞分布。结果证明,家兔鼻腔有丰富的鼻黏膜相关淋巴组织,且主要成条状分布于Ⅲ、Ⅳ段左右鼻腔的腹鼻道底部侧壁上。这些结果为进一步研究家兔NALT的功能特点提供了依据。

Absolute calibration of HY-2A and Jason-2 altimeters for sea surface height using GPS buoy in Qinglan, China

GPS buoy methodology is one of the main calibration methodologies for altimeter sea surface height calibration. This study introduces the results of the Qinglan calibration campaign for the HY-2A and Jason-2 altimeters. It took place in two time slices;one was from August to September 2014, and the other was in July 2015. One GPS buoy and two GPS reference stations were used in this campaign. The GPS data were processed using the real-time kinematic (RTK) technique. The fi nal error budget estimate when measuring the sea surface height (SSH) with a GPS buoy was better than 3.5 cm. Using the GPS buoy, the altimeter bias estimate was about -2.3 cm for the Jason-2 Geophysical Data Record (GDR) Version ‘D' and from -53.5 cm to -75.6 cm for the HY-2A Interim Geophysical Data Record (IGDR). The bias estimates for Jason-2 GDR-D are similar to the estimates from dedicated calibration sites such as the Harvest Platform, the Crete Site and the Bass Strait site. The bias estimates for HY-2A IGDR agree well with the results from the Crete calibration site. The results for the HY-2A altimeter bias estimated by the GPS buoy were verifi ed by cross-calibration, and they agreed well with the results from the global analysis method.