赤道东印度洋和孟加拉湾障碍层厚度的年际变化及其影响机制     

马天  程旭华  齐义泉  陈佳佳 《海洋学报(英文版)》2020,39(7):19-31

Interannual variability(IAV) in the barrier layer thickness(BLT) and forcing mechanisms in the eastern equatorial Indian Ocean(EEIO) and Bay of Bengal(BoB) are examined using monthly Argo data sets during 2002–2017. The BLT during November–January(NDJ) in the EEIO shows strong IAV, which is associated with the Indian Ocean dipole mode(IOD), with the IOD leading the BLT by two months. During the negative IOD phase, the westerly wind anomalies driving the downwelling Kelvin waves increase the isothermal layer depth(ILD). Moreover, the variability in the mixed layer depth(MLD) is complex. Affected by the Wyrtki jet, the MLD presents negative anomalies west of 85°E and strong positive anomalies between 85°E and 93°E. Therefore, the BLT shows positive anomalies except between 86°E and 92°E in the EEIO. Additionally, the IAV in the BLT during December–February(DJF) in the BoB is also investigated. In the eastern and northeastern BoB, the IAV in the BLT is remotely forced by equatorial zonal wind stress anomalies associated with the El Ni?o-Southern Oscillation(ENSO). In the western BoB, the regional surface wind forcing-related ENSO modulates the BLT variations.  相似文献   

深圳市连续运行参考站稳定性分析     

武曙光  聂桂根  邱蕾  汪善华 《测绘科学》2018,(6):78-82,87

针对深圳市连续运行参考站的稳定性分析相对较少的现状,基于深圳市2015年CORS数据,该文利用GAMIT软件计算并分析了参考站间基线以及与IGS站间基线的稳定性。结果表明,除因南山站点位异常引起了部分基线出现偏差外,大部分基线表现稳定且水平方向稳定性高于垂直方向。该文通过基线的稳定性分析方法,能够较为直观地检查出点位出现异常的参考站,这对于CORS站服务性能评估具有一定的参考意义。利用GLOBK软件平差得出了参考站坐标时间序列,并与PANDA的精密单点定位结果进行了对比分析;使用了SPSS软件的相关性分析法计算IGS站与参考站坐标变化的相关系数,得出SZCORS各参考站向东南方向偏移的趋势与板块漂移具有明显的相关关系这一结论。  相似文献   

基于差分GPS无人机交叉航线设计精度研究     

赵民  张会  唐鹏  邱文彬  蒋爱亲 《北京测绘》2018,32(6):658-661

GPS辅助空中三角测量被广泛应用于无人机航空摄影测量。本文结合实际项目,对低空无人机搭载小相幅单反相机使用GPS辅助空中三角测量技术,对同一测区规划南北航线和交叉航线,采用稀少像控布设方案,使用Pix4D Mapper软件空三加密,得出GPS辅助空中三角测量的精度与像控点分布和数量的关系。最后通过对检查点的精度分析,得出使用无人机搭载差分GPS快速制作大比例尺地形图方法的可行性结论,这对于低空无人机航摄系统应用于大比例尺地形图测量意义重大。  相似文献   

Estimating satellite phase fractional cycle biases based on Kalman filter     

Guorui Xiao  Lifen Sui  Bernhard Heck  Tian Zeng  Yuan Tian 《GPS Solutions》2018,22(3):82

Phase fractional cycle biases (FCBs) originating from satellites and receivers destroy the integer nature of PPP carrier phase ambiguities. To achieve integer ambiguity resolution of PPP, FCBs of satellites are required. In former work, least squares methods are commonly adopted to isolate FCBs from a network of reference stations. However, it can be extremely time consuming concerning the large number of observations from hundreds of stations and thousands of epochs. In addition, iterations are required to deal with the one-cycle inconsistency among FCB measurements. We propose to estimate the FCB based on a Kalman filter. The large number of observations are handled epoch by epoch, which significantly reduces the dimension of the involved matrix and accelerates the computation. In addition, it is also suitable for real-time applications. As for the one-cycle inconsistency, a pre-elimination method is developed to avoid iterations and posterior adjustments. A globally distributed network consisting of about 200 IGS stations is selected to determine the GPS satellite FCBs. Observations recorded from DoY 52 to 61 in 2016 are processed to verify the proposed approach. The RMS of wide lane (WL) posterior residuals is 0.09 cycles while that of the narrow lane (NL) is about 0.05 cycles, which indicates a good internal accuracy. The estimated WL FCBs also have a good consistency with existing WL FCB products (e.g., CNES-GRG, WHU-SGG). The RMS of differences with respect to GRG and SGG products are 0.03 and 0.05 cycles. For satellite NL FCB estimates, 97.9% of the differences with respect to SGG products are within ±?0.1 cycles. The RMS of the difference is 0.05 cycles. These results prove the efficiency of the proposed approach.  相似文献   

利用人工鱼群算法优化高斯过程模型及应用分析     

邱小梦  周世健  王奉伟  欧阳亮酉 《测绘通报》2018,(1):157-160,164

基于高斯过程利用传统共轭梯度法搜索超参数,存在对初始值依赖性强、获得局部最优解的不足。本文采用人工鱼群算法对超参数进行智能寻优,建立了基于人工鱼群算法的高斯过程模型对变形体形变进行预测分析。通过隧道和基坑两个工程实例计算比对分析,NN、SE和RQ 3种核函数中NN核函数的预测效果最好,平均相对误差分别为0.69%和1.06%。结果表明超参数优化模型的预测精度得到了较大的提高,改善了高斯过程算法本身存在的超参数求解方面的不足,效果明显。  相似文献   

环渤海地区GPS台站时间序列分析   总被引：2，自引：1，他引：1  

邱亚辉  薄志毅  郎博  岳彩亚 《测绘通报》2018,(6):17-21

环渤海区域环境和气候复杂多变,随着地区和区域的不同,地质、地貌间的差异较大。探究该地区GPS台站时间序列的变化规律和台站的主要噪声类型、频谱规律显得尤为重要。本文基于该区域内所积累的连续数年运行的GPS测站数据,采用GAMIT/GLOBK软件进行解算和平差,获得每一个台站的坐标时间序列,并使用Lomb周期图法分析了该区域台站的频谱特性和周期特性。最后通过对频率和功率谱线性拟合分析研究了台站的噪声类型。此方法对台站时间序列去除噪声和进一步研究测站的运动规律提供了理论依据。  相似文献   

2016年四川省PM2.5浓度时空分布研究     

张小璐  刘纪平  仇阿根  梁勇 《测绘与空间地理信息》2018,(4):40-42

PM2.5导致大气能见度下降,造成雾霾天气.本文基于2016年四川省89个空气质量监测站的PM2.5数据,对2016年四川省PM2.5浓度时空分布特征进行研究分析.结果表明,2016年四川省PM2.5浓度空间分布呈现出西北部PM2.5浓度较低、空气质量较好,东南部PM2.5浓度较高、空气质量较差的趋势;时间分布呈现夏季PM2.5浓度较低、空气质量较好,冬季PM2.5浓度较高、空气质量较差的趋势,从而得出四川省PM2.5浓度时间和空间分布规律及分布图.  相似文献   

Observational Subseasonal Variability of the PM_2.5 Concentration in the Beijing-Tianjin-Hebei Area during the January 2021 Sudden Stratospheric Warming     

Qian LU  Jian RAO  Chunhua SHI  Dong GUO  Ji WANG  Zhuoqi LIANG  Tian WANG 《大气科学进展》2022,39(10):1623-1636

It is still not well understood if subseasonal variability of the local PM_2.5 in the Beijing-Tianjin-Hebei (BTH) region is affected by the stratospheric state. Using PM_2.5 observations and the ERA5 reanalysis, the evolution of the air quality in BTH during the January 2021 sudden stratospheric warming (SSW) is explored. The subseasonal variability of the PM_2.5 concentration after the SSW onset is evidently enhanced. Stratospheric circumpolar easterly anomalies lasted for 53 days during the January–February 2021 SSW with two evident stratospheric pulses arriving at the ground. During the tropospheric wave weakening period and the intermittent period of dormant stratospheric pulses, the East Asian winter monsoon weakened, anomalous temperature inversion developed in the lower troposphere, anomalous surface southerlies prevailed, atmospheric moisture increased, and the boundary layer top height lowered, all of which favor the accumulation of pollutant particulates, leading to two periods of pollution processes in the BTH region. In the phase of strengthened East Asian winter monsoon around the very beginning of the SSW and another two periods when stratospheric pulses had reached the near surface, opposite-signed circulation patterns and meteorological conditions were observed, which helped to dilute and diffuse air pollutants in the BTH region. As a result, the air quality was excellent during the two periods when the stratospheric pulse had reached the near surface. The increased subseasonal variation of the regional pollutant particulates after the SSW onset highlights the important role of the stratosphere in the regional environment and provides implications for the environmental prediction.  相似文献   

青藏高原东部暴雨的中尺度有效位能收支分析          下载免费PDF全文

Kuo Zhou  Lingkun Ran  Yi Liu  Xiuxia Tian 《大气和海洋科学快报》2021,14(2):53-59

针对2018年7月10-11日青藏高原东部一次暴雨过程,利用模式模拟资料分析了有效位能分布特征,成因及其对降水发展演变的影响.结果表明,有效位能主要分布在对流层低层4km以下和高层8-14km,高层有效位能和降水有更好的对应性西北冷平流和降水粒子下落的蒸发作用是低层有效位能高值中心的主要成因,而降水过程释放潜热带来的热力扰动叠加高原大地形造成的位温扰动是导致高层有效位能高值的主要原因.有效位能收支分析表明,有效位能的通量输送项以及与动能间的转换项是主要源汇项.低层有效位能的经向通量输送和动能向有效位能的转化补给了有效位能的耗散;高层有效位能向垂直动能转化增强垂直运动是促进降水发展演变的主要因素.高层有效位能与垂直运动之间的正反馈过程使得两者相关性较强;低层较长时间内均存在垂直动能向有效位能的转化,削弱了垂直运动,而西北冷平流使得低层有效位能有增强的趋势,因此二者相关性较弱.  相似文献   

基于改进混合蛙跳算法的个性化旅游路线推荐     

申晓宁  王森林  吴俊潮  仇友辉  张磊  李常峰  王玉芳 《南京气象学院学报》2021,13(4):467-476

大众在旅游途中期望获得开销低、行程方便、舒适度高的旅游体验,同时还具有历史人文、自然景观、美食购物等不同游览需求.因此,本文提出了一种基于改进混合蛙跳算法的个性化旅游路线推荐方法.首先建立个性化旅游路线推荐问题的优化模型,并针对该模型的特点,设计改进混合蛙跳算法.通过调整可控精度,增加筛选准则和及时处理异常解等策略增强群体的多样性,降低遗漏最优解的风险,强化局部搜索能力,并提高算法的求解精度.以南京三日游个性化旅游路线推荐问题作为实例,收集南京市内知名景点的门票价格、开放时间、不同出行方式所需的时间和花费情况以及食宿费用等相关数据,基于改进混合蛙跳算法进行求解.实验结果表明,与改进前的方法相比,所提改进方法能够获取更优的路径解,推荐的路线能够更好地满足用户的个性需求.  相似文献