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上海地区地基GPS水汽三维层析技术和初步应用 总被引：1，自引：0，他引：1
地基GPS(Global Positioning System)探测大气水汽主要包括3个方面的内容:一是观测天顶方向的大气水汽总量(Precipitable Water vapor,PW);二是遥测倾斜的信号路径上的水汽总量(Slant-path Water vapor,SW);三是应用组网的GPS站倾斜路径观测反演局地上空的水汽三维信息,即水汽层析(watervapor tomography)技术.简单介绍了上海地区稠密的地基GPS网,并且在该网的基础上通过GAMIT软件计算出的整层水汽PW和各个方向上的梯度信息及观测残差,来获得GPS测定的SW,运用层析的技术可获得上海地区水汽的三维分布信息.以2008年8月25日上海罕见的大暴雨为例,分析了水汽三维结果在强对流天气中的应用. 相似文献
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随着GPS数据处理技术的提高以及计算精度的提高,GPS在大气科学中的应用日益广泛.在GPS气象学研究中,斜路径水汽含量(SWV)是一个有重要意义的参数.针对宋淑丽等在2004年提出的一种应用精密星历、IGS钟差、和经过周跳处理的LC组合观测值直接计算SWV的方法存在实时性较差的问题,在处理模糊度搜索的问题上应用了目前城市虚拟参考站(VRS)上应用较为成熟的LAMBDA方法.经过数据试算,验证方法可行,计算结果投影到天顶方向有较好的一致性,此方法得到的垂直方向大气延迟(ZTD)与GAMIT,BERNESE的结果比较,与BERNESE结果的符合精度一般小于1.5cm,与GAMIT结果的符合精度一般小于10cm. 相似文献
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《天文学报》2018,(6)
对流层是影响各类对地观测、地对空观测精度的主要因素之一.目前GNSS(Global Navigation Satellite System)技术由于其时空分辨率和精度方面的优越性,成为大气延迟和水汽监测的主要手段之一.水汽辐射计WVR (Water Vapor Radiometer)是传统的大气探测手段,由于其观测原理和灵敏度等方面的特点,也有其特殊的用途. WVR在正式投入使用前必须根据各个测站的具体情况进行标校,一般采用探空数据来进行,但探空数据采样频率低、数据量小, GNSS具有相对的优势.利用分布于北京(BJMY)、上海(SHAO)、昆明(YNKM)、乌鲁木齐(URUM) 4个VLBI (Very Long Baseline Interferometry)台站的GPS和水汽辐射计数据,开展了利用GPS数据标校WVR的方法研究,探讨了各个台站WVR的数据预处理方法,分析了影响水汽辐射计测量精度的因素.利用2015–2016年的4个并置台站的GPS和WVR观测数据,验证水汽辐射计数据的稳定性与可靠性.采用归一化处理方法,利用GPS数据对水汽辐射计进行了校准,为水汽辐射计的标校提供了一种新的思路和方法. 相似文献
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IGS产品在GPS时间比对中的应用 总被引：1，自引：0，他引：1
在利用GPS CV(GPS Common View)技术进行高精度时间比对时，电离层和卫星位置误差对观测到的卫星信号的影响是不容忽视的，需要对它进行精确的估计和改正．讨论IGS精密星历和CODE全球总电子含量图(TECMAPs)在GPS时间传递中的应用．计算结果表明，采用IGS产品可有效提高单站定时和远距离时间传递的精度。 相似文献
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上海天文台GPS气象学的研究现状 总被引：2，自引：0，他引：2
介绍了上海天台GPS气象学的背景,进展和研究成果,从90年代起,上海天台就分别开展了地基GPS气象学和空基GPS气象学的研究工作,在地基GPS气象研究中,利用国内分布的23个GPS网站及周边地区6个IGS台站,在1996年7月26日到31日（6天）的GPS观测资料,首先求得中性大气天顶延迟改正序列,然后推出测站上空可降水汽量积分,采样频率分别取为30分钟和2小时,得到的天顶延迟改正的精度好于1cm,后演出可降不汽含量的内部精度约1－2mm,把国内GPS网中具有探空气球观测的4个台站,上海,武汉,箍春和西宁的资料进行比较,发现GPS和探空气球的可降水汽含量之间的平均中误差为3－4mm,考虑到上海地区在台风和气候变化较剧烈的季节因素,选择了1997年8月2日到9日（8天）和8月17日至27日（11天）的两个观测时段,做了国内第一个GPS/storm实验,实验结果表明,地面GPS网有可能获得几乎实时的,连续的和主精度的可降水汽含量值,它的结果很好地与实时降雨量过程相对应,实验证明,利用预报轨道可以获得与精密轨道几乎相同的结果,在空基GPS气象研究中,发现地面GPS网水汽观测具有良好的时间覆盖率的优点,缺乏空间分辨率的缺点,而现在的GPS无线电掩星方法恰恰具有良好的空间分辨率而缺乏时间覆盖率,因此,在地球低轨道（LEO）卫星的轨道设计中,提出了通约LEO卫星的方法,希望通过改进轨道的LEO卫星获得长达200多天的观测序列,而它的地面观测点的漂移可以控制在于小100km,这种方法也可以用来设计对特定地面点上空大气剖面的测定,还在设计和建立GPS无线电掩星反演大气剖面的软件。 相似文献
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《天文学报》2018,(6)
长波授时具有覆盖范围广、信号传播稳定、抗干扰性能好的特点.长波授时的关键是精确计算长波信号在传播路径上的时间延迟.由于长波传播路径的复杂性以及气象条件的实时性变化,传统的时延预测方法难以实现较高的授时精度.借助于GPS信号,长波定时接收机可以间接获得较精确的传播路径时延.利用长波覆盖范围内相距不远的两接收点具有空间相关性以及传播路径上的电参数近似的特点,计算分析两接收点上传播路径时延的相关系数.在此基础上,提出了一种利用差分进行长波高精度授时的方法,该方法就是利用基准站上预报的差分改正数修正用户点上的传播路径时延.计算结果表明:差分修正后,传播路径时延的预测精度得到一定程度的提高,差分效果明显.这种长波差分授时计算方法可以有效利用传播路径上的公共误差,改善长波时延预测精度,提高长波的授时精度. 相似文献
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地面GPS观测探测大气可降水汽量的方法和前景 总被引：6，自引：0，他引：6
介绍了利用地面GPS观测探测大气可降水汽量（PWV）的基本原理和方法及其在气象学和天文定位上的应用．地面GPS测量的PWV估计的主要误差源来自天顶湿延迟的估计．为了提高天顶湿延迟的估计精度,根据大气湿分量随时间变化的特性,天顶湿延迟的估算可采用确定性参数估计和随机模型估计．采用这些方法能有效地提高GPS精密定位中高程测量的精度,且其估算的PWV的精度可达1-2mm,足以满足天气预报和气候研究的需要．简述了大气分布的非球对称性对PWV估计的影响并评述了利用地面GPS测量探测PWV的前景． 相似文献
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对称模式下的CHAMP弯曲角掩星数据同化 总被引：5，自引：0，他引：5
简单介绍了无线电掩星技术探测行星大气的发展史,列举了该技术中存在的若干问题。从 Eyre提出的统计学的最优估计反演方法,比较了用相位、弯曲角和折射率作为同化因子时出现的问题和各自的优缺点。对弯曲角同化因子,以欧洲中期天气预报中心(ECMWF)资料为背景场,运用一维变分技术,进行CHAMP掩星观测资料变分同化反演,从而获得水汽和温度剖面。将反演获得的气象剖面与非同化的剖面作比较,并且采用相应的探空气球资料作为验证,可以看出变分同化技术比传统的标准反演技术反演误差小。证实掩星数据资料的一维变分同化技术可以改进目前的数值天气预报模式。 相似文献
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With the improvement of the GPS data processing techniques and calculating accuracy, the GPS has been increasingly and widely applied to atmospheric science. In the research on GPS meteorology the slant path wet vapor content (SWV) is one of the significant parameters. In the light of the problem of poorer real time, which existed in the method proposed by Song Shuli et al. in 2004, for directly calculating the SWV by means of the precise ephemeris, IGS clock error and observed value of the LC combination after the cycle skip processing, the LAMBDA method which has more mature application to the city virtual reference station (VRS) is applied to the problem of the processing of ambiguity search. Through the trial calculation of data, it is tested and verified that the method is feasible and there is a better uniformity when the calculated result is projected into the zenith direction. The atmospheric delay in the vertical direction obtained by using this method is compared with the result of the GAMIT or the BERNESE, with the result showing that the accuracy of the coincidence of the result of the method with that of the BERNESE is generally smaller than 1.5 cm and the accuracy of the coincidence of the result of the method with that of the GAMIT is generally smaller than 10 cm. 相似文献
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GPS掩星折射率剖面一维变分同化 总被引：11，自引：1，他引：10
近年来,GPS／LEO(全球定位系统／低地球轨道)卫星无线电掩星技术给出了地球大气探测的新途径．从LEO卫星观测到的掩星数据可以反演的地球大气的气压、水汽、温度等剖面;它们对气象和大气科学研究,是具有潜在价值的数据资源．掩星数据资料的同化技术可以有效地改进这些气象参数的剖面,从而改进目前的数值天气预报模式．在当前采用的一维变分同化反演技术中,可以用掩星观测资料的大气折射率或弯曲角剖面进行同化,来反演大气水汽和温度剖面以及海平面压强．作为独立自主开发的GPD／LEO掩星技术系统的一部分,以欧洲中尺度天气预报分析(ECMWF)资料为背景场,CHAMP 掩星观测得到的折射率剖面为观测值,采用Levenberg—Marquardt方法实行GPS掩星资料一维变分同化．在讨论中,用掩星观测点附近相应的探空气球资料来检验CHAMP掩星资料变分同化的结果． 相似文献
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从LEO卫星观测到的掩星数据可以反演地球大气的气压、水汽、温度等廓线;它们对气象和大气科学研究是有价值的数据资源.掩星数据资料的同化技术可以有效地改进这些气象参数廓线,从而改进目前的数值天气预报精度.把掩星观测参数廓线用变分同化方法进入气象业务流程的最大困难是它的计算量太大,通过对一维变分同化价值函数进行改进和对迭代流程进行新的设计,避免了反复计算大维数矩阵的缺点,从而提高了变分同化的计算效率.在适用性讨论中,用背景场向量加上1个高斯白噪声作为真实值来检验CHAMP掩星资料变分同化的结果. 相似文献
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Sacit Özdemir Cahit Yeşilyaprak Bahadır Aktuğ Derya Öztürk Deniz Çoker Recep Balbay 《Experimental Astronomy》2018,46(2):323-336
We present preliminary statistics on the precipitable water vapor (PWV) content over the Karakaya Hills in Erzurum city, where the largest optical and near-infrared astronomical telescope in Turkey will be operated. Since the observatory will observe in the near-infrared (NIR), it is intended to perform PWV measurements of the atmosphere above the site by using signal delays in Global Positioning System (GPS) communication. The analysis of the GPS data recorded on the summit for almost one year shows that the atmosphere over the site of the observatory, which has an altitude of 3170 m, has favorable conditions for NIR observations. From GPS measurements, we report that the site had an average PWV of 3.2 mm and a median PWV of 2.7 mm between October 6, 2016, and June 15, 2017. We also present the time dependency of the PWV content and the correlations between the amount of PWV and the other meteorological records gathered from radiosonde flights and ground-based measurements. 相似文献
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《Chinese Astronomy and Astrophysics》2006,30(3):330-341
In recent years, the technique of Global Positioning System/Low Earth Orbit (GPS/LEO) radio occultation has opened up a new route for exploring the earth atmosphere. With this technique, the vertical profiles of pressure, temperature, water vapor of the earth atmosphere can be retrieved from GPS/LEO occultation data, thus making the latter a potentially valuable data resource for meteorological and atmospheric sciences. The technique may effectively improve the quality of the meteorological profiles, and so improve the current numerical weather forecasting model. In the one-dimensional variational (1DVAR) assimilation retrieval technique in current use, the profiles of atmospheric water vapor and temperature, as well as the sea level pressure are retrieved by assimilating the atmospheric refractivity or bending angle profile from GPS/LEO occultation data. In the system independently developed at Shanghai Observatory, the 1DVAR assimilation of CPS occultation data is accomplished by the Levenberg-Marquardt method with the analytical data from the European Center for Medium Range Weather Forecasting (ECMWF) as the background field, the refractivity profile obtained from CHAMP occultation data as the observational quantity. The result was checked with sounding balloon data near the occultation points. 相似文献
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Our ground-based measurements of martian atmospheric water vapor, made throughout Ls=34° to 249°, 24 September 1998 to 23 November 1999, during Mars year 24 (MY 24), show changes in Mars' humidity on hourly, daily, and seasonal timescales. We made concomitant measurement of nearby CO2 bands, and when possible, results were corrected for aerosol extinction using aerosol optical depths derived from our own CO2 analysis. Where there is spatial and temporal overlap, similar results are obtained for water vapor abundances and aerosol opacities as those observed from the Thermal Emission Spectrometer on Mars Global Surveyor. In addition some further discussion of our published earlier water vapor measurements (1991-1995) is included. Six results from this data set are: (1) the measured aerosol opacity in Mars atmosphere was variable but not greater than τ=1, with almost no clear atmosphere being observed, (2) measurements made with the slit crossing many hours of local time on Mars' Earth-facing disk show a diurnal pattern with highest abundances at mid-day and low abundance in very early morning and late afternoon for some but not all measurements, (3) water vapor abundance is patchy on hourly and daily time scales but follows the usual seasonal trends seen by instrumentation on the Mars Atmospheric Water Detector on the Viking Orbiters and by the Thermal Emission Spectrometer on Mars Global Surveyor, (4) there is a slight longitudinal correlation with the ground-ice observed by the Gamma Ray Spectrometer on Mars Odyssey, (5) there is evidence of the Low Southern Latitude Summer Minimum in our water vapor measurements but our data set for southern summer is limited, and (6) MY 24 appears to be wetter than MY 22 and MY 23. 相似文献
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Norbert Schorghofer 《Icarus》2010,208(2):598-607
Subsurface water ice on Mars evolves due to exchange of vapor with the atmosphere, in the form of loss of ice to the atmosphere or in the form of the growth of interstitial ice. Described here is an accelerated numerical method for the long-term evolution of subsurface ice. This accelerated method is five orders of magnitude faster than explicit vapor transport calculations, enabling fundamentally new types of climate models. Its speed matches that of purely thermal models. The speedup is achieved primarily by solving time-averaged equations for vapor transport and ice volume change. Processes incorporated are growth of interstitial pore ice, retreat of pore ice, retreat of an ice sheet, and retreat of pore ice due to geothermal heating from below. Two example applications illustrate this numerical method’s capabilities. Near the permafrost margin at 55° latitude, ice is periodically depleted and slowly recharged, leading to a pore ice layer estimated to be currently no more than a few meters thick. At the Phoenix Landing Site, it shows the formation of a three layered structure, whereby the layer of pore ice can be very thin. 相似文献