共查询到18条相似文献，搜索用时 500 毫秒
1.
利用无线电掩星探测在平流层具有较高精度和稳定性的优势,本文采用COSMIC资料验证我国风云3号(FY-3)系列卫星上微波温度探测仪(MWTS)通道4表征的平流层低层测量结果.两年的FY-3A/3B上MWTS通道4观测亮温与掩星数据模拟的亮温相比较分析表明:两颗卫星平台上MWTS通道4观测亮温都偏高,尤其在热带地区和极区夏季;FY3A/3B上MWTS通道4亮温偏差的月均值变化趋势较为一致,两个年份的变化趋势也较为一致.MWTS通道4表征的平流层低层观测亮温在不同纬度带呈现不同偏差分布特征:热带地区明显系统偏高2~4 K,中纬度地区偏高1 K;而高纬度地区则出现随季节显著变化的偏差,尤其在南极地区季节差异达到5 K,这种依赖于环境温度出现的较大亮温偏差不完全是频率偏移引起.热带地区观测与模拟亮温差异显著,并且热带地区样本对于全球总体亮温偏差影响程度达到20%,这表明COSMIC数据在热带地区的验证结果需谨慎使用. 相似文献
2.
COSMIC星座GPS无线电掩星探测利用GPS开环接收技术提高低层大气观测数据的质量和对上升掩星事件的跟踪能力.开环掩星观测数据受到GPS导航数据调制的影响,在其数据后处理中必须消除该影响以获得高质量的科学反演结果.利用GPS导航数据调制码数据和利用开环数据本身内在的关系等两种方法可以消除该影响.将上述方法应用于COSMIC的掩星事件个例反演,获得了修复的大气附加相位数据;并利用几何光学近似反演方法和全谱反演方法,获得了射线弯曲角. 全谱反演方法获得的弯曲角及其温度反演结果与COSMIC数据中心的结果一致,说明我们的算法是有效的. 相似文献
3.
<正>GPS(Global Positioning System,全球定位系统)无线电掩星技术具有全球覆盖、垂直分辨率高等优点,为电离层的研究提供了十分丰富的资料。本论文的研究主要基于COSMIC(Constellation Observing System for Meteorology Ionosphere and Climate)掩星电离层数据,详细介绍了电离层的基本理论;阐述利用掩星技术探测电离层的基本原理;针对COSMIC掩星数据分布特点,建立了数据分析和研究方法;目前的研究对电离层物理量不同区域分布差 相似文献
4.
从GPS/MET计划开始,基于GNSS的无线电掩星技术已成为一种强大的近地空间环境探测手段.截至到目前,已经有20多颗发射的低轨道卫星带GPS掩星接收机,其中COSMIC是首个专门用于掩星探测的卫星星座.这些掩星数据被广泛应用于气象预报、气候与全球变化研究、及空间天气监测和电离层研究.由于COSMIC的成功,相关合作单位目前正积极推动COSMIC-2计划,该计划将总共有12颗卫星,于2016年与2019年各发射6颗.COSMIC-2将携带一个高级的GNSS掩星接收机,它将接受GPS与GLONASS信号,并具备接受其他可获得信号源的能力(如中国北斗定位信号),其每日观测的掩星数量将是COSMIC的4~6倍.同时COSMIC-2还将携带两个空间天气载荷,加强空间天气的监测能力.本文以COSMIC与COSMIC-2计划为主线,对掩星的发展历史、技术要点进行了简单介绍,并简要综述了COSMIC取得的部分科学成果,同时对未来包括技术发展和众多的掩星观测进行了展望. 相似文献
5.
6.
本文利用2009年1月-2011年12月共3年的COSMIC大气掩星观测数据与SABER/TIMED探测数据开展15~60 km大气温度数据的比较分析研究,计算COSMIC与SABER/TIMED探测温度的绝对偏差(TSABER-TCOSMIC),并统计其平均温度偏差和标准偏差,分析温度偏差随高度、纬度和季节的分布特征,为COSMIC大气掩星与SABER/TIMED探测数据的应用提供更多的参考依据.结果表明:COSMIC与SABER/TIMED数据所反映的温度随高度的变化特征是一致的,数据的大体趋势吻合较好.全球范围的平均温度偏差在38 km左右接近于0 K,在38 km以上,平均温度偏差表现为负的系统性偏差,且随着高度逐渐增大,在38 km以下,平均温度偏差表现为正的系统性偏差,在23 km左右存在极大值,约为2.7 K.COSMIC与SABER/TIMED温度偏差的分布存在着随纬度和季节的变化特征,35 km以下,平均温度偏差在高纬地区和冬季较小,低纬地区和夏季较大,35 km以上,平均温度偏差在高纬地区和冬季较大,低纬地区和夏季较小.温度偏差的标准偏差在低纬地区和夏季较小,高纬地区和冬季较大.纬圈平均的温度偏差在南北半球的分布基本呈对称结构. 相似文献
7.
8.
山基GPS掩星技术可以精确获得低层大气折射率信息,其观测原理是:在高山的山顶安装GPS接收机,跟踪GPS卫星的低仰角和负仰角信号,通过载波相位的变化求出大气折射造成的弯曲角剖面,从而利用科学反演方法获得观测点高度以下的大气折射率剖面.为了对山基掩星测量数据进行验证,2005年8月1日～29日,在河北雾灵山(40.60°N,117.48°E,2118m)开展了为期一个月的山基GPS掩星观测与其他探测的时比实验.实验所用的JAVAD双频GPS接收机共工作576小时,接收机朝南观测,记录到山基掩星事件1136次,其中上升掩星621次,下降掩星515次.实验期间,在雾灵山顶利用自动气象观测仪每天24小时观测当地的温度、湿度和气压,由此可计算大气折射率.本文利用雾灵山GPS掩星实验所获得的观测数据,成功反演得到大气折射率剖面,并将所得接收机高度的折射率与雾灵山顶自动气象站观测结果进行比对,分析结果表明:山基GPS掩星和自动气象站观测结果是一致的.山基GPS掩星观测可为低层大气环境监测提供大量数据,具有潜在的应用前景. 相似文献
9.
分别在湖北省药姑山和九宫山的山头上开展GPS掩星观测实验，成功获取山基掩星观测数据，对掩星事件进行了分析和统计.给出利用山基掩星观测数据反演大气折射指数剖面和电波弯曲角的原理和算法.利用山基GPS掩星观测模拟数据，对反演方法进行试算和检验，结果表明反演方法准确可行.将该反演方法应用于观测数据的反演，获得了观测点高度以下的大气折射率剖面，以及电波弯曲角.实验结果和原理研究表明，山基掩星观测技术是一种潜在的低层大气环境监测新技术. 相似文献
10.
11.
The retrieval of Snow Water Equivalent (SWE) from remote sensing satellites continues to be a very challenging problem. In this paper, we evaluate the accuracy of a new SWE product derived from the blending of a passive microwave SWE product based on the Advanced Microwave Sounding Unit (AMSU) with a multi‐sensor snow cover extent product based on the Interactive Multi‐sensor Snow and Ice Mapping System (IMS). The microwave measurements have the ability to penetrate the snow pack, and thus, the retrieval of SWE is best accomplished using the AMSU. On the other hand, the IMS maps snow cover more reliably due to the use of multiple satellite and ground observations. The evolution of global snow cover from the blended, the AMSU and the IMS products was examined during the 2006 snow season. Despite the overall good inter‐product agreement, it was shown that the retrievals of snow cover extent in the blended product are improved when using IMS, with implications for improved microwave retrievals of SWE. In a separate investigation, the skill of the microwave SWE product was also examined for its ability to correctly estimate SWE globally and regionally. Qualitative evaluation of global SWE retrievals suggested dependence on land surface temperature: the lower the temperature, the higher the SWE retrieved. This temperature bias was attributed in part to temperature effects on those snow properties that impact microwave response. Therefore, algorithm modifications are needed with more dynamical adjustments to account for changing snow cover. Quantitative evaluation over Slovakia in central Europe, for a limited period in 2006, showed reasonably good performance for SWE less than 100 mm. Sensitivity to deeper snow decreased significantly. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
12.
人类活动引起全球变暖,衡量全球气候变化的指标有陆地、大气和海洋温度,水汽含量等等.研究对流层底层大气温度和水汽含量变化的传统方法是用数值天气预报模型和微波声纳,尚未实现用全球均匀覆盖的数据来做精确的定量研究.和GNSS系列卫星计划比较,最近发射的COSMIC卫星气象探测数据的空间、时间以及垂直分辨率都大大提高.采用COSMIC数据可以改进和量化南极洲的大气压力模型,并综合GNSS系列卫星测量的水汽和温度剖面研究全球气候变化.用一维协方差算法估计南极洲及附近海洋的大气压、温度和湿度剖面.把COSMIC卫星密集测量期间演算得到的大气折射率和GNSS系列卫星的结果进行比较.再和独立测量数据进行比较,包括南极洲自动气象观测站资料,数值天气预报模型资料,多种测高卫星水汽资料和海洋表面温度资料以及区域GPS水汽图.上述工作将改进发展中的气象遥感技术并应用于天气预报和空间天气预报及全球气候变化研究. 相似文献
13.
本文利用2007年1月至2012年12月的COSMIC卫星温度剖线,从中提取了垂直波长在3~10 km的重力波扰动信息,进而分析了全球平流层大气重力波的分布特征.赤道地区低平流层重力波表现出明显的准两年变化,这种变化与风场的准两年变化具有明显的相关性,向下发展速度约为1 km/月;赤道地区高平流层(35 km以上区域)的重力波活动则存在明显的半年变化.中高纬度重力波活动主要表现为冬季强夏季弱.在南极地区存在着与急流的时间、空间以及强度变化密切相关的重力波分布特征,这说明在南极极夜急流是非常重要的一个重力波源;而在北极极夜急流的作用则没有那么强.此外,通过考察不同高度的重力波活动特征,我们发现:30 km以下重力波活动较强区域主要在赤道地区且与强对流区分布基本吻合,地形诱发的以及与天气系统相关的强重力波活动在该高度范围内同样出现;而在30 km以上的区域重力波活动强度分布则会出现与平流层爆发性增温以及极夜急流有关的变化. 相似文献
14.
本文利用2006年6月至2014年6月COSMIC掩星观测的水汽廓线，分析了对流层/下平流层（TLS）比湿信号对ENSO的响应.在数据处理中，将COSMIC掩星水汽廓线计算得到的全球比湿数据内插为1000~30 hPa区间水平分辨率为5°×5°的三维格网，在各等压面上求取各格网点去除年/月际信号后的比湿月异常值.然后在对比湿月异常时间序列低通滤波的基础上，进行经验正交分解（EOF）得到比湿主成分，并对该主成分信号进行二项式平滑；接下来将平滑后的主成分信号与反映ENSO活动的ONI指数进行相关处理，得到各等压面主成分信号相对于ONI指数的相关系数及对应的时间延迟.论文分析了包括Niño-3.4的5个代表性区域的TLS比湿异常主成分信号，结果表明：在各区域，采用本文先低通滤波再EOF分解的处理方法获得的TLS比湿异常主成分信号与ONI指数均有很强相关性，对流层相关系数绝对值达0.8以上，低平流层高于0.7，在300~200 hPa的上对流层达到峰值；各等压面上比湿异常主成分信号相对于ONI指数的时间延迟不尽相同，在对流层中比湿异常主成分信号普遍滞后于ONI指数1~6个月；在各区域，比湿异常主成分与ONI指数相关系数绝对值达到最大的等压面都接近250 hPa，最大相关系数绝对值均达到0.9以上.进一步对全球250 hPa等压面比湿异常主成分与ONI指数相关性的分析表明：两者强相关的区域主要集中在热带；在这些强相关区域，比湿异常主成分相对于ONI主要表现为滞后，且相关系数越大，相应的时间延迟越短. 相似文献
15.
J. K. Angell 《Pure and Applied Geophysics》1980,118(1):378-386
Examined are temperature and ozone variations in the Northern Hemisphere stratosphere during the period 1958–77, as estimated from radiosondes rocketsondes, ozonesondes, and Umkehr measurements. The temperature variation in the low tropical stratosphere is a combination of the variation associated with the quasi-biennial oscillation, and a variation nearly out of phase with the pronounced 3-yearly temperature oscillation (Southern Oscillation) present in the tropical troposphere since 1963. Based on radiosonde and rocketsonde data, the quasibiennial temperature oscillation can be traced as high as the stratopause, the phase varying with both height and latitude. However, the rocketsonde-derived temperature decrease of several degrees Celsius in the 25–55 km layer of the Western Hemisphere between 1969 (sunspot maximum) and 1976 (sunspot minimum) is not apparent in high-level radiosonde data, so that caution is advised with respect to a possible solar-terrestrial relation.There has been a strong quasi-biennial oscillation in ozone in the 8–16 km layer of the north polar region, with ozone minimum near the time of quasi-biennial west wind maximum at a height of 20 km in the tropics. A quasi-biennial oscillation in ozone (of similar phase) is also apparent from both ozonesonde data and Umkehr measurements in 8–16 and 16–24 km layers of north temperate latitudes, but not higher up. Both measurement techniques also suggest a slight overall ozone decrease in the same layers between 1969 and 1976, but no overall ozone change in the 24–32 km layer. Umkehr measurements indicate a significant 6–8% increase in ozone amount in all stratospheric layers between 1964 and 1970, and in 1977 the ozone amount in the 32–46 km layer was still 4% above average despite the predicted depletion due to fluorocarbon emissions. The decrease in ozone in the 32–46 km, layer of mid latitudes following the volcanic eruptions of Agung and Fuego is believed to be mostly fictitious and due to the bias introduced into the Umkehr technique by stratospheric aerosols of volcanic origin. Above-average water vapor amounts in the low stratosphere at Washington, DC, appear closely related to warm tropospheric temperatures in the tropics, presumably reflecting variations in strength of the Hadley circulation. 相似文献
16.
Temperature profiles provided by the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) global positioning system (GPS) satellite constellation were used to study an eight-year series (2007 to 2015) of gravity wave (GW) potential energy in the stratosphere (18–30 km) around the Tibetan Plateau (TP). We found that with increasing altitude, the GW potential energy (E p) values in the stratosphere caused by convection decreases. The importance of GWs that are stimulated by topography is enhanced in this area. In the TP, which was considered to lack strong topographical GW activity, clear activity existed in the spring and winter of all studied years. Based on the latitudinal zone of the TP, the distribution of GW potential energy is highly consistent with the elevation of the local topography. The activities of topographical GWs are strongly filtered as they propagate upward to the area of zero speed wind. The analysis indicates that in the TP, clear orographic GW excitation exists and propagates upward to the upper stratosphere, where it is greatly influenced by the wind. 相似文献
17.
本文利用2006年5月至2013年4月COSMIC干温廓线数据,提取了青藏高原地区大气重力波势能,以此研究了青藏高原大气重力波势能的分布频率模型和大气重力波活动的时空变化特征,并进一步分析了高原大气重力波活动与高原地形、风速和高原大陆热辐射之间的相关性.青藏高原地区大气重力波势能的分布频率服从对数生长分布;青藏高原地区大气重力波在16~18km和28~31km高度较活跃,而在20~26km高度较平静;高原大陆边缘各季节重力波活动均较活跃,而高原大陆上空大气重力波活动呈明显季节性变化,其在冬春季节较活跃,在夏秋季节较平静;2010年冬季青藏高原大气重力波活动异常平静;各季节整个高原上空大气重力波活跃度有随大气高度升高而降低的趋势,高原上低层大气重力波向高层传播会发生耗散作用.地形与风速是影响青藏高原大气重力波活动的重要因素.地形主要影响平流层底部的重力波活动;纬向风比经向风对该地区平流层大气重力波活动的影响大,纬向风总体上会促进高原大气重力波活动.青藏高原大陆热辐射对高原大气的加热作用是导致青藏高原大气重力波活动呈季节性变化的重要因素. 相似文献
18.
Ching-Yuang Huang Ying-Hwa Kuo Shu-Ya Chen Anisetty S. K. A. V. Prasad Rao Chien-Ju Wang 《Pure and Applied Geophysics》2007,164(8-9):1577-1591
In this study, the Weather Research and Forecasting (WRF-2.0.3.1) model with three-dimensional variational data assimilation
(3DVAR) was utilized to study a heavy rainfall event along the west coast of India with and without the assimilation of GPS
occultation refractivity soundings in the monsoon period of 2002. The WRF model is a next-generation mesoscale numerical weather
prediction system designed to serve both operational forecasting and atmospheric research communities. The Global Positioning
System (GPS) radio occultation (RO) refractivity data, processed by UCAR, were obtained from the CHAMP and SAC-C missions.
This study investigates the impact of thirteen GPS occultation refractivity soundings only, as assimilated into the WRF model
with 3DVAR, on the rainfall prediction over the western coastal mountain of India. The model simulation, with the finest resolution
of 10 km, was in good agreement with rainfall observations, up to 72-h forecast. There are some subtle but important differences
in predicted rainfalls between the control run CN (without the assimilation of refractivity soundings) and G13 (with the assimilation
of thirteen GPS RO soundings). In general, the assimilation run G13 gives a better prediction in terms of both rainfall locations
and amounts at later times. The moisture increments were analyzed at the initial and forecast times to assess the impact of
GPS RO data assimilation. The results indicate that remote soundings in the forcing region could have significant impacts
on distant downstream regions. It is anticipated, based on this study, that considerably occultation soundings available from
the six-satellite constellation of FORMOSAT-3/COSMIC would have even more significant impacts on weather prediction in this
region. 相似文献