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利用大气分子的纯转动信号反演大气温度,被证明是一种精度很高的方法,目前已得到广泛的应用并在世界各地建立起多台纯转动拉曼激光雷达.全部的纯转动拉曼谱线之和是不依赖于温度的,利用这个特性,可以不需要任何的假设,反演大气气溶胶的消光.本文介绍了一种新的探测大气气溶胶的方法,首次提出通过提取纯转动单支谱(J=4和14),加上Rayleigh & Mie通道的激光雷达方程,不需要附加任何假设,导出了气溶胶后向散射系数的数学表达式. 相似文献
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工作波长为532 nm的机载大气环境探测激光雷达AEDAL（Atmospheric Environment Detecting Airborne Lidar）装载在CMS_3807飞机上，于2005年11月7～11日期间在青岛地区及周边海域上空进行了飞行探测.此次实验的目的有两个：验证我国用于大气环境探测的激光雷达技术已经具备从地基向空基乃至天基发展的条件；获得青岛地区及周边海域边界层结构及大气气溶胶时空分布变化的特点.激光雷达的高时空分辨率为获取飞行路径上的边界层结构及气溶胶时空分布提供了可能.为了研究下垫面对边界层及气溶胶时空分布的影响，预定的飞行路径上包含了丰富的地形变化，有城市、丘陵、海区等.通过给出11月8日及11日的探测结果，不仅得到了不同地区边界层结构及气溶胶的时空分布特点，还可以看到冷锋、地形、地面气象场等因素对它们的影响. 相似文献
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本文介绍了一套纯转动Raman测温激光雷达系统,通过高分辨光谱分光与滤光优化设计、收发精确匹配以及弱信号检测等技术,实现在武汉城市上空从10km至40km的中低空大气温度高精度探测.观测结果与同时段探空气球进行比对,在30km以下激光雷达探测温度与探空气球得到的温度数据吻合较好,最大偏差约为3.0K,表明了该激光雷达温度测量的可靠性.采用30min时间分辨率,在10~20km高度范围内温度统计误差约为0.3K(300m空间分辨);20~30km统计误差约为0.8K(600m空间分辨);30~40km统计误差约为3.0K(900m空间分辨).通过整晚的温度廓线反演,为研究中低层大气中的波动现象提供依据.该转动Raman激光雷达实现了至40km高度的高精度大气温度探测,进一步可与Rayleigh测温激光雷达30~80km的高度衔接,为实现中低层大气连续观测研究提供了重要手段. 相似文献
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在无线电GPS大气掩星观测中,GPS和LEO卫星的位置误差、速度误差、卫星钟的漂移、载波相位观测误差等会给其反演的大气参量带来一定的误差.为定量分析上述GPS测量误差对大气掩星反演精度的影响,本文采用模拟分析的方法,利用CHAMP实测轨道数据和大气与电离层经验模式,采用三维射线追踪方法模拟得到大气附加相位观测数据;然后根据各种GPS测量误差的不同性质,在模拟掩星观测大气附加相位数据中加入GPS测量误差并进行反演,将其反演结果与未加入误差时的反演结果进行比较,分析各测量误差所带来的掩星反演误差的特点;利用一天的151个分布全球的掩星事件的误差结果进行统计分析.结果表明:(1)±10 m的GPS径向位置误差引起的温度反演误差的平均误差在30 km的高度为(-+)0.8K,标准偏差为0.05K;±0.4 m的LEO径向位置误差引起的温度反演误差的平均误差在30 km的高度为(-+)1.2K,标准偏差为0.07K.(2)仅考虑卫星速度误差对掩星几何关系的影响,则±30 m/s的GPS速度误差引起的温度反演误差的平均误差最大为±0.02K,标准偏差为0.3K;±10 m/s的LEO速度误差引起的温度反演误差的平均误差最大为±0.4K,标准偏差为0.06K.(3)当卫星钟漂为1×10-9时,反演温度误差的平均误差在30 km的高度为263K,标准偏差为16K,当卫星钟漂为1×10-14时,反演温度误差的平均误差在30km的高度为0.019K,标准偏差为0.004K.(4)当L1和L2载波相位观测误差分别为1 mm和2 mm时,引起的温度反演的平均误差在30 km的高度为0.01K,标准偏差为0.4K.(5)利用较接近真实观测的三维大气和电离层背景下的模拟附加相位数据,同时加入国际最新指标的各种GPS测量误差进行反演,误差分析结果为:在30 km以下,折射率和密度的相对误差小于0.3%(1σ),压强的相对误差小于0.5%(1σ),温度误差小于1K(1σ). 相似文献
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热层大气密度是空间大气环境的重要参数,经过多年的研究已开发了多种大气模式,但其误差普遍较大,尤其在磁暴期间偏差值甚至超过100%.本文利用中国星载大气密度探测器和CHAMP卫星加速度计在轨获得的连续探测数据,针对近10年(2003—2014)中多次强磁暴事件和多次中等强度扰动事件,即2003年11月、2004年7月和2005年8~9月多次强磁暴事件(Kp值均达到9),2006年4月、2012年4月的两次中等强度磁暴事件(Kp值分别达到7和6),分析和比对不同强度磁扰事件期间不同高度全球大气密度就位探测值与模式值(NRLMSISE00)之间的差别.在2005年8月24日强磁扰事件中,560 km高度中国卫星就位探测值上涨幅度约2~3倍,扰动区中的增变比高达5.7倍,375 km高度CHAMP卫星就位探测值上涨幅度约0.8倍,扰动区中增变比达4.0倍,期间大气密度模式值不仅没有出现明显的涨落,更没有出现强烈的区域扰动;在2003年11月和2004年7月的强磁扰事件中,CHAMP卫星就位探测值均有显著涨变和强烈扰动变化,而模式值无明显扰动变化;在中等强度磁扰事件中,高度560 km附近就位探测值在北、南半球高纬地区显著上涨,远高于模式值,高度350 km附近就位探测值在地球阴影区域显著上涨,上涨幅度也大于模式值.分析结果表明现有大气模式对地磁扰动(尤其是强磁暴事件)期间全球热层大气密度的响应并不明显,需要进一步改善. 相似文献
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APOD卫星是我国首颗以热层大气密度探测与精密定轨为科学目标的微纳卫星,搭载大气密度探测器、双频GNSS接收机等载荷,于2015年9月20日发射入轨,2015年10月27日进入轨道高度460 km、轨道倾角97.4°、降交点地方时6∶20的工作轨道,各项载荷随即展开例行观测.本文给出了APOD卫星大气密度探测器的基本原理和数据处理流程,采用基于双行根数（TLE）反演获取的密度数据,对2015年12月至2016年12月的就位探测数据进行了标校,并与经验密度模式进行了比较.结果表明,反演密度与APOD卫星就位探测数据的线性相关性达到0.943,采用线性拟合与二次函数拟合的残差水平基本相当.两种不同方法标校密度相对于NRLMSIS00模式日均值误差的均值和标准偏差为10.1%、18.2%和5.1%、17.1%,二次函数标校略优于线性标校;相对于JB2008模式日均值误差的均值和标准偏差为0.6%、14.9%和3.9%、16.9%,线性标校略优于二次函数标校.总体而言,APOD卫星大气密度就位探测数据与常用经验模式精度基本一致,可为开展大气密度变化规律及应用研究提供数据基础. 相似文献
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GPS大气掩星探测技术可以获得全球大气折射率、气压、密度、温度和水汽压等气象参数，该技术基本原理是基于几何光学近似的Abel积分反演.地球扁率、电离层传播时间延迟、大气大尺度水平梯度、多路径传播现象等因素在某些高度范围影响大气反演的精度.本文采用模拟的方法，分析其中地球扁率及电离层对反演结果的影响，并讨论局部圆弧修正及电离层修正的效果.利用CHAMP掩星实测轨道数据和有关电离层和大气经验模式、采用三维射线追踪方法模拟计算几种情形下的GPS掩星观测附加相位数据，对模拟数据进行反演，将反演气象参量剖面与模拟时给定模式剖面进行比较，得到了0～60 km高度范围内的反演误差.误差统计分析结果表明，局部圆弧中心的修正以及电离层修正，对于高精度的GPS掩星反演是非常重要的；电离层修正残差仍是制约30～60 km高度范围内反演精度的重要因素，进一步完善和优化大气掩星反演需要发展新的电离层修正算法. 相似文献
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中层大气温度变化的探测与研究是当前气候变化研究课题的一个组成部分,本文基于海南激光雷达2010—2020年间的长期观测,通过对中层大气Rayleigh散射信号的反演,探讨了海口(19.9°N,110.3°E)上空中层大气(32～64 km)温度变化特性.研究结果显示,中层大气温度呈周期性变化趋势,年、半年、季节变化幅度最大值分别为6.0、3.8、1.7 K,平流层顶位于42～51 km高度,日平均温度最高为～262 K.平流层温度主要表现为年变化趋势,半年和季节变化不明显;平流层顶和低中间层温度变化趋势具有年和半年变化特征,季节变化不明显.在太阳活动性发生明显变化的周期里,平流层顶温度的年际变化趋势对辐射通量F10.7指数变化有较明显的响应;而在太阳活动平静的年份里,温度变化趋势与太阳辐射通量变化的相关性不明显. 相似文献
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NRLMSISE-00大气模型广泛应用于航天器定轨和预测等方面,但存在着较大的误差,尤其是在短期变化方面.为了提高低轨道大气密度短期预报的精度,我们提出了一种基于实测数据对NRLMSISE-00大气模型密度结果进行修正预报的方法:利用GRACE(Gravity Recovery and Climate Experiment)和CHAMP(Challenging Mini-Satellite Payload)卫星2002-2008年大气密度探测数据对NRLMSISE-00模型进行误差分析,获得模型的修正因子,再对模型的大气密度结果进行修正.采用该修正方法对GRACE-A和CHAMP卫星轨道上的大气密度进行3天短期预报试验验证,结果表明可显著提高大气密度的预报精度,在太阳活动低年,修正后的大气密度预报误差比NRLMSISE-00模型误差降低50%以上. 相似文献
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Height distribution of the stratospheric aerosol extinction coefficient was measured in the altitude range 10 to 20 km by a balloon-borne multi-color sunphotometer in May 1978. It is demonstrated that detailed structures of the distribution of stratospheric aerosol can be remotely measured by the solar occultation method as well as by lidar andin situ particle counter observations. In the aerosol layer appearing at 18 km altitude the extinction coefficient at 800–1000 nm wavelength reached to 3×10–7 m–1, which was reasonable compared with lidar observations. Wavelength dependence of the aerosol optical depth was crudely estimated to be proportional to
–1.5. 相似文献
12.
O. I. Shumilov E. A. Kasatkina K. Henriksen E. V. Vashenyuk 《Annales Geophysicae》1997,14(11):1119-1123
The lidar measurements at Verhnetulomski observatory (68.6°N, 31.8°E) at Kola peninsula detected a considerable increase of stratospheric aerosol concentration after the solar proton event of GLE (ground level event) type on the 16/02/84. This increase was located at precisely the same altitude range where the energetic solar protons lost their energy in the atmosphere. The aerosol layer formed precipitated quickly (1–2 km per day) during 18, 19, and 20 February 1984, and the increase of R(H) (backscattering ratio) at 17 km altitude reached 40% on 20/02/84. We present the model calculation of CN (condensation nuclei) altitude distribution on the basis of an ion-nucleation mechanism, taking into account the experimental energy distribution of incident solar protons. The meteorological situation during the event was also investigated.deceased 相似文献
13.
Two methods for low-altitude calibration of a single-rotor unmanned aircraft system using a real-time compensator are tested: (1) a stationary calibration where the unmanned aircraft system executes manoeuvres while hovering in order to minimize ambient field changes due to the local geology; and (2) an adapted box calibration flown in four orthogonal directions. Both methods use two compensator-specific limits derived from established methods for manned airborne calibration: the lowest frequency used by the compensator for the calibration algorithm and the maximum variation of the ambient magnetic intensity experienced by the unmanned aircraft system during calibration. Prior to flying, the unmanned aircraft system was magnetically characterized using the heading error and fourth difference. Magnetic interference was mitigated by extending the magnetometer-unmanned aircraft system separation distance to 1.7 m, shielding, and demagnetization. The stationary calibration yielded an improvement ratio of 8.595 and a standard deviation of the compensated total magnetic intensity of 0.075 nT (estimated Figure-of-Merit of 3.8 nT). The box calibration also yielded an improvement ratio of 3.989 and a standard deviation of the compensated total magnetic intensity of 0.083 nT (estimated Figure-of-Merit of 4.2 nT). The stationary and box calibration solutions were robust with low cross-correlation indexes (1.090 and 1.048, respectively) when applied to a non-native data set. 相似文献
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Astrid Lampert Johan Ström Christoph Ritter Roland Neuber Young Jun Yoon Nam Yi Chae Masataka Shiobara 《Acta Geophysica》2012,60(5):1287-1307
An inclined lidar with vertical resolution of 0.4 m was used for detailed boundary layer studies and to link observations at Zeppelin Mountain (474 m) and Ny-Ålesund, Svalbard. We report on the observation of aerosol layers directly above the Kongsfjord. On 29 April 2007, a layer of enhanced backscatter was observed in the lowest 25 m above the open water surface. The low depolarization ratio indicated spherical particles. In the afternoon, this layer disappeared. The ultrafine particle concentration at Zeppelin and Corbel station (close to the Kongsfjord) was low. On 1 May 2007, a drying process in the boundary layer was observed. In the morning, the atmosphere up to Zeppelin Mountain showed enhanced values of the backscatter coefficient. Around noon, the top of the highly reflecting boundary layer decreased from 350 to 250 m. The top of the boundary layer observed by lidar was confirmed by radiosonde data. 相似文献
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An airborne downward-pointing water vapor lidar provides two-dimensional, simultaneous curtains of atmospheric backscatter and humidity along the flight track with high accuracy and spatial resolution. In order to improve the knowledge on the coupling between clouds, circulation and climate in the trade wind region, the DLR (Deutsches Zentrum für Luft- und Raumfahrt) water vapor lidar was operated on board the German research aircraft HALO during the NARVAL (Next Generation Aircraft Remote Sensing for Validation Studies) field experiment in December 2013. Out of the wealth of about 30 flight hours or 25,000 km of data over the Tropical Atlantic Ocean east of Barbados, three ~ 2-h-long, representative segments from different flights were selected. Analyses of Meteosat Second Generation images and dropsondes complement this case study. All observations indicate a high heterogeneity of the humidity in the lowest 4 km of the tropical troposphere, as well as of the depth of the cloud (1–2 km thick) and sub-cloud layer (~ 1 km thick). At the winter trade inversion with its strong humidity jump of up to 9 g/kg in water vapor mixing ratio, the mixing ratio variance can attain 9 (g/kg)2, while below it typically ranges between 1 and 3 (g/kg)2. Layer depths and partial water vapor columns within the layers vary by up to a factor of 2. This affects the total tropospheric water vapor column, amounting on average to 28 kg/m2, by up to 10 kg/m2 or 36%. The dominant scale of the variability is given by the extent of regions with higher-than-average humidity and lies between 300 and 600 km. The variability mainly stems from the alternation between dry regions and moisture lifted by convection. Occasionally, up to 100-km large dry regions are observed. In between, convection pushes the trade inversion upward, sharpening the vertical moisture gradient that is colocated with the trade inversion. In most of the water vapor profiles, this gradient is stronger than the one located at the top of the sub-cloud layer. Lidar observations in concert with models accurately reproducing the observed variability are expected to help evaluate the role these findings play for climate. 相似文献
16.
R.L. Collins M.J. Taylor K. Nielsen K. Mizutani Y. Murayama K. Sakanoi M.T. DeLand 《Journal of Atmospheric and Solar》2009,71(3-4):446-452
We report observations of a noctilucent cloud (NLC) over central Alaska by a ground-based lidar and camera on the night of 9–10 August 2005. The lidar at Poker Flat Research Range (PFRR), Chatanika (65°N, 147°W) measured a maximum integrated backscatter coefficient of 2.4×10?6 sr?1 with a peak backscatter coefficient of 2.6×10?9 m?1 sr?1 corresponding to an aerosol backscatter ratio of 120 at an altitude of 82.1 km. The camera at Donnelly Dome, 168 km southeast of PFRR, recorded an extensive NLC display across the sky with distinct filamentary features corresponding to wave structures measured by the lidar. The occurrence of the maximum integrated backscatter coefficient corresponded to the passage of a bright cloud band to the southwest over PFRR. The camera observations indicate that the cloud band had a horizontal width of 50 km and a length of 150 km. The horizontal scale of the cloud band was confirmed by medium-frequency radar wind measurements that reported mesopause region winds of 30 m/s to the southwest during the period when the cloud band passed over PFRR. Comparison of these measurements with current NLC microphysical models suggests a lower bound on the water vapor mixing ratio at 83 km of 7–9 ppmv and a cloud ice mass of 1.5–1.8×103 kg. Satellite measurements show that this NLC display occurred during a burst of cloud activity that began on 5 August and lasted for 10 days. This cloud appeared 10 days after a launch of the space shuttle. We discuss the appearance of NLCs in August over several years at this lower polar latitude site in terms of planetary wave activity and space shuttle launches. 相似文献