共查询到19条相似文献，搜索用时 328 毫秒
1.
2016年6月23日14—15时，江苏省阜宁县突遭"增强藤田"4级龙卷、强风、短时强降水和冰雹等强对流天气，致使99人罹难，800多人受伤，属极其罕见的极端天气事件.本文利用加密自动站数据、探空数据、单部雷达观测数据以及双多普勒雷达三维风场反演数据，研究了此次龙卷发生的天气背景、龙卷超级单体的三维结构及其演变特征.研究表明：（1）龙卷发生期间，阜宁处于地面暖湿舌内、地面有γ中尺度气旋和辐合线；环境大气抬升凝结高度很低、中低层有很强的水平风的垂直切变；这有利于龙卷的生成.（2）此次龙卷超级单体左移风暴的低层有钩状回波和入流缺口，有界弱回波区位于垂直剖面中低层、悬垂回波位于风暴前部高层.（3）龙卷发生前，风暴质心高度、最大反射率因子高度和风暴回波顶高度均持续增加，风暴垂直累积液态含水量激增；龙卷发生在上述参数的数值首次同时减小时.（4）双多普勒雷达反演的三维风场揭示，超级单体形成之前的对流风暴内部中低层已经有中尺度气旋形成，中尺度气旋伴随着超级单体的生成、发展和强化的各个阶段.中尺度气旋位于钩状回波顶端、其南端有反气旋，此涡旋偶对于中层动量下传、龙卷生成、发展、加强和触地具有重要作用. 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
3.
子午工程二期漠河(122°E,53°N)大气风温金属成分激光雷达利用高空大气金属层共振荧光散射机制探测80～120 km区域的金属层成分，并将这些金属成分作为示踪物去研究中高层大气的各种复杂的化学和动力学过程.子午工程二期漠河钙原子激光雷达采用的时间分辨率为1.1 min，空间分辨率为30 m.在这种高时空分辨率下，仍然得到了高信噪比信号.通过对2023年1月钙原子数密度随时间和高度的演化过程进行分析，发现背景层钙原子峰值密度达到了33.55 cm-3左右，并且其突发层钙原子峰值密度可以达到约53.64 cm-3；在与延庆(116.0°E,40.5°N)钙原子数密度的比较研究中，我们发现延庆的钙原子数密度小于漠河的钙原子数密度；在与国外台站钙原子观测的比较研究中，我们发现漠河钙原子数密度和德国Kuhlungsborn(54°N,12°E)台站的钙原子数密度接近，比法国的Observatoire de Haute Provence(44°N,6°E)台站的钙原子数密度大.在2023年1月12日至14日，我们观测到了钙流星尾迹，并且流星尾迹往往出... 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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Fernald前向积分法能否用于机载大气探测激光雷达气溶胶后向散射系数的反演一直是一个有争议的课题.本文利用青岛机载大气探测激光雷达实测数据、国外机载大气探测激光雷达实测数据和机载大气探测激光雷达模拟数据,对Fernald前向积分法应用于不同高度的机载大气探测激光雷达气溶胶后向散射系数反演的误差进行了定量分析,分析结果表明:飞机的飞行高度在3.5 km左右,标定值存在20%的误差时,离地面2 km的高度范围内反演得到的气溶胶后向散射系数的相对误差在12%以内,但在标定点附近相对误差可达20%;飞机飞行高度在7 km左右,当标定值存在100%的误差时,反演得到的气溶胶后向散射系数的相对误差大都在10%~15%之间,标定值存在400%的误差时,反演得到的气溶胶后向散射系数的相对误差大部分在15%~50%之间.本文从理论上对Fernald前向积分法应用于机载大气探测激光雷达气溶胶后向散射系数反演出现负值的原因进行了探讨.研究表明:Fernald前向积分法能够较准确地反演出中高空探测(4.5 km以上)机载大气探测激光雷达气溶胶后向散射系数,但应用于低空探测(4.5 km以下)机载大气探测激光雷达气溶胶后向散射系数反演时,反演误差较大甚至反演结果会出现负值. 相似文献
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利用中国科学院国家空间科学中心廊坊站(40.0°N,116.3°E)钠荧光多普勒激光雷达2011年至2013年共约82 h的钠原子数密度和垂直风观测数据,分析了廊坊地区中间层顶区域大气重力波耗散引起的钠原子输送特征.分析得到,90~100km处重力波耗散引起的平均钠原子垂直通量整体为负,钠原子向下输送,在93 km处达到最大负值-1.47×10~8m~(-3)m·s~(-1),85~90km处平均钠原子垂直通量为正,钠原子向上输送,但通量值随高度递减.钠原子垂直通量方向在90km处发生转变,垂直通量随高度的变化造成钠原子汇聚,汇聚效应引起的平均钠原子产生率最大值在91km处达到了1.40×10~8m~(-3)/h,该值超过了相同高度上模式计算流星烧蚀注入引起的钠原子产生率峰值,说明重力波耗散对钠层结构的形成具有重要影响.与美国SOR和Maui观测结果相比,平均钠原子产生率峰值大小相近,但出现高度不同,说明大气重力波耗散引起的物质输送具有显著的地域变化特征.研究结果可为大气物质输送理论的完善以及大气金属层物理模式的改进提供观测事实参考. 相似文献
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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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激光雷达观测得到的密度、温度等数据被广泛应用于大气重力波研究.瑞利激光雷达可以获取激光路径上的大气密度、温度数据.对于大气中的三维波动而言,单条路径上的观测参量能提取得到的波动信息有限.本文首先以单色重力波为例,分析了利用激光雷达直接观测三维波动结构的可行性.激光雷达垂直观测即可得到重力波的垂直波长,当激光雷达以一定的天顶角斜向测量时,所得到的波长包含了重力波的垂直波长以及水平波长信息.因此,利用激光雷达同时以三个方向(垂直、向南(天顶角30°)以及向西(天顶角30°))测量,可以提取得到重力波的垂直波长和水平波长.本文利用中国科学院国家空间科学中心研制的车载532nm瑞利激光雷达的经向系统和纬向系统同时以不同的指向角观测大气重力波,对利用激光雷达获取三维波动结构的方法进行了分析研究.本文给出了北京地区激光雷达观测重力波的诸多案例,分析了30~60km高度范围内北京地区大气重力波的垂直及水平波长信息.并以2017年11月7日观测的准单色重力波为例,结合再分析资料的风场数据,分析了该重力波的水平波长,垂直波长及传播方向等信息. 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
10.
中间层顶/低热层区域(the Mesosphere/Lower Thermosphere,简称MLT)的高度为70～110 km,为了研究这一区域对太阳活动的响应,本文以钠原子为示踪物,对北京延庆(116.0°E,40.5°N)钠共振荧光激光雷达2010年1月—2021年8月近一个太阳活动周期的数据进行了分析,发现钠原子柱密度的长期变化显著,与太阳黑子数的变化呈现出正相关趋势.延庆钠层质心高度的线性趋势在这期间总共上升了311.4±706.6 m,长期变化趋势并不显著.自2018年开始,半高全宽对应的高度范围出现了明显的增加,但是上边沿升高的幅度不大,目前受到广泛关注的热层金属层的观测与研究更依赖于激光雷达探测灵敏度的提升. 相似文献
11.
利用子午工程海南激光雷达对我国海南地区上空进行持续观测,通过3年的累积观测数据对我国低纬度地区重力波活动的季节分布特性进行研究,依据重力波线性理论对海南地区上空的大气密度扰动规律、空间功率谱及时间频率谱进行分析,并通过选择波长在1km至8km范围内具有特定波长以及具有波动周期为60 min至25min的特定频率的重力波辅助研究大气密度扰动的季节变化规律,总结得出海南地区重力波活动具有夏季大、春秋季小、而冬季依然频繁的季节性分布规律.结合海南地区特殊的地理位置与当地季节性气候特征分析得出海南地区上空重力波活动季节性变化的可能原因为青藏高原地形及我国南海地区存在的热带强对流与赤道潜流共同作用的结果. 相似文献
12.
《Journal of Atmospheric and Solar》2008,70(10):1281-1288
Simultaneous and complete temperature profiles from near ground to about 100 km are essential for studying the dynamical coupling between different atmospheric layers. They are acquired by combining three different lidar techniques at Wuhan, China (30.5°N, 114.4°E). The atmospheric temperatures from about 3 to 25 km are calculated from the nitrogen molecule density profiles obtained from the N2 vibrational Raman backscatter, while the atmospheric temperatures between 30 and ∼75 km are calculated by the standard Rayleigh scattering method. The temperatures in the 80–100 km altitude region are derived from the Fe Boltzmann technique. The temperature profiles measured by our lidar systems exhibit good agreement when compared with the radiosonde and satellite data, as well as the model. A Lomb–Scargle spectral analysis of the normalized temperature perturbations in the altitude range from 4 to 60 km shows that the spectral slopes of the vertical wave number spectra tended to −3 for large vertical wave numbers. This is consistent with the model predictions of saturated gravity wave spectra. 相似文献
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14.
《Journal of Atmospheric and Solar》2005,67(7):739-748
A new retrieval method for satellite remote sensing of global sodium during nighttime is proposed. This method uses satellite limb observations of ozone density, neutral temperature, and Na D nightglow volume emission rate to retrieve sodium density. Our calculations show that, in the ideal condition in which there is no measurement noise, the retrieval error in the main region of sodium layer is very small (less than 1%). The retrieval error is mainly determined by the uncertainties in the observations of ozone, temperature and the Na D-line nightglow emission. 相似文献
15.
XueWu Cheng Yong Yang ZeLong Wang FaQuan Li GuoTao Yang ZhengYu Zhao Wei Gong JiHong Wang Xiong Hu Xin Lin XiaoCheng Wu ShaLei Song ShunSheng Gong 《中国科学:地球科学(英文版)》2016,59(2):418-424
During the total solar eclipse on July 22, 2009 in Wuhan, the joint observation test of Na layer and ionosphere was conducted by using the daytime observation atmospheric lidar and the GPS ionosphere detector. The results show that the full width at half maximum (FWHM) of Na layer density slightly narrowed during the total solar eclipse and broadened after the eclipse, while the height of Na peak slightly decreased in the eclipse and increased after the eclipse. These implying that Na layer changes reflect the rapid process of sunrise and sunset. The ionosphere total electron content (TEC) and the sky background light noise also presented an obvious fluctuation characteristic with the changes of solar irradiation during the process of total solar eclipse. The difference lies in that the changes of FWHM of Na layer atoms are much slower than that of ionosphere, the reason for this might be that the Na layer, after being disturbed by the total solar eclipse, will generate a series of complicated photochemical reactions and momentum transport processes, and then recombine the Na atoms. The Na atoms to be detected by the lidar need a lag process, which rightly conforms to the theoretical simulated results. 相似文献
16.
《Journal of Atmospheric and Solar》2008,70(7):991-1011
Using the technique developed by Gardner and Voelz [1987. Lidar studies of the nighttime sodium layer over Urbana, Illinois, 2. Gravity waves. Journal of Geophysical Research 92, 4673–4693] and a new method proposed by us, two groups of gravity wave parameters are extracted from 11 years sodium lidar measurements made at a southern low-latitude location. The wave occurrence frequencies, wave parameter distributions, and wave parameter relationships are given and compared with other lidar observations. The different lidar derived results can be attributed to different atmospheric parameters. The characteristics of these two groups of gravity waves are also compared, as well as that predicted by diffusive filtering theory, and we find the gravity wave relationships derived from our method are in better agreement with diffusive filtering theory predictions. 相似文献
17.
GuoHua Zhang XinHui Bi BingXue Han Ning Qiu ShouHui Dai XinMing Wang GuoYing Sheng JiaMo Fu 《中国科学:地球科学(英文版)》2016,59(2):320-327
Single particle mass spectrometry has been widely used to determine the size and chemical compositions of atmospheric aerosols; however, it is still rarely used for the microphysical properties measurement. In this study, two methods were developed for determining aerosol effective density by a single particle aerosol mass spectrometer (SPAMS). Method I retrieved effective density through comparison between measured light scattering intensities and Mie theoretical modelled partial scattering cross section. Method II coupled a differential mobility analyzer (DMA) with SPAMS to simultaneously determine the electric mobility and vacuum aerodynamic diameter, and thus the effective density. Polystyrene latex spheres, ammonium sulfate and sodium nitrate were tested by these methods to help validate their effectiveness for determining the aerosol effective density. This study effectively extends SPAMS measurements to include particle size, chemical composition, light scattering, and effective density, and thus helps us better understand the environment and climate effects of aerosols. 相似文献
18.
MingMin Zou LiangFu Chen JinHua Tao Lin Su Meng Fan Ying Zhang Dong Han 《中国科学:地球科学(英文版)》2014,57(8):1807-1815
We introduce the path length probability density function (PPDF) method, which is based on an equivalence theorem and parameterizes the aerosol scattering effect by adding four factors to the atmospheric transmittance model. Using simulated observations in the O2-A band, we examined the utility of the PPDF-based method to account for the aerosol scattering effect. First, observations were simulated using a forward model under different aerosol conditions; PPDF factors were then retrieved using an optimal estimation method; PPDF factors were used to reconstruct the observations; and finally, simulated true observations and reconstructions were compared. Analysis of the difference between the true observations and reconstructions confirmed the utility of the PPDF-based method. Additionally, the O2 band was demonstrated to be an efficient observing band for assisting the remote sensing of atmospheric trace gases in the near-infrared band. 相似文献
19.
S. Sridharan P. Vishnu Prasanth Y. Bhavani Kumar Geetha Ramkumar S. Sathishkumar K. Raghunath 《Journal of Atmospheric and Solar》2009,71(5):575-582
Resonance lidar observations of sodium density in the upper mesosphere region over Gadanki (13.5°N, 79.2°E) rarely show complex structures with rapid enhancements of sodium density, completely different from normal sporadic sodium structures. The hourly averaged meteor radar zonal winds over Trivandrum (8.5°N, 76.5°E) show an eastward shear with altitude during the nights, when these events are formed. As suggested by Kane et al. [2001. Joint observations of sodium enhancements and field-aligned ionospheric irregularities. Geophysical Research Letters 28, 1375–1378], our observations show that the complex structures may be formed due to Kelvin–Helmholtz instability, which can occur in the region of strong wind shear. 相似文献