Mixing layer height and meteorological measurements in Hefei China during the total solar eclipse of 22 July, 2009

Mixing layer height measurements with an elastic-backscattered lidar were carried out in Hefei, China, during the total solar eclipse of 22 July, 2009. The mixing layer height evolution is studied with the observation of changes in near-ground temperature, relative humidity and wind speed. The lidar emits the laser at the wavelengths of 532 and 355 nm, respectively, and obtains the backscattered signal with the resolution of 10 m. The whole eclipse witnessed the mixing layer change similar to that occurring during sunset. The results also show the mixing layer height decreased to 287 m rapidly during the total eclipse within only more than 1 min from the initial 354 m. The entrainment thickness reached the minimum of 43 m in the eclipse, indicating the weakening of the penetrative convection. Thereafter the thickness kept a constant value of 180 m. The temperature in the whole eclipse is uptrend, increasing only by 0.5 °C as a whole. The wind speed decreased and simultaneously the wind direction changed. The wind speed reached its minimum of 2 m/s at the end of the eclipse.     

日全食下城市热环境的变化特征分析

2009年7月22日,我国长江流域能很好地观测到一次千载难逢的日全食现象,且重庆是一个非常好的日全食观测点.作者观测了重庆地区7月21日及22日两天的室外气象数据(太阳辐射,空气温度,相对湿度等),基于实验观测数据,分析和探讨了日全食对室外热环境的影响.日全食当天,室外气温和地表温度随太阳辐射强度的减小而减小,空气温度...     

Measurements of atmospheric electrical conductivities during the total solar eclipse of 22 July, 2009

The effect of total solar eclipse on atmospheric conductivities has been studied. Continuous measurements of both types of positive and negative electrical conductivities and some meteorological parameters in conjunction with the total solar eclipse of 22 July, 2009 were made from 21 to 23 July, 2009 at Roorkee (29°52′ N, 77°53′ E, 275 m above sea level). Roorkee observed 90% maximum obscurity of eclipse since it was close to the path of totality. The event started from 05:28 AM IST and ended at 07:42 AM IST with the total eclipse at 06:30 AM IST. Considerable increase of both positive and negative conductivities were recorded during the eclipse with respect to those made on any other day. Increase in relative humidity and decrease in temperature were also observed during the period of eclipse.     

Observations of Acoustic Gravity Waves during the Solar Eclipse of March 20, 2015 in Kaliningrad

Results of observations of atmospheric and ionospheric parameters during the solar eclipse of March 20, 2015 have been described. The observations have been conducted by lidar sensing in the lower atmosphere and analysis of the total electron content (TEC) in the ionosphere in Kaliningrad. Observations at the troposphere altitudes have been conducted using an atmospheric lidar. Ionospheric parameter TEC has been determined according to observations of navigation satellite signals. The spectral analysis of the monitored parameters during the solar eclipse has shown that, in the lower atmosphere and the ionosphere in a period range of 2–20 min, internal gravity waves (IGWs) and infrasonic waves are excited. During the main phase of the eclipse, the major contribution to variations in the parameters of the medium comes from infrasonic vibrations. Changes in the variations in the atmospheric and ionospheric parameters with IGW periods are observed only in the initial and final phases of the eclipse.     

西藏日食太阳辐射观测研究

日食现象会对地球太阳辐射、大气气象以及人类活动等造成相应的影响。2020年6月21日（夏至）在西藏发生了一次日食现象,西藏阿里日环食最大食分达到了0.995,拉萨地区日偏食食分也高达0.953。两地日食均发生在当地正午前后。本研究利用罕见的日食出现机会,对西藏阿里和拉萨日食过程中的太阳光谱、太阳总辐射和太阳紫外线变化特征进行了同步观测研究。观测表明阿里日环食在当地正午（北京时间14:41分）前后持续了约3小时27分钟;拉萨日食出现时间比阿里滞后约26 min,持续时间比阿里短3分28秒。实地观测表明在日食期间,阿里光谱观测中最强单色（476.6 nm）光峰值从初亏（13:01分）时刻的1 669.234 mW·m-2·nm-1陡然衰减到食甚（14:44分）时刻的61.936 mW·m-2·nm-1,损失约96.0%;相应时刻太阳总辐射强度从1 221.217 W·m-2衰减到56.086 W·m-2,也损失约95.4%。拉萨日食期间最强单色（476.6 nm）光峰值从初亏（13:27分）时刻的1 563.876 mW·m-2·nm-1亏损到食甚（15:13分）时刻的26.391 mW·m-2·nm-1,亏损约98.3%;相应时刻太阳总辐射强度从1 605.663 W·m-2衰减到28.169 W·m-2,也亏损约98.2%。观测研究发现拉萨太阳紫外线B剂量率从初亏的60.8 W·m-2减弱到食甚的0.9 W·m-2值,减弱了98.5%。该次日食对西藏地面各种太阳辐射强度造成95%以上能量损失。     

A study on excitation of atmospheric gravity waves from annular solar eclipse

Utilizing the data of microbarometric waves on ground level,radiosonde reports and solar radiations obtained from various observation sta-tions in China during the annular solar eclipse on September 23,1987,themechanism of AGWs excited by the eclipse,the spectral characteristics and thelocal differences have been studied,and the results have been compared withthose from the ionospheric sounding at the same time.It turns out that therewere AGWs excited certainly during this annular solar eclipse,their periods areobviously in accordance with the duration of the fluctuation in the direct solarradiation.     

Amazonia Introduced to General Relativity: The May 29, 1919, Solar Eclipse from a North-Brazilian Point of View

In 1919, A. C. D. Crommelin and C. R. Davidson, British astronomers from the Greenwich Observatory in England, passed by Amazonia on their Brazilian journey aiming to measure the bending of stars' light rays during the total solar eclipse of May 29, 1919, and thereby put the theory of general relativity to the test. In the context of Crommelin’s and Davidson’s visit, we discuss how Amazonia was introduced to Einstein’s theory of gravitation, and also the observations and repercussions of the May 29, 1919, solar eclipse in Belém, capital city of the North-Brazilian Pará state.     

Feature of the multifractal structure of small-scale ionospheric turbulence during the solar eclipse of August 1, 2008

Using the method of radio sounding of the mid-latitude ionosphere by the satellite signals, we study the multifractal structure of small-scale ionospheric turbulence during a solar eclipse. The measured multipower and generalized multifractal spectra of small-scale ionospheric turbulence at the initial and closing stages of the eclipse turn out to be almost identical on the space radio paths with different orientations. This is indicative of a sufficiently high stability of the nonuniform spatio-temporal distribution of small-scale fluctuations of the ionospheric electron number density under conditions of geophysical disturbances due to global physical processes in the ionospheric plasma during a solar eclipse. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 52, No. 4, pp. 302–306, April 2009.     

2019年—2020年秋、冬季淮南市灰霾过程拉曼-米气溶胶雷达观测研究

拉曼-米气溶胶激光雷达因无需假设雷达比,而在准确测量气溶胶消光系数方面较传统米散射雷达更具优势。在合肥市的外场探空比对实验结果表明,2.5 km以下拉曼-米激光雷达反演的消光系数更为准确,相差可达0.04 km-1,且获取的水汽混合比廓线与探空数据一致性良好。利用该技术获得了2019年—2020年秋、冬季期间淮南市的气溶胶消光系数廓线和边界层高度等数据,进而对空气质量污染期间的污染类型（本地污染排放、传输型污染、传输型污染叠加本地污染累积）和颗粒物的时空演变特征进行了统计分析。结果显示该市在此期间受到20次细颗粒传输和8次沙尘传输影响。其中沙尘传输主要来自西北方向,由高空沉降至近地面（厚度达2 km以上）,平均大气边界层高度达1.23 km以上。在典型细颗粒传输过程中,边界层高度基本维持在1.1~1.2 km左右,近地面风向以西北风为主,少量东南风主导。在细颗粒传输叠加本地累积的复合污染过程中,边界层高度略低（平均高度在1.0 km左右）,近地面风向以偏北风为主,污染气团自低空出现后,其下沿高度持续降低并最终与近地面污染耦合。在细颗粒导致的重污染过程中,近地面水汽混合比及相对湿度数据与PM_2.5的浓度变化趋势一致性良好,说明颗粒物的吸湿性增长和气态污染物二次转化过程可能助推了PM_2.5的生成,加重污染形势。对边界层的统计结果表明,其高度变化对污染气团的沉降和近地面污染累积有十分明显的正相关性。秋冬季期间,该市的小时边界层高度大部分分布在1.6 km以下,平均为1.0 km左右,小时空气质量达重度污染期间,边界层高度普遍不足0.6 km。从气团后向轨迹模拟结果来看,该市空气质量为中度及以上污染期间的气流主要来自偏北方向,少量来自东南沿线,因而污染期间需要加强市区偏北方向污染源的管控,防止叠加影响。     

激光雷达探测北京城区夏季大气边界层

为了研究北京城区夏季大气边界层结构变化特征及大气边界层内气溶胶消光特性,2004年8月利用便携式米散射激光雷达对北京城区夏季大气边界层进行了系统观测。反演了观测站上空大气气溶胶的消光特性垂直分布以及大气边界层的高度。分析了气象条件和人类活动对大气边界层结构的影响。观测数据表明： 北京城区夏季大气边界层有明显的日变化特征,早晚比较低,日间有一个从低变高再变低的过程,中午前后达到最高。结合气象参数对测量数据进行的统计分析表明：北京城区夏季大气边界层高度相对稳定,多分布在1.8km以下,平均值为0.68km;大气边界层内存在浓度较高的气溶胶粒子,平均光学厚度（3km以内）在0.30左右。     

Long term variations of solar radius

Total and annular eclipses allow us to measure the angular solar diameter at unit distance up to an accuracy of some hundredths of arcsecond. Data of lunar limb features from Japanese mission Kaguya will be useful to detect also the solar oblateness signal, relevant from a General Relativistic point of view. Useful eclipse data are available for 1567, 1715, 1869, 1925 and from 1966 to 2009 with uneven sampling: only these data can allow a study of solar diameter evolution with significant resolution on secular basis.     

Solar eclipse effects of 22 July, 2009 on the propagation of radio signals

The results of investigation of the variation of radio signal strengths during the solar eclipse on July 22, 2009 are reported in this paper. Observations of the radio signals transmitted from different radio stations at different frequencies and received at a particular observing site indicate a distinct change in signal strength around the time the eclipse umbra passes the propagation paths. The three types of variations in the eclipse day and particularly during its peak period are different from propagation under normal condition. The phenomena of signal variations, the noted “Inverted U-shape“ at one of the frequencies before the occurrence of the eclipse and 13 to 15 minutes time difference between the enhancement of the signal strength and the onset of eclipse are some interesting characteristics. The results are interpreted by ionospheric D-layer behavior at such times.     

New measurements with a torsion pendulum during the solar eclipse

During the solar eclipse of 11 July 1991 in Mexico the period of a torsion pendulum was measured in order to reexamine possible anomalies observed in previous experiments of this kind. In our experiment no significant change was found as the relative change in the period associated with the eclipse was less than 2.0×10^–6 (90% confidence). Results were similar to our previous ones made during the eclipse in 1990 in Finland when the Sun was much lower in the horizon. However, two small but distinct shifts were observed in the horizontal position of the pendulum wire which were well correlated with the beginning and the end of the eclipse.     

Variations in the Characteristics of a HF Signal over an Oblique Sounding Path during the Solar Eclipse on August 11, 1999

We present the results of measurements of the HF-signal characteristics over the path Praha - Nizhny Novgorod during the solar eclipse on August 11, 1999. A 10-dB increase in the HF-signal amplitude and an increase in the frequency of quasiperiodic fading were observed during daytime in the course of the eclipse with phase about 68-85%. An interpretation of the effects observed is given. On the basis of simulations, we show that the increase in the amplitude is related to a decrease in absorption losses which is caused by the corresponding decrease in the electron density in D- and E-layers by about 30-45%. The increase in the fading frequency results from beating of the modes that have different Doppler shifts due to phase-path variations during the eclipse. An estimate for the rate of electron-density variation during the eclipse was obtained: dN/dt (2-2.5) ·10² cm^-3s^-1.     

Une retombée inattendue de l'éclipse du 11 août 1999

Examination of a painting from the Paris Observatory collections of a solar eclipse until now thought to be that of 22 May 1724, and a comparison with a recently published print, have led to the conclusion that the painted phenomenon is the eclipse of 3 May 1715.     

日食对Ne发射光谱强度的影响

为了观测日食时刻日－地空间发生的异常物理现象，本工作采用了观测Ne放电管光源的Ne光谱变化的方法，观测结果表明，日食对Ne光谱的强度产生影响，越接近食甚时刻，Ne光谱强度越弱。     

The abnormal influence of the partial solar eclipse on December 24th, 1992, on the time comparisons between atomic clocks

Summary During the partial solar eclipse on Dec. 24th, 1992, time comparisons between atomic clocks were made: direct comparisons between different clocks at one and the same station, clock transport comparisons, GPS comparisons and LOC comparisons. And it is concluded from the observations that solar eclipse exerts an influence on the rate of atomic clocks. Project Supported by the State Science and Technology Commission of China and by the National Natural Foundation of China.     

爱丁顿与广义相对论的验证

简单介绍了在广义相对论诞生之初,验证其理论正确性的三个天文实验,并详细介绍了爱丁顿为验证广义相对论,发起并组织的观测1919年5月29日的日全食考察队的具体情况.这是爱丁顿认为他在天文学研究中最激动人心的事件.     

Observations of the atmospheric boundary layer across the land-sea transition zone using a scanning Mie lidar

Optical properties of the atmospheric boundary layer (ABL) above the land-sea transition interface were measured using a scanning Mie lidar located 30 km away from the Adriatic coast. Based on the two-dimensional range-height-indicator scans, detailed information on the ABL was obtained, including parameters such as atmospheric optical depth, aerosol extinction coefficient and the height of the ABL. The presented case study indicates that the height of the ABL in the land-sea transition zone and the adjacent mountainous region was changing rapidly due to highly variable atmospheric conditions.     

Ionospheric response to the solar eclipse on March 29, 2006

In the present work, results of vertical sensing of the ionosphere at the Klyuchi (Novosibirsk) and Arti (Ekaterinburg) Geophysical Observatories during the solar eclipse on March 29, 2006 are given. The maximum eclipse was observed in Novosibirsk at 11:43 UT; the obscuring phase was 92%. A maximum obscuring phase of 80% was observed at the Arti Georhysical Observatory at 11:32 UT. The results obtained are compared with the analogous data obtained in the preceding and next days as well as with the data of many-year observations on March 28, 29, and 30. The results obtained demonstrate that the eclipse affects most strongly the characteristics of the F layer. The maximum variations of the critical frequency f₀F2 were delayed by about 10 min from the maximum eclipse phase, relaxation started half an hour after the maximum eclipse phase, and the frequency decreased at most by 1.5 MHz. A decrease in the critical frequency of the F1 layer has a greater delay and smaller amplitude. The results obtained are in good agreement with previous measurements. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 68–72, September, 2006.