卫星云图上日食阴影的订正

日食使卫星可见光云图上出现明显的阴影区，影响卫星云图的分析和利用。分析了日食对太阳辐射强度的影响，提出一种日食阴影区的订正方法，并给出订正个例。     

拉尼娜现象和日食的关系

通过资料分析 ,找出了日食和拉尼娜现象的因果关系 ,并揭示了日食形成拉尼娜现象的机制     

红外分层增强云图的温度标定及使用方法的探讨

增强卫星云图的问世,提供了卫星云图分析由定性向定量化发展的有用资料。本文讨论了GMS红外分层增强云图的增强方法、温度标定和使用方法,给出了这种云图的灰度级次与降水量的关系,以及根据这种云图推算云区面积、云顶温度梯度和定量估计降水量的方法     

1987年9月23日南京日食期间的辐射测量与计算

本文分析了1987年9月23日南京日食期间的辐射测量。结果表明:直接辐射因日食减小44.7％,这与日食期间大气对它的衰减43.2％很接近,而它与晴天无日食时大气的衰减没有显著差异。日食期间净辐射减小35.8％,散射辐射减小45.5％,紫外辐射减小23.1％。由于这次日食,全球净损失的能量1.8×10~(14)MJ与锋区运动系统的动能相当,是1981年7月31日日食期间能量净损失的9倍。     

日食与厄尔尼诺、拉尼娜现象

由资料分析出厄尔尼诺、拉尼娜现象是由日食形成的受迫振荡，以日食形成的有效位能说明日食改变大气环流，从而形成厄尔尼诺、拉尼娜的机制。     

云图模型与数值产品结合预报海洋气旋

分析了西北太平洋温带气旋爆发性发展前期的云图特征,概括了气旋爆发过程的5类云图模型。通过实例揭示了物理参数与云系的发展有很好的对应关系,最后给出了使用卫星云图和数值产品做气旋爆发性发展的短期预报思路和判断爆发性气旋生成的方法。     

基于OpenGL的AWX格式红外云图三维仿真技术应用

针对AWX格式红外云图数据特点,依据红外云图三维仿真原理,通过构建DEM模型和应用OpenGL技术,提出了适合云图自身特点真实感表现的颜色及透明度获取方法,实现了对AWX格式红外云图三维仿真显示,并给出了实现方法及流程。通过应用验证,该方法对AWX格式红外云图三维仿真显示速度快,更好地反映了云团的空间分布特征,增强了云图的显示效果。     

基于OpenGL的AWX格式红外云图三维仿真技术应用

针对AWX格式红外云图数据特点,依据红外云图三维仿真原理,通过构建DEM模型和应用OpenGL技术,提出了适合云图自身特点真实感表现的颜色及透明度获取方法,实现了对AWX格式红外云图三维仿真显示,并给出了实现方法及流程。通过应用验证,该方法对AWX格式红外云图三维仿真显示速度快,更好地反映了云团的空间分布特征,增强了云图的显示效果。     

卫星水汽图的干区轴线在台风路径预报中的应用

通过对卫星云图的水汽图或红外云图的分析,发现水汽图干区或红外云图上的无云区(晴空带)对台风的移动方向有制约作用,经过研究和实践,找到了应用水汽图干区轴线或红外云图上的无云区(晴空带)的中直线来预报台风移动路径的方法。     

小波变换在气象卫星云图压缩中的应用

该文分析了卫星云图和自然图像在小波系数分布上的特征差异,提出了基于小波变换的气象卫星云图压缩方案。方案选择对卫星云图压缩效果较好的、具有双正交性的Odegard 9/7滤波器组对卫星云图进行五级小波分解和重构;根据卫星云图小波分解系数相似性强、低频分量能量更为集中、分量系数层次衰减性明显的特点,使用改进后的零树编码算法对小波系数进行编码运算;最后,采用高效的自适应算术编码对输出数据流进行了进一步的压缩。该方法对卫星云图的压缩效果要优于经典的嵌入式零树小波编码,在失真允许情况下,对红外云图的最大压缩比可达40:1,水汽云图达60:1,可见光云图达35:1。     

Studies of the atmospheric stability characteristics during the solar eclipse of February 16, 1980

Observations made with a monostatic sodar and from a 120 m instrumented tower have been used to study the variations in the atmospheric boundary layer at Tarapur (19° 50 N, 72° 41 E) during the solar eclipse of February 16, 1980. Atmospheric instability was reduced below normal values during the eclipse but the atmosphere at no time became stable.     

Localized climatic responses during the 11 July 1991 eclipse: Phoenix AZ

Measurements taken from a variety of land use environments in and around the Phoenix AZ metropolitan area were compared to determine the effects of various land use characteristics on the thermal response to a reduction of 68% in solar radiation during the solar eclipse of 11 July 1991. The results include: (a) The magnitude of the change in ambient air temperature during the eclipse is related to land use. Heavily asphalted military sites and irrigated golf courses recorded small decreases in temperature while natural desert terrain experienced the largest decreases. Variations in thermal response are more closely related to the albedo of the specific land type than to other factors such as thermal admittance but this high correlation is probably an artifact of the combination of other variables such as moisture. (b) Due to the complex mix of land uses and timing of eclipse, marked wind speed changes associated with the eclipse do not appear to be linked directly to land use changes, and, (c) Temperature minima at residential/commercial stations occurred in general, before the minima at stations in agricultural/golf terrains. Because typical albedo differences are not significant between these two land uses, land use characteristics other than albedo are most likely controlling the timing of the temperature minima. Opportunities to empirically examine concepts previously testable only through numerical modeling such as solar reduction experiments should continue to be exploited.     

Solar eclipse-induced variations in solar flux, j(NO2) and surface ozone at Kannur, India

Surface ozone is mainly produced by the photodissociation of nitrogen dioxide (NO₂) by solar UV radiation. Subsequently, solar eclipses provide one of the unique occasions to explore the variations in the photolysis rate of NO₂ and their significant impact on the production of ozone at a location. This study aims to examine the diurnal variations in the photodissociation rate coefficient of NO₂, (j(NO₂*)), and mixing ratios of surface ozone and NO _X * (NO?+?NO₂*) during the solar eclipse that occurred on 15 January 2010 at Kannur (11.9°N, 75.4°E, 5?m amsl), a tropical coastal site on the Arabian Sea in South India. This investigation was carried out on the basis of the ground level observations of surface ozone and its prominent precursor NO₂*. The j(NO₂*) values were estimated from the observed solar UV-A flux data. A sharp decline in j(NO₂*) and surface ozone was observed during the eclipse phase because of the decreased efficiency of the ozone formation from NO₂. The NO₂* levels were found to increase during this episode, whereas the NO levels remained unchanged. The surface ozone concentration was reduced by 57.5%, whereas, on the other hand, that of NO _X * increased by 62.5% during the solar eclipse. Subsequently a reduction of *% in the magnitude of j(NO₂*) was found here during the maximum obscuration. Reductions in solar insolation, air temperature and wind speed were also observed during the solar eclipse event. The relative humidity showed a 6.4% decrease during the eclipse phase, which was a unique observation at this site.     

Atmospheric Surface-Layer Response to the Annular Solar Eclipse of 15 January 2010 over Thiruvananthapuram,India

On 15 January 2010, Thiruvananthapuram in India (8.5°N, 76.9°E) witnessed one of the longest possible noontime annular solar eclipses spanning a period of about 7 min centred at 1314 local time. Here, we present a case study on the behaviour of the atmospheric surface layer by comparing the eclipse-induced observations with similar measurements recorded on cloud-free/clear-sky days. During the peak period of the eclipse, the incoming solar irradiance was reduced by 87% of its normal values, resulting in an air-temperature decrease near the surface of 1.2°C in association with a significant reduction in turbulent kinetic energy, momentum flux and sensible heat flux. The rate of instantaneous decay in solar radiation and sensible heat flux from the first contact of the eclipse to its annularity was greater than that seen during normal evening hours.     

Atmospheric Surface-Layer Processes During the Total Solar Eclipse Of 11 August 1999

The central path of the total solar eclipse (TSE) of 11 August 1999 mostly passedthrough a region of active monsoon in India, with the eclipse ending around localsunset. Measurements in the surface layer (SL) were carried out close to the eclipseaxis at Akola (20°42' N, 77°2' E) in central India. The globalradiation flux reaching the surface vanishes around totality at 1803:24 (LT), followedby a small recovery before again dipping to zero at sunset. The temperatures in the SL, and subsoil at 50-mm depth, show a local minimum with a lag of about 10 min after the second contact, whereas the lag appears to vanish when the temperature series is detrended. The SL exhibits near-neutral, though generally stable, conditions from about 1500 hr itself due to heavy cloud cover followed by the eclipse-induced cooling of the surface. The wind component across the eclipse axis vanishes at totality, the wind vector aligning with the azimuth of the traversing moon shadow. The deceleration of the mean flow can be due to the combined effect of the colder surface and downward heat flux, where the locally altered horizontal temperature gradients may cause, as in this instance, the cessation of the cross flow.The oscillations in temperature and wind that show significant peaks, around 90–100 min as well as the semi-period of the eclipse near 60 min, persist for several hours past the eclipse event. A fresh analysis of the published data on the TSE of 7 March 1970 shows spectral peaks in the temperature nearly coincident with those already reported from the surface pressure records. The oscillations in the SL fields during the two TSE events are very similar implying that the source mechanism is also likely to be the same in both the cases.     

Remote Sensing And Surface Observations Of The Response Of The Atmospheric Boundary Layer To A Solar Eclipse

On 11 August 1999, a near-total solar eclipse (80%) was observed in Campistrous, France. The influence of this particular event on the atmospheric boundary layer was observed with a UHF-RASS radar, a sodar and an instrumented mast. The changes in turbulence intensity, radar reflectivity, and temperature on the radiative budget are described in relation to collocated ground meteorological data. The impact of the eclipse induces a clear response of the atmosphere, with a time lag of 15 to 30 min, perceptible in several mean and turbulent meteorological variables up to the top of the atmospheric boundary layer.     

从宽带太阳直接辐射小时或日曝辐量反演气溶胶光学厚度研究

从宽带的太阳直接辐射1天或1小时累计量(曝辐量)气象观测资料反演气溶胶光学厚度的一个有效方法是很有用的.作者把太阳曝辐量与"等效"的瞬时太阳直接辐射关联起来,建立了一个与曝辐量"等效"的瞬时太阳直接辐射的模式;应用该模式和一个"等效"波长模式,发展了一个从太阳直接曝辐量反演气溶胶光学厚度的方法.作者还从试验上比较分析了由某时刻的宽带太阳直接辐射、每小时或1天的太阳直接辐射曝辐量反演得到的气溶胶光学厚度以及由太阳光度计探测的气溶胶光学厚度.试验结果表明,由日太阳直接辐射曝辐量反演得到的气溶胶光学厚度可理解为辐射加权的日平均光学厚度.     

A solar eclipse seen from the High Arctic during the period of midnight sun: effects on the local meteorology

The solar eclipse on 1 August 2008 was studied on Svalbard (93% totality), an archipelago in the High Arctic, where midnight sun had been present for several months. Simultaneous observations over land and over a large fjord showed that the eclipse triggered downslope winds in the valleys surrounding the fjord, thereby creating low-level clouds over the water. These clouds were later advected in over land and created a fog that lasted for 3 days, grounding all air traffic to and from Svalbard. The atmospheric response was otherwise much slower and weaker over water than over land. Over land, the wind speed decreased, the atmospheric stability changed from unstable to stable and the air temperature sank by 0.3–1.5°C, while over the fjord no clear minima in these parameters could be found.     

Effects of a Total Solar Eclipse on the Mesoscale Atmospheric Circulation over Europe – A Model Experiment

Summary ?On August the 11th, 1999 Central Europe saw a spectacular astronomical event, a total solar eclipse. We present a model study concerning the meteorological effects of this eclipse in central Europe using the state-of-the-art limited area forecast model Deutschland-Modell DM from the German Weather Service DWD. Under typical summer radiation conditions very strong anomalies in the surface energy flux and temperature in screen height are simulated. The main temperature signal in the lower troposphere is delayed by about one hour with respect to the surface. Furthermore it is connected with a well defined dynamical signal which is reminiscent to a large scale land – sea circulation. The event could be used as a test case for mesoscale atmospheric models. Received February 19, 1999/Revised May 18, 1999