Geostationary satellite observations of the april 1979 soufriere eruptions

Infrared images from the geostationary satellite SMS-1 were used to study the growth of the eight major eruptions of Soufriere, St. Vincent, during April 1979. These eruptions differed considerably in growth and intensity, the most intense being that of 17 April which formed an ash cloud of 96,000 square kilometers in 4 hours. The weakest eruption formed a cloud of only 16,000 square kilometers.     

Voyager 2 radio science observations of the uranian system: atmosphere, rings, and satellites

Voyager 2 radio occultation measurements of the Uranian atmosphere were obtained between 2 and 7 degrees south latitude. Initial atmospheric temperature profiles extend from pressures of 10 to 900 millibars over a height range of about 100 kilometers. Comparison of radio and infrared results yields mole fractions near the tropopause of 0.85 and 0.15 +/- 0.05 for molecular hydrogen and helium, respectively, if no other components are present; for this composition the tropopause is at about 52 kelvins and 110 millibars. Distinctive features in the signal intensity measurements for pressures above 900 millibars strongly favor model atmospheres that include a cloud deck of methane ice. Modeling of the intensity measurements for the cloud region and below indicates that the cloud base is near 1,300 millibars and 81 kelvins and yields an initial methane mole fraction of about 0.02 for the deep atmosphere. Scintillations in signal intensity indicate small-scale stucture throughout the stratosphere and upper troposphere. As judged from data obtained during occultation ingress, the ionosphere consists of a multilayer structure that includes two distinct layers at 2,000 and 3,500 kilometers above the 100-millibar level and an extended topside that may reach altitudes of 10,000 kilometers or more. Occultation measurements of the nine previously known rings at wavelengths of 3.6 and 13 centimeters show characteristic values of optical depth between about 0.8 and 8; the maxim value occurs in the outer region of the in ring, near its periapsis. Forward-scattered signals from this ring have properties that differ from those of any of Saturn's rings, and they are inconsistent with a discrete scattering object or local (three-dimensional) assemblies of orbiting objects. These signals suggest a new kdnd of planetary ring feature characterized by highly ordered cylindrical substructures of radial scale on the order of meters and azimuthal scale of kilometers or more. From radio data alone the mass of the Uranian system is GM(sys) = 5,794,547- 60 cubic kilometers per square second; from a combination of radio and optical navigation data the mass of Uranus alone is GM(u) = 5,793,939+/- 60 cubic kilometers per square second. From all available Voyager data, induding imaging radii, the mean uncompressed density of the five major satellites is 1.40+/- 0.07 grams per cubic centimeter; this value is consistent with a solar mix of material and apparently rules out a cometary origin of the satellites.     

Preliminary results of the solar flux radiometer experiment aboard the pioneer venus multiprobe mission

The solar flux radiometer aboard the Pioneer Venus large probe operated successfully during its descent through the atmosphere of Venus. Upward, downward, and net fluxes from 0.4 to 1.0 micrometers were obtained at more than 390 levels between 185 millibars (at an altitude of approximately 61 kilometers) and the surface. Fluxes from 0.4 to 1.8 micrometers were also obtained between 185 millibars and about the level at which the pressure was 2 atmospheres. Data from 80 to 185 millibars should be available after additional decoding by the Deep Space Network. Upward and downward intensities in a narrower band from 0.59 to 0.66 micrometers were also obtained throughout the descent in order to constrain cloud properties. The measurements indicate three cloud regions above the 1.3-atmosphere level (at an altitude of approximately 49 kilometers) and a clear atmosphere beneath that level. At the 67 degrees solar zenith of the probe entry site, some 15 watts per square meter are absorbed at the surface by a dark ground, which implies that about 2 percent of the solar energy incident on the planet is absorbed at the ground.     

Clouds of venus: a preliminary assessment of microstructure

The multimodal microstructure of the Venus cloud system has been examined. In addition to confirmed H(2)SO(4) droplets and suspected elemental sulfur, a highly concentrated aerosol population has been observed extending above, within, and below the cloud system. These aerosols appear to cycle through the cloud droplets, but can never be removed by the weak precipitation mechanisms present. All cloud particles are likely laced with aerosol contaminants. Sedimentation and decomposition of H(2)SO(4) in the droplets of the lower cloud region contribute more than 7 watts per square meter of heat flux equaling one-fourth of the solar net flux at 50 kilometers.     

呼伦贝尔市2013年7月14-16日暴雨天气分析

利用常规气象资料和红外云图资料,对2013年7月14—16日呼伦贝尔市一次暴雨天气过程进行成因分析、,结果表明：此次降水的环流形势为典型的副热带高压与西风槽相互作用的暴雨天气形势．系统垂直发展旺盛且坡度陡直,使得中低层影响系统始终处于上升运动区：地面气旋的辐合作用和辐合线的抬升作用是这次暴雨产生的触发机制;中低空急流的耦合配置为对流发展创造了有利条件,同时低空急流为这次暴雨天气提供了源源不断的水汽输送：南北长达数千公里带状云系上的对流云团强盛发展与暴雨落区时应很好、     

Tropical deforestation and habitat fragmentation in the Amazon: satellite data from 1978 to 1988

Landsat satellite imagery covering the entire forested portion of the Brazilian Amazon Basin was used to measure, for 1978 and 1988, deforestation, fragmented forest, defined as areas less than 100 square kilometers surrounded by deforestation, and edge effects of 1 kilometer into forest from adjacent areas of deforestation. Tropical deforestation increased from 78,000 square kilometers in 1978 to 230,000 square kilometers in 1988 while tropical forest habitat, severely affected with respect to biological diversity, increased from 208,000 to 588,000 square kilometers. Although this rate of deforestation is lower than previous estimates, the effect on biological diversity is greater.     

Preliminary results of the pioneer venus small probe net flux radiometer experiment

Net radiation measurements in the atmosphere of Venus indicate that the bulk of the atmosphere is radiatively cooling at high latitudes and heating at low latitudes. Similarity of features observed by all three probes indicate planetwide stratification. Flux variations within the clouds provide evidence of significant differences in cloud structure. A feature of unusually large opacity found near 60 kilometers at the north probe site is probably related to the unique circulation regime revealed by ultraviolet and infrared imagery. A stable layer between the cloud bottoms and about 35 kilometers contains several features in the flux profiles probably resulting from large-scale compositional stratifications rather than clouds. In the layer below 35 kilometers unexpectedly large fluxes were observed.     

Rapid and extensive surface changes near Titan's equator: evidence of April showers

Although there is evidence that liquids have flowed on the surface at Titan's equator in the past, to date, liquids have only been confirmed on the surface at polar latitudes, and the vast expanses of dunes that dominate Titan's equatorial regions require a predominantly arid climate. We report the detection by Cassini's Imaging Science Subsystem of a large low-latitude cloud system early in Titan's northern spring and extensive surface changes (spanning more than 500,000 square kilometers) in the wake of this storm. The changes are most consistent with widespread methane rainfall reaching the surface, which suggests that the dry channels observed at Titan's low latitudes are carved by seasonal precipitation.     

新一代星载云雨测量雷达系统技术研究

双频率、多极化星载云雨测量雷达是遥感探测技术发展的必然趋势。深入研究了新一代双频多极化星载云雨测量雷达系统技术,给出了双频多极化雷达系统框图与主要指标,分析了天线子系统实现方案,提出了天线子系统的技术指标;考虑了中央电子设备子系统的实现方案,并计算了星载云雨测量雷达的数据率。该研究为开展空间云雨测量雷达系统研究进行了有益的尝试,可为我国未来空间云雨测量雷达的设计与研制提供参考。     

Atmospheric Physics and Earth Observations: Observations of Lyman-agr Emissions of Hydrogen and Deuterium

A spectrophotometer was flown on Spacelab 1 to study various mechanisms of Lyman-alpha emission in the upper atmosphere. The use of absorption cells filled with H(2) and D(2) gases allowed us to discriminate a number of weak Lyman-alpha emissions heretofore masked by the strong H geocoronal emission due to resonance scattering of solar photons. Preliminary results are presented on three topics: the first optical detection of the deuterium Lyman-alpha emission at 110 kilometers, with an intensity of 330 rayleighs indicating an eddy diffusion coefficient of 1.3 x 10(6) square centimeters per second; auroral proton precipitations seen on both the night and the day side; and an emission located above 250 kilometers of altitude, interpreted as the result of charge exchange of magnetospheric protons with geocoronal atoms.     

基于三维激光扫描仪法的大型立式罐容量的计量

介绍了一种基于三维激光扫描技术的立式罐容量计量方法,利用三维激光扫描仪获取立式罐表面点云数据,进行罐体三维模型重构,计算罐体容积并建立容积表。阐述了基于点云分析的立式罐容积计算模型,以及观察法、中值滤波、莱以特准则（3盯准则）在点云数据预处理中的应用,并给出了利用最小二乘法、加速迭代法、等效面积法计算圈板半径的相关公式。采用HDS7000三维激光扫描仪对某2×10^4m^3立式罐进行了试验测试,检验了HDS7000三维激光扫描仪和相应方法在容量计量中的重复性和复现性。测量结果表明：三维激光扫描仪法与立式金属罐容量计量检定规程中规定的全站仪法测得的圈板半径最大偏差仅为0．1mm,容积相对偏差不超过1％o,满足检定规程要求。（表5,图8,参9）     

Expansion and contraction of the sahara desert from 1980 to 1990

Data from polar-orbiting meteorological satellites have been used to determine the extent of the Sahara Desert and to document its interannual variation from 1980 to 1990. The Sahara Desert ranged from 8,633,000 square kilometers in 1980 to 9,982,000 square kilometers in 1984. The greatest annual north-south latitudinal movement of the southern Saharan boundary was 110 kilometers from 1984 to 1985 and resulted in a decrease in desert area of 724,000 square kilometers.     

Land-use allocation protects the Peruvian Amazon

Disturbance and deforestation have profound ecological and socioeconomic effects on tropical forests, but their diffuse patterns are difficult to detect and quantify at regional scales. We expanded the Carnegie forest damage detection system to show that, between 1999 and 2005, disturbance and deforestation rates throughout the Peruvian Amazon averaged 632 square kilometers per year and 645 square kilometers per year, respectively. However, only 1 to 2% occurred within natural protected areas, indigenous territories contained only 11% of the forest disturbances and 9% of the deforestation, and recent forest concessions effectively protected against clear-cutting. Although the region shows recent increases in disturbance and deforestation rates and leakage into forests surrounding concession areas, land-use policy and remoteness are serving to protect the Peruvian Amazon.     

Thermal contrast in the atmosphere of venus: initial appraisal from pioneer venus probe data

The altitude profiles of temperature and pressure measured during the descent of the four Pioneer Venus probes show small contrast below the clouds but significant differences within the clouds at altitudes from 45 to 61 kilometers. At 60 kilometers, the probe which entered at 59.3 degrees north latitude sensed temperatures 25 K below those of the lower latitude probes, and a sizable difference persisted down to and slightly below the cloud base. It also sensed pressure below those of the other probes by as much as 49 millibars at a mean pressure of 200 millibars. The measured pressure differences are consistent with cyclostrophic balance of zonal winds ranging from 130 +/- 20 meters per second at 60 kilometers to 60 +/- 17 meters per second at 40 kilometers, with evidence in addition of a nonaxisymmetric component of the winds. The clouds were found to be 10 to 20 K warmer than the extended profiles of the lower atmosphere, and the middle cloud is convectively unstable. Both phenomena are attributed to the absorption of thermal radiation from below. Above the clouds, in the lower stratosphere, the lapse rate decreases abruptly to 3.5 K per kilometer, and a superimposed wave is evident. At 100 kilometers, the temperature is minimum, with a mean value of about 170 K.     

Areal spread of the effect of cloud seeding at the whitetop experiment

With reference to arguments that weather modification technology is sufficiently advanced for the federal government to finance cloud-seeding operations as a means of alleviating water shortages, an analysis of the Whitetop rain stimulation experiment was performed. The average 24-hour precipitation in six concentric regions up to 180 miles from the center of the target on 102 days of cloud seeding was less than that on the 96 experimental days without seeding. For distances less than 30 miles, the apparent loss of rain due to seeding was 32 percent. With the increase in distance, this apparent loss decreased to a minimum of 9 percent for gages between 120 and 150 miles from the center. However, the 48 gages at distances between 150 and 180 miles showed a 22 percent apparent loss of rain due to seeding. The estimated average loss of rain within the whole region of about 100,000 square miles was 21 percent of what would have fallen without seeding. When a 5-year experiment, expected to produce a 5 to 10-percent increase, shows a 20-percent decrease in rainfall, the relevant technology does not appear reliable enough for practical use.     

Clouds of venus: evidence for their nature

The linear polarization of sunlight multiply scattered by the atmosphere, and cloud particles of Venus has been computed and compared with observations over the wavelength range from the ultraviolet to the infrared region. The following properties of the visible cloud layer are derived: the refractive index of the cloud particles is 1.45 +/- 0.02 at a wavelength of 0.55 micron, and there is an indication of a slight decrease in the value from the ultraviolet to the near-infrared region; the mean particle radius is very near 1 micron, and most of the particles are spherical; the cloud layer occurs high in the atmosphere where the pressure is about 50 millibars (equivalent to an altitude of approximately 20 kilometers on the earth). The results for the index of refraction eliminate the possibility that the visible clouds are composed of pure water or ice.     

Thunderstorms: an important mechanism in the transport of air pollutants

Acid deposition and photochemical smog are urban air pollution problems, and they remain localized as long as the sulfur, nitrogen, and hydrocarbon pollutants are confined to the lower troposphere (below about 1-kilometer altitude) where they are short-lived. If, however, the contaminants are rapidly transported to the upper troposphere, then their atmospheric residence times grow and their range of influence expands dramatically. Although this vertical transport ameliorates some of the effects of acid rain by diluting atmospheric acids, it exacerbates global tropospheric ozone production by redistributing the necessary nitrogen catalysts. Results of recent computer simulations suggest that thunderstorms are one means of rapid vertical transport. To test this hypothesis, several research aircraft near a midwestern thunderstrom measured carbon monoxide, hydrocarbons, ozone, and reactive nitrogen compounds. Their concentrations were much greater in the outflow region of the storm, up to 11 kilometers in altitude, than in surrounding air. Trace gas measurements can thus be used to track the motion of air in and around a cloud. Thunderstorms may transform local air pollution problems into regional or global atmospheric chemistry problems.     

Direct observations of excess solar absorption by clouds

Aircraft measurements of solar flux in the cloudy tropical atmosphere reveal that solar absorption by clouds is anomalously large when compared to theoretical estimates. The ratio of cloud forcing at an altitude of 20 kilometers to that at the surface is 1.58 rather than 1.0, as predicted by models. These results were derived from a cloud radiation experiment in which identical instrumentation was deployed on coordinated stacked aircraft. These findings indicate a significant difference between measurements and theory and imply that the interaction between clouds and solar radiation is poorly understood.     

Structure of the Atmosphere of Venus up to 110 Kilometers: Preliminary Results from the Four Pioneer Venus Entry Probes

The four Pioneer Venus entry probes transmitted data of good quality on the structure of the atmosphere below the clouds. Contrast of the structure below an altitude of 50 kilometers at four widely separated locations was found to be no more than a few degrees Kelvin, with slightly warmer temperatures at 30 degrees south latitude than at 5 degrees or 60 degrees north. The atmosphere was stably stratified above 15 or 20 kilometers, indicating that the near-adiabatic state is maintained by the general circulation. The profiles move from near-adiabatic toward radiative equilibrium at altitudes above 40 kilometers. There appears to be a region of vertical convection above the dense cloud deck, which lies at 47.5 to 49 kilometers and at temperature levels near 360 K. The atmosphere is nearly isothermal around 100 kilometers (175 to 180 K) and appears to exhibit a sizable temperature wave between 60 and 70 kilometers. This is where the 4-day wind is believed to occur. The temperature wave may be related to some of the wavelike phenomena seen in Mariner 10 ultraviolet photographs.     

Deceleration of interstellar hydrogen at the heliospheric interface

High-resolution spectra of nearby stars show absorption lines due to material in the local interstellar cloud. This cloud is deduced to be moving at 26 kilometers per second with respect to the sun, and in the same direction as the "interstellar wind" flowing through the solar system. Measurements by the Ulysses spacecraft show that neutral helium is drifting through the solar system at the same velocity, but neutral hydrogen appears to be moving at only 20 kilometers per second, a result confirmed by new measurements of the hydrogen emission line taken by the High-Resolution Spectrograph on the Hubble Space Telescope. These results indicate that neutral hydrogen atoms from the local interstellar cloud are preferentially decelerated at the heliospheric interface, most likely by charge-exchange with interstellar protons, while neutral helium is unaffected by the plasma. The magnitude of the observed deceleration implies an interstellar plasma density of 0.06 to 0.10 per cubic centimeter, which in turn implies that the heliospheric shock should be less than 100 astronomical units from the sun.