Description of possible causes of the formation of anomalies of the cloud field over the Atlantic-European sector in the spring of 1996

We describe one of possible mechanisms of the formation of anomalies of the cloud field over the North Atlantic and Europe by using, as an example, the processes developed in the Atlantic-European sector during the natural synoptic season in the spring of 1996. It is shown that the anomalies of the cloud field can be classified with the use of the index of the North Atlantic oscillation and the latitude of the center of the Azorean maximum. Translated by Peter V. Malyshev and Dmitry V. Malyshev     

On the formation of atmospheric seasonal precipitation in the Black Sea region

The climatic features of the formation of precipitation and their correlation with the baric situation in the Atlantic-European sector are studied on the basis of the data of the Sevastopol and Feodosiya coastal hydrometeorological stations. As the source data, we use the data arrays of daily precipitation at these stations in 1900–2005 and the data of reanalysis of the fields of atmospheric pressure in the Atlantic-European sector. The comparative statistical analysis of daily precipitation for the wet and dry summer and winter seasons and the estimates of extremely high levels of precipitation for the specified periods of repeatability are presented. The existence of the dependence of occurrence of wet and dry winter seasons in Sevastopol and Feodosiya on the large-scale baric fields in the Atlantic-European sector is confirmed. Translated from Morskoi Gidrofizicheskii Zhurnal, No. 4, pp. 43–51, July–August, 2008.     

The response of cloudiness in the Atlantic-European section to the interannual variability of the North Atlantic Oscillations

The paper discusses the conditions corresponding to the largest and smallest North Atlantic Oscillations (NAOs). It is shown that in winter, when NAOs are at a minimum, the number of cyclones over the Black Sea increases. At the same time, cloudiness in the Atlantic-European section becomes heavier, compared with the largest NAO. Heavy cloudiness over the Balkan and Karpaty mountains, with NAO at a minimum, may imply the greater likelihood of Balkan cyclones’ penetration into the Black Sea region. The mechanism responsible for the generation of maximum (minimum) cloudiness in the Atlantic-European section is discussed. Translated by Vladimir A. Puchkin.     

Interannual and seasonal variability of hydrometeorological fields in some regions of the Atlantic-European sector as a manifestation of the abnormal behaviour of the North-Atlantic Oscillation

We study the interannual and seasonal variability of hydrometeorological fields in some regions of the Atlantic-European sector. These low-frequency processes are analyzed depending on the index ΔP (an analog of the index of the North-Atlantic Oscillation). It is shown that the average value of the index ΔP over the winter natural synoptic season can be used for the determination of stable locations of the centre of the Azorean maximum in 1971–1980 and 1981–1990, the typical state of cloudiness in the Atlantic-European sector, and the fields of precipitations and atmospheric temperature in some regions of the Crimea. Typical anomalies of the fields of precipitations and atmospheric temperature over the west and south coasts of the Crimea are described. The signs of the anomalies of precipitations in the winter natural synoptic season are in good agreement with the signs of the corresponding anomalies of the field of cloudiness in the Black-Sea region. Translated by Peter V. Malyshev and Dmitry V. Malyshev     

基于改进SICP算法的多源点云配准研究

三维激光点云数据具有精度高、数据获取高效、几何信息丰富的优势,在地形数据获取方面起到了越来越重要的作用。但在实际的外业测量中,由于视场角限制,一般都难以获取待测物体完整的点云数据,发生数据缺失现象。而根据摄影测量技术生成密集的影像点云,能获取复杂区域的测量数据。针对三维激光点云数据外业采集缺失的状况,结合影像密集点云特征,提出了一种加入动态迭代因子和分步最优求解尺度的改进尺度迭代最近点(scaling iterative closest point, SICP)算法,对影像点云与三维激光点云进行配准研究。实验结果表明:基于改进的SICP算法提高了影像点云与三维激光点云的配准精度、减少了迭代次数,能有效解决不同源平台获取的点云数据融合问题。     

Atlantic multidecadal oscillation and its manifestations in the Atlantic-European region

We present a brief survey of the works devoted to the investigation of the Atlantic Multidecadal Oscillation, i.e., of the quasiperiodic variations of sea-surface temperature in the North Atlantic with typical time scales of 50–100 yr. This oscillation is a manifestation of the natural variability in the ocean-atmosphere system. The characteristic scale of the Atlantic Multidecadal Oscillation is determined by the speed of the meridional oceanic circulation in the North Atlantic. The analyzed oscillation affects various climatic characteristics: air temperature, river discharge in the European and North-American regions, the number and intensity of tropical cyclones in the Atlantic Ocean, and the parameters of mid-latitude cyclones and anticyclones in the Atlantic-European region. The main mechanism by which the Atlantic Multidecadal Oscillation affects the climatic characteristics of the regions neighboring with the North Atlantic is the atmospheric response to the thermal anomalies in the ocean leading to a shift of the centers of atmospheric action and to the changes in the intensity and predominant directions of propagation of atmospheric cyclones and anticyclones. By using the results of long-term instrumental observations carried out in Eastern Europe and the data array of reconstructed temperature in the Alpine region, it is shown that the Atlantic Multidecadal Oscillation is responsible for a significant part of low-frequency variations of temperature in Europe. This fact confirms the potential predictability of the regional atmospheric manifestations of the Atlantic Multidecadal Oscillation on the decadal-scale. Translated from Morskoi Gidrofizicheskii Zhurnal, No. 4, pp. 69–79, July–August, 2008.     

一种准确通用的台风路径预报模式

应用天气学理论,对台风云图的晴空区轴线制约台风移动的规律进行物理解释。根据台风云团与晴空区之间存在的干、湿梯度力和推动台风前进的惯性力的互相关系,建立台风移向预报方程和轨迹预报方程,分析论证了台风移向变化的物理过程,把影响台风移动的复杂因子转化为单一的预报因子。     

Effect of the Southern Oscillation on the Variability of the Surface Temperature and Pressure in the Atlantic-European Region in Spring

On the basis of reanalysis of the data of the European Center of Medium-Range Weather Forecasts for 1979–1993, we study the relationship between the interannual and intramonthly variability of the fields of surface temperature and pressure in the Atlantic-European region and the Southern Oscillation (SO). In spring, the SO is responsible for 25% of the variance of surface temperature for periods of 8–30 days in the east part of Europe and in the Mediterranean region. In this case, the zonal circulation over the North Atlantic is intensified, which manifests itself in the deepening of the Iceland Low and Azores High. For low indices of SO, 8–15-day temperature fluctuations are predominant over the Black-Sea region. At the same time, 3–4-week fluctuations are predominant over West Mediterranean. An important role in the formation of abnormal temperature conditions in the analyzed region is payed by the events of La Niño.     

Water inrush risk assessment for an undersea tunnel crossing a fault: An analytical model

Abstract

The geological conditions of subsea tunnels are extremely complex, and a water inrush disaster is prone to occur when crossing a fault. Based on a geological analysis using cloud theory, analytic hierarchy process (AHP), and entropy weight theory, we aim to establish a normal cloud model with combination weight for water inrush risk evaluation in subsea tunnels. We select seven main factors, namely, the surrounding rock grade, rock integrity, overburden thickness, seawater thickness, tunnel section, permeability coefficient, and construction technology level as risk assessment indicators for the evaluation model. The risk is divided into five levels, and the numerical characters of the cloud model are calculated based on the standard of each risk level. The subjective weight and the objective weight are determined using AHP and the entropy weight method. The combination weight is calculated using the Delphi method. The comprehensive certainty degree is used to determine the risk level of water inrush. The model is applied to the Qingdao subsea tunnel to evaluate the water inrush risk crossing the F_4-1 fault, and the results are basically consistent with the actual excavation conditions. This article provides a new idea for the risk assessment of water inrush in the subsea tunnel.     

Investigation of the action of hygroscopic particles on a warm convective cloud from the results of numerical simulation

The results of a numerical simulation of the action of hygroscopic particles on a warm convective cloud with the purpose of obtaining additional precipitation are presented. The one-dimensional numerical model considered in this work describes the evolution of the cloud medium in the central part of an axisymmetric convective cloud at the specified height-variable velocity of the upward air flow which forms the cloud. Our model comprehensively describes microphysical processes in the cloud medium with the use of the kinetic equation for the size distribution of cloud droplets. This model makes it possible to obtain the spatiotemporal pattern of the cloud formation and development and to analyze regular features in the cloud evolution under the action of hygroscopic reagents. The cloud characteristics calculated with the use of this model correspond to the cloud parameters observed in natural conditions of the atmosphere. The process of precipitation stimulation by hygroscopic particles in convective clouds with vertical thicknesses of 2.5–4.5 km was analyzed on the basis of the results of numerical calculations. The results of calculations of the dependence of the intensity and total amount of precipitation on the vertical cloud thickness and parameters of particles introduced into the cloud are presented. It is shown that hygroscopic particles with root-mean-cube radii of 1–1.5 μm are the most effective for acting on warm convective clouds with the purpose of obtaining additional precipitation. In this case, the required reagent expenditure is 100–200 kg/km². The conditions necessary for obtaining the maximal positive effect of the action are elucidated.     

Statistical Modeling of Monthly Anomalies of Atmospheric Precipitations for the Region of the Ukraine and Black Sea

The data array accumulated for the period 1946–1995 is used to select the most significant predictor of monthly anomalies of precipitation in the region of the Ukraine and Black Sea, namely, a large-scale circulation in a sector covering the North Atlantic and Europe. Three large-scale predictors (geopotential at a level of 500GPa, sea-level pressure, and the difference between the geopotentials at levels of 500 and 1000GPa) give almost identical results: their correlation with anomalies of precipitation is equal to 0.7–0.8 in winter and 0.4–0.5 in summer. The predominant mechanism of the influence of circulation on precipitations at low frequencies is the response of the trajectories of European cyclones to changes in the upper-tropospheric jet currents in the Atlantic-European sector described as the superposition of the North-Atlantic oscillation and the Eurasian mode. The decomposition of the fields of precipitations and circulation in the eigenmodes of the canonical correlation analysis opens a possibility of direct computation of the monthly average fields of precipitations for the entire territory of the Ukraine and Black Sea region according to the large-scale geopotential fields.     

Formation of the Anomalies of Hydrometeorological Fields on the South Coast of Crimea in the Years of Decreasing Solar Activity in Its 11-Year Cycles

We study the anomalies of some hydrometeorological fields in the Atlantic-European sector and on the South Coast of Crimea (SCC) in the years of decrease in solar activity in its even and odd 11-year cycles. It is shown that, in the first half of summer, the values of the sea level and surface temperature at the SCC averaged over the years of decrease of an even cycle are lower than for the same years of an odd cycle. As a result, we make a conclusion that there exists a tendency to the formation of quasi-22-year variability of some hydrometeorological characteristics near the SCC. We also discover a trend to the antiphase variability of the number of upwellings and the surface temperature at the SCC in the years of decrease in solar activity in its even and odd 11-year cycles.     

北极中央区海冰密集度与云量相关性分析

本文使用海冰密集度以及低云、中云、高云的日平均数据,借助滑动相关分析方法,研究了北极中央区海冰密集度与云量之间的相关性,分析了海冰与云的相互作用机制。研究表明,在春季海冰融化季节(4、5月)、秋季海冰冻结季节(10、11月),低云与海冰密集度之间表现为较好的负相关,表明在这段时间内冰区海面蒸发强烈,对低云的形成有重要贡献。在10月和11月,中云与海冰密集度也有很好的负相关,表明秋季低云可以通过抬升形成中云。高云与海冰密集度之间并没有明显的相关性,可能原因:一方面海冰的空间分布对高云无影响,另一方面,高云主要影响到达的短波辐射,从而影响海冰的融化和冻结速度,与海冰厚度有直接显著的关系,而与海冰密集度的关系不明显。此外,在海冰密集度与低云存在较好负相关的情况下会出现某些年份相关性不好的情况,我们的研究发现这是北极中央区与周边海区发生了海冰交换或云交换的结果。     

Numerical simulation of the Valentine's day storm during the 1990 winter icing and storms project

This paper discusses numerical simulation of the first day of the 1990 winter icing and storms project's (WISP) Valentine's day storm (VDS) case with the Purdue mesoscale model (PMM) and comparison of the results to aircraft, satellite, radiometer and other observations. This situation is marked by many observations of supercooled liquid water (SLW) contents of 0.2 g m⁻³ to 0.3 g m⁻³ by the WISP research aircraft. The PMM was initialized with the ECMWF analysis for 13 February 1990 at 0000 GMT and used to make an 18-h forecast with output every 6 h. This paper focuses on comparison of the forecast to observations made at about 1800 GMT since the aircraft encountered significant amounts of SLW during its flight between 1723 GMT and 1928 GMT. Dual channel radiometer, satellite visible imagery, and other observational data sources are also utilized. For this study, the PMM includes a new stable cloud parameterization that is discussed here. In it, cloud water and ice are explicitly calculated while rain and snow are implicitly handled. Between 0 and − 40 °C, cloud water and cloud ice can coexist; the conversion of cloud water to cloud ice is governed by the depositional growth rate of ice crystals whose concentration is diagnosed on the basis of temperature. After accounting for precipitation, a saturation adjustment is done to remove either supersaturated vapor or subsaturation in the presence of cloud drops. In mixed phase conditions, both saturation vapor pressure and the apportionment of condensate into ice or liquid are on a mass-weighted basis according to the existing amounts of ice and liquid or on the basis of temperature if there is neither.     

Characteristics of satellite cloud maps of typhoon movement in midsummer of 1985

There were 8 typhoons over the northwestern Pacific Ocean in August of 1985. Their movement characteristics were mainly northward or recurvature northward. At the same time, a complex movement of 3 typhoons clustering was observed. In this paper, the typhoon movement tendency is studied by using satellite cloud maps. The westward and northward tendencies can be distinguished clearly. Based on this rule, typhoon movement can be forecasted 12-48 h before. Some characteristics models of the typhoon moving northward or recurving northward on the satellite cloud maps are also given in this paper.     

FY-4A卫星海域云图图像增强融合方法研究

FY-4A卫星是我国目前最先进的气象卫星,为缓解光照对其可见光和红外云图影响,增强图像质量和显示细节,通过分析中央气象台发布的FY-4A卫星云图中可见光和红外云图资料,指出云图可见光和红外云图存在极强互补性的特征,提出一种基于灰度均值的自适应非线性Gamma图像增强融合方法。仿真实验结果指出利用本文方法得到的融合云图拥有显示云的更多细节和识别云层云类的特点。该方法有效性的验证,为21世纪海上丝绸之路气象预报保障提供了新的云图识别处理技术。     

Validation and Improvement of Satellite-Derived Surface Solar Radiation over the Northwestern Pacific Ocean

The purpose of this study is to validate and improve satellite-derived downward surface shortwave radiation (DSSR) over the northwestern Pacific Ocean using abundant in situ data. The DSSR derivation model used here assumes that the reduction of solar radiation by clouds is proportional to the product of satellite-measured albedo and a cloud attenuation coefficient. DSSR is calculated from Geostationary Meteorological Satellite-5/Visible Infrared Spin-Scan Radiometer data in 0.05° × 0.05° grids. The authors first compare the satellite DSSR derived with a cloud attenuation coefficient table determined in past research with in situ values. Although the hourly satellite DSSR agrees well with land in situ values in Japan, it has a bias of +13∼+34 W/m² over the ocean and the bias is especially large in the low latitudes. The authors then improve the coefficient table using the ocean in situ data. Usage of the new table successfully reduces the bias of the satellite DSSR over the ocean. The cloud attenuation coefficient for low-albedo cases over the ocean needs to be larger in the low latitudes than past research has indicated. Daily and hourly DSSR can be evaluated from the satellite data with RMS errors of 11–14% and 30–33%, respectively, over a wide region of the ocean by this model. It is also shown that the cloud attenuation coefficient over land needs to be smaller than over the ocean because the effect of the radiation reflected by the land surface cannot be ignored.     

基于混合云模式的海洋基础地理信息云服务

GIS的表现形式已经由早期的系统转向了服务,而云计算已经成为支撑GIS服务的一种重要模式。面对广泛而迫切的海洋基础地理信息数据与应用需求,亟需构建一个统一的服务平台。结合云计算和GIS云服务发展现状,提出一个面向海洋基础地理信息、基于混合云模式、面向服务架构的海洋基础地理信息云服务体系架构设想,分析了需要重点研究的存储优化、自适应可视化与并行处理等关键问题,为构建"按需、实时、动态、易用"的服务平台提供了参考依据。     

基于模糊C均值聚类的云图样本修正与云类自动识别

基于云类样本的红外-可见光二维灰度空间投影,采用模糊聚类方法调整优化云类样本特征区域,消除采样误差。针对常规模糊C均值聚类(FCM)方法在处理上述问题时表现出的局限性,提出用样本特征均值替代FCM中随机初始中心的改进办法,既避免了常规FCM方法对初始中心敏感的缺陷,又可纠正其聚类结果对云类样本特征结构的歪曲。改进后的聚类结果既消除了采样误差,又保持了云类样本的基本特征属性。基于该判据的分类结果,可较为准确地分辨出陆地、水体、低云、中云、卷云、对流云和积雨云,分割判另9结果符合客观实际。     

黄海海雾短时临近预报中云水路径的EnKF同化研究

在海雾的短时临近预报中,初始场的水汽凝结状态扮演着重要角色。为了改进初始场的云水含量,本文提出直接同化雾体云水信息的思路。针对2011年5月一次大范围的黄海海雾,借助EnKF (Ensemble Kalman Filter)方法,尝试进行了极轨卫星反演云水路径数据的同化试验。结果表明:(1)通过利用EnKF将云水混合比增加到背景场和分析场的控制变量中,构建云水观测数据与背景场之间的关系,实现云水路径数据的直接同化是可行的;(2)同化云水路径可显著改善海面气温与湿度状态,大幅提高海雾预报效果;(3)EnKF能够基于集合体动态统计流依赖的背景误差协方差是其取得良好同化效果的主要原因。值得指出的是,受集合样本误差的影响,需要特别关注云水含量与风之间的相关关系。