GCOM-W AMSR2资料在CMA_GFS 四维变分中的同化应用

卫星微波仪器的辐射率资料,由于兼具卫星观测的全天空优势和微波观测的全天候特性,成为数值天气预报系统同化的日益重要的角色。微波成像仪作为被动微波辐射计的重要一类,其在数值预报中的应用潜力亟待进一步的检验和更充分的挖掘。针对全球水循环变化观测卫星GCOM-W上搭载的第2代先进微波扫描辐射计AMSR2的10个通道,建立了半径200 km的稀疏化方案;研发了包含9项检验的质量控制方案,对于污染低频通道观测的太阳耀光现象和无线电信号干扰等因素进行屏蔽;设计基于经典预报因子的偏差订正方案,对仪器系统偏差进行有效的校正;采用基于变分同化后验估计的观测误差统计,克服了观测误差难以准确估计的问题。通过以上方法,GCOM-W AMSR2共有10个通道辐射率资料在中国自主研发的全球/区域同化预报系统（CMA_GFS,原名为GRAPES_GFS）3.0版的四维变分同化系统（4DVar）中实现了直接同化应用。1个月的批量试验证明,同化GCOM-W AMSR2后,CMA_GFS湿度分析场得到了一定的改进,各量级定量降水中期预报评分有所提高,同时,GCOM-W AMSR2辐射率直接同化对CMA_GFS南半球和赤道地区预报有明显正贡献。研究证实AMSR2能够很好地弥补常规观测资料稀疏区的资料匮乏,发挥水汽敏感特性,改进湿度分析和降水预报的技巧。      

高被引论文选编

<正>"对流有效位能"主题来源数据库:SCI-E和CAJD,检索时段:2015-2016年美国东部的极端降水对温度和对流有效位能的依赖性——Temperature and CAPE dependence of rainfall extremes in the eastern United States.Geophysical Research Letters,2015,Vol.42,No.1.     

AMSR2辐射率资料同化对台风“山神”分析和预报的影响研究

在WRFDA-3DVar（Weather Research and Forecasting model's 3-dimensional variational data assimilation）的框架下,添加了新的探测器AMSR2（Advanced Microwave Scanning Radiometer 2）微波辐射率资料的同化模块,实现了AMSR2辐射率资料在中小尺度同化系统中的有效使用。台风"山神"（Son-Tinh）直接同化AMSR2资料的个例试验结果表明,AMSR2资料可以很好的探测出台风的形态,并且与没有同化该资料的控制试验相比,同化AMSR2辐射率资料可以有效提高模式分析场的质量,进一步提高了台风中心气压,最大风速和台风路径的预报。     

高被引论文选编

<正>"电网气象"主题来源数据库:SCI-E和CAJD,检索时段:2015—2016年气候变化和变率对电力发电的影响 ——The impact of climate change and variability on the generation of electrical power.Meteorologische Zeitschrift,2015,Vol.24,No.2.发电与气候变率和变化之间存在密切联系。电力行业的化石燃料燃烧是人为气候变化的主要驱动因素,而水力发电对气候的影响仍有     

Observational evidence for the Monin-Obukhov similarity under all stability conditions

Data collected in the surface layer in a northern suburban area of Nanjing from 15 November to 29 December 2007 were analyzed to examine the Monin-Obukhov similarity for describing the turbulent fluctu- ations of 3D winds under all stability conditions and to obtain the turbulence characteristics under different weather conditions. The results show that the dimensionless standard deviations of turbulent velocity com- ponents (σ u /u* , σ v /u* , σ w /u * ) and dimensionless turbulent kinetic energy (TKE) can be well described by "1/3" power law relationships under stable, neutral, and unstable conditions, with σ u /u * > σ v /u * > σ w /u* . Land use and land cover changes mainly impact dimensionless standard deviations of horizontal component fluctuations, but they have very little on those of the vertical component. The dimensionless standard devi- ations of wind components and dimensionless TKE are remarkably affected by different weather conditions; the deviations of horizontal wind component and dimensionless TKE present fog day > clear sky > overcast > cloudy; the trend of the vertical wind component is the reverse. The surface drag coefficient at a Nan- jing suburban measurement site during the observation period was obviously higher than at other reported plains and plateau areas, and was approximately one order larger in magnitude than the reported plains areas. Dimensionless standard deviation of temperature declined with increasing |z /L| with an approximate "-1/3" slope in unstable stratification and "-2/3" slope in stable stratification.     

Conditions for producing and maintaining plasma ball lightning in the atmosphere

Based on the results of plasma experiments and research work done by Dawson and Jones, Trubnikov, Endean, and other researchers, three requirements for producing and maintaining plasma ball lightning have been found: 1) rotation of plasma, 2) the density of charged particles nc > 3.15 × 10-10ω2,3) a stable confinement of plasma. In this model, the energy density of ball lightning ranged from 10-2 J / cm3 to 104 J/ cm3, the formation, shape, stability, energy, maintaining processes and other properties of ball lightning were explained reasonably.     

Conditions for Producing and Maintaining Plasma Ball Lightning in the Atmosphere

Based on the results of plasma experiments and research work done by Dawson and Jones, Trubnikov, Endean, and other researchers, three requirements for producing and maintaining plasma ball lightning have been found: 1) rotation of plasma, 2) the density of charged particles nc > 3.15 × 10-10ω2,3) a stable confinement of plasma. In this model, the energy density of ball lightning ranged from 10-2 J / cm3 to 104 J/ cm3, the formation, shape, stability, energy, maintaining processes and other properties of ball lightning were explained reasonably.     

THE ENERGY BUDGETS UNDER DIFFERENT SYNOPTIC CONDITIONS OVER HUAIHE RIVER BASIN DURING HUBEX FIELD OBSERVATION PERIODS IN 1999

In different synoptic conditions and at different time scales,the analysis of the energy budgetsby Bowen Ratio Method and Bulk Schemes over Huaihe River Basin during the field observationperiods of HUBEX in 1999 shows that,(1)the averaged latent heat flux is an order of magnitudemore than the averaged sensible heat flux during the observation period:(2)the variation of totalcloud amount is out of phase with the terms of energy budgets except for the downward longwaveradiation which maybe is related to the cloud's height and class:(3)the values of sensible andlatent heat fluxes are small during rain episodes,but thereafter,the values become high and thenup to maximum.It is similar to the other terms of the energy budgets except for the downwardlongwave radiation.The diurnal variation of energy budgets indicates that the daytime precipitationexerts great influence to the energy budgets,but the nighttime precipitation makes little influence;(4)the variation of the latent heat flux is in phase with the evaporation,which indicates that thelatent heat flux calculated by bulk schemes is reliable:(5)the means of the sensible and latentheat flux and momentum flux by bulk schemes for the time period from May to August are,respectively,30.71W/m~2.116.81W/m~2.2.86×10~(-2)N/m~2 in 1998 and 30.28W/m~2,107.35W/m~2,2.74×10~(-2)N/m~2 in 1999.The values of these two years are similar.During summer in1999 the magnitude and activity of sensible heat flux are strongest in June and those of the latentheat flux are in August.     

高被引论文选编 上海气象局参与发表的高被引论文

正来源数据库:SCI-E和CAJD,检索时段:2015—2016年中国上海城市综合气象观测实践与经验——URBAN INTEGRATED METEOROLOGICAL OBSERVATIONS practice and experience in Shanghai,China.Bulletin of the American Meteorological Society,2015,Vol.96,No,1.     

Characteristics of Lake Breezes and Their Impacts on Energy and Carbon Fluxes in Mountainous Areas

In mountainous lake areas, lake–land and mountain–valley breezes interact with each other, leading to an "extended lake breeze". These extended lake breezes can regulate and control energy and carbon cycles at different scales. Based on meteorological and turbulent fluxes data from an eddy covariance observation site at Erhai Lake in the Dali Basin,southwest China, characteristics of daytime and nighttime extended lake breezes and their impacts on energy and carbon dioxide exchange in 2015 are investigated. Lake breezes dominate during the daytime while, due to different prevailing circulations at night, there are two types of nighttime breezes. The mountain breeze from the Cangshan Mountain range leads to N1 type nighttime breeze events. When a cyclonic circulation forms and maintains in the southern part of Erhai Lake at night, its northern branch contributes to the formation of N2 type nighttime breeze events. The prevailing wind directions for daytime, N1, and N2 breeze events are southeast, west, and southeast, respectively. Daytime breeze events are more intense than N1 events and weaker than N2 events. During daytime breeze events, the lake breeze decreases the sensible heat flux(Hs) and carbon dioxide flux(F_{CO_2}) and increases the latent heat flux(LE). During N1 breeze events, the mountain breeze decreases Hs and LE and increases F_{CO_2}. For N2 breeze events, the southeast wind from the lake surface increases Hs and LE and decreases suppress carbon dioxide exchange.     

ATMOSPHERIC TURBULENCE STRUCTURE AND SPECTRAL CHARACTERISTICS AT NEAR SURFACE LAYER ON TROPICAL COASTS

By use of an observational experiment at the village of Tianwei, Haikou, Hainan province in 1990,characteristic turbulence values such as velocity component spectra and turbulence intensity are studied.The data were mostly obtained in cloudy condition, so that the stability parameter (L) and thermal flux (wt) did not vary diurnally while the turbulent energy and mean-temperature did. The basic characteristics of turbulence spectra are similar to those with fine weather, hems close to local isotropy in the inertial subrange. The velocity spectra agree with the law of "-2/3 th power"in Kolmogrov's similarity theory. The relationship between turbulent intensity of components δ_i/U (i=u,v,w) and stability Z/L is studied follow ins the Monim-Obukhov(M-O) similarity theory. It is shown that the two observe the law of "1/3 th power", though the turbulent intensity and energy are generally larger than those on the flat underlying topography.     

A NUMERICAL STUDY OF THE PBL CONDITIONS OVER RECLAIMED GRASSLAND

PBL conditions over reclaimed grassland in North China(49°19′N, 119°55′E) are examined using the improved ver-sion of the model developed by Nickerson et al. (1986). Basic results are presented as follows: i) the reclaimed section, orthe "heat island", has noon intensity of 4—6℃, the surface disturbance can be felt at 700 m AGL and convectiveperturbance at the PBL top, with a convective speed of 1—2 cm / s; ii) once grassland is reclaimed on a large scale, thePBL climate will develop into further aridity; iii) irrigation can alleviate the intensity and dryness of the "island" but failsto prevent the climate from aridization; iv) the local circulation in the PBL keeps its direction unchanged in 24 hours, i.e.,wind blows toward the "island" at the height below 150—200 m at roughly 2 m/s and returns at higher levels with aslightly smaller speed. Further, moist flow can extend 30—50 km horizontally inside the reclamation.     

AN INTEGRATION METHOD WITH FITTING CUBIC SPLINE FUNCTIONS TO A NUMERICAL MODEL OF 2ND-ORDER SPACE-TIME DIFFERENTIAL REMAINDER——FOR AN IDEAL GLOBAL SIMULATION CASE WITH PRIMITIVE ATMOSPHERIC EQUATIONS

In this paper,the forecasting equations of a 2nd-order space-time differential remainder are deduced from the Navier-Stokes primitive equations and Eulerian operator by Taylor-series expansion.Here we introduce a cubic spline numerical model(Spline Model for short),which is with a quasi-Lagrangian time-split integration scheme of fitting cubic spline/bicubic surface to all physical variable fields in the atmospheric equations on spherical discrete latitude-longitude mesh.A new algorithm of"fitting cubic spline—time step integration—fitting cubic spline—……"is developed to determine their first-and2nd-order derivatives and their upstream points for time discrete integral to the governing equations in Spline Model.And the cubic spline function and its mathematical polarities are also discussed to understand the Spline Model’s mathematical foundation of numerical analysis.It is pointed out that the Spline Model has mathematical laws of"convergence"of the cubic spline functions contracting to the original functions as well as its 1st-order and 2nd-order derivatives.The"optimality"of the 2nd-order derivative of the cubic spline functions is optimal approximation to that of the original functions.In addition,a Hermite bicubic patch is equivalent to operate on a grid for a 2nd-order derivative variable field.Besides,the slopes and curvatures of a central difference are identified respectively,with a smoothing coefficient of 1/3,three-point smoothing of that of a cubic spline.Then the slopes and curvatures of a central difference are calculated from the smoothing coefficient 1/3 and three-point smoothing of that of a cubic spline,respectively.Furthermore,a global simulation case of adiabatic,non-frictional and"incompressible"model atmosphere is shown with the quasi-Lagrangian time integration by using a global Spline Model,whose initial condition comes from the NCEP reanalysis data,along with quasi-uniform latitude-longitude grids and the so-called"shallow atmosphere"Navier-Stokes primitive equations in the spherical coordinates.The Spline Model,which adopted the Navier-Stokes primitive equations and quasi-Lagrangian time-split integration scheme,provides an initial ideal case of global atmospheric circulation.In addition,considering the essentially non-linear atmospheric motions,the Spline Model could judge reasonably well simple points of any smoothed variable field according to its fitting spline curvatures that must conform to its physical interpretation.     

Impacts of Drying on the Agricultural Structure of North China

It is one of subprojects of the National Basic Theoretical Research Project "The Living Environment Evolution and the Prediction Research on Drying Trend in North China." The project includes three parts:(1) the regionalization of ecological functional zones and discussions;(2) changes of water resources and their impacts on the agricultural production;(3) impacts of drying on the agricultural structure of arid or semiarid areas in North China and the corresponding countermeasures.     

高被引论文选编

正"气候基准站"主题来源数据库:SCI-E和CAJD,检索时段:2015—2016年美国气候基准站网(USCRN)和合作观测计划(CO O P)网的观测视角:基于温度和降水的对比——Observational perspectives from USC limate Reference Network(USCRN)and Cooperative Observer Program(COOP)Network:Tem perature and precipitatio n comparison.Journal of Atmospheric     

AN OBSERVATIONAL ANALYSIS OF A TORRENTIAL RAINSTORM IN THE WARM SECTOR OF SOUTH CHINA COASTAL AREAS

On May 20 th 2007, a brief but severe downpour rainstorm occurred in the coastal areas of Maoming and Yangjiang with rainfall of 115 mm per hour. Data from NCEP/NCAR reanalysis with 1°×1° resolution, Doppler weather radar, conventional surface observations, high-altitude radiosonde and wind profiler radar were used to analyze characteristics and contributions of synoptic scale and mesoscale systems during this torrential rainstorm. The results showed that:(1) the storm was caused by a quasi-linear mesoscale convective system(MCS) and the slow-movement of this system was the primary trigger of the torrential downpour;(2) water vapor was abundant, nearly saturated and in steady state throughout the atmosphere before the storm; intrusion of the weak dry and cold air in the middle level and a striking "dry above and wet below " structure had increased the atmospheric instability;(3) low-level southwesterly airflow from a low pressure(trough) at the Beibu Gulf provided abundant water vapor at the onset of the rainstorm; a deep dry layer was formed by dry and cold air behind the high-level trough, which facilitated latent heat release;upper-level divergence and low-level convergence circulations also provided vertical uplift for warm and moist air at the lower level;(4) Topography only played a minor role as the MCS developed and strengthened over relatively flat coastal terrain. Low level density flow induced by convection triggered new convective cell generation at the leading edge of the convective system, thereby playing a key role in the change of temperature gradient at lower layers, and resulting in strengthening atmospheric instability.     

Observations of NO2 and O3 during thunderstorm activity using visible spectroscopy

Simultaneous observations for the total column densities of NO2, O3 and H2O were carried on using the porta-ble Spectrometer (438-450 nm and 400-450 nm) and the visible Spectrometer (544.4-628 nm) during premonsoon thunderstorms and embedded hail storm activity at Pune (18o32’N & 73o51’E), India. These observations confirm the fact that there is an increase in O3 and NO2 column densities during thunderstorms. The increase in O3 was observed following onset of thunderstorm, while the increase in NO2 was observed only after the thunder flashes occur. This implies that the production mechanisms for O3 and NO2 in thunderstorm are different. The observed column density of NO2 value (1 to 3 × 1017molecules · cm-2) during thunderstorm activity is 10 to 30 times higher than the value (1 × 1016molecules · cm-2) of a normal day total column density. The spectrometric observations and observations of thunder flashes by electric field meter showed that 6.4 × 1025molecules / flash of NO2 are produced. The increased to-tal column density of ozone during thunderstorm period is 1.2 times higher than normal (clear) day ozone concentra-tion. The multiple scattering in the clouds is estimated from H2O and O2 absorption bands in the visible spectral re-gion. Considering this effect the calculated amount of ozone added in the global atmosphere due to thunderstorm ac-tivity is 0.26 to 0.52 DU, and the annual production of ozone due to thunderstorm activity is of the order of 4.02 × 1037 molecules /year. The annual NO2 production may be of the order of 2.02 × 1035molecules / year.     

A STUDY ON DEFORMATIONS OF RAY AND ITS RELEVANT FACTORS*

In this paper,the effects of first and second meridional derivative(i.e.h_s^u,d²f/dy²,u″)of the Coriolis parameter,Westerly profile and topography structure on ray routes are qualitatively analysed by use of a simplified mathematical model.The analysis indicates that the second derivatives of the above relevant factors play an important role in the formation of great circle route.A profile of west wind similar to the real atmosphere may result in a "sine wave pattern" of ray.The effects of west wind shear,β factor and the slope of topography on the scale of radius of great circle,critical latitude of rays ard the amplitude of wave train of teleconnection are also discussed.Additionally,the characters of critical velocity profile for meridionally trapped wave are mentioned.     

VICARIOUS RADIOMETRIC CALIBRATION OF SATELLITE FY-ID SENSORS AT VISIBLE AND NEAR INFRARED CHANNELS

For the problem of in-flight test site radiometric calibration for the FY-1D Meteorological Satellite onboard sensor's visible and near infrared channels,this paper described the calibration method,satellite-ground synchronous observation data acquired at China Dunhuang Calibration Test Site,parameter derivation and radiative transfer computation during the calibration,and the calibration result analysis.At FY-1D seven channels (with central wavelength at Channels 1:630 nm,2:865 nm;6:1610 nm;7:455 nm,8:505 nm;9:555 nm;10:932 nm),calibration coefficients obtained during the ground site calibration were compared with that respectively of prelaunch calibration.It is demonstrated that results of FY-1D onboard two sensors' (A and B) at channels 1,2,6 and 10 were close to pre-calibration,and the absolute difference of Gobi desert reflectance computed using test site and pre-launch calibration coefficients was no more than 2%. At other channels,large pre-launch calibration errors resulted in a poor consistency between the test site and pre-launch calibration.The errors can be corrected by the test site calibration results. Based on a rough estimation,the overall error of the calibration was about 6%. The paper also presented the in-flight vicarious calibration at the visible and near infrared channels of FY-1C sensor A which was launched in 1999 and has been put into operational mode since 2002.The results exhibit that FY-1C sensor's response has 23% attenuation at Channels 7 and 8,while only minor degradation at the other channels was found. During the mission,calibrations were also conducted at NOAA-17's Channels 1 and 2 (1:430-830 nm,2:500-1072 nm).A very good consistency has been achieved between the test site and pre-launched calibration results.     

新书架上

《Chemistry of atmospheres An introductionto the Chemistry of the Atmospheres of Earth,theplanets,and their satellites》(大气化学/地球、行星及其卫星大气化学引论),Richard P.Wayne 著,CL-ARENDON PRESS OXFORD 出版,1985年,361页。本书作者是牛津大学的物理化学讲师,本书把大气化学与传统的自然科学联系起来。全书分九章:1.化学组成;2.大气的物理性质;3.大气光化学