Assessment and Assimilation of FY-3 Humidity Sounders and Imager in the UK Met Office Global Model     

Fabien CARMINATI  Brett CANDY  William BELL  Nigel ATKINSON 《大气科学进展》2018,35(8):942-954

China's Feng Yun 3(FY-3) polar orbiting satellites are set to become an important source of observational data for numerical weather prediction(NWP),atmospheric reanalyses,and climate monitoring studies over the next two decades.As part of the Climate Science for Service Partnership China(CSSP China) program,FY-3 B Microwave Humidity Sounder 1(MWHS-1) and FY-3 C MWHS-2 observations have been thoroughly assessed and prepared for operational assimilation.This represents the first time observations from China's polar orbiting satellites have been used in the UK's global NWP model.Since 2016,continuous data quality monitoring has shown occasional bias changes found to be correlated to changes in the energy supply scheme regulating the platform heating system and other transient anomalies.Nonetheless,MWHS-1 and MWHS-2 significantly contribute to the 24-h forecast error reduction by 0.3% and 0.6%,respectively,and the combination of both instruments is shown to improve the fit to the model background of independent sounders by up to 1%.The observations from the Microwave Radiation Imager(MWRI) also are a potentially significant source of benefits for NWP models,but a solar-dependent bias observed in the instrument half-orbits has prevented their assimilation.This paper presents the bases of a correction scheme developed at the Met Office for the purpose of a future assimilation of MWRI data.  相似文献   

Contribution of syncollisional felsic magmatism to continental crust growth: A case study of the Paleogene Linzizong volcanic Succession in southern Tibet   总被引：50，自引：0，他引：50  

Xuanxue Mo  Yaoling Niu  Guochen Dong  Zhidan Zhao  Zengqian Hou  Su Zhou  Shan Ke 《Chemical Geology》2008,250(1-4):49-67

The Linzizong volcanic succession (~ 65–45 Ma) and the coeval batholiths (~ 60−40 Ma) of andesitic to rhyolitic composition represent a magmatic response to the India–Asia continental collision that began at ~ 70–65 Ma and ended at ~ 45–40 Ma with convergence continuing to present. These syncollisional felsic magmatic rocks are widely distributed along much of the > 1500 km long Gangdese Belt immediately north of the India–Asia suture (Yarlung–Zangbo) in southern Tibet. Our study of the Linzizong volcanic rocks from the Linzhou Basin (near Lhasa) suggests that syncollisional felsic magmatism may in fact account for much of the net contribution to continental crust growth. These volcanic rocks show a first-order temporal change from the andesitic lower Dianzhong Formation (64.4–60.6 Ma), to the dacitic middle Nianbo Formation (~ 54 Ma), and to the rhyolitic upper Pana Formation (48.7–43.9 Ma). The three formations show no systematic but overlapping Nd–Sr isotope variations. The isotopically depleted samples with ε_Nd(t) > 0 indicate that their primary sources are of mantle origin. The best source candidate in the broad context of Tethyan ocean closing and India–Asia collision is the remaining part of the Tethyan ocean crust. This ocean crust melts when reaching its hydrous solidus during and soon after the collision in the amphibolite facies, producing andesitic melts parental to the Linzizong volcanic succession (and the coeval batholiths) with inherited mantle isotopic signatures. Ilmenite as a residual phase (plus the effect of residual amphibole) of amphibolite melting accounts for the depletion of Nb, Ta and Ti in the melt. The effect of ocean crust alteration plus involvement of mature crustal materials (e.g., recycled terrigeneous sediments) enhances the abundances of Ba, Rb, Th, U, K and Pb in the melt, thus giving the rocks an “arc-like” geochemical signature. Residual amphibole that possesses super-chondritic Nb/Ta ratio explains the sub-chondritic Nb/Ta ratio in the melt; residual plagioclase explains the slightly depleted, not enriched, Sr (and Eu) in the melt, typical of continental crust. These observations and reasoning plus the remarkable compositional similarity between the andesitic lower Dianzhong Formation and the model bulk continental crust corroborates our proposal that continental collision zones may be sites of net crustal growth (juvenile crust) through process of syncollisional felsic magmatism. While these interpretations are reasonable in terms of straightforward petrology, geochemistry and tectonics, they require further testing.  相似文献   

全球植被与大气之间碳通量的模式估计   总被引：15，自引：0，他引：15  

Li Yinpeng  Ji Jinjun 《大气科学进展》2001,18(5):807-818

用大气植被相互作用模式(AⅥM)模拟了全球陆地植被的净初级生产力(NPP)。AⅥM由相互耦合的两部分组成：物理过程，包括陆地表面水分和能量在土壤、植被与大气之间的传输；以及生理生态过程，如：光合、呼吸、干物质分配、凋落和物候等。全球的植被分为13类，土壤按质地分为6类。用EMDI提供的全球1637个包括不同植被类型的NPP观测点数据对模型进行了检验。NPP模拟的结果表明：全球陆地植被的平均NPP为405.13 g C m-2yr-1，不同植被类型的平均NPP变化范围在99.58 g C m-2yr-l(苔原)到996.2 g C m-2yr-l(热带雨林)之间。全球年总NPP为60.72 Gt C yr-l，其中最大的部分为热带雨林，15.84 Gt C yr-1，占全球的26.09％。最大的碳汇是在北半球的温带。模式模拟的NPP在全球的空间和季节分布是合理的。  相似文献   

Potential economic benefits from sablefish farming in British Columbia     

Ussif Rashid Sumaila  John Volpe  Yajie Liu 《Marine Policy》2007

We present in this paper results of an analysis of the potential economic contribution of sablefish farming in British Columbia (BC). This is necessary because a BC sablefish hatchery has recently begun production of juvenile sablefish for grow-out in marine net pens. The production from this single hatchery is anticipated to effectively support sablefish production that will match the entire current BC sablefish capture fishery. Two key questions we address are, how will net benefits (added value) to BC from the sablefish sector be affected if (i) BC and the rest of the world engage in sablefish farming, and (ii) BC bans sablefish farming while the rest of the world does not. We find that at low BC aquaculture production levels, small economic gains are possible. However, gains quickly disappear as production increases towards anticipated levels. A sablefish-farming ban in BC could be beneficial to the province and Canada if BC wild sablefish landings command a price premium of at least 20–25%.  相似文献   

Practical spreading of driving forces for wave-driven currents     

Hyoseob Kim   《Ocean Engineering》2004,31(3-4):435-453

Profiles of wave-induced current on plane beaches are generally smooth. Previously, the smooth nature was often explained by involving lateral mixing concept. This paper describes a new spreading approach instead of the previous lateral mixing approach. The spreading of the driving forces leads to similar results on the velocity profiles of the previous approach. The results of the new method show good agreement with some laboratory measurements for a plane beach. The present method was then extended for two-dimensional plan problems. The present approach was tested against a laboratory experiment, and the computed flow field agrees reasonably well with the measured flow field. A merit of the present method is that the computational time increment is not restricted by the lateral mixing.  相似文献   

A B-spline-based method for radiation and diffraction problems     

Ranadev Datta  Debabrata Sen   《Ocean Engineering》2006,33(17-18):2240-2259

An open uniform B-spline-based panel method is developed for solution of potential flow problems. In this method, both geometry as well as the field variables are represented by the same open uniform B-spline basis function. The method is initially applied for the radiation problem in unbounded fluid. Computed results for a spheroid of different aspect ratio are found to be in excellent agreement with analytical results. The method is then applied for diffraction problem formulated based on the transient (time-domain) Green's function. Computed results for a hemisphere and Wigley hull are compared with published results and the comparison shows good agreement.  相似文献   

Wave radiation by a uniform cylinder in front of a vertical wall     

B. Teng  D. Z. Ning  X. T. Zhang 《Ocean Engineering》2004,31(2):201-224

In this paper, an exact analytical method is developed for the problem of wave radiation by a uniform cylinder in front of a vertical wall. Based on the image principle, the hydrodynamic problem of a cylinder in front of a vertical wall is transformed into the equivalent problem of double cylinders in unbounded fluid domain. Consequently, an analytical method of eigenfunction expansion is adopted to calculate the radiation of the cylinder due to the motion in surge, sway, roll and pitch, respectively. Moreover, numerical analysis has been carried out in detail in order to discuss the influences of the distance between the cylinder and the vertical wall and water depth on the added mass and radiation damping of the cylinder. It is shown that added mass and damping of the cylinder in front of a vertical wall are evidently different from those in case of the cylinder in unbounded fluid domain from the numerical results. It is also found that the added mass and radiation damping oscillate with wave number, and the oscillating frequency increases with the increasing of the distance between the cylinder and the wall.  相似文献   

Quasiintegrals of the photogravitational eccentric restricted three-body problem with Poynting–Robertson drag     

G. F. Chörny 《Celestial Mechanics and Dynamical Astronomy》2007,97(4):229-248

A restricted three-body problem for a dust particle, in presence of a spherical cometary nucleus in an eccentric (elliptic, parabolic or hyperbolic) orbit about the Sun, is considered. The force of radiation pressure and the Poynting– Robertson effect are taken into account. The differential equations of the particle’s non-inertial spatial motion are investigated both analytically and numerically. With the help of a complex representation, a new single equation of the motion is obtained. Conversion of the equations of motion system into a single equation allows the derivation of simple expressions similar to the integral of energy and integrals of areas. The derived expressions are named quasiintegrals. Relative values of terms of the energy quasiintegral for a smallest, largest, and a mean comet are calculated. We have found that in a number of cases the quasiintegrals are related to the regular integrals of motion, and discuss how the quasiintegrals may be applied to find some significant constraints on the motion of a body of infinitesimal mass.  相似文献   

Theoretical and Experimental Studies of Radiative Shocks     

C. Michaut  T. Vinci  L. Boireau  M. Koenig  S. Bouquet  A. Benuzzi-Mounaix  N. Osaki  G. Herpe  E. Falize  B. Loupias  S. Atzeni 《Astrophysics and Space Science》2007,307(1-3):159-164

This paper deals with the radiative shock from both theoretical and numerical points of view. It is based on the whole experimental results obtained at Laboratoire d'Utilisation des Lasers Intenses (LULI, école Polytechnique). Radiative shocks are high-Mach number shocks with a strong coupling between radiation and hydrodynamics which leads to a structure governed by a radiative precursor. These shocks are involved in various astrophysical systems: stellar accretion shocks, pulsating stars, interaction between supernovae and the interstellar medium. In laboratory, these radiative shocks are generated using high power lasers. New diagnostics have been implemented to study the geometrical shape of the shock and the front shock density. Data were obtained varying initial conditions for different laser intensities and temperature. The modeling of these phenomena is mainly performed through numerical simulations (1D and 2D) and analytical studies. We exhibit results obtained from several radiative hydrodynamics codes. As a result, it is possible to discuss about the influence of the geometry and physical parameters introduced in the 1D and 2D models.  相似文献   

New evidence for strong nonthermal effects in Tycho’s supernova remnant     

H. J. Völk  E. G. Berezhko  L. T. Ksenofontov 《Astrophysics and Space Science》2007,309(1-4):389-394

For the case of Tycho’s supernova remnant (SNR) we present the relation between the blast wave and contact discontinuity radii calculated within the nonlinear kinetic theory of cosmic ray (CR) acceleration in SNRs. It is demonstrated that these radii are confirmed by recently published Chandra measurements which show that the observed contact discontinuity radius is so close to the shock radius that it can only be explained by efficient CR acceleration which in turn makes the medium more compressible. Together with the recently determined new value E _sn=1.2×10⁵¹ erg of the SN explosion energy this also confirms our previous conclusion that a TeV γ-ray flux of (2–5)×10⁻¹³ erg/(cm² s) is to be expected from Tycho’s SNR. Chandra measurements and the HEGRA upper limit of the TeV γ-ray flux together limit the source distance d to 3.3≤d≤4 kpc.  相似文献