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Comparison of air-sea heat fluxes calculated from national centers for enviromental prediction (NCEP) reanalysis data and moored buoy measurement data
NCEP 再分析资料和浮标观测资料计算海气热通量的比较

黄艳松,宋金宝
海洋科学 , 2011,
Abstract: In this paper, the U.S. national centers for enviromental prediction (NCEP 1 and 2) reanalysis data and the data come from measurement of the moored buoy located in the north of the Yellow Sea are compared and the analysis shows that the NCEP reanalyzed marine meteorological parameters including the wind speed, humidity, air temperature and the ocean surface temperature are reliable. The marine meteorological parameters come from NCEP2 are more close to those come from the buoy measurement, while the net radiation flux computed from NCEP1 is more close to that comes from the buoy measurement. A more appropriate bulk algorithm to recalculate air-sea heat fluxes is recommended. The NCEP1 recalculated net heat flux is underestimated by 42% while the NCEP2 recalculated net heat flux is overestimated by 5% compared with buoy measurement data. The recalculated turbulent heat flux calculated using the combined wind field (the high wind speed is from NCEP1 while the low wind speed is from NCEP2) is much closer to the buoy measurement data. All these provide valuable information for how to select proper reanalysis data for Chinese ocean research.
Arctic Clouds and Surface Radiation – a critical comparison of satellite retrievals and the ERA-Interim reanalysis
M. Zygmuntowska, T. Mauritsen, J. Quaas,L. Kaleschke
Atmospheric Chemistry and Physics (ACP) & Discussions (ACPD) , 2012,
Abstract: Clouds regulate the Earth's radiation budget, both by reflecting part of the incoming sunlight leading to cooling and by absorbing and emitting infrared radiation which tends to have a warming effect. Globally averaged, at the top of the atmosphere the cloud radiative effect is to cool the climate, while at the Arctic surface, clouds are thought to be warming. Here we compare a passive instrument, the AVHRR-based retrieval from CM-SAF, with recently launched active instruments onboard CloudSat and CALIPSO and the widely used ERA-Interim reanalysis. We find that in particular in winter months the three data sets differ significantly. While passive satellite instruments have serious difficulties, detecting only half the cloudiness of the modeled clouds in the reanalysis, the active instruments are in between. In summer, the two satellite products agree having monthly means of 70–80 percent, but the reanalysis are approximately ten percent higher. The monthly mean long- and shortwave components of the surface cloud radiative effect obtained from the ERA-Interim reanalysis are about twice that calculated on the basis of CloudSat's radar-only retrievals, while ground based measurements from SHEBA are in between. We discuss these differences in terms of instrument-, retrieval- and reanalysis characteristics, which differ substantially between the analyzed datasets.
A Comparison between Numerical Simulations of Forced Local Hadley (Anti-Hadley) Circulation in East Asian and Indian Monsoon Regions
Yuan Zhuojian,Wang Tongmei,He Haiyan,Luo Huibang,Guo Yufu,
Yuan Zhuojian
,Wang Tongmei,He Haiyan,Luo Huibang,Guo Yufu

大气科学进展 , 2000,
Abstract: Two numerical simulations of forced local Hadley circulation are carried out based on a linear diagnostic equation to provide an insight into the mechanisms of monsoon evolution in different monsoon regions. One simulation is for the zonal mean Hadley circulation over East Asia (from95oE to 122.5oE), another over India (from 70oE to 85oE).With the NCEP / NCAR re-analysis data re-processed by Chinese Academy of Science in Beijing, the former simulation displays a dominant anti-Hadley circulation pattern over East Asia at 1200 UTC May 1, 1994. The simulated circulation pattern is consistent well enough with the circulation pattern plotted directly from the data for lack of the radiation information at each level. Although the simulation over India is not as good as that over East Asia, a dominant Hadley circulation pattern is obvious as data show. Further ana-lysis shows that the defective simulation over India is due to the presence of statically unstable condition at some grid points in the lower troposphere. This circumstance slightly violates the hydrodynamic stability cri-terion required by the elliptic diagnostic equation for the forced circulation.Since the simulations are reliable enough compared with the given data, the linear equation facilitates a systematic assessment of relative importance of each internally forcing process. The assessment shows that among the internal processes, the horizontal temperature advections account obviously for the Hadley (anti-Hadley) circulation over India (East Asia) at 1200 UTC May 1, 1994 in addition to the process associ-ated with the latent heat releasing. The calculation of latent heat energy is a little bit unreliable due to the unclear cloud physics in the convection processes and the less accurate humidity data. These preliminary results are consistent with the results of previous studies which show that the feature of the seasonal warming in the upper troposphere and the corresponding processes are part of key processes closely related to the evolution of the summer monsoon over East Asia and India.
Changes in the strength and width of the Hadley circulation since 1871  [PDF]
J. Liu,M. Song,Y. Hu,X. Ren
Climate of the Past Discussions , 2012, DOI: 10.5194/cpd-8-695-2012
Abstract: Recent studies demonstrate that the Hadley Circulation has intensified and expanded for the past three decades, which has important implications for subtropical societies and may lead to profound changes in global climate. However, the robustness of this intensification and expansion that should be considered when interpreting long-term changes of the Hadley Circulation is still matters of debate. It also remains largely unknown how the Hadley Circulation has evolved over longer periods. Here we present long-term variability of the Hadley Circulation using the 20th Century Reanalysis. It shows a slight strengthening and widening of the Hadley Circulation since the late 1970s, which is not inconsistent with recent assessments. However, over centennial timescales (1871–2008), the Hadley Circulation shows a tendency towards more intense and narrower state. More importantly, the width of the Hadley Circulation has not yet completed a life-cycle since 1871. The strength and width of the Hadley Circulation during the late 19th and early 20th century show strong natural variability, exceeding variability that coincides with global warming in recent decades. These findings raise the question that the recent change of the Hadley Circulation is primarily attributed to greenhouse warming or a long-period oscillation of the Hadley Circulation substantially longer than that observed in previous studies.
Changes in the strength and width of the Hadley Circulation since 1871
J. Liu, M. Song, Y. Hu,X. Ren
Climate of the Past (CP) & Discussions (CPD) , 2012,
Abstract: Recent studies demonstrate that the Hadley Circulation has intensified and expanded for the past three decades, which has important implications for subtropical societies and may lead to profound changes in global climate. However, the robustness of this intensification and expansion that should be considered when interpreting long-term changes of the Hadley Circulation is still a matter of debate. It also remains largely unknown how the Hadley Circulation has evolved over longer periods. Here, we present long-term variability of the Hadley Circulation using the 20th Century Reanalysis. It shows a slight strengthening and widening of the Hadley Circulation since the late 1970s, which is not inconsistent with recent assessments. However, over centennial timescales (1871–2008), the Hadley Circulation shows a tendency towards a more intense and narrower state. More importantly, the width of the Hadley Circulation might have not yet completed a life-cycle since 1871. The strength and width of the Hadley Circulation during the late 19th to early 20th century show strong natural variability, exceeding variability that coincides with global warming in recent decades. These findings raise the question of whether the recent change in the Hadley Circulation is primarily attributed to greenhouse warming or to a long-period oscillation of the Hadley Circulation – substantially longer than that observed in previous studies.
The Zonal Structure of the Hadley Circulation
Peter G BAINES,
Peter
,G.,BAINES

大气科学进展 , 2006,
Abstract: A discussion of the mass transport of the Hadley circulation is presented, with regard to its longitudinal structure. Data from the NCEP/NCAR reanalysis data set for the period 1948-2005 is examined,focusing on the solsticial seasons of June-August and December-February. Quantitative estimates have been extracted from the data to observe connections between the zonal mean of the upper tropospheric north/south mass transports and their relationship to the driving factor of tropical precipitation (implying latent heat release) and subsidence in the subtropical high pressure belts. The longitudinal structure of this flow is then examined with regard to these three main variables. The poleward upper tropospheric transport has four (JJA) or three (DJF) main branches, which link regions of major precipitation with corresponding regions of large subsidence, and one (June, July, August) or two (December, January, February) reverse branches. This structure has remained stable over the past sixty years. Although the total upper tropospheric transport in each season is less than the total sinking transport in the target subtropical high pressure belt, this does not apply to the individual branches, the balance being made up by the upper tropospheric reverse transports. An analysis of correlations between all of these various components shows, however, that the complete picture is more complex, with some precipitation regions being linked to subsidence regions outside their own branch.
Trend in the atmospheric heat source over the central and eastern Tibetan Plateau during recent decades: Comparison of observations and reanalysis data
MeiRong Wang,ShunWu Zhou,AnMin Duan
Chinese Science Bulletin , 2012, DOI: 10.1007/s11434-011-4838-8
Abstract: The trend in the atmospheric heat source over the central and eastern Tibetan Plateau (CE-TP) is quantitatively estimated using historical observations at 71 meteorological stations, three reanalysis datasets from 1980–2008, and two satellite radiation datasets from 1984–2007. Results show that a weakening of sensible heat (SH) flux over the CE-TP continues. The most significant trend occurs in spring, induced mainly by decelerated surface wind speeds. The ground-air temperature difference shows a notable increasing trend over the last 5 years. Trends in net radiation flux of the atmospheric column over the CE-TP, evaluated by two satellite radiation datasets, are clearly different. Trends in the atmospheric heat source calculated by the three reanalysis datasets are not completely consistent, and even show opposite signals. Results from the two datasets both show a weakening of the heat source but the magnitude of one is significantly stronger, whereas an increase is indicated by the other data. Therefore, it is challenging to accurately calculate the trend in the atmospheric heat source over the CE-TP, particularly from the estimates of the reanalysis datasets.
Scanned carbon beam irradiation of moving films: comparison of measured and calculated response
Christoph Bert, Daniel Richter, Marco Durante, Eike Rietzel
Radiation Oncology , 2012, DOI: 10.1186/1748-717x-7-55
Abstract: All calculations were performed with GSI's treatment planning system TRiP. Interplay patterns between scanned particle beams and moving film detectors are very sensitive to slight deviations of the assumed motion parameters and therefore ideally suited to validate 4D calculations. In total, 14 film motion parameter combinations with lateral motion amplitudes of 8, 15, and 20 mm and 4 combinations for lateral motion including range changes were used. Experimental and calculated film responses were compared by relative difference, mean deviation in two regions-of-interest, as well as line profiles.Irradiations of stationary films resulted in a mean relative difference of -1.52% ± 2.06% of measured and calculated responses. In comparison to this reference result, measurements with translational film motion resulted in a mean difference of -0.92% ± 1.30%. In case of irradiations incorporating range changes with a stack of 5 films as detector the deviations increased to -6.4 ± 2.6% (-10.3 ± 9.0% if film in distal fall-off is included) in comparison to -3.6% ± 2.5% (-13.5% ± 19.9% including the distal film) for the stationary irradiation. Furthermore, the comparison of line profiles of 4D calculations and experimental data showed only slight deviations at the borders of the irradiated area. The comparisons of pure lateral motion were used to determine the number of motion states that are required for 4D calculations depending on the motion amplitude. 6 motion states per 10 mm motion amplitude are sufficient to calculate the film response in the presence of motion.By comparison to experimental data, the 4D extension of GSI's treatment planning system TRiP has been successfully validated for film response calculations in the presence of target motion within the accuracy limitation given by film-based dosimetry.Radiotherapy of tumors influenced by organ motion benefits from dedicated treatment planning. Our treatment planning system for scanned particle beams (Treatment plan
Comparison of Form Factors Calculated with Different Expressions for the Boost Transformation  [PDF]
A. Amghar,B. Desplanques,L. Theussl
Physics , 2002, DOI: 10.1016/S0375-9474(02)01370-2
Abstract: The effect of different boost expressions is considered for the calculation of the ground-state form factor of a two-body system made of scalar particles interacting via the exchange of a scalar boson. The aim is to provide an uncertainty range on methods employed in implementing these effects as well as an insight on their relevance when an ``exact'' calculation is possible. Using a wave function corresponding to a mass operator that has the appropriate properties to construct the generators of the Poincar\'{e} algebra in the framework of relativistic quantum mechanics, form factors are calculated using the boost transformations pertinent to the instant, front and point forms of this approach. Moderately and strongly bound systems are considered with masses of the exchanged boson taken as zero, 0.15 times the constituent mass $m$, and infinity. In the first and last cases, a comparison with ``exact'' calculations is made (Wick-Cutkosky model and Feynman triangle diagram). Results with a Galilean boost are also given. Momentum transfers up to $Q^2=100 m^2$ are considered. Emphasis is put on the contribution of the single-particle current, as usually done. It is found that the present point-form calculations of form factors strongly deviate from all the other ones, requiring large contributions from two-body currents. Different implementations of the point-form approach, where the role of these two-body currents would be less important, are sketched.
ПОР ВНЯННЯ ВИМ РЯНИХ РОЗРАХОВАНИХ КОНЦЕНТРАЦ Й ЗАБРУДНЕННЯ ПОВ ТРЯ ВИКИДАМИ В Д ДВИГУН В В АЕРОПОРТУ Comparison of measured and calculated concentrations of air pollution from engines at the airport Сравнение измеренных и рассчитанных концентраций загрязнения воздуха выбросами от двигателей в аэропорту  [cached]
О.?. Запорожець,К.В. Синило
Proceedings of National Aviation University , 2009,
Abstract: Надано опис проведених експериментальних досл джень концентрац й забруднення пов тря викидами в д двигун в пов тряних корабл в в аеропорту х пор вняння з розрахованими значеннями за моделями програмного комплексу PolEmiCa. Experimental measuring of air pollution in airport, produced by aircraft emission, is described and compared with calculated values due to modeling software PolEmiCa. Даны описание проведенных экспериментальных исследований концентраций загрязнения воздуха выбросами от двигателей воздушных судов в аэропорту и их сравнение с рассчитанными значениями по моделям программного комплекса PolEmiCa.
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