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An Algorithm to Detect Tropical Deep Convective Clouds Through AMSU-B Water Vapor Channels

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Journal of Ocean University of China 2009年第1期8卷 9-14页

作者： XU Xu georg heygster ZHANG Suping Ocean-Atmosphere Interaction and Climate Laboratory Ocean University of China Qingdao 266003 P. R. China Institute of Environmental Physics University of Bremen Germany

An algorithm to detect tropical deep convective clouds and deep convective overshootings based on the measurements from the three water vapor channels （1833GHz± 1GHz, 183.3GHz±3GHz and 183.3GHz±7GHz） of the Advanced Microwave Sounding Unit-B （AMSU-B） is presented. This algorithm is an improved version of the method of Hong et al. （2005）. The proposed procedure is based on the statistical analysis of seven years＇（2001-2007） measurements from AMSU-B on NOAA-16. From the 1-d histograms of the brightness temperature of the three water vapor channels and the 2-d histograms of the brightness temperature dif- ference between these channels, new thresholds for brightness temperature differences and the *** temperature of chamM 18 （183.3 GHz 4-1 GHz） are suggested. The new algorithm is employed to investigate the mean distribution of tropical deep convective clouds and convective overshootings from 30＇S to 30＇N for the years 2001 to 2007. The major concentration of deep convective clouds and convective overshootings is found over the Intertropical Convergence Zone （ITCZ）, the South Pacific Convergence Zone （SPCZ）, tropical Africa, South America, the Indian Ocean and Indonesia ruth an average fraction of 0.4%. In terms of these clouds we identity, the secondary Intertropical Convergence Zone located in the eastern South Pacific and parallel to the main ITCZ in the North Pacific. The convective overshooting is more frequently observed over land than over the ocean.

关键词： microwave remote sensing AMSU-B deep convective clouds tropics

应用AMSR-E 89GHz遥感数据反演北极多年冰密集度

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极地研究 2009年第3期21卷 186-196页

作者：王欢欢 georg heygster 韩树宗程斌中国海洋大学海洋环境学院青岛266100 德国不莱梅大学环境物理学院德国不莱梅28359 芬兰气象研究所赫尔辛基fi00101

被动微波辐射计AMSR-E在89GHz频段的空间分辨率几乎是其它低频段的2倍。到目前为止,已经有成熟的算法采用AMSR-E 89GHz频段的数据来反演整体海冰的密集度,而本文根据89GHz频段亮温数据针对一年冰、多年冰以及无冰水面的不同特性,提出了... 详细信息

被动微波辐射计AMSR-E在89GHz频段的空间分辨率几乎是其它低频段的2倍。到目前为止,已经有成熟的算法采用AMSR-E 89GHz频段的数据来反演整体海冰的密集度,而本文根据89GHz频段亮温数据针对一年冰、多年冰以及无冰水面的不同特性,提出了一种反演多年冰密集度的方法(AC)。计算了2007年北极的整体海冰和多年冰密集度,并与NASA TEAM算法(NT)的结果作了比较。对于整体海冰密集度,两种算法反演的结果基本一致。从日平均上来看,AC算法得到的整体海冰覆盖面积只比NT算法多25万km2。但是对于多年冰的反演结果,AC算法得到的结果比NT的结果要多出146万km2,冬季差别尤其大。造成这种差别的原因可能是AC算法对于北极表面气温的变化比较敏感。另外,AC算法计算得到2007年最大海冰覆盖面积为1400万km2,最小海冰覆盖面积为400万km2,这与其它研究结果一致。

关键词： AMSR-E 北极多年冰亮温遥感

Fingerprint of COVID-19 in Arctic sea ice changes

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Science Bulletin 2021年第20期66卷 2050-2053页

作者： Zhuoqi Chen Shaoyin Wang Yufang Ye Jiping Liu georg heygster Mohammed Shokr Fengming Hui Xiao Cheng School of Geospatial Engineering and Science Sun Yat-sen UniversityZhuhai 519000China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai 519000China Department of Atmospheric and Environmental Sciences State University of New York at AlbanyAlbanyNY 12222USA georg-Lab(Geophysical Remote Sensing Lab) Bremen 28359Germany Science and Technology Branch Environment and Climate Change CanadaToronto ON M3H 5T4Canada University Corporation for Polar Research Zhuhai 519000China

Arctic sea ice plays an essential role in regional and global climate by dynamic processes and feedbacks associated with its high reflectivity, thermal insulation especially in presence of snow cover, and brine rejection [1]. Both observations and model simulations show that Arctic sea ice extent has dramatically declined and thinned in the past few decades [2] in response to global warming and cumulative anthropogenic greenhouse gas(GHG)emissions [3,4].

关键词：北极海冰 Arctic greenhouse

CO_2 mitigation potential in farmland of China by altering current organic matter amendment pattern

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Science China Earth Sciences 2010年第9期53卷 1351-1357,1407-1417页

作者： CADISCH georg Institute of Plant Production and Agroecology in the Tropics and Subtropics University of Hohenheim

The estimation of the global warming mitigation potential in terrestrial ecosystems is of great importance for decision makers to adopt measures to increase soil organic carbon (SOC) as well as to reduce greenhouse gas (GHGs) emissions. In this paper, we compiled data published in peer-reviewed journals, and conducted a holistic analysis of the effects of organic matter amendment on soil organic carbon sequestration, methane (CH4) and nitrous oxide (N2O) emissions in paddy and upland systems. Results showed that organic matter amendment increased soil organic carbon content, and apparent conversion rate of organic matter carbon to soil organic carbon in paddies was constant, while that in uplands decreased along with amendment years at 25 years time scale. Organic matter amendment during the rice season led to large CH4-C emissions, e.g on average 99.5 g CH4-C per kg organic carbon input under intermittent flood conditions, and 191.7 g CH4-C per kg organic carbon input under continuous flood conditions, respectively. By alteration of organic matter amendment from rice season to off-rice upland crop season, estimated CH4-C emissions in China could be cut by 3.5 Tg yr-1, accounting for 63% of current CH4-C emissions (5.5 Tg). If organic matter amendment percentage was increased from current 30% to future 50% of organic matter production and by alteration of organic matter amendment from rice season to off-rice upland crop season, the equivalent CO2-C mitigation potential in farmland of China would be 49.2 Tg yr-1 at the 10th year organic matter amendment and 36.0 Tg yr-1 at the 30th year amendment. These findings are important not only for China but also for the other rice production countries to increase farmland global warming mitigation.

关键词： climate change global warming radiative forcing SOC GHGs CH4 N2O

Yield Improvement and Advanced Defect Control——Driving Forces for Modeling of Bulk Crystal Growth

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Journal of Rare Earths 2006年第Z1期24卷 200-207页

作者： georg Mueller Jochen Friedrich Crystal Growth Laboratory University Erlangen-Nürnberg (WW6) and Fraunhofer Institute of Integrated Systems and Device Technology (IISB) Martensstrasse 7 D-91058 Erlangen Germany Crystal Growth Laboratory University Erlangen-Nürnberg (WW6) and Fraunhofer Institute of Integrated Systems and Device Technology (IISB) Martensstrasse 7 D-91058 Erlangen Germany

Yield improvement and advanced defect control can be identified as the driving forces for modeling of industrial bulk crystal growth. Yield improvement is mainly achieved by upscaling of the whole crystal growth apparatus and increased processing windows with more tolerances for parameter variations. Advanced defect control means on one hand a reduction of the number of deficient crystal defects and on the other hand the formation of beneficial crystal defects with a uniform distribution and well defined concentrations in the whole crystal. This "defect engineering" relates to the whole crystal growth process as well as the following cooling and optional annealing processes, respectively. These topics were illustrated in the paper by examples of modeling and experimental results of bulk growth of silicon (Si), gallium arsenide (GaAs), indium phosphide (InP) and calcium fluoride (CaF2). These examples also involve the state of the art of modeling of the most important melt growth techniques, crystal pulling (Czochralski methods) and vertical gradient freeze (Bridgman-type methods).

关键词： yield improvement advanced defect control crystal growth

RESILIENCE 2.0： COMPUTER-AIDED DISASTER MANAGEMENT

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Journal of Systems Science and Systems Engineering 2017年第3期26卷 321-335页

作者： Gerhard Chroust georg Aumayr Institute for Telecooperation Johannes Kepler University Linz Austria Johanniter Osterreich Ausbildung und Forschung Vienna Austria

Many factors （larger population, more dependency on technology, more human-caused interference in the natural systems and equilibria, climate changes,... ） contribute to the seemingly growing number and severity of disasters. Additional exaggeration is generated by public media. As a consequence Disaster Prevention and Disaster Management must be given increased attention. The ultimate goal of Disaster Management is resilience of the affected system and thus the adequate and acceptable survival of the affected population. We discuss system behavior in the case of an assault or disturbance： from being fragile （loss of their functionality due to the assault） to being resilient （having the capacity ... of bouncing back to dynamic stability after a disturbance）, or even antifragile （being able to ＂learn＂ so as to improve disaster resilience）. Resilience 2. 0 identifies a new paradigm： modem Information and Communication Technologies （ICT） are employed as a basis for enabling and improving resilience of a system. ICT provide the basis for sufficient preparation before an assault, for quick recognition of, and for effective, efficient reactions to disasters. Only the coordinated intra- and interphase deployment of ICT promises sufficient success and can bring resilience to currently as yet fragile systems. We discuss stressors （time and performance pressure, physical and psychological stress on personnel） and problems due to damaged ICT-platforms and communication infrastructure. The basic message is that computer-aided Disaster Management is able to offers a new level of reactivity： Resilience 2.0.

关键词： Disaster vulnerability resilience human reaction hazard threat systemic reaction

On the Connection Between the Spectral Difference Method and the Discontinuous Galerkin Method

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Communications in Computational Physics 2011年第4期9卷 1071-1080页

作者： georg May Aachen Institute for Advanced Study in Computational Engineering Sciences RWTH Aachen UniversitySchinkelstr.252062 AachenGermany

In this short note we present a derivation of the Spectral Difference Scheme from a Discontinuous Galerkin(DG)discretization of a nonlinear conservation *** allows interpretation of the Spectral Difference Scheme as a particular discretization under the quadrature-free nodal DG ***,it enables identification of the key differences between the Spectral Difference Scheme and standard nodal DG schemes.

关键词： Spectral difference method discontinuous Galerkin method hyperbolic conservation laws quadrature-free schemes nodal schemes

Introducing robustness in model predictive control with multiple models and switching

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Control Theory and Technology 2014年第3期12卷 284-303页

作者： Sachin PRABHU Koshy georg Department of Telecommunication Engineering PES Institute of Technology Bangalore 560085 India PES Centre for Intelligent Systems Bangalore 560085 IndiaE

Model predictive control is model-based. Therefore, the procedure is inherently not robust to modelling uncertainties. Further, a crucial design parameter is the prediction horizon. Only offline procedures to estimate an upper bound of the optimal value of this parameter are available. These procedures are computationally intensive and model-based. Besides, a single choice of this horizon is perhaps not the best option at all time instants. This is especially true when the control objective is to track desired trajectories. In this paper, we resolve the issue by a time-varying horizon achieved by switching between multiple model-predictive controllers. The stability of the overall system is discussed. In addition, an introduction of multiple models to handle modelling uncertainties makes the overall system robust. The improvement in performance is demonstrated through several examples.

关键词： Receding horizon control Time-varying horizon Multiple models Switching Tracking Robustness

The quest for conditional independence in prospectivity modeling： weights-of-evidence, boost weights-of-evidence, and logistic regression

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Frontiers of Earth Science 2016年第3期10卷 389-408页

作者： Helmut SCHAEBEN georg SEMMLER Department of Geophysics and Geoinformatics TU Bergakademie Freiberg Freiberg 09596 Germany

The objective of prospectivity modeling is prediction of the conditional probability of the presence T = 1 or absence T = 0 of a target T given favorable or prohibitive predictors B, or construction of a two classes {0,1} classification of T. A special case of logistic regression called weights-of-evidence （WofE） is geolo- gists＇ favorite method of prospectivity modeling due to its apparent simplicity. However, the numerical simplicity is deceiving as it is implied by the severe mathematical modeling assumption of joint conditional independence of all predictors given the target. General weights of evidence are explicitly introduced which are as simple to estimate as conventional weights, i.e., by counting, but do not require conditional independence. Complementary to the regres- sion view is the classification view on prospectivity modeling. Boosting is the construction of a strong classifier from a set of weak classifiers. From the regression point of view it is closely related to logistic regression. Boost weights-of-evidence （BoostWofE） was introduced into prospectivity modeling to counterbalance violations of the assumption of conditional independence even though relaxation of modeling assumptions with respect to weak classifiers was not the （initial） purpose of boosting. In the original publication of BoostWofE a fabricated dataset was used to ＂validate＂ this approach. Using the same fabricated dataset it is shown that BoostWofE cannot generally compensate lacking condi- tional independence whatever the consecutively proces- sing order of predictors. Thus the alleged features of BoostWofE are disproved by way of counterexamples, while theoretical findings are confirmed that logistic regression including interaction terms can exactly com- pensate violations of joint conditional independence if the predictors are indicators.

关键词： general weights of evidence joint conditionalindependence naive Bayes model Hammersley-Cliffordtheorem interaction terms statistical significance