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1996 Vol. 13, No. 4

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Numerical Simulation of the Effect of the SST Anomalies in the Tropical Western Pacific on the Blocking Highs over the Northeastern Asia
Lu Riyu, Huang Ronghui
1996, 13(4): 411-424. doi: 10.1007/BF03342034
The effects of the sea surface temperature (SST) anomalies in the tropical western Pacific on the atmospheric cir-culation anomalies over East Asia are simulated by the IAP-GCM with an observed and idealized distributions of the SST anomalies in the tropical western Pacific, respectively Firstly, the atmospheric circulation anomalies during July and August, 1980 are simulated by three anomalous experiments including the global SST anomaly experiment, the tropical SST anomaly experiment and the extratropical SST anomaly experiment, using the observed SST anomalies in 1980. It is shown that the SST anomalies in the tropical ocean greatly influence the formation and maintenance of the blocking high over the northeastern Asia, and may play a more important role than the SST anomalies in the extratropical ocean in the influence on the atmospheric circulation anomalies Secondly, the effects of the SST anomalies in the tropical western Pacific on the atmospheric circulation anoma?lies over East Asia are also simulated with an idealized distribution of the SST anomalies in the tropical western Paci?fic. The simulated results show that the negative anomalies of SST in the tropical western Pacific have a significant ef?fect on the formation and maintenance of the blocking high over the northeastern Asia.
The Dynamics of ENSO Anomaly as Revealed in Ensemble Climate Simulations-Impact of Mean Stationary Wave
X.L. Wang, H.L. Rui, A. Leetmaa
1996, 13(4): 425-444. doi: 10.1007/BF03342035
A series of climate ensemble experiments using the climate model from National Centers for Environmental Pre-diction (NCEP) were performed to exam impact of sea surface temperature (SST) on dynamics of El-Nino / South-ern Oscillation (ENSO). A specific question addressed in this paper is how important the mean stationary wave influ-ences anomalous Rossby wave trains or teleconnection patterns as often observed during ENSO events Evidences from those ensemble simulations argue that ENSO anomalies, especially over Pacific-North America (PNA) region, appear to be a result of modification for climatological mean stationary wave forced by persistent trop?ical SST anomalies. Therefore, the role of SST forcing in maintaining climate basic state is emphasized. In this argu?ment, the interaction between atmospheric internal dynamics and external forcing, such as SST is a key element to understand and ultimately predict ENSO.
Low Frequency Characteristics of Tropical Pacific Wind Stress Anomalies in Observations and Simulations from a Simple and a Comprehensive Models
Ni Yunqi, Zhang Qin
1996, 13(4): 445-460. doi: 10.1007/BF03342036
Low frequency characteristics of tropical Pacific wind stress anomalies in observation and simulations; from the CZ simple atmospheric model and COLA R15 AGCM are analyzed. The results show that ENSO event may be a multi-scale process, that is, ENSO time scale has the period longer than three yean; biennial oscillation and annual variability Dynamical characteristics are involved in the evolution process of wind stress anomaly with ENSO time scale: 1) the development and eastward movement of a cyclonic anomaly circulation in subtropical northwestern Pacific and weakening of Southern Oscillation result in the eastward propagation of westerly anomaly along the equator, there?fore, interactions between flows in subtropics and in tropics play an important role in the evolution of wind stress anomaly with ENSO time scale; 2) easterly and westerly anomalies with ENSO time scale are one kind of propagating wave, which differs from Barnetts (1991). It is interesting that the evolution of observed and simulated wind stress anomalies with biennial time scale bears a strong resemble to that with ENSO time scale although their period it dif?ferent. Observed annual variability it weak during 1979-1981 and intensified after 1981, especially it reaches to max?imum during 1982-1984, and the spatial structure of the first mode is the ENSO-like pattern.
Study on Instability in Baroclinic Vortex Symmetric Disturbance under Effect of Nonuniform Environmental Parameters
Fei Jianfang, Lu Hancheng
1996, 13(4): 461-470. doi: 10.1007/BF03342037
With the aid of the baroclinicity parameter M2, inertial instability parameter F2 and the stratification instability paramter N2 as the slowly varying function both spatially and temporally, an energetic equation is derived of symmetric perturbation waves in baroclinic vortices in the framework of progressively changing wavetrain theory, or WKB, alongside the examination of effects of these parameters upon the vortex disturbance.
Machine Learning of Weather Forecasting Rules from Large Meteorological Data Bases
Honghua Dai
1996, 13(4): 471-488. doi: 10.1007/BF03342038
Discovery of useful forecasting rules from observational weather data is an outstanding interesting topic. The traditional methods of acquiring forecasting knowledge are manual analysis and investigation performed by human scientists. This paper presents the experimental results of an automatic machine learning system which derives fore-casting rules from real observational data. We tested the system on the two large real data sets from the areas of cen-tral China and Victoria of Australia. The experimental results show that the forecasting rules discovered by the sys-tem are very competitive to human experts. The forecasting accuracy rates are 86.4% and 78% of the two data sets respectively.
Inversion and Ill-Posed Problem Solutions in Atmospheric Remote Sensing
Huang Sixun
1996, 13(4): 489-504. doi: 10.1007/BF03342039
With the swift advances in earth observation, satellite remote sensing and application of atmospheric radiation theory have been developed in the past decades, atmospheric sensing inversion with its algorithms is getting more and more importance. It is known that since a remote sensing equation falls into an integral equation of the first kind, thus leading to the fact that it is ill-posed and particularly the solution is unsteady, tremendous difficulties arise from the retrieval. This paper will present a simple review on the inversion techniques with some necessary remarks, before in-troducing the successful efforts with respect to such equations and the encouraging solutions achieved in recent dec-ades by researchers of the world.
ICE Particle Size and Shape Effect on Solar Energy Scattering Angular Distribution
Yao Keya, Liu Chunlei
1996, 13(4): 505-510. doi: 10.1007/BF03342040
The rare occurrence of the halos produced by cirrus ice crystals in nature has been investigated by modelling the incident solar (visible) light scattering angular distribution using the Monte Carlo / ray tracing method. The results show that the irregular shapes of ice crystals and large population of small ice particles in cirrus are responsible for the rare occurrence of halos.
Determination of the Drag Coefficient over the Tibetan Plateau
Li Guoping, Duan Tingyang, Wan Jun, Gong Yuanfa, Shigenori Haginoya, Chen Longxun, Li Weiliang
1996, 13(4): 511-518. doi: 10.1007/BF03342041
In this paper, a preliminary study is given on the drag (i.e. bulk transfer for momentum) coefficient, on the basis of data from four sets of AWS in Tibet during the first observational year from July 1993 to July 1994 according to China-Japan Asian Monsoon Cooperative Research Program. The results show that the drag coefficient over the Tibetan Plateau is 3.3 to 4.4 10-3. In addition, monthly and diurnal variations of drag coefficient and the relation-ship among the drag coefficients and the bulk Richardson number, surface roughness length and wind speed at 10 m height are discussed in detail.
A Study of Linke Turbidity Factor over Qena / Egypt
Sayed M. Elshazly
1996, 13(4): 519-532. doi: 10.1007/BF03342042
Data on instantaneous atmospheric Linke turbidity factor TL (m) are reported for clear days at Qena / Egypt in the period from June 1992 to May 1993. TL (m) is determined using the values of irradiance of direct solar radiation (I), which are calculated from global (G) and diffuse (D) - solar radiation measurements. Monthly and seasonally va?riations of both diurnal and daily average values of TL (m) increases steadily in the direction of sunset in the months from June to December 1992 as well as Summer and Autumn seasons, while it falls generally in this direction for the months from January to March and Winter season. In April and May, TL (m) fluctuates obviously through the day hours. It is also shown that the average values of TL (m) are particularly large during Summer months compared to other months of the year. This behavior of TL (m) is discussed in view of the variations of some weather elements, which affect the content of water vapor and dust particle in the atmosphere of the study region. It seems t be of simi?lar trends to that of other locations inside and outside Egypt. The virtual variation of TL (m) is eliminated by re?ducing its value to relative optical air mass m = 2, according to Kasten formula. The resulting TL (2) is more represen?tative for the content of dust particles and water vapor in the atmosphere.
Helicity as a Method for Forecasting Severe Weather Events
Ding Jincai, Dai Jianhua, Chen Yamin, Hu Fuquan, Tang Xinzhang
1996, 13(4): 533-538. doi: 10.1007/BF03342043
This paper introduces a method for forecasting severe weather which is yieded by integrating helicity at a dynamical parameter with K and TOT indexes as thermal parameters. The results of operational tests for two years are detailed. And the seasonal suitability of the method applications it discussed as well.
Preliminary Results from Numerical Experiments of a Heavy Rain Process with PENN STATE / NCAR MM5
Xiao Qingnong, Guo Weidong, Zhou Xiaoping
1996, 13(4): 539-547. doi: 10.1007/BF03342044
PENN STATE/ NCAR MM5 is used to simulate precipitation of the heavy rain process during 12-13 July 1994. The effects of different PBL parameterizations, resolvable scale moisture schemes and cumulus parameterization on the process rainfall simulation are investigated. By comparing the results of hydrostatic and nonhydrostatic experiments, the nonhydrostatic impact upon precipitation is also examined. It is found in this study that PENN STATE / NCAR MM5 has advantage not only in theory but also in simulating results with real data. In MM5, however, the selection of physical processes, especially water-cycle process, is very important and crucial to precipitation forecast of the case. It is concluded that the model with Grell (1993) scheme for convection and conden?sation method for resolvable scale precipitation captured the rainstorm during 12-13 July 1994 in Beijing area more successfully.