Vol.16, NO.2, 2005

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DISTRIBUTION AND VARIATION FEATURES OF SOIL HUMIDITY ANOMALY IN HUAIHE RIVER BASIN AND ITS RELATIONSHIP WITH CLIMATIC ANOMALY
Sun Chenghu, Li Wei jing, Zhang Zuqiang, He Jinhai
2005, 16(2): 129-138.
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Abstract:
With rotated empirical orthogonal function (REOF) analysis technique, the mainly anomalous spatial features of soil humidity in the 0-50 cm layer of Huaihe River basin and its relationship with precipitation and air temperature in different periods were specially analyzed by using the observed data including dekad averaged soil moisture data, precipitation and air temperature data in the east of China from 1990 to 2000. The results indicate that in the springtime the 30 cm soil layer can be treated as a boundary. From 0 cm layer to 30 cm layer, the first rotated loading vector field in every layer reflects the anomalous soil humidity pattern in the Huaihe river basin, named the pattern structure as "Huaihe river pattern". While from 30 cm layer to 50 cm layer, the second rotated loading vector field in every layer is also quite similar to "Huaihe river pattern". In summer and autumn, the "Huaihe river pattern" is still remarkable but the feature is less prominently than that in spring. It is also found soil moisture anomaly of this pattern in every layer has notable duration and a prominent period of nearly forty dekads. Furthermore, positive (negative) correlation between soil moisture and precipitation (air temperature) during prophase and the same period can be found. Also, negative (positive) correlation between soil moisture and the precipitation (air temperature) of nearly half a year later can by noted.
PRECIPITATION RECYCLINGOVER THE NORTHERN CHINA
Kang Hongwen, Gu Xiangqian, Fu Xiang, Xu Xiangde
2005, 16(2): 139-147.
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Abstract:
The precipitation recycling over the Northern China was evaluated using 20 years' NCEP reanalysis data. It is found that only 19% of the precipitation in the Yellow River basin comes from the local evaporation, while the other 81% comes from outside vapor. Precipitation over the upper reaches of the Huanghe River are mainly contributed by the strong vapor flow from the Tibet Plateau, so the recycling in the upper reaches is less than 15%. With the westerly winds, water vapor from evaporation in the upper reaches of the Huanghe River are brought into its lower reaches, combining with the moisture from the south and north, are contributed to the local precipitation, resulting in a elliptic region with high recycling rates over 30% in the lower reaches of the Huanghe River. The precipitation recycling varies obviously with seasons: it has the highest value of about 0.32 in August, while it does not reach 0.05 in November, December and January. Both evaporation and precipitation show good correspondence in spatial distribution and yearly variation, which reveals that evaporation is strongly influenced by local precipitation. Evaporation, precipitation and recycling ratios increase during the 20 years, which may be the effect of the climate warming.
A STUDY ON IMPACTS OF DIFFERENT RADIATIVE TRANSFER SCHEMES ON MESOSCALE PRECIPITATIONS
Zhou Guangqiang, Zhao Chunsheng, Ding Shouguo, Qin Yu
2005, 16(2): 148-158.
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Abstract:
A radiative transfer scheme based on delta-4 stream, correlated-k distribution and with relative detailed cloud water, rain water, ice crystal and graupel radiative properties description, is employed into PSU/NCAR MM5. A study on impacts of different radiative transfer schemes on mesoscale precipitations is carried out using a case of South China Severe Storm in 1998. The calculations show that radiation process plays an important role in the mesoscale precipitations. The cloud radiative properties descriptive accuracy in the radiative transfer schemes in influences the surface rainfall obviously. Different radiative transfer schemes result in different precipitation processes and the disagreement among the schemes in the daytime is much bigger than that at night. Radiative processes have distinct effect on the maximum rainfall centers, while little on the surface rainfall geographic distribution. The difference of the solar radiation calculation among the radiative transfer schemes causes more notable surface precipitation varieties than that on the longwave radiation. The employment of new radiative transfer scheme is successful and it improves the mesoscale precipitation simulation ability to a certain extent.
THE THERMAL STRUCTURE CHARACTERISTICS OF TROPICAL CYCLONES WITH DIFFERENT INTENSITY REVEALED BY AMSU DATA
Wang Jin, Jiang Jixi
2005, 16(2): 159-166.
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Abstract:

The data from NOAA/16 AMSU and the numerical prediction data from NCEP are used to study the thermal structure of tropical cyclones (TCs) occurred over the northwest Pacific Ocean during June 10—September 10 in 2002. The results show that various geophysical parameters of the different intensities of tropical cyclones can be detected sensitively and measured further by AMSU data. Therefore, some aspects of the warm core associated with these storms can be found. In addition, the substantial correlations between this satellite-depicted warm temperature anomaly at the mid-and upper-troposphere and surface pressure at the storm center can be found by the differences from height, magnitude, scale and form of temperature anomaly regions of the different intensity tropical cyclones at the target levels, the differences of height, size and distribution of negative temperature anomaly at upper troposphere and the structure characteristics of relevant humidity field. By the thermal structure of tropical cyclones, the intensity changes of tropical cyclones in the future and be acquired further. At the same time, the results show that for the temperature anomaly the magnitude, height and area of typhoon's warming is the most, and the strong tropical storm's follow it, while those of the tropical storm are the lowest. At far as the height of the negative temperature anomaly at the upper troposphere, typhoon is the topmost, the follow is strong tropical storm and the tropical storm is the lowest.
A CASE STUDY OF THE STRUCTURE OF THE HETAO HIGH WHICH CAUSED LONG-LASTING HOT WEATHER IN BEIJING
Qian Ting ting, Wang Yingchun, Zheng Zhifang, Zheng Yongguang
2005, 16(2): 167-173.
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Abstract:
Based on the severe hot weather case taken place on July 11—14, 2000 in Beijing, we analyzed the horizontal and vertical structure of the Hetao High on 700 hPa associated with the hot weather. The result shows that the High is a deep negative vorticity system and related with a large-scale, eastward moving warm air mass in western arid region. The Hetao High is a relatively small and locomotive system, so hot weather usually sustains only several days. As a warm high, the Hetao High reached the high level of troposphere in vertical direction. Located between the exit region of Polar-front jet and the entrance region of subtropical jet, the upper level convergence makes Hetao High under the control of downward current. Adiabatic warming because of sinking and radiation heating are in favor of hot weather. At last, the paper pointed out that the formation of the Hetao High might be associated with dynamically pressure increase.
CHARACTERISTICS OF RADIATION BALANCE OVER MOVING DUNE AND FIELD AREA IN KEERQIN DESERT REGION OF CHINA
Wang Kai, Zhang Hongsheng, Liu Huizhi, Du Jinlin, Hu Fei, Chen Jiayi
2005, 16(2): 174-180.
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Abstract:
The characteristics of the surface radiation components are analyzed by using the measurement data obtained the moving dune and the field area in the Keerqin desert region of Nei Mongol, China in the summer of 2001. The results show that the characteristics of the radiation, such as global solar radiation and long-wave radiation, over the moving dune area are similar to those over the field area. The value of net radiation over the moving dune area is obviously lower than over the field area. Meanwhile, the value of albedo and the effective radiation over the moving dune are higher than those over the field respectively. The value of albedo over the moving dune exceeds that of the Desert station in HEIFE by 10%, and the effective radiation is lower than that of the Desert station.
RESEARCHES ON ANOMALOUS CHARACTERISTICS OF THE SUBTROPICAL HIGH OVER THE WESTERN PACIFIC DURING 1998 SUMMERTIME
Zhuang Shiyu, Zhao Shengrong, Yao Mingming
2005, 16(2): 181-192.
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Abstract:
Using NCEP reanalysis data, the anomalous characteristics and mechanisms of the subtropical high over the western Pacific during 1998 summer was analyzed. Contrast to the case of climate mean, the subtropical of 1998 summer was stronger with its ridge extending westward far more. In addition, the abnormal latitudinal fluctuation of the subtropical high occurred, especially on withdrawing abruptly from north to south at the mid of July and then maintaining at lower latitudes until the beginning of August. This caused the second Meiyu precipitation over the Yangtze regions. The latitudinal fluctuation started at east of the subtropical high belt over the mid-Pacific, propagated westward gradually. It shows that the anomalous variation of the 1998 subtropical high is due to the adjustment of the East Asian circulation, in which anomalous variation of the subtropical westly jet is important of the retreat of the subtropical high. The variation on location and intensity of the jet and the induced secondary circulation at entrance/exit of the jet, as well as the instability impacts on the anomaly of the subtropical high on July. The sensitivity numerical experiment by T106L19 global spectral model indicates that the response of geopotential height to weakening of the jet is consistent with the result by observational analysis. Heat source/vapour sink analysis, OLR analysis and SVD analysis with heat source and geopotential height presents that the diabatic heating over the tropical monsoon region is notably weakened before the retreat of subtropical high, which makes for the subtropical high maintaining at lower latitude. The analysis on the meridional circulation also proves above view.
THE AFFECTION OF SEA-SURFACE TEMPERATURE ANOMALY TO MEIYU ONSET DATEOF YANGTSE-HUAIHE RIVER VALLEY
Wang Zhongrui, Qian Yong fu
2005, 16(2): 193-204.
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Abstract:
By using the correlation analysis between the Meiyu onset date (MOD) of the Yangtze-Huaihe River valley and SST, and composite analysis of general circulation in years of anomalous SST, the affection of SST to MOD is studied. The results show that the SSTA of Pacific, Indian Ocean and Atlantic can affect the MOD. When the SST of warm pool of western Pacific is high (low) from last Nov. to Jan., the MOD is early (late). The MOD is late when the SST of middle Pacific is high from Feb. to May. From May to June, the SST near Mascarene high has good indication to MOD, that is early (late) when the SST is high (low). From Feb. to May, the SST near the warm pool of western Pacific has good indication to MOD. In June, the SST to the east of Taiwan and southern Atlantic has affection to MOD.
AN IMPROVED METHOD OF EXTENDED VELOCITY-AZIMUTH DISPLAY ANALYSIS TO ENHANCE ACCURACY OF HORIZONTAL DIVERGENCE
Tao Yue, Tang Dazhang, Xiao Wenan, Xia Wenmei
2005, 16(2): 205-212.
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Abstract:
?The method that have improvements to the previously reported EVAD technique to obtain horizontal divergence are discussed in detail. Sirmans' method of radar simulated precipitation signal is applicable to the nonlinear wind field including the three harmonic, and a Doppler velocity field is obtained that is approximated to the real velocity field. The improved EVAD method, Srivastava's and Matejke's EVAD methods are applicable to this simulated Doppler velocity field, and three methods are compared. Computing results indicate that the accuracy of horizontal divergence is obtained by the improved EVAD method is enhanced at not full azimuth wind field, at different v and SNR.
RADAR RAINFALL CALIBRATION BY USING THE KALMAN FILTER METHOD
Yin Zhonghai, Zhang Peiyuan
2005, 16(2): 213-219.
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Abstract:
The Kalman Filter calibration method was tested by "973" project (Research on the Formation Mechanism and Prediction Theory of Severe Synoptic Disasters in China) field data—a rainfall case on June 22, 2002. The analysis of parameters impacting on the result which the Kalman Filter calibration method figures out is done. The result shows that the Kalman Filter calibration method can improve the accuracy of radar rainfall measurement well. With the increase of observing times, the value which the Kalman Filter calibration method figures out is more accurate
PRELIMINARY RESEARCH ON THE CLIMATIC CHARACTERISTICS AND CHANGE OF FOG IN CHINA
Liu Xiaoning, Zhang Hong zheng, Li Qing xiang, Zhu Yanjun
2005, 16(2): 220-230.
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Abstract:
Based on the observational data of thick fog from 679 base stations of China in 50 years, the basic climatic characteristics of fog in our country in temporal and spatial distribution are analyzed. In general, the distribution of fog in our country presents the characteristics of more fog in the southeast part while less in the northwest part. The spatial difference between south and north, west and east as well as the obvious regional characteristics can be shown in the distribution of monthly day numbers with fog, monthly maximum day numbers with fog and the seasonal distribution of fog. The analysis indicates that in most areas of our country, the day numbers with fog have a decreasing trend, but the annual change of days with fogs is not obvious. The initial study on the change of days with fog has also been made in this paper.
A SIMULATION OF A HIGH IMPACT WEATHER EVENT
Jiang Jianying, Shi Li, Ni Yunqi
2005, 16(2): 231-237.
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Abstract:
Owing to a light snowfall on December 7, 2001, traffic jams and congestion were occurred in Beijing. A diagnostic study and numerical simulations using MM5 were conducted on this high impact weather. The result of diagnosis shows that the weak trough at 500 hPa which moving eastward slowly and the 850 hPa high which brought in suitable water vapor from the South China Sea and East China Sea resulted in the happening of the light snowfall in Beijing. The results of the simulations indicate that the case can be simulated successfully by the numerical model MM5. The successive development of the background filed, the trigger mechanism and the water source, as well as the snowfall in Beijing, were well reproduced. Based on the results of diagnosis and simulations, possible factors contributed to the traffic jams and congestion were also discussed. Thus study on city disaster meteorology, i. e. high impact weather and setting up a monitory and forecast system are inevitable, which can synthetically evaluate the impact of meteorology phenomena on city life in China.
DUST DETECTION USING THERMAL INFRARED CHANNEL
Yan Hao, Jiao Meiyan, Wang Jianlin, Zhou Yong
2005, 16(2): 238-242.
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Abstract:
The thermal infrared temperature difference ΔT(T11μm-T12μm) is investigated as a possible method for detecting dust outbreaks. Based on radiative properties of the winter dust aerosol defined by Almeida, this paper calculated the thermal infrared temperature difference ΔT(T11μm-T12μm) as a function of optic thickness of dust aerosol. The result of atmospheric radiation calculations indicates that the temperature difference △T over and surface will decline when optic thickness of dust aerosol increases. Similarly, atmospheric transmittance calculations of thermal infrared channel as a function of optic thickness of dust aerosol also indicate that 11μm atmospheric transmittance is bigger that 12μm atmospheric transmittance when optic thickness of dust aerosol increases. Sensitive test of △T (T11μm-T12μm) to surface temperature (ST) and water vapor (W) is also illustrated. It indicates that W remarkably affects △T. △T can be used to detect heavy dust when W is big; however, △T can be used to detect light dust when W is small. The sensitive test indicates that △T is not sensitive to the change of ST. Furthermore, the feasibility of dust detection using this technology is demonstrated by comparing satellite observations and surface observations of meteorological stations. The validation of three dust detection indicates that dust using remote sensing coincides with observed dust.
THE CLIMATIC CHANGE OF GLOBAL SOLAR RADIATION OVER THE YELLOW RIVER BASIN DURING 1960 —2000
Yang Xianmin, Zeng Yan, Qiu Xinfa, Jiang Aijun
2005, 16(2): 243-248.
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Abstract:
A series of global solar radiation models of different temporal and spatial scales were developed using the technique of data integration. The accuracy of different models was analyzed thoroughly. The empirical coefficients of monthly single station models, belonging to 35 solar observation stations distributed within and surround the Yellow River Basin, were extended spatially by Inverse Distance Weight Interpolation Method. By virtue of the spatial distribution of coefficients for global solar radiation simulation as well as the relative sunshine duration data observed from 164 convention meteorological stations, the global solar radiation of the Yellow River Basin from 1960 to 2000 were estimated and their climatic change tendency were analyzed in detail. The results show that the global solar radiation is significantly decreased, especially in the seasons of summer and winter.
T213L31 OPERATION SCHEME AND FORECAST EFFECT EVALUATION IN NATIONAL METEOROLOGICAL CENTER OF CHINA
Hu Jiangkai, Wang Yu, Wang Yi tao
2005, 16(2): 249-259.
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Abstract:
T213L31 is the new medium-range numerical weather forecast operational system in China. The operational suite of T213L31 was introduced. It elaborated the scheme that how to monitor the real time system. The operations analysis of T213L31 entire sequence and the introduction of functions, interruption events and related running information make readers have a more complete knowledge complete knowledge of T213L31 in operation in National Meteorological Center of China. The forecasting effect of T213L31 after comprehensive verifications during quasioperation and operation in NMC was evaluated. The result shows that forecasting effect of the T213L31 operational system has an obvious improvement that the original operational system T106L19 in NMC. The valid forecast day was prolonged about 1 day. But comparing with ECMWF forecast, there is still a certain gap, especially in the valid forecast day of medium-range weather forecast. It will be improved and developed further in the future.
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