应用气象学报

THE IMPACT OF CLOUD PARAMETERS ON THE SIMULATED ERRORS IN RTTOV5

Ma Gang, Fang Zongyi, Zhang Fengying

2001, 12(4): 385-392.

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Abstract:
TOVS/ATOVS data from meteorologic satellite can provide the vertical distribution of temperature and humidity in the atmosphere. In order to use these data in NWP models directly, then to make the initial field of NWP model more accurate and improve forecast finally, a fast transmittance model (RT model) is required in a multi-dimensional data variational assimilation system. There will be big errors while simulating HIRS data by an RT model, because HIRS data in TOVS/ATOVS can not get the information of the vertical distribution of temperature and humidity below the clouds. Before assimilating TOVS/ATOVS data into NWP model, it is a necessary task to analyze the impact of the cloud parameters (the top of cloud and cloud fraction are included mainly) on simulated errors using RTTOV5, based on the actuality of operational TOVS data every day (about 70% observation points are partly cloudy).The temperature and humidity profiles from operational TOVS data, as well as some others data necessary to run RTTOV5, are used to compute the brightness temperature with respect to HIRS channels in NOAA14. Then the impact of the cloud fraction and the top of cloud on simulated errors in models are estimated. Finally an adjoint model and a Jacobine model of RTTOV5 are used to analyze the sensitivity of the simulated errors of RTTOV5 to initial cloud parameters (the cloud fraction and the pressure of of cloud top).

IMPACT STUDY OF ATTITUDE AND PITCH MISALIGNMENT PARAMETERS ON FY-2 IMAGE NAVIGATION WITH SIMULATION METHOD

Lu Feng, Xu Jianmin, Zhang Qishong

2001, 12(4): 393-399.

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Abstract:
Impact of attitude and pitch misalignment parameters on FY-2 image navigation is studied with simulation method. The simulation result indicates that the parameters affect navigation result orderly; inappropriate parameter assignment will not only result in image displacement but also cause image distortion; different parameters affect image navigation in different ways. Parameters simulated also result in a series of typical images, that is very useful in image navigation error diagnosis. Based on this and other simulation studies, an image navigation model is established, and the automatic operation of image navigation for FY-2 meteorological satellite is realized with high accuracy.

ENRICHMENT CHARACTERRISTICS AND ORIGIN OF ATMOSPHERIC AEROSOL ELEMENTS AT MT. WALIGUAN

Wen Yupu, Xu Xiaobin, Tang Jie, Zhao Yucheng, Zhang Xiaochun

2001, 12(4): 400-408.

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Abstract:

Samples of atmospheric aerosol were collected at Mt. Waliguan (CGAWBO/GAW). The filter samples were analyzed by NAA (neutron activation analysis), PIXE (proton induced x-ray emission). The concentrations of 42 trace elements combined with the measurements of black carbon were determined. Based on the statistical analysis of element concentrations, enrichment factors and the principal factor analysis, combined with the corresponding back trajectory, the elemental compositions and the sources of aerosol over Waliguan are discussed. The results indicate that the natural sources identified as major contributors to the aerosol over Mt. Waliguan are the soil and crust. The factor analysis shows that the contributing rate of these sources accounts for approximately 70% or more of the aerosol. However, anthropogenic origins, such as coal burning, automobile and industrial emissions form a certain proportion of aerosol. The measurement results of the black carbon at Waliguan indicate that there exist influences from human activities. It is estimated that the pollutants mainly come from the more developed areas in the Qinghai Province and the Hexi Corridor. Both local influences, such as the elements of soil in the adjoining area, and long-range transport of aerosols can affect, in varying degrees, the composition of the background aerosol over Mt Waliguan.

NUMERICAL SIMULATION OF CH₄ EMISSION FROM RICE PADDY FIELDS DURING RECENT 50 YEARS

Liu Jiandong, Zhou Xiuji, Wang Jianlin, Yu Qiang

2001, 12(4): 409-418.

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Abstract:
Based on the DNDC model of American, a numerical model for simulating CH₄ emission from rice paddy fields is established. Validation of the model with the observed data shows that the mean relative error is about 15%. The simulation analysis results show that the CH₄ emission is interrelated well with average temperature during rice growth periods. Analysis of CH₄ emission and meteorological factors by using power spectrum indicates that the change of CH₄ emissions has 4-5 year cycles, which is the same as that of temperature. Simple statistical models are given based on the results of the numerical model, which can be applied conveniently to estimate and monitor CH₄ emissions in the rice paddy fields.

DIAGNOSES OF THE MESOSCALE HEAT AND MOISTURE BUDGETS DURING THE "98.7" EXTRAORDINARY HEAVY RAINFALL

Feng Wuhu, Cheng Linsheng

2001, 12(4): 419-432.

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Abstract:
During the period of 20-23 July 1998 ("98.7"), an extraordinary heavy rainfall event occurred in the eastern and southwest parts of Hubei Province, which was in close relationship with the low vortex with shear line on 700 hPa as well as with the successively generated and intensively developing MαCS and MβCS along the shear line. The numerical simulation for this event is conducted successfully using nonhydrostatic version MM5 (V2.12). The mesoscale heat and moisture budgets are diag nosed using the output data of MM5. The finding sare as follows: strong apparent heat sources Q₁ and apparent moisture sink Q₂ would appear while the strong convection occurs with heavy rainfall; Q₁ and Q₂ are basically correspondent with the regions of heavy rains; Q₁ increases with height while the maximum heating level is located at 486.1 hPa (σ=0.54); the deep and thick heating layer in the middle troposphere is the main thermody namic mechanism for the both cumulus convective activities and the successive generation and development of severe rainstorms; the relatively cool layer in the upper troposphere provides a favorable thermody namic condition for intensive cumulus convection over the heavy rain areas; the condensation latent heating of cumulus convection in the lower and middle troposphere is not only heating the middle troposphere atmosphere, but also heating the upper environment atmosphere through transporting heat upward; the double-peak structure of Q₂ at the early stage of heavy rainfall is relevant to the drying associated with convective condensation of both stratocumulus at the lower levels and cumulus at the middle levels; the peak value of Q₂ in the middle level is basically corresponding with that of Q₁; the deep and thick drying layer is consistent with the deep and thick condensation-heating layer of Q₁. The diagnostic results show that it is reasonable to diagnose Q₁ and Q₂ using successfully stimulated output data with high resolution. The reliable physical proof for improving heating and moisturizing profiles in the cumulus convective parameterization can be obtained through diagnosing Q₁ and Q₂ of the rainstorm event.

SEVREE LOCAL STORMS INITIATED BY THE SEA BREEZE FRONT IN THE PEARL RIVER DELTA DURING THE LATE SPRING AND SUMMER

Liu Yunce, Zhuang Xudong, Li Xianzhou

2001, 12(4): 433-441.

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Abstract:
By using data of auto-observing weather station observations, weather radar echoes, satellite images, surface observations and wind profiles, eight severe weather events which were initiated by sea breeze fronts in the Pearl River Delta, Guangdong Province during the first half of July 1998 are investigated and a severe local storm event in 3 July 1998 is completely and systematically analyzed. A pattern and some activity characteristics of such severe local storms are inducted.

METEOROLOGICAL AND HYDROLOGICAL CHARACTERISTICS OF SEVERE FLOODING IN CHINA DURING THE SUMMER OF 1998

Zhang Shunli, Tao Shiyan, Zhang Qingyun, Zhang Xiaoling

2001, 12(4): 442-457.

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Abstract:
An extremely great flood occurred over the Yangtze River, Nenjiang-Song huajiang regions, and Pearl River during the summer of 1998, its meteorological and hydrological characteristics and causes are presented. Pearl River, Yangtze River, Nenjiang-Songhuajiang basins had successive heavy rains in the second half of June. Yangtze River valley experienced the second period of the Meiyu in the last ten-day period of July. Heavy rainfalls centered in Zhalantun were observed over Nenjiang-Songhuajiang regions in first half of August. Frequent heavy rainfalls brought about the rapidly rising water level in most part along the middle reaches of Yangtze, Nenjiang, and Pearl River, and led to the greatest floods in the recent 100 years. The southward shifted subtropical high over the West Pacific was responsible for the second period of Meiyu. The right mixture of subtropical high, monsoon swell from South China Sea, cold air mass coming from mid-high latitudes, and MCSs from the Tibetan Plateau contributed to successive heavy rains over the Yangtze River valley.

THE VARIATION OF SURFACE HEAT FLUX OVER TIBET PLATEAU AND ITS INFLUENCES ON THE EAST ASIA CIRCULATION IN EARLY SUMMER

Dong Min, Zhu Wenmei, Xu Xiangde

2001, 12(4): 458-468.

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Abstract:
Using the NCEP reanalysis data, the climatology of the surface heat flux over Tibetan Plateau and its relation with the East Asia Circulation in early summer are studied. It is found that: the surface heat flux over Tibet shows strong annual cycle; both the latent heat flux over Tibet enhances the upward vertical motion in the middle troposphere over Tibetan area; the heat flux over the Tibetan Plateau enhances the High system over Tibetan area and its adjacent regions. It also enhances the westerly jet stream in the north side of the Plateau. The abnormal surface heat over Tibet will speed up the seasonal transition process in the East Asia from winter to summer. The surface heat condition over Tibetan Plateau in the preceding seasons has some significant linkage with the succeeding height and zonal wind fields in early summer. These relations can be used as predictors for the circulation anomalies in early summer of East Asia

STUDY ON ASSESSMENT OF CLIMATE RISK FOR SEED-BREEDING BASE AREA OF BILINEAR HYBRID RICE

Yin Jianmin, Wei Li, Wang Huaiqing

2001, 12(4): 469-477.

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Abstract:
The climate risk for seed-breeding of bilinear hybrid rice is defined on the basis of Jiangxi geographical data on the scale of 1:250000, climate data in 40 years of 84 observatory stations and analysis of the relationship between climate factors and height above sea level, using spatial analyzing method of GIS. The climate risk for seed breeding of bilinear hybrid rice is assessed and the best region and season for seed-breeding is sought. It is important to agricultural production. Analyzing results were proved by the production practice.

CHARACTERISTICS OF ATMOSPHERIC CIRCULATION DURING SUMMER DROUGHTS/FLOODS OVER BEIJING AREA AND THEIR RELATION WITH THE EARLIER STAGE SST OVER THE NORTH PACIFIC

Wu Zhenghua, Li Qingchun, Lu Chen

2001, 12(4): 478-487.

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Abstract:
Using the monthly re-analyzed NOAA/NCAR grid point data of 1979 to 1995, the monthly SST data over the Pacific and summer equivalent torrential rain day data of the Beijing area, a composite analysis of the mean atmospheric circulation during droughts and floods and the correlation analysis between summer mean atmospheric circulation and earlier Pacific SST are carried out. There exist obvious discrepancies in the mean atmospheric circulation during summer droughts and floods over the Beijing area. Both the departure field of the mean atmospheric circulation in summer in flood years and the correlation field between the summer mean atmospheric circulation in East Asia and the number of summer equivalent torrential rain days in the Beijing area possess the main characteristics of the mean circulation pattern for the torrential rain process in North China. The correlation between SST of the Warm Pool and the number of summer equivalent torrential rain days in the Beijing area passed the significance test. The earlier SSTA of the warm pool is a strong signal for the summer droughts/floods over the Beijing area.

WIND-FIELD RETRIEVAL THROUGH SINGLE DOPPLER WEATHER RADAR AND ITS APPLICATION TO NWP

Ma Qingyun, Li Zechun, Tao Shiwei

2001, 12(4): 488-493.

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Abstract:
The local VAD method is used for the wind retrieval from radical wind measured by Doppler radar (data from CAMS, at 12:00UTC, 5 July 1998) into horizontal wind and an experiment is made on the impact of horizontal wind on numerical weather prediction assimilation system for the heavy rain occurred from afternoon to night of 5 July 1998 in the Beijing area.The result shows that the retrieved wind is primarily consistent with the weather process and it can be used in the analysis and prediction of mesoscale systems with smaller temporal and spatial scales.

DIAGNOSTIC ANALYSIS OF HIGH TEMPERATURE DISTRIBUTION IN SHANGHAI

Ding Jincai, Ye Qixin, Ding Changgen

2001, 12(4): 494-500.

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Abstract:
Based on the intensive observation data of temperature in July and August of 1997 to 1998, by means of the EOF technique, the high temperature distribution in Shanghai is analyzed. The result indicates that the high temperature distribution in Shanghai can be composed of the climatic and the first characteristic fields. The variance contribution of the first characTeristic filed is over 90% of the total variance. The results indicate that the mean distribution of the high temperature field in Shanghai is depended on the topography and urban heat island effect of Shanghai and is a relatively stable interannual variable. The coefficient of the first characTeristic filed is a day-to-day variable with high correlation with wind direction. The equation of the first characteristic filed coefficient is formulated based on the data from two weather stations and whereafter the method for determining the high temperature distribution in Shanghai is developed. The trial calculation of 13 high temperature days in 1999 and 2000 is satisfactory.

ACCURACY EVALUATION OF SHORT-CLIMATIC FORECAST ON TROPICAL CYCLONE FREQUENCY

Lei Xiaotu

2001, 12(4): 501-506.

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Abstract:
The tropical cyclone frequency (TCF) is actually a certain integer, but these exists uncertainty in the subjective and objective short-climatic forecasts, so the contiguous degree must be evaluated. In order to evaluate the accuracy of short-climatic forecasting on TCF, fistly three parameters, determine index (d), absolute error (E) and skill score (S), are defined comparatively with climatic probability forecast (CPF) which was regard as naught forecast. Then, the accuracy was evaluated of subjective forecast from 1988 to 1997. The results indicate: d, E and S of typhoon season are 0.3, 1.7 and 0.06; d, E and S of July are 0.9, 0.8 and 0.06; d、E and S of August are 0.7, 0.75 and 0.13; d, E and S of September are 0.65, 0.9 and 0.01, respectively.

THE POSSIBLE IMPACTS OF METEOROLOGICAL CONDITIONS ON CONTENT OF MIDDLE AND TRACE ELEMENTS FOR WINTER WHEAT

Gao Suhua, Guo Jianping, Wang Lianmin, Wang Lizhi

2001, 12(4): 507-512.

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Abstract:
Through experiment, the impacts of meteorological conditions on the contents of middle elements (Mg, Ca, S) and trace elements (Zn, Fe) for wheat leaves, stalks and grains, and yield are studied. The results show that the high CO₂ concentration and water stress are favorable to the accumulation of the 5 elements. High CO₂ concentration accompanying with high temperature will shorten the growth period and decrease the number of grains. Synthesizing the positive effect of middle and trace elements and the negative effect of yield, the amount of wheat supply will run short if the same trace elements as in normal meteorological condition are required.

Vol.12, NO.4, 2001