Vol.24, NO.2, 2013

Display Method:
Causal Analysis of Consecutive Torrential Rains in Guangdong Province Before the Onset of South China Sea Monsoon
Wu Naigeng, Lin Liangxun, Zeng Qin, Wu Zhifang, Jin Ronghua, Deng Wenjian
2013, 24(2): 129-139.
Guangdong suffers from consecutive torrential rains before the onset of South China Sea Monsoon (SCSM) in May 2010, which is rarely seen in South China. Based on meteorological observations, regional automatic weather station data and NCEP data, the characteristics of the consecutive torrential rains are analyzed through a comparative analysis of consecutive torrentials and persistent rains. And the possible mechanism of the consecutive torrential rains are analyed with a complete (including dynamic and thermodynamic mechanisms) linear-diagnostic model for the local-meridional circulation.The results show that the blocking high plays an important role in both consectutive torrential rains and persistent rains. The consectcutive torrential rains are associated with the south-eastward propagation of short wave troughs and the blocking high located over Mount Ural, while the persistent torrential rains are associated with the northward movement of the SCSM and the blocking located over central of Asian continent. There are obvious differences among the weather patterns of the three consecutive torrential rains, although the large-scale background circulations are similar. "5.7" torrential rain occurs behind upper-level trough, lower-level shear line and cold front far from the rain belt, which is rarely observed in South China. "5.9" torrential rain is relatively typical since it occurs near the front and in the south of lower-level shear line, but upper-level short-wave trough is not clearly indentified. "5.14" torrential rain featured typical rainfall pattern in South China, heavy rainfall occurs in front of upper-level trough, in the south of low-level shear line and near the front.Numerical quantitative diagnosis shows that the contributors to the local meridional circulation associated with the consecutive torrential rains are mainly latent heating, horizontal temperature advection and westerly momentum transport. Latent heating is the major contributor and provides positive feedback to the torrential rain, while horizontal temperature advection and westerly momentum transport play an important role in triggering consecutive torrential rains (0—1.5 d prior to the torrential rains). The upper-level westly jet is in favor of the rising motion and upper-level divergence of Guangdong through the horizonal westerly momentum transport and vertical air mass adjustment. On the other side, the vertical westerly momentum transport and the upper-level trough provide favorable conditions for the southward moverment of cold air mass, which triggering stronger rising motion over Guangdong and more moisture convergence (latent heat release). Therefore, it is necessary to pay more attention to the evolution of mid-latitude synoptic circulation associated with westerly momentum and horizontal temperature advection in forecasting the consecutive torrential rains before the onset of SCSM.
Weather Impacts on Air Quality of the World Expo in Shanghai
Chen Min, Ma Leiming, Wei Haiping, Shi Hong, Ma Jinghui, Zhou Guangqiang, Gu Songqiang, Zhang Guolian
2013, 24(2): 140-150.
From the statistics of environmental observations, it shows that the air quality in Shanghai during the 2010 World Expo (1 May to 31 Oct) is the best for the same period since 2001. The number with good air quality days adds up to 181, accounting for 98.4% of the total 184 days. From the integrated data of the near-surface meteorological observation in Shanghai in recent 10 years, NCEP/NCAR reanalysis data from 1981, and the circulation indices of National Climate Center of CMA since 1951, the phenomenon is preliminary investigated, revealing the near-surface meteorological situation and the atmospheric circulation characteristics which affect the dispersion and deposition of air pollution during the 2010 World Expo and the same period in history. The detailed mechanisms for the impact of atmospheric condition on air quality are further investigated, and the major results are as follows.The greatly enhanced easterly winds, less calm wind days, significantly less near-surface temperature inversion and more precipitation favor the dispersion and deposition of air particles and the improvement of air quality in Shanghai during the 2010 World Expo.Subtropical high over the western Pacific during the 2010 World Expo is more intensive and extensive, and extending further west compared to that of recent years. As a result, the easterly airflow to the south of subtropical high is strengthened which leads to the prevailing easterly winds in Shanghai.During the 2010 World Expo in Shanghai under the same situation of various dominant wind, e.g., calm wind, NNE-SSE wind, or NNW-SSW wind, corresponding API indices are lower than the value of the same period in 2001—2009, which reflects the effect of pollution reduction due to "Joint Implementation of Air Quality Regulating and Controlling over the Yangtze River Delta Region during the World Expo" carried out by Jiangsu, Zhejiang and Shanghai.Although, with the joint action and its advantage, it is noticed that there are three heavy pollution episodes occurred in Shanghai during the World Expo due to the depressed weather conditions of transportation and dispersion. This result depicts that weather situation plays one of the major roles which decide the good air quality during the World Expo in Shanghai.
Characteristics of Atmospheric Pollutants at Dinghushan Station During the Asian Games in Guangzhou
Chen Lin, Wang Lili, Ji Dongsheng, Wang Shigong, Wang Yuesi
2013, 24(2): 151-161.
To understand the air quality status and influences of meteorological factors on concentrations of regional background pollutants in Southern China, online measurements of nitrogen oxide, sulfur dioxide, ozone, PM10 and PM2.5 observations are conducted in Mount Dinghu Background Monitoring Station in November of 2010. MICAPS data, NCEP FNL data and HYSPLIT model are used to deeply analyze the relationship between synoptic circulation, divergence and vorticity, meteorological factors, pollutant source regions and variation characteristics of pollutants in different periods. The results show that the average concentrations of NO2, SO2 and O3 in Mount Dinghu area are (7.2±3.1)×10-9, (8.5±3.8)×10-9 and (28.7±9.8)×10-9, respectively, during the Asian Games period.The aerosol pollution in this region is serious, with the monthly average concentration of PM10 for 113 μg·m-3 and PM2.5 for 81 μg·m-3, and the daily average concentration of PM2.5 exceeds the WHO IT.1 air quality standard for 13 days. The analyses on air pollutants during high-level pollution periods show that the average concentrations of NOx and O3 are 13.2×10-9 and 20.9×10-9, which decreases by 41.3% and 10.7% than those in 2009, but the average concentration of SO2 hardly changes in 2010 compared with that in 2009. All the results suggest that the air quality control measure is effective in some degree. However, the concentrations of PM10 and PM2.5 during the period of the Asian Games are higher than those during the same period in 2009, due to relatively stable meteorological conditions, fine weather and high temperature, while the continuous precipitations leads to the lower values of PM10 and PM2.5 during the same period in 2009. High temperature and humidity caused by uniform pressure and temperature fields of the generation of high pressure, continued convergence, weak rising mechanism, the weak surface wind at the surface layer and regional transport lead to the accumulation of primary air pollutants and fine particles. Backward trajectory simulation results show that the flows, originating from east, lead an obvious increase in primary air pollutants, fine particles and atmospheric oxidation in the areas of Mount Dinghu, which pass the industrial areas in Pearl River Delta. In summary, higher concentrations of PM2.5 in Pearl River Delta regional background area are attributed to adverse meteorological condition and pollutant transport.
The Application of the Local Analysis and Prediction System to GRAPES
Liu Chunwen, Lin Yonghui, Cao Yancha
2013, 24(2): 162-170.
The local analysis and prediction system (LAPS) is widely applied, providing fast comprehensive analysis products for forecasters and assimilating various observational information. GRAPES_Meso is a new generation of global/regional assimilation and prediction system, developed by Chinese Academy of Meteorological Sciences, and has been used in operation and research. However, LAPS itself does not provide any interface system with GRAPES_Meso.Based on the investigation of LAPS and GRAPES_Meso, the output data of LAPS are used as the initial condition of GRAPES_Meso model (GRAPES-LAPS), and compared with the original initial scheme of GRAPES_Meso model (GRAPES-3DVAR). Twenty-eight rainfall events in Southern China from 2008 to 2010 are simulated with the two initial schemes, which both assimilate data including 14 Doppler radar observations, 30 radiosonde observations and about 530 surface observations.The results show that the initial fields obtained by the GRAPES-LAPS scheme accurately represent the moisture fields and meso-scale environmental circulations. The simulated moisture and convergence at low level by the GRAPES-LAPS scheme are stronger than the results of the GRAPES-3DVAR scheme, and these initial fields are beneficial to improve the GRAPES_Meso model simulation. The mean square error (MSE) and threshold scores (TS) of two schemes of the twenty-eight rainfall events are equivalent, but ten rainstorm events are accurately simulated by using GRAPES-LAPS scheme and only five rainstorm events are accurately simulated by GRAPES-3DVAR scheme. The TS scores of moderate rain, heavy rain and rainstorm by the GRAPES-LAPS scheme are a little better than those of the GRAPES-3DVAR scheme, indicating that the GRAPES-LAPS scheme is more suitable to forecast strong rainfall events than the GRAPES-3DVAR scheme.
Comparison of Two Verification Methods for 6 h Precipitation Forecasts of Regional Models
Wang Yu, Gong Ying, Chen Fajing, Zhang Kun, Zhao Tianhao
2013, 24(2): 171-178.
6 h precipitation forecast for different lead times of operational models for North China Regional Center, South China Regional Center, East China Regional Center and Numerical Weather Prediction Center of CMA (NWPC) are verified and compared from May to September in 2011. The two methods which are used to average verification results for some period are discussed in detail.The verification results show the forecasting performance is different according to the observational time, the forecasting lead time and coverage area of models. Compared with NWPC GRAPES_Meso model in the same area, the performance for most lead times of operational models of three regional centers is better, particularly for over 24 h lead time forecast. Furthermore, verification score of East China Regional Center model is the best, TS of this model is higher than that of NWPC model except that 0.1 mm or more precipitation of 18 h forecast with 0600 UTC observation and 24 h forecast with 1200 UTC observation, and the bias is close to 1 for most verification grades. Moreover, TS of intense precipitation of three Regional Centers models is higher than that of NWPC model most of the time, but TS of North China regional center model is lower for 6 h and 18 h forecast with 0600 UTC observation and for 6 h forecast with 1800 UTC observation. On the other hand, the verification results derived from the different averaging approaches have few impacts on TS comparison results for regional model and NWPC model, but the TS value by new method is higher than that of the former method, except when the difference of TS between the two models is very small. For the new method, the model performs better for the large-scale rainfall process perhaps getting higher TS than the model that is only good at meso-scale rainfall. But the difference for heavy rain with little probability, especially for precipitation heavier than 13 mm is significant. If there is more false alarms for the forecast of greater grades small meso-scale precipitation, and there is some missing for the large scale rainfall, the differences between the two methods will be larger. Under this condition, the bias of the new method shows that forecast rainfall is less obviously comparing with observation, but that of the former method indicates more. Such situation usually occurs in North China. Because the two averaging approaches show distinct differences, more studies are needed so that users can understand the differences better and make a correct decision on how to use the forecasts of models properly.
An Experiment Study of All-sky Cloud Amount Observation Based on Infrared Real-time Threshold
Hu Shuzhen, Ma Shuqing, Tao Fa, Qiao Xiaoyan, Zhang Chunbo
2013, 24(2): 179-188.
The cloud typically covers about 50% of the earth surface, affecting the energy balance, water circulation of the earth, and influencing global climate. Cloud cover and cloud base height are the primary elements in the observation of clouds, wherein the cloud amount reflects the regional weather and climate characteristics. However, the operating artificial observation method for cloud amount in China lacks objectivity and costs too much workforce. Therefore, the research and development of an automatic measuring cloud device is extremely necessary.An infrared cloud detector based on the different characteristics of visible and infrared cloud images is developed in order to measure cloud amount. The infrared sensors regularly scan the whole sky under the control of the rotating platform, and stitching all-sky images of infrared brightness temperature. Based on the different characteristics of cloud images shown in infrared, different temperature at different elevation for the cloud point and non-cloud point is considered, combining with real-time infrared brightness temperature and ground environmental parameters. The temperature threshold functions are real-time determined from the zenith to the horizontal, the all-sky cloud distribution and cloud amount are derived using the method of segmentation. This method is effective in reducing the ground environmental parameters and the sunlight on the cloud images, and it can run properly throughout the day. The cloud measuring system can provide real-time analysis of the sky condition, cloud distribution and cloud amount. The system is fully automated and adaptable for all weather conditions, with high temporal resolution and accurate observation time, and it can show the cloud trajectory of the whole period and cloudiness trends.Measurements of cloud system has been performed experimental observation in the synthesize experiment base of Meteorological Observation Center of CMA since May 2011. Through the comparative data analysis with the results of artificial observations and the visible cloud images, this measurement of cloud systems are proved to be able to provide results with high accuracy.
Numerical Simulation of Effects of Building Tip on Atmospheric Electric Field Distortion
Guo Xiufeng, Tan Yongbo, Guo Fengxia, Shi Zheng, Wang Ningning
2013, 24(2): 189-196.
The effects of building tip on atmospheric electric field distortion are an important part of atmospheric electricity, especially in the research of corona layer above the inhomogeneous underlying surface, upward lightning leader and even upward lightning initiated from tall building, and also an influencing factor in lightning protection. For the account that the existing measurements are ineffectual in measuring the electric intensity above the tip, numerical simulation becomes very helpful.Assuming the building to be an ideal conductor and fully connected with earth and the potential is 0, which satisfies the Dirichlet boundary condition; three other air boundaries all satisfying Numann boundary condition and the electric potential gradient on these boundaries are constants. A two-dimensional finite difference method of calculation is used to obtain the potential distribution around the building and electric intensity near the tip in further. What's more, the two-dimensional finite difference equation is solved by successive over-relaxation method.The effects on the atmospheric electric field distortion by the height, width and location of building's tip are discussed, respectively. The result shows that λi (maximum distort coefficient of electric field) is linearly increasing with height and the slope of linear equation is decreasing with width. λi shows symmetrical increasing trend when the tip is located from the center to the each edge on the roof of a structure. It grows evidently with the increasing height of structure. Furthermore, λi is declined exponentially with the tip width, particularly when less than five meters, λi has a sensitive response to width, and the effect on λi by width is more obviously presented with the increasing height. Taking no account of the extinction effect of corona layer, electric field intensification shows much greater on the top when the structure is taller and thinner. In actual problems, the effects on electric field distortion mainly depend on the structure height when the top is flat. But when there is an obvious tip such as lightning conductor and so on, the height, width and location of tip should be taken into consideration.
Environment Characteristics and Causes of a Continuous Hail Fall Event Occurred Within the Cold Air Mass to the North of a Cold Front
Xu Aihua, Chen Yunhui, Chen Tao, Zhang Juanjuan
2013, 24(2): 197-206.
A continuous hail fall process occurred over Southern China during 24 February—5 March of 2009 is analyzed. This process happens under the background of typical continuous rain weather in spring over Southern China. During this period, a steady two-trough and one-ridge pattern maintains over the Euro-Asian, the stronger subtropical high is further north and west, the Indo-China Peninsula is occupied by a low trough, five short wave troughs move eastward from the Tibet Plateau, and 700 hPa warm-moist airflow is strong. The hail fall occurs within the cold air mass, 300—600 km north of the surface cold front. The vertical distribution of moisture presents dry over 500 hPa and wet (with the relative humidity more than 80%) under 500 hPa. The strong frontal zone in the middle and low levels exists between 25°—30°N of 850 hPa, with the temperature difference between south and north (frontal intensity) more than 14℃ per 5-latitude distances. There is a significant temperature inversion between 700—850 hPa. The 700 hPa southwest jet (≥20 m·s-1) area ranges more than 1000 km. The 700—850 hPa vertical wind shear is strong, with the vector difference reaching 16—20 m·s-1. Averagely, the temperature difference of 500—700 hPa exceeds 16℃, and the temperature lapse rate is about 0.74℃/100 m. The height of the 0℃ layer is very low (below 3 km). 500—700 hPa weak convective instability and symmetric instability may be the causes which result in the formation of this kind of hail. During the hail fall process, Δθse700-500 is 2—6℃ mostly. The minus baroclinic term of moist potential vorticity increases absolutely, which induces the southward expansion of the negative MVP value area. Meanwhile, MVP1, MVP2 and MVP present the variations that form or strengthen the latitudinal frontal zone. The hail fall happens on the south side of frontal zone, which is close to the negative MVP value area. The mechanism of this kind of hail formation is that the strong southwest airflow in middle troposphere lifts in the strong frontal zone, and induces the convective instability and symmetric instability. When trough passes over the strong frontal zone, the inclination of frontal surface becomes steep, the ascending motion strengthens, which form the typical elevated thunderstorm, and the ice embryo grows to hail in middle troposphere. This kind of trough often presents minus temperature variation or a preceding temperature trough. There is a melting layer in 700—850 hPa, and the thickness of upflow is small, therefore, the diameters of this kind of hail are less than 10 mm, few of them are 10—20 mm. The potential forecast index and criterion of this kind of hail falling area includes strong horizontal temperature frontal area, Δθse700-500 > 0℃ or T700-500≥16℃, axis of 700 hPa is more than 20 m·s-1 southwest airflow, area of strong 700-850 hPa vertical wind shear and 500 hPa shortwave trough.
Evolutions and Cloud-to-ground Lightning Features of Two Mesoscale Convective Thunder Storm Systems in Yunnan
Zhang Tengfei, Yin Liyun, Zhang Jie, Xie Yiran, Zhu Li
2013, 24(2): 207-218.
The circulation background of mesoscale convective thunderstorm system is diagnostically analyzed from 21 September to 23 September in 2010 by NCEP/NCAR data, and the evolutions and cloud-to-ground lightning activity features of two mesoscale convective thunderstorm systems are analyzed by synchronous stack of lightning detection system observations and FY-2E satellite images. Results show that the advantageous circulation background conditions of high energy, high humidity, and lifting dynamism are also supplied for the mesoscale convective thunderstorm systems by the weakened thermal depression. Mesoscale arc convective cloud belts appears first, on which partial convective cloud clusters gradually develop to mesoscale storm cloud clusters and then run into mesoscale convective storm complexes moving to the west along the same route, leading to strong thunderstorm weather and frequent CG lightning activities on the way.The negative cloud-to-ground (negative CG) lightning is predominant compared to the positive cloud-to-ground (positive CG) lightning during the whole lifetime of a thunder cloud cluster. But not only the storm cloud cluster contracture and the CG lightning activity feature change with time, but also positive CG and negative CG lightning frequency is well related to the cloud top temperature, which is related to the three-negative-polar structure of thunder cloud over the lower latitude plateau of China. When the cloud top temperature TBB descends and TBB isoline density increases, the thunder cloud cluster develops gradually, the low TBB center locates to its foreside, and the negative CG lightning frequency leaps. When the TBB descends to the minimum, the thunder cloud cluster develops to the maturation, negative CG lightning frequency gets to an apex, and positive CG lightning begin to take place. When the TBB ascends and TBB isoline density decreases, the thunder cloud cluster weakens gradually, the low TBB center closes up its center, the negative CG lightning frequency decreases rapidly, and positive CG lightning frequency increases to the apex gradually. In the meantime when TBB of a thunder cloud cluster is lower, convective development is stronger and CG lightning activity is more furious.The storm cloud cluster contracture and the CG lightning spatial distribution are asymmetric. In its foreside TBB is lower and the TBB isoline density and grads are bigger than those in its rearward. Negative CG lightning mainly cluster in its foreside with big TBB grads and within the low center where TBB is no higher than-56℃, while sparse positive CG lightning usually disperse within the low center when TBB is no higher than-56℃, namely taking place in the rearward of dense negative CG lightning. The activity of positive CG and negative CG lightning are negatively correlated. Positive CG lightning hardly takes place during the negative CG rapid incremental phase, it usually begins during the negative CG lightning mild phase, and it increases when negative CG lightning weaken. So negative CG lightning is the result of storm cloud cluster development and positive CG lightning is the result of storm cloud cluster developing to mature.
Characteristics and Conceptual Models of Convective Rainstorm Clouds in Henan Province
Su Aifang, Sun Jinglan, Gu Xiujie, Lü Xiaona, Chen Weimin
2013, 24(2): 219-229.
Study on severe weather's conceptual models is important for improving forecasting and early warning capabilities of severe weather. Using FY-2C/E and MODIS satellite data, A0 data, precipitation data of automatic weather stations and conventional observations, meso-scale convective systems criteria of convective rainstorm is revised, and their activity rhythm, as well as rainfall characteristics, are analyzed during convective rainstorm processes. In addition, convective rain storm conceptual models in Henan Province are studied based on analysis of cloud systems and synoptic situations. MCSs of convective rainstorm in Henan Province include newborn convective cloud clusters, MαCS, MβCS and banded MCSs. MCSs with different shape and scale have different characteristics of precipitation. Newborn convective clusters are easy to produce 20—29.9 mm·h-1 rain intensity. The probability of exceeding 30.0—49.9 mm·h-1 rain intensity brought by MβCS is obviously greater. The rain intensity exceeding 30.0 mm·h-1 is most likely caused by MαCS, but banded convective systems have higher probability of exceeding 50.0 mm·h-1 rain intensity than MαCS. However, each type of MCS can form strong intensity of rainfall over 80 mm·h-1 and the strongest intensity of rainfall is made by MβCS. The spatial and temporal variations and morphological characteristics of MCSs can give important information for forecasting thunder-rainstorm, and thunder-rainstorm is easy to occur during the formation and development of MCSs, and in the regions with big gradient of TBB in the back and the center of MCSs. Regions with high cloud optical thickness are potential areas of thunder-rainstorm. Dry and cold air masses in the processes of trough (vortex)-shear and trough's style play an important triggering role of MCSs. In the processes of high pressure's rear, MCSs are closely related to increasing temperature by radiation in boundary layer. Furthermore, energy front and convergence lines in boundary are the trigging systems. Dry lines in the shear line's processes are very important. Formation and development information of MCSs may be dependent on optical thickness. What's more, in the processes of high pressure's rear, the north of dark area on vapor images is easy to bring about MCSs. There are five potential regions of convective rainstorm in Henan Province, and four regions of them are near mountains. The routes of MCSs include eastward, northeastward and southeastward paths. Cloud track wind on high level can provide forecasting information of MCSs.
Characteristics of GPS Vapor in a Persistent Heavy Rainfall Related to Southwest Vortex
Hao Liping, Deng Jia, Li Guoping, Yang Jinqing
2013, 24(2): 230-239.
Using GPS Precipitable Water Vapor (GPS-PWV) observations from the ground-based GPS network in Chengdu Plain, NCEP reanalysis data, observed precipitation from automatic weather stations (AWS) and the specific humidity of single radiosonde station, the variations of water vapor in a persistent heavy rainfall process over the northeastern Sichuan Basin from 15 July to 18 July in 2010 is analyzed, focusing on the changes of GPS-PWV under the influencing system (southwest vortex) and its relationship with precipitation. Usually, there is a sharp rise of GPS-PWV when the precipitation occurs, and the altitude or terrain of each GPS station has an obvious impact on the value of GPS-PWV, precipitation and its peak. The GPS-PWV is not simple proportional related with the actual rainfall, the occurrence time and value of the precipitation have a certain relationship with the observatory sites and the movement of the southwest vortex. When the vortex circulation begins to develop, the instability of water vapor transport makes the GPS-PWV fluctuant increases. A large surge of GPS-PWV increase can be observed 13—17 h before the formation of the southwest vortex, reaching the maximum about 0—4 h before the vortex formation. The increase ends when it is fully formed, and the GPS-PWV gradually drops to the original level or even lower with the eastward shift of the southwest vortex. The positive area of the vertical flux of moisture divergence is well correspond with the area of precipitation, and it can better describe the strong rise, the movement of the convergence and divergence and water vapor transport than moisture flux divergence in the process, and the change of GPS-PWV is consistent with the vertical flux of moisture divergence. In addition, the trend of the water transport and convergence in the development process of the vortex circulation is consistent with the change of GPS-PWV, the surge and drop of GPS-PWV have some indicating significance in the formation or weakening of heavy rainfall. Compared with the radiosonde stations, AWS can well reflect the changes of water vapor near the ground, and radiosonde stations can provide the vertical distribution of the specific humidity. The regional ground-based GPS station network may capture the overall changes of the whole layer of atmospheric water vapor with the high time resolution. Therefore, more attention should be paid to the comprehensive application of water vapor information that obtained by these different observations means. Also, the southwest vortex as one of the major systems that induce the rainstorm process of the Sichuan Basin and the Yangtze Valley, adding to the important significance of GPS-PWV to discuss the variation of water vapor field before and after the generation of the southwest vortex.
Rice Growth Model Based on Energy Model
Liu Chun, Zhang Chunhui, Guo Sasa
2013, 24(2): 240-247.
The one-dimensional energy model is introduced from thermodynamics, considering relationship among the life activity, the mass exchange and energy flow. On the basis of the one-dimension energy model, rice growth model with temperature change is built, linking intake capacity of rice on the outside and temperature variation in growing season. Combined with temperature increasing rate, the optimal temperature and the biomass in different stages, and the optimal fitting of parameters is obtained, which is about natural growth rate of rice, temperature amplitude and initial values, with Xu Shiliang simplex optimization algorithm and two-dimensional equation parameter fitting of Forcal. The growth curve and trend along with the temperature change are obtained, through the optimal fitting data into the rice growth model. And rice critical temperature and occurrence time of maximum growth rate are analyzed. It's found that the critical temperature is unconcerned with the temperature of rice growth rate, illustrating the critical temperature of rice is the natural disposition. The occurrence time of maximum growth rate is found to be the heading stage of rice. To investigate the abnormal temperature effects on the growth of rice, rice growth is simulated with lower temperature in tiller stage and higher temperature in the reproductive growth stage, and the rice growth trend is achieved under the two abnormal temperature conditions, taken Matlab as the numerical analysis tool. Through numerical comparison, the following conclusion is drawn: The impact of high temperature on rice in the later stage is more severe than the impact of low temperature on rice in the earlier stage. The result shows that meteorological disasters in the later stage of rice growth has a direct impact on the yield, while the impact of disaster in the earlier stage can be made up later. By means of numerical analysis and qualitative analysis methods, the growth of rice is analyzed in detail. And some scientific basis is provided for rice yield prediction and impact assessment of temperature on rice biomass. This energy model is superior to some traditional pure mathematics model without biological meaning, and it also can be used to analyze agricultural ecological chain effect mechanism. At the same time, the consideration of combining mathematical biology and climate condition provides reference for future ecological meteorology research.
The Multiple-meteorological-factor Indexes for Orange Frozen Injury in Jiangxi Province
Yang Aiping, Du Xiaoling, Wang Baosheng, Guo Ruige, Liu Wenying
2013, 24(2): 248-256.
A persistent period of low temperature weather is the main cause to the frozen injury of orange during the winter, which is usually accompanied by the sleet and frost weather process (or drought). And the sleet and frost weather process (or drought) may aggravate the injury to the orange. The single-meteorological-factor index of the orange frozen injury is well known and commonly used to analyze the degree of the disaster, which only refers to the low temperature factor while neglects other ones. Considering the climate characteristics which may bring about the frozen injury, a series of frozen injury indexes for orange, including the single-station index and the regional index, are designed by employing multiple meteorological factors, such as temperature, rainfall amount and persistent days of rain. Tallied with the freezing disasters happened in Jiangxi Province from 1959 to 2009 and compared with the single-meteorological-factor index, the surveying effects of the multiple-meteorological-factor indexes are assessed. The calculation results of the single-station index for the typical years, such as 1992 or 2000, compared with the single-meteorological-factor index, are more in line with the freezing disaster happened in Jiangxi Province. Both the reflection on the damage degree and the characteristic of spatial distribution of the single-station grade of the multiple-meteorological-factor indexes are consistent with the actual situation. Taken the typical counties Nanfeng and Xinfeng as example, compared with the single-meteorological-factor index, the calculation result of the frequency for each single-station grade of the multiple-meteorological-factor indexes is more accordant with the cultivation habit and the disaster experience. And the calculation result of single-station grade is much more in line with the actual orange frozen disaster in Nanfeng from 1957 to 2000. The accuracy of the regional index from 1959 to 2009 is about 90%. Meanwhile, the freezing years, in which the calculation grade of regional multiple-meteorological-factor index is extreme-serious, are completely accordant with the actual situation. According to the record from the Department of Agriculture of Jiangxi Province, 80% of the calculation result of the regional grade for each districts in the typical year (for example, in 1992) is in accordance with the actual orange frozen disaster.Results indicate that the single-station multiple-meteorological-factor index for orange can reflect the damage degree and the characteristic of the spatial distribution better than the single-meteorological-factor index. In addition, the analyzing results suggest that the regional multiple-meteorological-factor index is able to assess the regional degree of frozen injury, which can be used to analyze the climate suitability of orange.