Zhang Jijia's main contribution

Zhang Jijia first studied the long-term evolution of atmospheric circulation in the northern hemisphere since 189 1 and the relationship between China evolution and precipitation anomaly, which opened up the research field of long-term climate prediction and short-term climate vibration in China. For the first time, he systematically studied the objective division of natural weather seasons and the objective classification of average circulation of natural weather seasons in Asian natural areas by using modern mathematical statistics methods, and on this basis, he put forward an objective method of long-term weather forecast. The Basis of Medium and Long-term Weather Forecast compiled by him fills the gap in this field in China.

The Contemporary Meteorological Cause in China edited by him systematically reflects the achievements and experiences of meteorological cause in China. He presided over and organized long-term forecast research, medium-term numerical forecast project construction, short-term forecast research of local disastrous weather, Antarctic meteorological investigation and the compilation of the book National Climate Lampi, which made great contributions to promoting the development of meteorological science and meteorological modernization.

He has been engaged in atmospheric circulation and long-term weather forecasting business, teaching and scientific research for a long time, and is an academic leader in this field in China. In China, it is the first to introduce the positive function method into the study of atmospheric circulation and long-term weather forecast, objectively divide the natural weather seasons, and put forward an objective forecast scheme of weather anomalies. In the study of long-term weather process, the influence of various physical factors on the movement and intensity change of ultra-long waves is revealed qualitatively, which deepens the understanding of the basic laws of ultra-long wave activities and has a unique view on the physical causes of seasonal change of circulation in the northern hemisphere. In the study of the thermal and dynamic effects of the Qinghai-Tibet Plateau, the picture of the interconnection of large-scale phenomena is given for the first time. The book "Fundamentals of Medium and Long-term Weather Forecast" fills the gap in domestic monographs in this field.

1. Theoretical study on atmospheric low-frequency oscillation and teleconnection.

After band-pass filtering and spectral analysis, Zhang Jijia and his colleagues found that the oscillation over the Qinghai-Tibet Plateau and its adjacent areas for 30-60 days in summer has the most important spectral peak, and its mean square deviation accounts for more than 40% of the mean square deviation of unfiltered daily variation and more than 60% of the mean square deviation of atmospheric low-frequency variation. The high center of mean square deviation is located in the middle and east of the plateau, with baroclinic structure in the south of the upper troposphere plateau and quite barotropic structure in the north of the plateau. In the lower troposphere, the situation is just the opposite.

The anomaly of marine thermal conditions is an important forcing factor for long-term weather anomalies. Therefore, they used the principal oscillation (POP) analysis method in modern statistics to study the evolution law of the monthly anomaly time series of SST in the tropical Pacific Ocean for 40 years, and found that the conjugate pair of principal oscillation can well describe the oscillation process of El Ni? o and anti-El Ni? o events, with an average period of 39.3 months, which is consistent with the actual situation. In addition, the adjoint correlation patterns (ACP) of low latitude circulation (Walker circulation and Hadley circulation) and summer weather (temperature and precipitation) in East Asia are obtained, and the air-sea interaction images with clear physical meaning are given, which deepens the understanding of the relationship between El Ni? o events and weather anomalies in China.

In view of the importance of the global ocean thermal state to the long-term weather process, they further calculated and analyzed the teleconnection spatial distribution pattern and time-lag correlation matrix of the monthly average sea surface temperature in 87 sea areas and the monthly average diabatic heat flow and temperature field in 576 grids in the northern hemisphere by using the global sea surface temperature data provided by COADS. According to the spatio-temporal teleconnection of air-sea system, the prediction model of diabatic heat flux and temperature is established, and the prediction experiments of related and independent data are carried out. The results show that the prediction model is feasible as the basis of long-term prediction for about 6 months.

2. Abnormal atmospheric circulation and long-term drought, flood and low temperature

Research on forecasting method

The drought and flood in summer in China mainly depend on three circulation systems: East Asia blocking in the north, Western Pacific subtropical high in the east and South Asia high in the west and their mutual configuration. On this basis, considering the external factors such as El Nino event and sunspot activity in the Pacific Ocean, and based on many years' practical experience, the conceptual model and method of summer drought and flood trend forecast in China were established, which were used in the Central Meteorological Observatory from 65438 to 0990 and achieved good results. The linear and nonlinear monthly and seasonal temperature grade forecasting equations are established and put into use in the long-term weather forecasting operation of 1988 Central Meteorological Observatory, and the forecasting accuracy obviously exceeds that of climate forecasting and continuous forecasting.

On the basis of the above-mentioned routine research, they have also successfully developed five kinds of long-term forecasting microcomputer business systems suitable for joint use by central, provincial and regional meteorological stations. Because of its reasonable structure, complete functions, high degree of automation and easy expansion and transplantation, the system has been popularized and used in more than 40 units in meteorological, hydrological and military departments all over the country, and has played a very good role.

Third, study the non-atmospheric factors that affect the long-term weather process

ENSO (abbreviated as ENSO and Southern Oscillation) is the strongest signal of interannual variation in the air-sea coupling system of tropical Pacific Ocean, and its variation period is 2-7 years, with an average of 3.5 years, which has obvious influence on global atmospheric circulation and short-term climate change. The research group carried out the analysis and research on the ENSO event in June 1986, and established the ENSO monitoring, diagnosis and analysis system for the first time in China, which is a short-term climate monitoring operational system in China. In the past five years, * * * has issued 33 issues of ENSO Monitoring Bulletin, which basically correctly diagnosed the occurrence, development and decline of El Ni? o events in the late 1980s.

They also found that there is a lag correlation between polar ice and subtropical high for about half a year, and there is a negative correlation between polar ice in winter and East Asian summer monsoon. In summer, Arctic sea ice can excite a two-dimensional Rossby wave train of 500 hPa.

4. Study on Long-term Numerical Weather Forecast

The so-called long-term numerical weather forecast refers to the circulation and weather forecast made by numerical integration of the fluid thermodynamic-dynamic equation (weather equation) of 1 month or longer under certain boundary conditions and actual initial conditions.

Many research achievements of Zhang Jijia have been popularized and applied in business practice, which has played an important role in improving the theoretical basis and business level of China's long-term weather forecast, and is not inferior to a few advanced countries. However, due to the complexity of the long-term weather forecast problem, there is still a considerable gap between these achievements and the satisfactory solution of the problem. Mr Zhang Jijia, who is famous for his diligence, hard work and talent, is working hard. He and his colleagues will continue to explore and strive for greater new achievements.