Diagnosis Analysis Of An Extreme High-Temperature Weather Event In North China On 15 July 2002

Extreme high-temperature weather is no: only harmful to human' s health, but also produces significant influence on industrial and agricultural activities, such as traffic, travel, urban water and power supplies, commerce and so on. A typical extreme high-temperature event warmer than 40 was observed in large area of north China at 06 UTC 15 July 2002. In many regions, the local air temperature exceeded to the maximum temperature record of history. This extreme high-temperature weather event significantly influenced the people's normal life, and attracted the newj -media' s concern. Thus, it is of great importance to study this extreme high-'.emperature weather event from the point of view to improve the ability of predicting this type of weather event in order for people to take various measures to reduce the extreme high-temperature weather impact on people's lormal life, and to offer positive help for social life and economic development.In this paper, various kinds of observational data such as satellite pictures, surface observations, soundings anc solar radiation data at Jinan were employed. Synoptic situations from lower-level to upper-level prior to and during the high-temperature were analyzed. Also, the spatial-temporal distributions of various variables were introduced. It is shown that the extreme high-temperature weather system is behind the surface low-pressure and in front of the high - pressure area. When the air-temperature was high, the sky was sunny, and the relative humidity and pressure of air dropped to their minimum values. The upper-level situation appeared as that high in the west and low in the east, and the northwest currents was dominated. T.'iere was cold air activity in the upper stream of the extreme high-temperature weather area. In the middle and lower-levels, the relative humidity of air was small. There were warm regions lasting relatively long time in the lower-level. The position of surface extreme high-temperature weather area coupled well with the lower-level warm area. Besides, there was a stable energy area abDve the extreme high-temperature weather area. By means of temperature vertical lapse rate and dry adiabaticequation, the calculated ground high temperatire is close to the observational data. Through thermodynamics equation, it :.s indicated that this extreme high-temperature weather is mainly caused by tie joint effects of the advection of potential temperature, the vertical transportation of potential temperature and the non- adiabatic factor.